@article {KNZ002044, title = {Fire history as a key determinant of grassland soil CO2 flux}, journal = {Plant and Soil}, volume = {460}, year = {2021}, pages = {579{\textendash}592}, keywords = {LTER-KNZ, aboveground net primary production, carbon cycling, ecosystem, fire, grassland, soil CO2 flux, soil respiration}, doi = {10.1007/s11104-020-04781-0}, url = {http://link.springer.com/10.1007/s11104-020-04781-0}, author = {Slette, Ingrid J. and Liebert, Alannah and Alan K. Knapp} } @article {KNZ001937, title = {Effects of patch-burn grazing on breeding density and territory size of Dickcissels}, journal = {Avian Conservation and Ecology}, volume = {14}, year = {2019}, month = {Jan-01-2019}, pages = {7}, abstract = {

Ongoing habitat loss and intensification of management of remaining grasslands have led to large population declines of grassland songbirds in North America. As an alternative to intensive and homogeneous use of rangelands, patch-burn grazing creates heterogeneity in vegetative structure across the landscape by restoring the historical interaction of fire and grazing by large ungulates. Patch-burn grazing can increase diversity and abundance of grassland songbirds, but effects on local breeding density and territory size remain unknown, despite both being important in regulating population dynamics of species. Understanding patterns of density and territory size across the landscape is especially important for species experiencing steep declines in breeding habitat, such as grassland songbirds. During a two-year field study, we tested how densities and territory sizes of Dickcissels (Spiza americana), a common grassland songbird, varied among treatment units that were managed with patch-burn grazing or annual burning with or without grazing at a tallgrass prairie site in northeastern Kansas. We found that local densities of male Dickcissels did not differ among management regimes. However, within the patch-burn grazing treatment, densities were highest in the patch that was burned the previous year and lowest in the most recently burned patch. Furthermore, densities of male Dickcissels were lower in 2013 than in 2014, especially in burned and grazed units that had little vegetative structure and nest cover after the drought conditions of the previous two years. Territory size was not affected by rangeland management, while local densities of Dickcissels only explained ~10\% of the variation in territory size. Our results show that patch-burn grazing does not negatively impact densities of breeding Dickcissels compared to annual burning and grazing. Moreover, Dickcissel populations might benefit from patch-burn grazing if males preferentially settle in unburned patches with high forb cover, especially during or directly following drought conditions.

}, keywords = {LTER-KNZ, distance sampling, grassland, songbird, Spiza americana, tallgrass prairie, territoriality}, doi = {10.5751/ACE-01343-140107}, url = {http://www.ace-eco.org/vol14/iss1/art7/}, author = {Verheijen, B.H.F. and Clipp, H.L. and Bartolo, A.J. and Jensen, W.E. and Sandercock, B.K.} } @article {KNZ001818, title = {Effects of grazing and fire frequency on floristic quality and its relationship to indicators of soil quality in tallgrass prairie}, journal = {Environmental Management}, volume = {60}, year = {2017}, pages = {1075}, chapter = {1062}, abstract = {

Fire and grazing are widely used to manage grasslands for conservation purposes, but few studies have evaluated the effects of these drivers on the conservation value of plant communities measured by the floristic quality index (FQI). Further, the influence of fire and grazing on soil properties and functions are difficult for land managers and restoration practitioners to assess. The objectives of this study were to: (1) quantify the independent and interactive effects of grazing and fire frequency on floristic quality in native tallgrass prairie to provide potential benchmarks for community assessment, and (2) to explore whether floristic quality can serve as an indicator of soil structure and function for more holistic ecosystem assessments. A factorial combination of fire frequencies (1\–2, 4, and 20 years return intervals) and grazing (by bison or ungrazed) treatments were sampled for plant species composition, and for several indicators of soil quality in lowland tallgrass prairie. Floristic quality, diversity, and richness were higher in grazed than ungrazed prairie over all fire frequencies (P\ \<\ 0.05). Available inorganic N, microbial biomass N, total N, and soil bulk density were also higher in grazed prairie soil over all fire frequencies (P\ \<\ 0.05). Microbial biomass C, total organic C, and total soil N were positively correlated with FQI (P\ \<\ 0.05). This study shows that floristic quality and soil N pools are more strongly influenced by grazing than fire and that floristic quality can be an indicator of total soil C and N stocks in never cultivated lowland prairie.

}, keywords = {LTER-KNZ, bison, grassland, Microbial biomass, nitrogen, restoration, Soil carbon}, doi = {10.1007/s00267-017-0942-0}, url = {https://www.ncbi.nlm.nih.gov/pubmed/28963572}, author = {Manning, G.C. and S.G. Baer and John M. Blair} } @mastersthesis {KNZ001832, title = {Grassland soil microbial responses to long-term management of N availability}, volume = {MS Thesis}, year = {2017}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS}, abstract = {

Anthropogenic actions have significantly increased biological nitrogen (N) availability on a global scale. In tallgrass prairies, this phenomenon is exacerbated by land management changes, such as fire suppression. Historically, tallgrass prairie fire removed N through volatilization, but fire suppression has contributed to increased soil N availability as well as woody encroachment. Because soil microbes respond to N availability and plant growth, these changes may alter microbial composition and important microbially-mediated functions. Grassland management affects the soil environment on multiple time scales including short (fertilization or fire event), seasonal (growing vs. non-growing season), and long-term (decadal plant turnover and nutrient accumulation), therefore my goal was to understand community variability at different time scales affecting the population and community dynamics of soil microbes. I predicted soil microbes would be sensitive to environmental changes at all time scales, seasonal variation would reflect increased plant rhizodeposit-supported populations during summer and decomposers during winter, and long-term fire suppression and chronic fertilization would drive soil microbial community turnover associated with accumulation of plant litter and N.

To address these predictions, soils were collected from the Belowground Plot Experiment (BGPE) at Konza Prairie Biological Station: a 30-y factorial field manipulation of N fertilization and burning. Surface soils (0-15 cm) were sampled monthly between Nov 2014 \– Dec 2015, including one week post-fire (April) and post-fertilization (June). Genomic DNA was extracted from each sample for qPCR and PCR for Illumina MiSeq library sequencing of the prokaryotic 16S rRNA gene and fungal ITS, to estimate population and community dynamics of soil microbes. Soil environmental characteristics and plant communities were measured in July 2015 to evaluate correlations between plant and microbial communities, and environmental variability.

Soil microbial responses to short-term fire/fertilization events were minimal, while microbial population sizes fluctuate seasonally and synchronously, and microbial community composition varied more with management history than at shorter time scales. Bacterial populations increased 10x during growing-season plant rhizodeposition, while fungal populations were less dynamic, but decreased in fall, possibly reflecting a shift to subsistence on soil organic matter. In contrast, microbial community composition was seasonally stable, but distinct between long-term management treatments, which may indicate accumulation of niche-defining plant or soil properties over decades. Prokaryotic communities responded to altered N availability via both fertilization and loss due to fire, with the highest abundance of \"copiotrophic\" (r-selected) taxa in unburned, fertilized soils. Fungal communities responded to N fertilization with higher abundance of arbuscular mycorrhizal fungi, pathogens, and saprotrophs, possibly due to changes in nutrient stoichiometry and litter availability in fertilized plots. However, fungal response to fire was largely independent of N availability, and plant community differences were correlated with fungal, but not bacterial, community composition, highlighting the likely nutritional codependence of fungi and plants, and fungal competitive advantages for plant litter substrates. The timing of changes in soil microbial communities is critical for plant nutrition and nutrient cycling in prairies, and this novel dataset on the temporal resolution of microbial responses to environmental variability contributes to the broader understanding of ecosystem responses to global change.

}, keywords = {LTER-KNZ, Communities, grassland, management, nitrogen, Soil microbes}, url = {http://krex.k-state.edu/dspace/handle/2097/36228}, author = {Carson, Christine} } @article {KNZ001768, title = {High dissimilarity within a multiyear annual record of pollen assemblages from a North American tallgrass prairie}, journal = {Ecology and Evolution}, volume = {6}, year = {2016}, pages = {5273 - 5289}, abstract = {

Grassland vegetation varies in composition across North America and has been historically influenced by multiple biotic and abiotic drivers, including fire, herbivory, and topography. Yet, the amount of temporal and spatial variability exhibited among grassland pollen assemblages, and the influence of these biotic and abiotic drivers on pollen assemblage composition and diversity has been relatively understudied. Here, we examine 4 years of modern pollen assemblages collected from a series of 28 traps at the Konza Prairie Long-Term Ecological Research Area in the Flint Hills of Kansas, with the aim of evaluating the influence of these drivers, as well as quantifying the amount of spatial and temporal variability in the pollen signatures of the tallgrass prairie biome. We include all terrestrial pollen taxa in our analyses while calculating four summative metrics of pollen diversity and composition \– beta-diversity, Shannon index, nonarboreal pollen percentage, and Ambrosia:Artemisia \– and find different roles of fire, herbivory, and topography variables in relation to these pollen metrics. In addition, we find significant annual differences in the means of three of these metrics, particularly the year 2013 which experienced high precipitation relative to the other 3 years of data. To quantify spatial and temporal dissimilarity among the samples over the 4-year study, we calculate pairwise squared-chord distances (SCD). The SCD values indicate higher compositional dissimilarity across the traps (0.38 mean) among all years than within a single trap from year to year (0.31 mean), suggesting that grassland vegetation can have different pollen signatures across finely sampled space and time, and emphasizing the need for additional long-term annual monitoring of grassland pollen.

}, keywords = {LTER-KNZ, fire, grassland, Great Plains, Herbivory, Pollen, Tauber traps}, doi = {10.1002/ece3.2259}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.2259}, author = {Commerford, J.L. and McLauchlan, K.K. and Minckley, T.A.} } @article {KNZ001781, title = {Rangeland responses to predicted increases in drought extremity}, journal = {Rangelands }, volume = {38}, year = {2016}, pages = {191-196}, keywords = {LTER-KNZ, Drought, grassland, savanna, shrubland, state and transition, woodland}, url = {http://dx.doi.org/10.1016/j.rala.2016.06.009}, author = {Breshears, D.D. and Alan K. Knapp and Law, D.J. and M.D. Smith and Twidwell, D. and Wonkka, C.L.} } @article {KNZ001748, title = {Shared drivers but divergent ecological responses: Insights from long-term experiments in mesic savanna grasslands}, journal = {BioScience}, volume = {66}, year = {2016}, pages = {666 - 682}, type = {Journal Articles}, abstract = {

Fire and grazing, key determinants of structure and function of savanna grasslands worldwide, have been extensively altered by humans. We used existing long-term manipulations of fire and grazing in North American and South African mesic savanna grasslands, as well as new experiments, to determine whether the impacts of fire and grazing by large herbivores differed between these systems. We found that despite a body of literature suggesting that these savanna grasslands respond uniquely to fire and grazing, their ecosystem responses (aboveground productivity) were generally similar. In contrast, plant-community responses to fire and herbivores diverged strongly between systems. The differences in plant-community responses, as well as convergence in ecosystem function, were underpinned by a common mechanism: the response of grass dominance to changing fire and grazing regimes. As a result, divergent responses of plant communities to altered fire and grazing regimes did not preclude convergence in ecosystem function.

