@mastersthesis {KNZ001909, title = {Facilitating nurse plant survival with mycorrhizal inoculum following eradication of a non-native grass}, volume = {MS Thesis}, year = {2018}, school = {Oklahoma State University}, type = {M.S. Thesis}, address = {Stillwater, OK}, keywords = {LTER-KNZ}, url = {https://shareok.org/handle/11244/317698}, author = {Wilson, L.O.R.} } @article {KNZ001771, title = {Above- and below-ground responses of native and invasive prairie grasses to future climate scenarios}, journal = {Botany}, volume = {94}, year = {2016}, pages = {471 - 479}, abstract = {

More intense and frequent droughts, coupled with elevated temperatures, are projected for grasslands worldwide. Although it has been suggested that alterations in temperature and precipitation will increase the success of biological invasions, studies that combine these climate change scenarios are limited. These changes in climate may increase the success of non-native, invasive plant species directly, as these species often possess traits that are favored by variable climates, or indirectly through negative impacts on native vegetation or alterations in soil microbial communities, such as arbuscular mycorrhizal (AM) fungi. The goal of our research was to assess above- and below-ground production and mycorrhizal fungal abundance of functionally similar native and invasive non-native grass species under projected climate-change scenarios. We assessed plant biomass, intra-radical AM root colonization, and relative abundance of extra-radical fungal biomass of two native (Schizachyrium scoparium