}, keywords = {LTER-KNZ, Aboveground net primary productivity, fire, grassland, Grazing, plant community}, doi = {10.1093/biosci/biw077}, url = {https://academic.oup.com/bioscience/article/66/8/666/2464141}, author = {M.D. Smith and Alan K. Knapp and Scott. L. Collins and Burkepile, D.E. and Kirkman, K.P. and Koerner, S.E. and Thompson, D.I. and John M. Blair and Burns, C.E. and Eby, S. and Forrestel, E.J. and Fynn, R.W.S. and Govender, N. and Hagenah, N. and Hoover, D.L. and K.R. Wilcox} } @article {KNZ001756, title = {Tight coupling of leaf area index to canopy nitrogen and phosphorus across heterogeneous tallgrass prairie communities}, journal = {Oecologia}, volume = {182}, year = {2016}, pages = {889 - 898}, abstract = {

Nitrogen (N) and phosphorus (P) are limiting nutrients for many plant communities worldwide. Foliar N and P along with leaf area are among the most important controls on photosynthesis and hence productivity. However, foliar N and P are typically assessed as species level traits, whereas productivity is often measured at the community scale. Here, we compared the community-level traits of leaf area index (LAI) to total foliar nitrogen (TFN) and total foliar phosphorus (TFP) across nearly three orders of magnitude LAI in grazed and ungrazed tallgrass prairie in north-eastern Kansas, USA. LAI was strongly correlated with both TFN and TFP across communities, and also within plant functional types (grass, forb, woody, and sedge) and grazing treatments (bison or cattle, and ungrazed). Across almost the entire range of LAI values and contrasting communities, TFN:TFP ratios indicated co-limitation by N and P in almost all communities; this may further indicate a community scale trend of an optimal N and P allocation per unit leaf area for growth. Previously, results from the arctic showed similar tight relationships between LAI:TFN, suggesting N is supplied to canopies to maximize photosynthesis per unit leaf area. This tight coupling between LAI, N, and P in tallgrass prairie suggests a process of optimal allocation of N and P, wherein LAI remains similarly constrained by N and P despite differences in species composition, grazing, and canopy density.

}, keywords = {LTER-KNZ, Co-limitation, fire, grassland, grazers, nutrients}, issn = {0029-8549}, doi = {10.1007/s00442-016-3713-3}, url = {https://link.springer.com/article/10.1007\%2Fs00442-016-3713-3}, author = {Klodd, A.E. and Jesse B. Nippert and Z. Ratajczak and Waring, H. and Phoenix, G.K.} } @article {KNZ001677, title = {Effects of grazing and prescribed fire on resource selection and nest survival of upland sandpipers in an experimental landscape}, journal = {Landscape Ecology}, volume = {30}, year = {2015}, pages = {325 -337}, abstract = {

Context Conservation of grassland vertebrates requires a mechanistic understanding of the effects of landscape heterogeneity on habitat selection and demographic performance. Objectives Our goal was to investigate the effects of rangeland management on resource selection and nest survival of upland sandpipers (Bartramia longicauda). Methods We conducted our project at Konza Prairie, a Long-Term Ecological Research site. The station has 60 experimental units with replicated grazing and fire treatments that create a heterogeneous landscape of different habitat patches. We radio-tracked sandpipers for two breeding seasons (2003\–2004, n = 37 birds) and monitored sandpiper nests for eight seasons (2001\–2008, n = 246 nests). We used resource utilization functions to examine resource selection with respect to five landscape features. Results Home ranges of sandpipers were large in contiguous prairie (x\¯=8.4km2x\¯=8.4km2) and explain area-sensitive occurrence in fragmented prairie. Upland sandpipers selected grazed and burned sites with short vegetation within their home range. In contrast, nest site selection was influenced by fire frequency and birds selected infrequently burned sites with greater vegetative structure. Settlement decisions affected fitness because nest survival was low in burned and grazed sites (0.068), but higher in unburned and ungrazed sites (0.201\–0.247). Conclusions Our results raise concerns for conservation because private rangelands managed for livestock production are often homogeneous landscapes with heavy grazing and frequent fires. Rotational grazing and fire could be used to restore heterogeneity to grasslands but the duration of rotation, patch size, and optimal configuration require further investigation.

}, keywords = {LTER-KNZ, Bartramia longicauda, fire, grassland, Habitat selection, Home range, Landscape heterogeneity, Nest survival, Radio-telemetry, Resource utilization functions, tallgrass prairie}, doi = {10.1007/s10980-014-0133-9}, url = {https://link.springer.com/article/10.1007\%2Fs10980-014-0133-9}, author = {Sandercock, B.K. and M. Alfaro-Barrios and Casey, A.E. and Johnson, T.N. and Mong, T.W. and Odom, K.J. and Strum, K.M. and Winder, V.L.} } @article {KNZ001610, title = {Convergent and contingent community responses to grass source and dominance during prairie restoration across a longitudinal gradient}, journal = {Environmental Management}, volume = {53}, year = {2014}, pages = {252 -265}, abstract = {

Restoring prairie on formerly cultivated land begins by selecting propagule seed sources and the diversity of species to reintroduce. This study examined the effects of dominant grass propagule source (cultivar vs. non-cultivar) and sown propagule diversity (grass:forb sowing ratio) on plant community structure. Two field experiments were established in Kansas and Illinois consisting of identical split plot designs. Dominant grass source was assigned as the whole-plot factor, and sown dominance of grasses (five levels of seeded grass dominance) as the subplot factor. Species density, cover, and diversity were quantified for 5 years. The effect of dominant grass source on the cover of focal grasses, sown species, and volunteer species was contingent upon location, with variation between dominant grass sources observed exclusively in Kansas. Species density and diversity showed regionally convergent patterns in response to dominant grass source. Contrary to our hypotheses, total species density and diversity were not lower in the presence of grass cultivars, the grass source we had predicted would be more competitive. Sown grass dominance effects on the cover of the focal grass species were contingent upon location resulting from establishment corresponding better to the assigned treatments in Illinois. All other cover groups showed regionally convergent patterns, with lower cover of volunteers and higher cover of sown forbs, diversity, and species density in the lowest sown grass dominance treatment in both sites. Thus, decisions regarding the diversity of propagules to reintroduce had more consequence for plant community structure than cultivar or non-cultivar source of dominant grasses.

}, keywords = {LTER-KNZ, Ecotype, grassland, restoration, Seed source}, doi = {10.1007/s00267-013-0209-3}, url = {https://link.springer.com/article/10.1007\%2Fs00267-013-0209-3}, author = {Klopf, R.P. and S.G. Baer and D.J. Gibson} } @article {KNZ001564, title = {Fitness among population sources of a dominant species (Andropogon gerardii Vitman) used in prairie restoration}, journal = {Torrey Botanical Society}, volume = {140}, year = {2014}, pages = {269 -279}, abstract = {

Planting native grasses can provide a source of seed for prairie restorations, but requires knowledge of how the plants that establish will perform. This study sought to determine variation in fitness of population sources of Andropogon gerardii, a dominant grassland species, when grown in a mesic common garden. Using multiple population sources, we tested the hypothesis that plants from populations within the local region would exhibit a \‘home-site advantage\’ as measured by higher fitness compared to plants from populations collected from drier regions of the tallgrass prairie ecosystem (up to 986 km west of the common garden). Plants collected from four pristine, never restored population sources from each of three regions (central Kansas, eastern Kansas, and southern Illinois) were raised in the greenhouse from seeds and planted in a common garden in Illinois. To estimate fitness, we used commonly measured traits related to seed production, including flowering tiller number and number of flowering raceme branches, seed number, viability, and percentage germination. There was no evidence of a \‘home-site advantage\’ for populations originating from southern Illinois. Rather, there was high within-region variability in fecundity. Plants from southern Illinois had the largest number of raceme branches per plant. Plants from eastern Kansas had the highest number of vegetative tillers per plant. Plants from central Kansas produced the most germinable seeds. Under the current climate, plants from any one of the three regions may be suitable to propagate seeds for restoration, but other traits may vary among populations to affect height, cover, and productivity.

}, keywords = {LTER-KNZ, Andropogon gerardii, fitness, grassland, reproductive effort, restoration}, doi = {10.3159/TORREY-D-12-00063.1}, url = {https://doi.org/10.3159/TORREY-D-12-00063.1}, author = {D.J. Gibson and Sendor, G. and Donatelli, J. and S.G. Baer and Johnson, L.} } @article {KNZ001553, title = {Geographic variation in growth and phenology of two dominant Central US grasses: Consequences for climate change}, journal = {Journal of Plant Ecology}, volume = {7}, year = {2014}, pages = {211 -221}, abstract = {

Aims The rate of climate change may exceed many plant species\’ migration rates, particularly for long-lived perennial species that dominate most ecosystems. If bioclimatic envelopes shift more rapidly than dominant species can migrate, individuals located peripheral to biomes or in adjacent biomes may become a significant source of traits for future dominant populations (DPs). Thus, traits of individuals from peripheral populations (PPs) may affect future ecosystem functioning more than those of today\’s DPs. Methods We assessed key traits of individuals collected from populations that currently dominate two central US grasslands, the shortgrass steppe (Bouteloua gracilis) and the tallgrass prairie (Andropogon gerardii). We compared these to individuals from PPs in a reciprocal-transplant common garden experiment with gardens at the Shortgrass Steppe Long Term Ecological Research site in Colorado and the Konza Prairie Biological Station Long Term Ecological Research site in Kansas. DPs and PPs were subjected to high and reduced water availability in common gardens located in each biome. Traits measured included the following: individual plant biomass, reproductive allocation, specific leaf area (SLA) and plant\–water relations. We focused on the climate-change relevant comparisons of traits from PPs versus DPs expressed under the climate of DPs. Important Findings PPs of B. gracilis differed from DPs primarily in phenological traits. Under a semiarid shortgrass steppe climate, PPs initiated flowering later in the season, produced fewer reproductive tillers and were more sensitive to water stress. Biomass differences between populations were minimal. For A. gerardii, biomass in PPs was 50\% lower than in DPs under the mesic tallgrass prairie climate and reproductive tillers were considerably smaller, despite higher SLA in PPs. Biomass of PPs was less sensitive to water stress, however. From these results, we conclude that key traits of PPs differed from DPs in both grassland types, but potential effects on reproductive phenology were greater for the bioclimatic shift in which a mesic biome becomes arid, whereas aboveground productivity may be affected more when a semiarid biome becomes more mesic.

}, keywords = {LTER-KNZ, grassland, phenology, productivity, traits, water stress}, doi = {10.1093/jpe/rtt036}, url = {https://academic.oup.com/jpe/article/7/3/211/905746}, author = {Giuliani, A.L. and Kelly, E.F. and Alan K. Knapp} } @article {KNZ001611, title = {No effect of seed source on multiple aspects of ecosystem functioning during ecological restoration: cultivars compared to local ecotypes of dominant grasses}, journal = {Evolutionary Applications}, volume = {7}, year = {2014}, pages = {323 -335}, abstract = {

Genetic principles underlie recommendations to use local seed, but a paucity of information exists on the genetic distinction and ecological consequences of using different seed sources in restorations. We established a field experiment to test whether cultivars and local ecotypes of dominant prairie grasses were genetically distinct and differentially influenced ecosystem functioning. Whole plots were assigned to cultivar and local ecotype grass sources. Three subplots within each whole plot were seeded to unique pools of subordinate species. The cultivar of the increasingly dominant grass, Sorghastrum nutans, was genetically different than the local ecotype, but genetic diversity was similar between the two sources. There were no differences in aboveground net primary production, soil carbon accrual, and net nitrogen mineralization rate in soil between the grass sources. Comparable productivity of the grass sources among the species pools for four years shows functional equivalence in terms of biomass production. Subordinate species comprised over half the aboveground productivity, which may have diluted the potential for documented trait differences between the grass sources to influence ecosystem processes. Regionally developed cultivars may be a suitable alternative to local ecotypes for restoration in fragmented landscapes with limited gene flow between natural and restored prairie and negligible recruitment by seed.

}, keywords = {LTER-KNZ, genetic diversity, genetic structure, grassland, prairie, propagule, soil}, doi = {10.1111/eva.12124}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/eva.12124}, author = {S.G. Baer and D.J. Gibson and Benscoter, A.M. and Reed, L.K. and Campbell, R.E. and Klopf, R.P. and Willand, J.E. and Wodika, B.R.} } @article {KNZ001546, title = {Correlations between genetic and species diversity: effects of resource quantity and heterogeneity}, journal = {Journal of Vegetation Science}, volume = {24}, year = {2013}, pages = {1185 -1194}, abstract = {

Questions It is hypothesized that species and genetic diversity are correlated because niche differentiation among species and genotypes is either affected by the same processes (positive) or each level restricts the amount of diversity in the other (negative). Although many studies have observed both positive and negative relationships, others have found no correlation between the two diversity measures. Are measures of species (richness, diversity and evenness) and genetic diversity correlated, and how does resource (soil moisture, light, nitrogen and phosphorus) quantities and heterogeneity affect both levels of diversity? Location Intact tallgrass prairie at Konza Prairie Biological Station, northeast Kansas, US. Methods We investigate the correlation between plant species and genetic diversity in a long-term precipitation manipulation experiment \– the Rainfall Manipulation Plots (RaMPs) \– located in intact tallgrass prairie as well as adjacent non-manipulated prairie. The RaMPs experiment has been imposing ambient and more variable precipitation regimes (a 50\% increase in timing between rainfall events without changing total rainfall amount) during the growing season since 1998, resulting in reduced mean soil moisture and increased soil moisture variability. Thus, the RaMPs and non-manipulated prairie plots capture a range of soil moisture amounts and variability. Genetic diversity (measured as genotype richness and genomic dissimilarity among individuals) was quantified for the dominant grass species, Andropogon gerardii, which has large impacts on plant community structure and ecosystem function. Results We found species and genetic diversity were not significantly correlated. Genotypic richness was negatively related to soil moisture variability, but measures of species diversity were not. In the non-manipulated plots only, we found generally negative relationships between resource quantity (light and nitrogen) and community diversity, and positive relationships between resource heterogeneity (CV of light) and community diversity. Conclusions Our results suggest that a lack of a positive or negative relationship between species and genetic diversity could be due to these two levels of diversity responding differently to the identity, quantity and heterogeneity of resources.

}, keywords = {LTER-KNZ, Andropogon gerardii, C4 grass, dominant species, grassland, Resource heterogeneity, Resource quantity, Species genetic diversity correlation}, doi = {10.1111/jvs.12042}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jvs.12042}, author = {M.L. Avolio and M.D. Smith} } @article {KNZ001565, title = {Limited effects of dominant species population source on community composition during community assembly}, journal = {Journal of Vegetation Science}, volume = {24}, year = {2013}, pages = {429 -440}, abstract = {

Question To what extent do dominant species population sources and subordinate species pools affect diversity and composition of an assembling grassland community? Location Illinois, USA. Methods Percentage cover of all species were recorded annually in 36 1-m2 quadrats assigned to a factorial combination of dominant species population source (functionally distinct cultivar or non-cultivar seed source) and designed species pool (three levels varying in species identity, but with equal functional group representation and richness) during the first 4 yr of community assembly in an experimental grassland restoration. Results Univariate and multivariate analyses showed that individual species abundance, life form and community composition differed significantly among designed species pools, but were not strongly affected by population source of the dominant species (cultivar or non-cultivar). There were fewer C4 species in cultivar plots but only in one of three designed species pools during one of 4 yr of community assembly. The number of legume and forb species was higher in cultivar plots, but also only in one of the 4 yr of study. Other changes in species richness and abundance were solely related to successional change. Conclusions Non-dominant species introduced to restore plant communities strongly affects plant community composition, and composition can show fidelity to designed species pools. Only marginal or temporary effects of dominant species seed source were observed in the assembling plant community. Thus, we found no strong evidence that the source of dominant species, in this case cultivars compared to local ecotypes, has consequences for community assembly in the early stages of restoration (1\–4 yr). The absence of a strong dominant species source effect may be exacerbated by the assembly of diverse plant communities, resulting in a stronger effect of subordinate species seed mixture in restoration.

}, keywords = {LTER-KNZ, Community assembly, dominant species, Extended phenotype, grassland, restoration, Seed pool, tallgrass prairie}, doi = {10.1111/j.1654-1103.2012.01475.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1654-1103.2012.01475.x}, author = {D.J. Gibson and S.G. Baer and Klopf, R.P. and Reed, L.K. and Wodika, B.R. and Willand, J.E.} } @article {KNZ001495, title = {Effects of fire, grazing and topographic variation on vegetation structure in tallgrass prairie}, journal = {Journal of Vegetation Science}, volume = {23}, year = {2012}, pages = {563 -575}, abstract = {

Questions How do fire and grazing by bison affect the composition and structure of tallgrass prairie plant communities and their temporal stability? Are these responses modulated by topographic location? Location Konza Prairie Biological Station, Kansas, USA. Methods Plant community composition was monitored in permanent plots in native grassland sites receiving different long-term prescribed burning and bison grazing regimes across a topographic gradient (lowlands, slopes, uplands) following 20 yr of variable burning treatments and 13 yr of grazing by bison. A combination of multivariate analyses was used to determine how community structure, life forms and individual species responded to the accumulated effects of long-term fire and grazing by native bison in upland, slope and lowland soils. Results Species diversity was maximized in sites that were infrequently burned and grazed by bison with the strongest response on infrequently burned slope sites, while diversity was lowest on frequently burned ungrazed sites and on frequently burned slope sites. In general, grass cover was highest in infrequently burned ungrazed sites and lowest on frequently burned grazed sites, while forb richness was highest in infrequently burned and grazed sites. Community response to fire and grazing differed across the topographic gradient. In general, frequent burning favoured C4 grasses, which reduced the abundance of C3 forbs, especially in lowland sites. Responses of dominant grasses and forbs to fire and grazing varied depending on topographic position. Community stability was positively correlated with species richness. Conclusions Overall, we found that fire and grazing are the main determinants of plant community composition and structure in this grassland system, but that topography mediates these effects. A combination of bison grazing and periodic fire is necessary to maximize diversity and community stability across this native grassland landscape.

}, keywords = {LTER-KNZ, disturbance, fire, grassland, Grazing, Plant community structure, Species diversity}, doi = {10.1111/j.1654-1103.2011.01369.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1654-1103.2011.01369.x}, author = {Scott. L. Collins and Calabrese, L.B.} } @article {KNZ001497, title = {Incorporating clonal growth form clarifies the role of plant height in response to nitrogen addition}, journal = {Oecologia}, volume = {169}, year = {2012}, pages = {1053 -1062}, abstract = {

Nutrient addition to grasslands consistently causes species richness declines and productivity increases. Competition, particularly for light, is often assumed to produce this result. Using a long-term dataset from North American herbaceous plant communities, we tested whether height and clonal growth form together predict responses to fertilization because neither trait alone predicted species loss in a previous analysis. Species with a tall-runner growth form commonly increased in relative abundance in response to added nitrogen, while short species and those with a tall-clumped clonal growth form often decreased. The ability to increase in size via vegetative spread across space, while simultaneously occupying the canopy, conferred competitive advantage, although typically only the abundance of a single species within each height-clonal growth form significantly responded to fertilization in each experiment. Classifying species on the basis of two traits (height and clonal growth form) increases our ability to predict species responses to fertilization compared to either trait alone in predominantly herbaceous plant communities.

}, keywords = {LTER-KNZ, Clonal growth, Competition, grassland, Nitrogen addition, productivity}, doi = {10.1007/s00442-012-2264-5}, url = {https://link.springer.com/article/10.1007\%2Fs00442-012-2264-5}, author = {Gough, L. and Gross, K.L. and Cleland, E.E. and Clark, C.M. and Scott. L. Collins and Fargione, J.E. and Pennings, S.C. and K.N. Suding} } @article {KNZ001467, title = {Invasion of an intact plant community: the role of population vs. community level diversity}, journal = {Oecologia}, volume = {168}, year = {2012}, pages = {1091 -1102}, abstract = {

To improve the understanding of how native plant diversity influences invasion, we examined how population and community diversity may directly and indirectly be related to invasion in a natural field setting. Due to the large impact of the dominant C4 grass species (Andropogon gerardii) on invasion resistance of tallgrass prairie, we hypothesized that genetic diversity and associated traits within a population of this species would be more strongly related to invasion than diversity or traits of the rest of the community. We added seeds of the exotic invasive C4 grass, A. bladhii, to 1-m2 plots in intact tallgrass prairie that varied in genetic diversity of A. gerardii and plant community diversity, but not species richness. We assessed relationships among genetic diversity and traits of A. gerardii, community diversity, community aggregated traits, resource availability, and early season establishment and late-season persistence of the invader using structural equation modeling (SEM). SEM models suggested that community diversity likely enhanced invasion indirectly through increasing community aggregated specific leaf area as a consequence of more favorable microclimatic conditions for seedling establishment. In contrast, neither population nor community diversity was directly or indirectly related to late season survival of invasive seedlings. Our research suggests that while much of diversity\–invasion research has separately focused on the direct effects of genetic and species diversity, when taken together, we find that the role of both levels of diversity on invasion resistance may be more complex, whereby effects of diversity may be primarily indirect via traits and vary depending on the stage of invasion.

}, keywords = {LTER-KNZ, Andropogon bladhii, dominant species, genetic diversity, grassland, tallgrass prairie}, doi = {10.1007/s00442-011-2157-z}, url = {https://link.springer.com/article/10.1007\%2Fs00442-011-2157-z}, author = {Chang, C.C. and M.D. Smith} } @article {KNZ001527, title = {Recovery of native plant community characteristics on a chronosequence of restored prairies seeded into pastures in West-Central Iowa}, journal = {Restoration Ecology}, volume = {20}, year = {2012}, pages = {170 -179}, abstract = {

Restored grasslands comprise an ever-increasing proportion of grasslands in North America and elsewhere. However, floristic studies of restored grasslands indicate that our ability to restore plant communities is limited. Our goal was to assess the effectiveness of restoration seeding for recovery of key plant community components on former exotic, cool-season pastures using a chronosequence of six restoration sites and three nearby remnant tallgrass prairie sites in West-Central Iowa. We assessed trends in Simpson\&$\#$39;s diversity and evenness, richness and abundance of selected native and exotic plant guilds, and mean coefficient of conservatism (mean C). Simpson\&$\#$39;s diversity and evenness and perennial invasive species abundance all declined with restoration site age. As a group, restoration sites had greater richness of native C3 species with late phenology, but lower richness and abundance of species with early phenology relative to remnant sites. Total native richness, total native abundance (cover), mean C, and abundance of late phenology C3 plants were similar between restoration and remnant sites. Observed declines in diversity and evenness with restoration age reflect increases in C4 grass abundance rather than absolute decreases in the abundance of perennial C3 species. In contrast to other studies, restoration seeding appears to have led to successful establishment of tallgrass prairie species that were likely to be included in seeding mixtures. While several floristic measures indicate convergence of restoration and remnant sites, biodiversity may be further enhanced by including early phenology species in seeding mixes in proportion to their abundance on remnant prairies.

}, keywords = {LTER-KNZ, grassland, Invasive, mean C, phenology, succession, tallgrass}, doi = {10.1111/j.1526-100X.2010.00760.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00760.x}, author = {Carter, D.L. and John M. Blair} } @article {KNZ001506, title = {Tracking C and N flows through microbial biomass with increased soil moisture variability}, journal = {Soil Biology \& Biochemistry}, volume = {49}, year = {2012}, pages = {11 -22}, abstract = {

Changes in soil moisture with cycles of soil wetting and drying are associated with shifts in osmotic potentials that can induce physiological stress for microbial communities. These instances of soil moisture stress can be of sufficient magnitude to alter flows of C and N at an ecosystem scale. In this study we manipulated the duration and severity of soil moisture stress and disturbance in grassland soils from four sites along a precipitation gradient. After subjecting soils to a two-month long incubation under two different wetting-drying regimes, one of high and one of low stress and disturbance, we moistened soils with 13C- and 15N-labeled glycine solution to trace C and N though the soil and its microbial communities as they dried. Contrary to our predictions, we found evidence for preferential use of N-free osmolytes with increased soil moisture stress in soils from the mesic end of the precipitation gradient. Soils from the western, semi-arid end of the gradient were less sensitive to soil moisture stress and did not differ in N demand under high and low stress. Specific respiration rates were higher in all soils under greater soil moisture stress immediately after re-wetting, then returned to levels equal to or below rates in soils under low soil moisture stress regimes. Nitrification outpaced denitrification processes in soils under the highest levels of soil moisture stress. These results suggest increases in both soil CO2 release and N losses as stress induced by greater soil moisture variability increases in relatively mesic grassland systems, a predicted consequence of climate change in this region.

}, keywords = {LTER-KNZ, Carbon use efficiency, Climate change, grassland, Precipitation regime, Soil carbon, Soil moisture variability, Soil nitrogen}, doi = {10.1016/j.soilbio.2012.01.030}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0038071712000521?via\%3Dihub}, author = {Tiemann, L.K. and Billings, S.A.} } @article {KNZ001451, title = {Variable effects of dipteran parasitoids and management treatment on grasshopper fecundity in a tallgrass prairie}, journal = {Bulletin of Entomological Research}, volume = {102}, year = {2012}, pages = {123 -130}, abstract = {

Grasshoppers host a number of parasitoids, but little is known about their impact on grasshopper life history attributes or how those impacts may vary with land use. Here, we report on a three-year survey of nine grasshopper species in a tallgrass prairie managed with fire and bison grazing treatments. We measured parasitoid prevalence and the impact of parasitoid infection on grasshopper fecundity to determine if grasshopper-parasitoid interactions varied with management treatment. Adult female grasshoppers were collected every three weeks from eight watersheds managed with different prescribed burning and grazing treatments. Grasshopper fecundity with and without parasitoids was estimated through dissections of reproductive tracts. Dipteran parasitoids from two families (Nemestrinidae and Tachinidae) were observed infecting grasshoppers. We found significant effects of grazing treatment, but not burn interval, on grasshopper-parasitoid interactions. Parasitoids were three times more abundant in watersheds with bison grazing than in ungrazed watersheds, and the relative abundance of nemestrinid and tachinid flies varied with grazing treatment. Parasitoid prevalence varied among grasshopper species from \<0.01\% infected (Mermiria bivittata) to 17\% infected (Hypochlora alba). Parasitoid infection reduced individual grasshopper fecundity, with stronger effects on current reproduction than on past reproduction. Furthermore, current fecundity in parasitized grasshoppers was lower in grazed watersheds compared to ungrazed watersheds. Nemestrinid parasitoids generally had stronger impacts on grasshopper fecundity than tachinid parasitoids, the effects of which were more variable.

}, keywords = {LTER-KNZ, grassland, Grazing, host-parasitoid interactions, Konza Prairie Biological Station, Orthoptera, reproduction}, doi = { http://dx.doi.org/10.1017/S0007485311000472}, url = {https://www.cambridge.org/core/journals/bulletin-of-entomological-research/article/variable-effects-of-dipteran-parasitoids-and-management-treatment-on-grasshopper-fecundity-in-a-tallgrass-prairie/EB1AD93DB7D975E1009489797D88DF2E}, author = {Laws, A. and Anthony Joern} } @article {KNZ001444, title = {Population genetic structure and landscape connectivity of the Eastern Yellowbelly Racer (Coluber constrictor flaviventris) in the contiguous tallgrass prairie of northeastern Kansas, USA}, journal = {Landscape Ecology}, volume = {26}, year = {2011}, pages = {281 -294}, abstract = {

The tallgrass prairie of North America has undergone widespread habitat loss and fragmentation (\<4\% remains). The Flint Hills region of Kansas and Oklahoma is the largest tallgrass prairie remaining and therefore provides an opportunity to study the population genetic structure of grassland species in a relatively contiguous landscape and set a baseline for evaluating changes when the habitat is fragmented. We adopted a landscape genetics approach to identify how landscape structure affected dispersal, population genetic structure, and landscape connectivity of the Eastern Yellowbelly Racer (Coluber constrictor flaviventris) across a 13,500-km2 landscape in northeastern Kansas, USA. The racer population had high allelic diversity, high heterozygosity, and was maintaining migration-drift equilibrium. Autocorrelation between genetic and geographic distance revealed that racers exhibited restricted dispersal within 3 km, and isolation-by-distance. Significant isolation-by-distance occurred at broad regional scales (\>100 km), but because of sufficient gene flow between locations, we were unable to define discrete subpopulations using Bayesian clustering analyses. Resistance distance, which considers the permeability of habitats, did not explain significant variation in genetic distance beyond Euclidean distance alone, suggesting that racers are not currently influenced by landscape composition. In northeastern Kansas, racers appear to be an abundant and continuously distributed snake that perceives the landscape as well connected with no cover type currently impeding snake dispersal or gene flow.

}, keywords = {LTER-KNZ, Autocorrelation, conservation, dispersal, Fragmentation, Gene flow, grassland, Isolation-by-distance, Landscape genetics, Microsatellites, Snake}, doi = {10.1007/s10980-010-9554-2}, url = {https://link.springer.com/article/10.1007\%2Fs10980-010-9554-2}, author = {Klug, P.E. and Wisely, S.M. and With, K.A.} } @mastersthesis {KNZ001429, title = {Responses of switchgrass (Panicum virgatum L.) to precipitation amount and temperature}, volume = {MS Thesis}, year = {2011}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS}, abstract = {

Anthropogenic climate change is likely to alter the function and composition of ecosystems worldwide through increased precipitation variability and temperatures. To predict ecosystem responses, a greater understanding of the physiological and growth responses of plants is required. Dominant species drive ecosystem responses, and it is essential to understand how they respond to understand potential ecosystem changes. Dominant species, such as switchgrass (Panicum virgatum L.), posses large genotypic and phenotypic variability, which will impact the degree of responses to projected climate changes. I studied the physiological and growth responses of switchgrass, a common perennial warm-season C4 grass that is native to the tallgrass prairie, to alterations in precipitation amount and temperature. The first experiment I conducted focused on the responses of three ecotypes of P. virgatum to three precipitation regimes (average, 25\% below, 25\% above). I concluded that the physiological responses of photosynthesis, stomatal conductance, transpiration, dark-adapted fluorescence, and mid-day water potential in P. virgatum were explained by ecotypic differences. Robust responses to altered precipitation were seen in the water use efficiency, mid-day water potential, and aboveground biomass. Ecotypic differences were also seen in several aboveground biomass variables, and most strikingly in flowering times and rates. There were few interactions between ecotype and precipitation, suggesting precipitation is a strong driver of biomass production, whereas adaption of ecotypes to their local environment affects physiological processes. A second experiment studied the response of local populations of P. virgatum to nocturnal warming. Results showed significant differences in daytime E, daytime gs, and flowering phenology between treatments. Differences in aboveground biomass were between topographic positions. I concluded that water availability, based on topographic position, is a strong driver of P. virgatum aboveground biomass production, but nocturnal warming has the potential to impact flowering phenology, physiological responses, and exacerbate plant water stress. I also reviewed the literature on the ecological effects of implementing switchgrass cultivation for biofuel. From the literature review, I concluded that large-scale switchgrass cultivation will have widespread ecological impacts. If landscape heterogeneity is maintained through harvest rotations, no till farming, and mixed species composition, ecosystem services can be maintained while providing economic value.

}, keywords = {LTER-KNZ, Aboveground biomass, Biofuel, Climate change, Ecophysiology, grassland}, url = {http://hdl.handle.net/2097/10720}, author = {Hartman, J.C.} } @article {KNZ001361, title = {Soil moisture controls on temperature sensitivity of soil organic carbon decomposition for a mesic grassland}, journal = {Soil Biology and Biochemistry}, volume = {43}, year = {2011}, pages = {455 -457}, abstract = {

We examined relationships between soil moisture and the temperature sensitivity of decomposition of labile soil organic carbon at a central North American grassland. For soils collected from shallow, xeric uplands, temperature sensitivity was greatest at intermediate soil moisture. For soils collected from the deeper, mesic lowlands, temperature sensitivity increased with increasing soil moisture. For example, lowland soils incubated at 75\% WHC exhibited an apparent activation energy (Ea) that was 15 kJ mol\−1 greater than soils incubated at 30\% WHC, the equivalent of a Q10 of 2.8 vs. 2.3. Although further research is still needed to understand why moisture\–temperature sensitivity relationships would differ between topographic positions, the magnitude of the soil moisture effect is large enough to alter soil C budgets and should be considered explicitly when predicting ecosystem responses to global change scenarios.

}, keywords = {LTER-KNZ, grassland, Microbial respiration, soil moisture, Soil organic carbon, Temperature sensitivity, Warming}, doi = {10.1016/j.soilbio.2010.10.011}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0038071710003949?via\%3Dihub}, author = {Craine, J.M. and Gelderman, T.M.} } @mastersthesis {KNZ001305, title = {Calibrating vegetation cover and pollen assemblages in the Flint Hills of Kansas, USA}, volume = {MS Thesis}, year = {2010}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS. 73 pp}, abstract = {

The quantitative relationship between pollen assemblages in sediment and vegetation cover is largely unknown because many factors influence this relationship. This lack of quantitative relationship is particularly acute in grassland regions, where both past and future climate change have the potential to determine grassland composition and cover. The tool used to reconstruct past grassland cover is the relative abundance of distinct fossil pollen types preserved in sediment. However, the interpretation of grassland pollen assemblages as grassland vegetation types needs to be refined to improve these reconstructions. Using pollen found in the surface sediments from 24 artificially-constructed ponds in the Flint Hills ecoregion of Kansas, USA, I examined relationships between pollen and vegetation in the tallgrass prairie biome, which includes woody components. By comparing the pollen data to field-surveyed vegetation data and land cover classifications taken from Kansas Gap Analysis Program data, I correlated pollen and vegetation in this ecoregion. Pollen productivity estimates for Artemisia, Ambrosia, Asteraceae, Chenopodiaceae, Cornus, Fabaceae, Juniperus, Maclura, Poaceae, Populus, Quercus, and Salix were calculated via the Extended R-Value Model. Common pollen types identified in sediments are mostly herbaceous grassland plant species such as Poaceae, Artemisia, and Ambrosia, but woody plants such as Populus, Quercus, and Juniperus are also represented. PPEs have been calculated for four of these taxa in Europe, and values from the Flint Hills are higher. These are the first PPEs reported for eight of these taxa. This research will further advance quantitative vegetation reconstructions in the Great Plains of North America and refine interpretations of how climate change affects grasslands.

}, keywords = {LTER-KNZ, grassland, Kansas- Flint Hills, Pollen, prairie vegetation}, url = {http://hdl.handle.net/2097/4170}, author = {Commerford, J.L.} } @article {KNZ001295, title = {Net carbon fluxes over burned and unburned native tallgrass prairie}, journal = {Rangeland Ecology \& Management}, volume = {63}, year = {2010}, pages = {72 -81}, abstract = {

Prescribed burning of aboveground biomass in tallgrass prairie is common and may influence dynamics and magnitudes of carbon (C) movement between the surface and atmosphere. Carbon dioxide (CO2) fluxes were measured for 2 yr using conditional sampling systems on two adjacent watersheds in an ungrazed tallgrass prairie near Manhattan, Kansas. One watershed was burned annually (BA) and the other biennially (BB). Leaf and soil CO2 fluxes were measured in the source area. Net ecosystem exchange (NEE) of CO2 reached a maximum daily gain of 26.4 g CO2 \· m\−2 \· d\−1 (flux toward surface is positive) in July 1998 (year when both sites were burned and precipitation was above normal); gains were similar between sites in 1998. The maximum daily NEE loss of CO2 was \−21.8 g CO2 \· m\−2 \· d\−1 from BA in September 1997 (year when only BA was burned and precipitation was below normal). When data were integrated over the two years, both sites were net sources of atmospheric CO2; NEE was \−389 g C \· m\−2 \· 2 yr\−1 on BA and \−195 g C \· m\−2 \· 2 yr\−1 on BB. Burning increased canopy size and photosynthesis, but the greater photosynthesis was offset by corresponding increases in respiration (from canopy and soil). Carbon losses from fire represented 6\–10\% of annual CO2 emissions (bulk came from soil and canopy respiration). Data suggest that annual burning promotes C loss compared to less-frequently burned tallgrass prairie where prairie is not grazed by ungulates. Greater precipitation in 1998 caused large increases in biomass and a more positive growing season NEE, indicating that C sequestration appears more likely when precipitation is high. Because C inputs (photosynthesis) and losses (canopy and soil respiration) were large, small measurement or modeling errors could confound attempts to determine if the ecosystems are long-term CO2 sources or sinks.

}, keywords = {LTER-KNZ, conditional sampling, fire, grassland, Konza Prairie, Land management, net ecosystem exchange}, doi = {10.2111/REM-D-09-00010.1}, url = {https://www.sciencedirect.com/science/article/pii/S1550742410500101?via\%3Dihub}, author = {D. Bremer and J.M. Ham} } @article {KNZ001234, title = {Annual fire and mowing alter biomass, depth distribution, and C and N content of roots and soil in tallgrass prairie}, journal = {Plant and Soil}, volume = {323}, year = {2009}, pages = {235 -247}, abstract = {

Management practices, such as fire and mowing, can affect the distribution and quality of roots and soil C and N in grasslands. We examined long-term (13 years) effects of annual fire and mowing on fine (\<2 mm) roots and soil C and N content in a native tallgrass prairie at Konza Prairie Biological Station in northeastern Kansas, USA. Using 90 cm deep soil cores, we determined that fire and mowing independently and interactively influenced the quantity and depth distribution of fine root biomass, root C and N concentration, and soil C and N content. Annual burning increased total fine root biomass by 48\% and total C storage in roots by 47\% compared to unburned unmowed plots, and resulted in a deeper distribution of roots. There was a significant interaction of fire and mowing, whereby mowing reduced root biomass and root C storage by ~30\% in annually burned plots, but did not affect total root biomass in unburned plots. Mowing also resulted in shallower distribution of roots regardless of fire treatment. Root N concentration was reduced by 15\–25\% in plots that were burned, mowed, or both. Mowing effects on soil C and N were restricted to surface soils (0\–10 cm), where mowing reduced soil C concentrations by ~20\% and N concentrations by 17\% regardless of burning treatment. In contrast, burning alone did not significantly influence soil C and N concentrations. In general, root biomass, root C and N mass, and soil C and N concentrations declined with depth, and most responses to burning and mowing exhibited significant interactions with depth. Different long-term fire and mowing regimes can significantly alter belowground root biomass and C and N dynamics in grasslands, and in particular at depths in the profile that are not typically sampled.

}, keywords = {LTER-KNZ, fire, grassland, Mowing, Root biomass depth distribution, Soil C and N, tallgrass prairie}, doi = {10.1007/s11104-009-9931-2}, url = {https://link.springer.com/article/10.1007\%2Fs11104-009-9931-2}, author = {Kitchen, D.J. and John M. Blair and Callaham, M.A.} } @article {KNZ001275, title = {Landscape-level variation in temperature sensitivity of soil organic carbon decomposition}, journal = {Soil Biology \& Biochemistry}, volume = {42}, year = {2009}, pages = {373 -375}, abstract = {

We examined landscape-level variation in temperature sensitivity of labile SOC across 71 sites at a central North American grassland. The observed range in activation energy of decomposition (Ea), an index of temperature sensitivity, was as great at the landscape scale as has been observed at the continental scale. Ea was lower for soils with more labile C, consistent with the \‘Carbon quality-temperature\’ hypothesis. Soil pH explained 67\% of the variation in Ea. Although there are strong environmental correlates with the Ea of SOC decomposition at landscape scales, the amount of variation within landscapes could confound regional- to global-scale predictions of the response of soil C to warming.

}, keywords = {LTER-KNZ, grassland, Microbial respiration, Soil organic carbon, Temperature sensitivity, Warming}, doi = {10.1016/j.soilbio.2009.10.024}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0038071709004015?via\%3Dihub}, author = {Craine, J.M. and Spurr, R. and McLauchlan, K.K. and Fierer, N.} } @article {KNZ001162, title = {Comparison of damage to native and exotic tallgrass prairie plants by natural enemies}, journal = {Plant Ecology}, volume = {198}, year = {2008}, pages = {197 -210}, abstract = {

We surveyed the prevalence and amount of leaf damage related to herbivory and pathogens on 12 pairs of exotic (invasive and noninvasive) and ecologically similar native plant species in tallgrass prairie to examine whether patterns of damage match predictions from the enemy release hypothesis. We also assessed whether natural enemy impacts differed in response to key environmental factors in tallgrass prairie by surveying the prevalence of rust on the dominant C4 grass, Andropogon gerardii, and its congeneric invasive exotic C4 grass, A. bladhii, in response to fire and nitrogen fertilization treatments. Overall, we found that the native species sustain 56.4\% more overall leaf damage and 83.6\% more herbivore-related leaf damage when compared to the exotic species. Moreover, we found that the invasive exotic species sustained less damage from enemies relative to their corresponding native species than the noninvasive exotic species. Finally, we found that burning and nitrogen fertilization both significantly increased the prevalence of rust fungi in the native grass, while rust fungi rarely occurred on the exotic grass. These results indicate that reduced damage from enemies may in part explain the successful naturalization of exotic species and the spread of invasive exotic species in tallgrass prairie.

}, keywords = {LTER-KNZ, Enemy release hypothesis, grassland, Invasiveness, Leaf damage, Rust fungi}, doi = {10.1007/s11258-008-9395-0}, url = {https://link.springer.com/article/10.1007\%2Fs11258-008-9395-0}, author = {Han, X. and Dend, S.P. and Garrett, K.A. and Fang, L. and M.D. Smith} } @article {KNZ001202, title = {Conversion of grassland to coniferous woodland has limited effects on soil nitrogen cycle processes}, journal = {Soil Biology \& Biochemistry}, volume = {40}, year = {2008}, pages = {2627 -2633}, abstract = {

In the last century, conversion of native North American grasslands to Juniperus virginiana forests or woodlands has dramatically altered ecosystem structure and significantly increased ecosystem carbon (C) stocks. We compared soils under recently established J. virginiana forests and adjacent native C4-dominated grassland to assess changes in potential soil nitrogen (N) transformations and plant available N. Over a 2-year period, concentrations of extractable inorganic N were measured in soils from forest and grassland sites. Potential gross N ammonification, nitrification, and consumption rates were determined using 15N isotope-dilution under laboratory conditions, controlling for soil temperature and moisture content. Potential nitrification rates (Vmax) and microbial biomass, as well as soil physical and chemical properties were also assessed. Extractable NH4+ concentrations were significantly greater in grassland soils across the study period (P \≤ 0.01), but analysis by date indicated that differences in extractable inorganic N occurred more frequently in fall and winter, when grasses were senescent but J. virginiana was still active. Laboratory-based rates of gross N mineralization (ammonification) and nitrification were greater in grassland soils (P \≤ 0.05), but only on one of four dates. Potential nitrification rates (Vmax) were an order of magnitude greater than gross nitrification rates in both ecosystems, suggesting that nitrification is highly constrained by NH4+ availability. Differences in plant uptake of N, C inputs, and soil microclimate as forests replace grasslands may influence plant available N in the field, as evidenced by seasonal differences in soil extractable NH4+, and total soil C and N accumulation. However, we found few differences in potential soil N transformations under laboratory conditions, suggesting that this grassland-to-forest conversion caused little change in mineralizable organic N pools or potential microbial activity.

}, keywords = {LTER-KNZ, Extractable N, Forest encroachment, grassland, Isotope dilution, Juniperus, Microbial biomass, Mineralization, nitrification, Nitrogen cycling, prairie}, doi = {10.1016/j.soilbio.2008.07.005}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0038071708002320?via\%3Dihub}, author = {McKinley, D.C. and C. W. Rice and John M. Blair} } @phdthesis {KNZ001104, title = {Belowground bud banks as regulators of grassland dynamics}, volume = {PhD Dissertation}, year = {2007}, pages = {1 -93}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS}, abstract = {

In perennial grasslands, the belowground population of meristems (the bud bank) plays a fundamental role in local plant population structure and dynamics. I tested the \“meristem limitation hypothesis\” prediction that bud banks increase along an increasing precipitation/productivity gradient in North American grasslands. I sampled bud populations quarterly at six sites across a 1,100 km gradient in central North America. Bud banks increased with average annual precipitation, which explained 80\% of variability in bud banks among sites. Seasonal changes in grass bud banks were surprisingly similar across a 2.5-fold range in precipitation and a 4-fold range of aboveground net primary productivity (ANPP). Secondly, I tested the hypothesis that tallgrass prairie plants respond to increases in a limiting resource (nitrogen) through demographic effects on the bud bank. I parameterized matrix models for individual genets, considering each genet as a population of plant parts (buds and stems). Nitrogen addition significantly impacted bud bank demography of both Sporobolus heterolepis and Koeleria macrantha. In 2005, emergence from the bud bank and growth rates (λ) of the tiller population were significantly higher in S. heterolepis genets that received nitrogen. In contrast, nitrogen addition decreased λ in K. macrantha. Both prospective and retrospective analyses indicated that bud bank dynamics are the key demographic processes driving genet responses to nutrient availability. Lastly, I tested the hypothesis that the effects of fire and grazing on plant species composition and ANPP are mediated principally through demographic effects on bud banks. I found that plants respond to fire and grazing with altered rates of belowground bud natality, bud emergence, and both short-term (fire cycle) and long-term changes in bud density. The size of the bud bank is an excellent predictor of long-term ANPP, supporting my hypothesis that ANPP is strongly regulated by belowground demographic processes. Meristem limitation due to water or nutrient availability or management practices such as fire and grazing may constrain grassland responses to inter-annual changes in resource availability. An important consequence is that grasslands with a large bud bank may be the most responsive to future climatic change or other phenomena such as nutrient enrichment, and may be most resistant to exotic species invasions.

}, keywords = {LTER-KNZ, Bud bank, grassland, plant ecology, population biology}, url = {http://krex.k-state.edu/dspace/handle/2097/312}, author = {Dalgleish, H.J.} } @article {KNZ001097, title = {Consumptionof mycorrhizal and saprophytic fungi by Collembola in grassland soils}, journal = {Soil Biology and Biochemistry}, volume = {39}, year = {2007}, pages = {2594 -2602}, abstract = {Although soil-dwelling Collembola can influence plant growth and nutrient cycling, their specific role in soil food webs is poorly understood. Soil-free microcosm studies suggest that Collembola are primarily fungivores where they feed preferentially on saprophytic fungi (SF) over other fungal types. We directly assessed collembolan consumption of arbuscular mycorrhizal fungi (AMF) and SF using plant{\textendash}soil mesocosms and natural abundance stable carbon isotope techniques. Mycorrhizal Andropogon gerardii (C4 grass) seedlings were placed in pots containing Collembola and soil from a C3 plant dominated site, while mycorrhizal Pascopyrum smithii (C3 grass) seedlings were placed in pots with Collembola and soil collected at a C4 plant dominated site. After 6 weeks, collembolans assimilated carbon derived from C3 and C4 sources in both A. gerardii and P. smithii treatments. Comparing Collembola isotope values in AMF vs. AMF-suppressed treatments, our data show that both AMF and SF were consumed in these experimental soil environments.}, keywords = {LTER-KNZ, Andropogon gerardii, Arbuscular mycorrhizal fungi, Collembola, grassland, Natural abundance stable isotopes, Pascopyrum smithii, Saprophytic fungi, δ13C}, doi = {10.1016/j.soilbio.2007.05.004}, author = {Jonas, J.L. and G.T. Wilson and White, P.M. and Anthony Joern} } @article {KNZ001141, title = {Diurnal activity and habitat associations of white-tailed deer in tallgrass prairie of eastern Kansas}, journal = {Transactions of the Kansas Academy of Science}, volume = {110}, year = {2007}, pages = {145 -154}, abstract = {Diurnal and seasonal patterns of activity and habitat associations of white-tailed deer (Odocoileus virginianus) were assessed in a mosaic of grassland and woodland habitats on the Konza Prairie Biological Station, Kansas. We recorded deer seen during daylight hours in summer, autumn and winter periods from June 1997 through February 1998. Overall, diurnal activity increased from summer to winter and was largely crepuscular (i.e., early morning and late evening). Deer were observed primarily in lower uplands during summer and winter, and in lowlands during autumn. At a coarse scale (6.25 ha), white-tailed deer selected areas that had woody vegetation and avoided those that were dominated by grassy vegetation. In contrast, at a fine scale, groups of deer most often were observed foraging in the immediate vicinity of grassland vegetation, rather than in or by woody vegetation.}, keywords = {LTER-KNZ, Flint Hills, grassland, Konza Prairie, Odocoileus virginianus, seasonal activity, topography, woodland, woody invasion}, doi = {10.1660/0022-8443(2007)110[145:DAAHAO]2.0.CO;2}, author = {Volk, M.D. and D.W. Kaufman and Kaufman, G.A.} } @article {KNZ00993, title = {Intra-annual rainfallvariability and grassland productivity: can the past predictthe future}, journal = {Plant Ecology}, volume = {184}, year = {2006}, pages = {65 -74}, abstract = {Precipitation quantity has been shown to influence grassland aboveground net primary productivity (ANPP) positively whereas experimental increases in of temporal variability in water availability commonly exhibit a negative relationship with ANPP. We evaluated long term ANPP datasets from the Konza Prairie Long Term Ecological Research (LTER) program (1984{\textendash}1999) to determine if similar relationships could be identified based on patterns of natural variability (magnitude and timing) in precipitation. ANPP data were analyzed from annually burned sites in native mesic grassland and productivity was partitioned into graminoid (principally C4 grasses) and forb (C3 herbaceous) components. Although growing season precipitation amount was the best single predictor of total and grass ANPP (r 2=0.62), several measures of precipitation variability were also significantly and positively correlated with productivity, independent of precipitation amount. These included soil moisture variability, expressed as CV, for June (r 2=0.45) and the mean change in soil moisture between weekly sampling periods in June and August (\%wv) (r 2=0.27 and 0.32). In contrast, no significant relationships were found between forb productivity and any of the precipitation variables (p>0.05). A multiple regression model combining precipitation amount and both measures of soil moisture variability substantially increased the fit with productivity (r 2=0.82). These results were not entirely consistent with those of short-term manipulative experiments in the same grassland, however, because soil moisture variability was often positively, not negatively related to ANPP. Differences in results between long and short term experiments may be due to low variability in the historic precipitation record compared to that imposed experimentally as experimental levels of variability exceeded the natural variability of this dataset by a factor of two. Thus, forecasts of ecosystem responses to climate change (i.e. increased climatic variability), based on data constrained by natural and recent historical rainfall patterns may be inadequate for assessing climate change scenarios if precipitation variability in the future is expected to exceed current levels.}, keywords = {LTER-KNZ, ANPP, Climate change, grassland, Precipitation variability, soil moisture, tallgrass prairie}, doi = {10.1007/s11258-005-9052-9}, author = {Jesse B. Nippert and Alan K. Knapp and J. M. Briggs} } @article {KNZ00938, title = {The role of seed and vegetative reproduction in plant recruitment and demography in tallgrass prairie}, journal = {Plant Ecology}, volume = {187}, year = {2006}, pages = {163 -177}, abstract = {Recruitment, establishment and survivorship of seed- and vegetatively-derived shoots were quantified biweekly in annually burned and infrequently burned tallgrass prairie to investigate the contributions of seed and vegetative reproduction to the maintenance and dynamics of tallgrass prairie plant populations, the demography of seedlings and ramets, and the influence of fire on the demography of grasses and forbs. Clonally produced grass and forb ramets comprised >99\%of all established shoots present at the end of the growing season, whereas established seedlings accounted for <1\%,emphasizing the rarity of successful seedling establishment and the importance of vegetative reproduction in driving the annual regeneration and dynamics of aboveground plant populations in tallgrass prairie. Most recruitment from vegetative reproduction occurred early in the growing season and was higher in annually burned than infrequently burned sites, although low levels of new stem recruitment occurred continuously throughout the growing season. Peak recruitment on annually burned prairie coincided with peak recruitment of the dominant C4 grasses Andropogon gerardii and Sorghastrum nutans prior to prescribed spring fire, with a second peak in recruitment occurring following fire. On infrequently burned prairie, grass and forb recruitment was highest in early April and declined steadily through May. The naturalized C3 grass, Poa pratensis, was responsible for most of the early recruitment on unburned sites, whereas A. gerardii contributed most to recruitment later in May. Infrequently burned prairie was dominated by these two grasses and contained a larger forb component than annually burned prairie. The principal demographic effect of fire was on ramet natality rather than mortality. Fire regime, plant functional group, or timing of cohort emergence before or after fire did not affect ramet survivorship. C4 grass shoots that emerged early and were damaged by fire showed similar survivorship patterns to tillers that emerged after fire. Differences in species composition between annually burned and infrequently burned prairie are driven by fire effects on vegetative reproduction and appear to be related principally to the effect of fire and detritus accumulation on the development of belowground vegetative meristems of C4 grasses and their emergence dynamics.}, keywords = {LTER-KNZ, fire ecology, grassland, Rhizomes, Sexual reproduction, Survivorship}, doi = {10.1007/s11258-005-0975-y}, author = {Benson, E. and D.C. Hartnett} } @article {KNZ001024, title = {Indicators of plant species richness in AVIRIS spectra of a mesic grassland}, journal = {Remote Sensing of Environment}, volume = {98}, year = {2005}, pages = {304 -316}, abstract = {Hyperspectral imagery of the Konza Prairie Biological Station in northeastern Kansas was used to evaluate upwelling spectral radiance, prairie spectral reflectance and band ratios of each as potential indicators of vascular plant species richness in a mesic grassland. The extent to which spatial variability in these parameters related to plant species richness also was investigated. A 224 channel hyperspectral data cube acquired in June 2000 by the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) provided complete coverage of the 400{\textendash}2500 nm range at approximately 10 nm per channel. After band deletions accounted for detector overlap and strong atmospheric attenuation features, 176 bands were retained for analysis and spanned the 404{\textendash}2400 nm range. Prairie reflectance was estimated via radiative transfer modeling and scaling to a library spectrum of highway construction material. Data were sampled from pixels having a 19 m ground sample distance (GSD) to represent each of 93 vegetation sampling transects. Reflectance and radiance at mid-infrared wavelengths (e.g., 1553 nm), and band ratios that were based on atmospheric windows in the red, near-infrared and mid-infrared spectra estimated species richness to within 6 to 7 species per transect. The 856 to 780 nm radiance or reflectance ratio yielded maximum adjusted coefficients of determination (r2) of approximately 0.4 in regressions with richness when data from bison-grazed and ungrazed areas were combined. These regressions remained significant (p <= 0.001) when only ungrazed areas were assessed although r2 reduced to approximately 0.2. Richness was related significantly also to the 433 to 674 nm reflectance ratio for grazed-plus-ungrazed and ungrazed-only areas. In contrast, the effectiveness of the 433 to 674 nm radiance ratio was reduced by atmospheric backscatter. Species richness did not correlate strongly or consistently with transect spatial variability (coefficient of variation or range) in radiance, reflectance or band ratio value, apparently as a consequence of the relatively small area sampled for each transect (approximately 0.5 ha). Relationships between richness and prairie spectral features were explained by the influence of soil exposure on both parameters. Richness and estimated soil exposure tended to increase from ungrazed lowlands, to ungrazed slopes, to ungrazed uplands to grazed areas. Remotely sensed estimates of soil exposure may be particularly useful in addressing plant species richness on grazed grasslands owing to an overall similarity in spectral reflectance among dominant plant species.}, keywords = {LTER-KNZ, AVIRIS, Biodiversity, Bison grazing, grassland, Hyperspectral, Plant species richness, Radiance, Reflectance, Soil exposure, Spatial variability, Spectral mixing}, doi = {10.1016/j.rse.2005.08.001}, author = {Carter, G.A. and Alan K. Knapp and Anderson, J.E. and Hoch, G.A. and M.D. Smith} } @article {KNZ001173, title = {Quantifying sediment transport across an undisturbed prairie landscape using cesium-137 and high resolution topography}, journal = {Geomorphology}, volume = {76}, year = {2005}, pages = {430 -440}, abstract = {Soil erosion is a global environmental problem, and anthropogenic fallout radionuclides offer a promising tool for describing and quantifying soil redistribution on decadal time scales. To date, applications of radioactive fallout to trace upland sediment transport have been developed primarily on lands disturbed by agriculture, grazing, and logging. Here we use 137Cs to characterize and quantify soil erosion at the Konza Prairie Long-Term Ecological Research (LTER) site, an undisturbed grassland in northeastern Kansas. We report on the small scale (< 10 m) and landscape scale (10 to 1000 m) distribution of fallout 137Cs, and show significant variability in the concentrations and amounts of 137Cs in soils at our site. 137Cs soil concentrations and amounts typically vary by 10\% to 30\% on small scales, which most likely represents the spatial heterogeneity of the depositional processes. Landscape scale variability of soil 137Cs was significantly higher than small scale variability. Most notably, soils collected on convex (divergent) landforms had 137Cs inventories of 2500 to 3000 Bq m- 2, which is consistent with the expected atmospheric inputs to the study area during the 1950s and 1960s. Concave landforms, however, had statistically lower inventories of 1800 to 2300 Bq m- 2. The distribution of 137Cs on this undisturbed landscape contrasts significantly with distributions observed across disturbed sites, which generally have accumulations of radioactive fallout in valley bottoms. Because the upslope contributing area at each sampling point had a significant negative correlation with the soil inventory of 137Cs, we suggest that overland flow in convergent areas dominates soil erosion at Konza on time scales of decades. Very few points on our landscape had 137Cs inventories significantly above that which would be predicted from direct deposition of 137Cs on the soil surface; we conclude therefore that there is little net sediment storage on this undisturbed landscape.}, keywords = {LTER-KNZ, Erosion, Geomorphology, grassland, Konza Prairie, Overland flow}, doi = {10.1016/j.geomorph.2005.12.007}, author = {Kaste, J.M. and Heimsatha, A.M. and Hohmann, M.} } @article {KNZ00893, title = {Regional patterns in carbon cycling across the Great Plains of North America}, journal = {Ecosystems}, volume = {8}, year = {2005}, pages = {106 -121}, abstract = {The large organic carbon (C) pools found in noncultivated grassland soils suggest that historically these ecosystems have had high rates of C sequestration. Changes in the soil C pool over time are a function of alterations in C input and output rates. Across the Great Plains and at individual sites through time, inputs of C (via aboveground production) are correlated with precipitation; however, regional trends in C outputs and the sensitivity of these C fluxes to annual variability in precipitation are less well known. To address the role of precipitation in controlling grassland C fluxes, and thereby soil C sequestration rates, we measured aboveground and belowground net primary production (ANPP-C and BNPP-C), soil respiration (SR-C), and litter decomposition rates for 2 years, a relatively dry year followed by a year of average precipitation, at five sites spanning a precipitation gradient in the Great Plains. ANPP-C, SR-C, and litter decomposition increased from shortgrass steppe (36, 454, and 24 g C m-2 y-1) to tallgrass prairie (180, 1221, and 208 g C m-2 y-1 for ANPP-C, SR-C, and litter decomposition, respectively). No significant regional trend in BNPP-C was found. Increasing precipitation between years increased rates of ANPP-C, BNPP-C, SR-C, and litter decomposition at most sites. However, regional patterns of the sensitivity of ANPP-C, BNPP-C, SR-C, and litter decomposition to between-year differences in precipitation varied. BNPP-C was more sensitive to between-year differences in precipitation than were the other C fluxes, and shortgrass steppe was more responsive than were mixed grass and tallgrass prairie.}, keywords = {LTER-KNZ, grassland, Great Plains, litter decomposition, Net primary production, Precipitation, Regional trends, soil respiration}, doi = {10.1007/s10021-004-0117-8}, author = {McCulley, R.L. and Burke, I.C. and Nelson, J.A. and Lauenroth, W.K. and Alan K. Knapp and Kelly, E.F.} } @article {KNZ00978, title = {Soil heterogeneity effects on tallgrass prairie community heterogeneity: anapplication of ecological theory to restoration ecology}, journal = {Restoration Ecology}, volume = {13}, year = {2005}, pages = {413 -424}, abstract = {Spatial heterogeneity of resources can influence plant community composition and diversity in natural communities. We manipulated soil depth (two levels) and nutrient availability (three levels) to create four heterogeneity treatments (no heterogeneity, depth heterogeneity, nutrient heterogeneity, and depth + nutrient heterogeneity) replicated in an agricultural field seeded to native prairie species. Our objective was to determine whether resource heterogeneity influences species diversity and the trajectory of community development during grassland restoration. The treatments significantly increased heterogeneity of available inorganic nitrogen (N), soil water content, and light penetration. Plant diversity was indirectly related to resource heterogeneity through positive relationships with variability in productivity and cover established by the belowground manipulations. Diversity was inversely correlated with the average cover of the dominant grass, Switchgrass (Panicum virgatum), which increased over time in all heterogeneity treatments and resulted in community convergence among the heterogeneity treatments over time. The success of this cultivar across the wide range of resource availability was attributed to net photosynthesis rates equivalent to or higher than those of the native prairie plants in the presence of lower foliar N content. Our results suggest that resource heterogeneity alone may not increase diversity in restorations where a dominant species can successfully establish across the range of resource availability. This is consistent with theory regarding the role of ecological filters on community assembly in that the establishment of one species best adapted for the physical and biological conditions can play an inordinately important role in determining community structure.}, keywords = {LTER-KNZ, grassland, Panicum virgatum, restoration, soil heterogeneity, switchgrass, tallgrass prairie}, doi = {10.1111/j.1526-100X.2005.00051.x}, author = {S.G. Baer and Scott. L. Collins and John M. Blair and Fiedler, A. and Alan K. Knapp} } @article {KNZ00889, title = {Plant community responses to resource availability and heterogeneity during restoration}, journal = {Oecologia}, volume = {139}, year = {2004}, pages = {617 -629}, abstract = {Availability and heterogeneity of resources have a strong influence on plant community structure in undisturbed systems, as well as those recovering from disturbance. Less is known about the role of resource availability and heterogeneity in restored communities, although restoration provides a valuable opportunity to test our understanding of factors that influence plant community assembly. We altered soil nitrogen (N) availability and soil depth during a prairie restoration to determine if the availability and/or heterogeneity of soil resources influenced plant community composition in restored grassland communities. Plant community responses to three levels of N availability (ambient, enriched by fertilization, and reduced by carbon amendment) and two levels of soil depth (deep and shallow) were evaluated. In addition, we evaluated plant community responses to four whole plot heterogeneity treatments created from the six possible combinations of soil N availability and soil depth. The soil depth treatment had little influence on community structure during the first 3 years of restoration. Total diversity and richness declined over time under annual N enrichment, whereas diversity was maintained and richness increased over time in soil with reduced N availability. Non-native species establishment was lowest in reduced-N soil in the initial year, but their presence was negligible in all of the soil N treatments by the second year of restoration. Panicum virgatum, a native perennial C4 grass, was the dominant species in all soil N treatments by year three, but the magnitude of its dominance was lowest in the reduced-N soil and highest in enriched-N soil. Consequently, the relative cover of P. virgatum was strongly correlated with community dominance and inversely related to diversity. The differential growth response of P. virgatum to soil N availability led to a higher degree of community similarity to native prairie in the reduced-N treatment than in the enriched-N treatment. There were no differences in plant community structure among the four whole plot-level heterogeneity treatments, which all exhibited the same degree of similarity to native prairie. Diversity and community heterogeneity in the whole-plot treatments appeared to be regulated by the dominant species{\textquoteright} effect on light availability, rather than soil N heterogeneity per se. Our results indicate that a strong differential response of a dominant species to resource availability in a restored community can regulate community structure, diversity, and similarity to the native (or target) community, but the importance of resource heterogeneity in restoring diversity may be dampened in systems where a dominant species can successfully establish across a range of resource availability.}, keywords = {LTER-KNZ, diversity, grassland, nitrogen, tallgrass prairie}, doi = {10.1007/s00442-004-1541-3}, author = {S.G. Baer and John M. Blair and Scott. L. Collins and Alan K. Knapp} } @article {KNZ00861, title = {Effects of fire, mowing and fertilization effects on density and biomass of macroinvertebrates in North American tallgrass prairie soils}, journal = {Soil Biology \& Biochemistry}, volume = {35}, year = {2003}, pages = {1079 -1093}, abstract = {The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.}, keywords = {LTER-KNZ, biomass, Cicadidae, Curculionidae, disturbance, earthworms, Elateridae, Fertilization, Fertilizer, fire, grassland, insect herbivores, nitrogen, Phosphorus, Scarabaeidae}, doi = {10.1016/S0038-0717(03)00153-6}, author = {Callaham, M.A. Jr. and John M. Blair and T.C. Todd and Kitchen, D.J. and M.R. Whiles} } @inbook {KNZ0010, title = {Applications of advanced technologies in studying and managing grassland landscape integrity}, booktitle = {Integrating Landscape Ecology into Natural Resource Management}, year = {2002}, pages = {390 -411}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge, U.K.}, keywords = {LTER-KNZ, grassland, landscape}, author = {Hoch, G. and B. Brock and J. M. Briggs}, editor = {Liu, J. and Taylor, W.W.} } @article {KNZ001, title = {Changes in ecosystem structure and function along a chronosequence of restored grasslands}, journal = {Ecological Applications}, volume = {12}, year = {2002}, pages = {1688 -1701}, abstract = {Changes in aboveground vegetation, roots, and soil characteristics were examined from a 12-yr chronosequence of formerly cultivated fields restored to native C4 grasses through the Conservation Reserve Program (CRP). Following 6{\textendash}8 yr in the CRP, the native grasses dominated vegetation composition, and the presence of forbs was negligible. Productivity of the restored grasslands did not exhibit any directional changes with the number of years in the CRP, and productivity was generally higher than native prairie in this region. Over time, the restored grasslands accumulated root biomass of decreasing quality as indicated by increasing root biomass and C:N ratio of roots along the 12-yr chronosequence. Root biomass, root C:N ratio, C storage in roots, and N storage in roots of restored grasslands approached that of native tallgrass prairie within the 12 yr of restoration. Establishment of the perennial vegetation also affected soil physical, chemical, and biological characteristics. Soil bulk density in the surface 10 cm decreased with time since restoration. Total C, microbial biomass C, and C mineralization rates increased as a function of time since restoration. The greatest change in total C occurred in the surface 5 cm, where total C was 26\% greater in 12- vs. 2-yr restored grasslands. Extractable soil nitrate and soil N transformations (i.e., net N mineralization rates and net nitrification rates) declined over the restoration chronosequence, but these values were not representative of steady-state conditions due to the high variability in these measures among the native prairies. Although complete restoration of ecosystem structure and function was not the primary intention of the CRP, this study demonstrates that establishment of the matrix vegetation (i.e., native C4 grasses) drives ecosystem processes in the trajectory of the original system. Moreover, restoration may hasten the recovery of soil C pools relative to formerly cultivated systems undergoing natural succession.}, keywords = {LTER-KNZ, ecosystem, function, grassland, structure}, doi = {10.1890/1051-0761(2002)012[1688:CIESAF]2.0.CO;2}, author = {S.G. Baer and Kitchen, D.J. and John M. Blair and C. W. Rice} } @article {KNZ00758, title = {Different behavioral patterns of the earthworms Octolasion tyrtaeum and Diplocardia spp . in tallgrass prairie soils: potential influences on plant growth}, journal = {Biology and Fertility of Soils}, volume = {34}, year = {2001}, pages = {49 -56}, abstract = {This study addressed differences between Diplocardia spp. (a native North American earthworm) and Octolasion tyrtaeum (an introduced European species), with respect to behavior, influence on soil microbial biomass, and plant uptake of N in tallgrass prairie soils. We manipulated earthworms in PVC-encased soil cores (20 cm diameter) over a 45-day period under field conditions. Treatments included: (1) control with no earthworms, (2) Diplocardia spp. only, and (3) O. tyrtaeum only. Prior to addition of earthworms, seedlings of Andropogon gerardii (a dominant tallgrass) were established in each core, and a dilute solution of 13C-labeled glucose and 15N-labeled (NH4)2SO4 was added to the soil to facilitate examination of earthworm/microbe/plant interactions. We found that Diplocardia spp. were significantly more active than O. tyrtaeum, and quickly assimilated 13C and 15N from the tracer. Individuals of Diplocardia spp. were present at shallower soil depths than O. tyrtaeum throughout the study. Contrary to expectation, this greater activity of Diplocardia spp. did not result in increased plant productivity. Rather, the activity of Diplocardia spp. was associated with less plant growth and smaller amounts of N acquired by A. gerardii seedlings compared to controls or O. tyrtaeum treatments. We observed few significant influences of earthworm treatments on microbial biomass C or N pool sizes, but the microbial C/N ratio was consistently greater in the presence of Diplocardia spp. relative to O. tyrtaeum. Results of this study indicate that activity of earthworms may enhance competition for N between microbes and plants during the growing season in tallgrass prairie.}, keywords = {LTER-KNZ, grassland, Microbial biomass, nitrogen, Soil invertebrates, Stable isotopes}, doi = {10.1007/s003740100370}, author = {Callaham, M.A. Jr. and John M. Blair and Hendrix, P.F.} } @article {KNZ00774, title = {Frequency and extent of water limitation to primary production in a mesic temperate grassland}, journal = {Ecosystems}, volume = {4}, year = {2001}, pages = {19 -28}, abstract = {The frequency and extent of water limitation to aboveground net primary production (ANPP) in a mesic grassland in NE Kansas (Konza Prairie, USA) was assessed with an 8-year irrigation experiment. Since 1991, transects spanning upland and lowland sites in annually burned, ungrazed tallgrass prairie were provided with supplemental water to satisfy evapotranspirational demands. This protocol minimized water limitations during the growing season, as well as interannual variability in water stress. Irrigation of this mesic grassland increased ANPP in 6 of 8 years by an average of 26\% when compared to control transects. Although interannual variation in ANPP was greater in uplands than lowlands at nominal levels of precipitation, reducing interannual variability in water availability via irrigation eliminated topographic differences; the irrigation protocol also reduced interannual variability in ANPP by as much as 40\%. The addition of supplemental water enabled us to extend the relationship between annual precipitation and ANPP in grasslands to precipitation levels (average, 1153 mm; maximum, 1346 mm) similar to those experienced by more mesic grasslands that today exist only as remnants several hundred kilometers east of Kansas. This relationship was linear (r 2= 0.81), with maximum ANPP (738 g/m2) similar to values reported for sites in Illinois and Wisconsin. After 8 years of irrigation, production of the C3 forb component was twice that in control sites. These results indicate that water limitations in grasslands at the western edge of the presettlement extent of tallgrass prairie affect ANPP in most years and that this high frequency of water limitation may lead to greater dominance of the C4 grasses than is seen in more eastern grassland sites.}, keywords = {LTER-KNZ, Andropogon gerardii, C 4 grasses, forbs, grassland, irrigation, leaf water potential, Primary production, tallgrass prairie, water limitation}, doi = {10.1007/s100210000057}, author = {Alan K. Knapp and J. M. Briggs and Koelliker, J.K.} } @article {KNZ00788, title = {Physiological and morphological traits of exotic, invasive exotic, and native plant species in tallgrass prairie}, journal = {International Journal of Plant Sciences}, volume = {162}, year = {2001}, pages = {785 -792}, abstract = {We compared 13 traits of invasive exotic, noninvasive exotic, and ecologically similar native species to determine if there are generalizable differences among these groups that relate to persistence and spread of exotic species in tallgrass prairie plant communities. When species were grouped as invasive (two species), noninvasive (five species), and native (six species), no differences were found for the suite of traits examined, likely because of the high variability within and between groups. However, when exotic species, regardless of invasiveness, were compared with the native species, specific leaf area was ca. 40\% higher for the exotic species, a result that is consistent with that of other studies. This pattern was also observed for five of seven pairwise comparisons of exotic and native species with similar life history traits. In contrast, total end-of-season biomass was as much as three times higher for the native species in five of seven of the native-exotic species pairs. For other traits, differences between exotic and native species were species-specific and were generally more numerous for noninvasive than for invasive exotic species pair-wise comparisons. Thus, contrary to predictions, exotic species capable of successfully invading tallgrass prairie did not differ considerably from native species in most traits related to resource utilization and carbon gain. Moreover, invasive exotic species, those capable of displacing native species and dominating a community, were not distinct for the observed traits from their native counterparts. These results indicate that other traits, such as the ability to respond to resource pulses or herbivory, may explain more effectively why certain invasive species are able to invade these communities aggressively.}, keywords = {LTER-KNZ, biomass allocation, grassland, invasive plants, photosynthesis, specific leaf area}, doi = {10.1086/320774}, author = {M.D. Smith and Alan K. Knapp} } @article {KNZ00724, title = {Feeding ecology and emergence production of annual cicadas (Homoptera: Cicadidae) in tallgrass prairie}, journal = {Oecologia}, volume = {123}, year = {2000}, pages = {535 -542}, abstract = {The emergence phenology and feeding ecology of annual cicadas in tallgrass prairie are poorly documented. However, these large insects are abundant, and their annual emergence represents a potentially important flux of energy and nutrients from belowground to aboveground. We conducted a study at Konza Prairie Research Natural Area in eastern Kansas to characterize and quantify cicada emergence and associated energy and nutrient fluxes. We established emergence trap transects in three habitat types (upland prairie, lowland prairie, and riparian forest), and collected cicadas every 3 days from May to September. A subset of trapped cicadas was used for species- and sex-specific mass, nutrient, and stable isotope analyses. Five species were trapped during the study, of which three were dominant. Cicadetta calliope and Tibicen aurifera exhibited significantly higher emergence production in upland prairie than in lowland prairie, and were not captured in forested sites at all. T. dorsata emerged from all three habitat types, and though not significant, showed a trend of greater abundance in lowland grasslands. Two less abundant species, T. pruinosa and T. lyricen, emerged exclusively from forested habitats. Nitrogen fluxes associated with total cicada emergence were estimated to be \~{}4 kg N ha{\textendash}1 year{\textendash}1 in both grassland habitats, and 1.01 kg N ha{\textendash}1 year{\textendash}1 in forested sites. Results of stable isotope analyses showed clear patterns of resource partitioning among dominant cicada species emerging from grassland sites. T. aurifera and C. calliope had δ13C and δ15N signatures indicative of feeding on shallowly rooted C4 plants such as the warm-season grasses dominant in tallgrass prairie ecosystems, whereas T. dorsata signatures suggested preferential feeding on more deeply rooted C3 plants.}, keywords = {LTER-KNZ, grassland, Insect emergence, Nutrient flux, resource partitioning, Stable isotopes}, doi = {10.1007/s004420000335}, author = {Callaham, M.A. Jr. and M.R. Whiles and Meyer, C.K. and B. Brock and Charlton, R.E.} } @article {KNZ00675, title = {Effect of spring burning on the surface energy balance in a tallgrass prairie}, journal = {Agricultural and Forest Meteorology}, volume = {97}, year = {1999}, pages = {43 -54}, abstract = {Spring burning of dead biomass in tallgrass prairie is a common practice that may influence heat and water vapor transport from the landscape. Bowen ratio methods were used to measure the surface energy balances and evapotranspiration (ET) from burned (B) and unburned (UB) prairie near Manhattan, KS, USA. Data were collected from day of year (DOY) 109{\textendash}258, 1997 following fire on the B site on DOY 107. Early in the growing season, differences in albedo and surface conductance to water vapor transport (gs, i.e., mulch effect) caused large variations in energy fluxes between B and UB sites. During a 44-day period immediately after the burn (DOY 109{\textendash}152), albedo averaged 43\% lower on the B compared with the UB site. Consequently, available energy (net radiation minus soil heat flux) was 8.6\% higher on the B than on the UB site. The gs during that time was over three times higher on the B site, a result of dead biomass removal by fire. During the same period, the daytime Bowen ratios averaged 0.79 on the B site and 2.89 on the UB site, with ET rates of 2.97 mm per day (B site) and 1.40 mm per day (UB site). By DOY 152, canopy growth had moderated differences in albedo and available energy between sites. However, gs and ET remained higher on the B site between DOY 152 and 181. Green leaf area index averaged 71\% higher on the B site, and was the primary cause for this mid-season effect (i.e., differences in transpiration). By DOY 182, the effects of the burn on energy fluxes were negligible. Cumulative estimates of ET during the 150-day period were 503 mm on the B site and 408 mm on the UB site, thus, burning increased seasonal ET by 23.3\%. Results suggest that land management or environmental factors that affect dead litter, albedo, or green leaf area will have strong impacts on the water and energy balances of a grassland.}, keywords = {LTER-KNZ, Bowen ratio, Evapotranspiration, fire, grassland, Land management, Seasonal variation}, doi = {10.1016/S0168-1923(99)00034-9}, author = {D. Bremer and J.M. Ham} } @article {KNZ00696, title = {Elevated CO2 and leaf longevity in the C4 grassland dominant Andropogon gerardii}, journal = {International Journal of Plant Sciences}, volume = {160}, year = {1999}, pages = {1057 -1061}, abstract = {In central U.S. grasslands, plant and ecosystem responses to elevated CO2 are most pronounced when water availability is limited. In a northeast Kansas grassland, responses to elevated CO2 in leaf area, number, development, and longevity were quantified for the tallgrass prairie dominant, Andropogon gerardii. Plants were grown in open-top chambers (OTCs) modified to limit water availability and to maximize responses to elevated CO2. In OTCs with elevated ({\texttimes}2 ambient) levels of CO2, aboveground biomass production and leaf water potentials were increased significantly compared with those of plants in OTCs with ambient CO2. There were no differences in leaf area or leaf number per tiller in A. gerardii in elevated compared with ambient OTCs. However, leaf area in adjacent unchambered plots with greater water availability was significantly higher than in the OTCs. The time required for developing leaves to achieve maximum leaf area was reduced by 29\%, and the period of time until leaves senesced was increased by 20\% for plants exposed to elevated compared with ambient CO2. Thus, leaves of this C4 grass species expanded more rapidly (6 d) and remained green longer (9 d) when exposed to elevated CO2. Such CO2-mediated increases in leaf longevity in the dominant species may allow this grassland to respond more opportunistically to temporally variable rainfall patterns in high-CO2 environments. These responses should be included in leaf-based simulation models that attempt to mechanistically link physiological alterations to predicted canopy responses to increased CO2.}, keywords = {LTER-KNZ, Ecophysiology, elevated carbon dioxide, grassland, leaf lifespan, tallgrass prairie, Water relations}, doi = {10.1086/314202}, author = {Alan K. Knapp and Bargman, N. and Maragni, L.A. and McAllister, C.A. and D. Bremer and J.M. Ham and Owensby, C.E.} } @article {KNZ00710, title = {Exotic plant species in a C4-dominated grassland: Invasibility, disturbance and community structure}, journal = {Oecologia}, volume = {120}, year = {1999}, pages = {605 -612}, abstract = {We used data from a 15-year experiment in a C4-dominated grassland to address the effects of community structure (i.e., plant species richness, dominance) and disturbance on invasibility, as measured by abundance and richness of exotic species. Our specific objectives were to assess the temporal and spatial patterns of exotic plant species in a native grassland in Kansas (USA) and to determine the factors that control exotic species abundance and richness (i.e., invasibility). Exotic species (90\% C3 plants) comprised approximately 10\% of the flora, and their turnover was relatively high (30\%) over the 15-year period. We found that disturbances significantly affected the abundance and richness of exotic species. In particular, long-term annually burned watersheds had lower cover of exotic species than unburned watersheds, and fire reduced exotic species richness by 80{\textendash}90\%. Exotic and native species richness were positively correlated across sites subjected to different fire (r = 0.72) and grazing (r = 0.67) treatments, and the number of exotic species was lowest on sites with the highest productivity of C4 grasses (i.e., high dominance). These results provide strong evidence for the role of community structure, as affected by disturbance, in determining invasibility of this grassland. Moreover, a significant positive relationship between exotic and native species richness was observed within a disturbance regime (annually burned sites, r = 0.51; unburned sites, r = 0.59). Thus, invasibility of this C4-dominated grassland can also be directly related to community structure independent of disturbance.}, keywords = {LTER-KNZ, community structure, disturbance, exotic species, grassland, Invasibility}, doi = {10.1007/s004420050896}, author = {M.D. Smith and Alan K. Knapp} } @article {KNZ00656, title = {Is leaf-level photosynthesis related to plant success in a highly productive grassland?}, journal = {Oecologia}, volume = {117}, year = {1998}, pages = {40 -46}, abstract = {We addressed the question: {\textquotedblleft}Are short-term, leaf-level measurements of photosynthesis correlated with long-term patterns of plant success?{\textquotedblright} in a productive grassland where interspecific competitive interactions are important. To answer this question, seasonal patterns of leaf-level photosynthesis were measured in 27 tallgrass prairie species growing in sites that differed in species composition and productivity due to differences in fire history. Our specific goals were to assess the relationship between gas exchange under field conditions and success (defined as aerial plant cover) for a wide range of species, as well as for these species grouped as dominant and sub-dominant grasses, forbs, and woody plants. Because fire increases productivity and dominance by grasses in this system, we hypothesized that any relationship between photosynthesis and success would be strongest in annually burned sites. We also predicted that regardless of fire history, the dominant species (primarily C4 grasses) would have higher photosynthetic rates than the less successful species (primarily C3 grasses, forbs and woody plants). Because forbs and woody species are less abundant in annually burned sites, we expected that these species would have lower photosynthetic rates in annually burned than in infrequently burned sites. As expected, the dominant C4{\textvisiblespace}grasses had the highest cover on all sites, relative to{\textvisiblespace}other growth forms, and they had the highest maximum and seasonally averaged photosynthetic rates (17.6 {\textpm} 0.42 μmol m-2 s-1). Woody species had the lowest average cover as well as the lowest average photosynthetic rates, with subdominant grasses and forbs intermediate in both cover and photosynthesis. Also as predicted, the highest overall photosynthetic rates were found on the most productive annually burned site. Perhaps most importantly, a positive relationship was found between leaf-level photosynthesis and cover for a core group of species when data were combined across all sites. These data support the hypothesis that higher instantaneous rates of leaf-level photosynthesis are indicative of long-term plant success in this grassland. However, in contrast to our predictions, the subdominant grasses, forbs and woody species on the annually burned site had higher photosynthetic rates than in the less frequently burned sites, even though their average cover was lower on annually burned sites, and hence they were less successful. The direct negative effect of fire on plant cover and species-specific differences in the availability of resources may explain why photosynthesis was high but cover was low in some growth forms in annually burned sites.}, keywords = {LTER-KNZ, Competition, grassland, photosynthesis, Plant cover, tallgrass prairie}, doi = {10.1007/s004420050629}, author = {McAllister, C.A. and Alan K. Knapp and Maragni, L.A.} } @article {KNZ00613, title = {Contingent effects of plant species on soils along a regional moisture gradient in the Great Plains}, journal = {Oecologia}, volume = {110}, year = {1997}, pages = {393 -402}, abstract = {The central grassland region of the United States encompasses major gradients in temperature and precipitation that determine the distribution of plant life forms, which in turn may influence key ecosystem processes such as nutrient cycling and soil organic matter dynamics. One such gradient is the threefold increase in precipitation from the eastern Colorado shortgrass-steppe, in the rain shadow of the Rocky Mountains, to the tallgrass prairie in eastern Kansas. We investigated the relative roles of plant species and plant cover in influencing soil C and N cycling in three sites along this gradient. Plant cover (i.e., the presence or absence of an individual plant) was relatively more important than plant species in explaining variability in soil properties at the dry site, the Central Plains Experimental Range in{\textvisiblespace}northeastern Colorado. However, plant species explained relatively more of the variability in soil properties than did plant cover at the two wetter sites, Hays and Konza, in central and eastern Kansas. The wetter sites had more continuous plant cover, resulting in less plant-cover-induced variation in soil C and N, than did the dry site, which had distinct patches of bare ground. Plant species at the wetter sites had higher and more variable levels of tissue C:N than plant species at the dry site, due to both within species changes and changes in species composition. Aboveground tissue C:N was better correlated with net nitrogen mineralization rates at the wet sites than the dry site. Thus, tissue chemistry appears to exert more control on nitrogen dynamics at the wet than the dry sites. The results suggest that plant species traits that are relevant to nutrient cycling (e.g., tissue C:N ratios, spatial patterns, productivity) reflect environmental limitations as well as species{\textquoteright} physiological potentials. Furthermore, a dominant environmental driver such as precipitation may ameliorate or exaggerate the importance of individual species traits for nutrient cycling.}, keywords = {LTER-KNZ, grassland, Litter quality, Plant-soil interactions, Soil carbon, Soil nitrogen}, doi = {10.1007/s004420050174}, author = {Vinton, M.A. and Burke, I.C.} } @mastersthesis {KNZ0031, title = {Seasonal nitrogen translocation in big bluestem, Andropogon gerardii Vitman, in Kansas during a drought year}, volume = {MS Thesis}, year = {1982}, pages = {1 -75}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ, grassland, nitrogen, translocation}, url = {http://krex.k-state.edu/dspace/handle/2097/12760}, author = {Hayes, D.C.} }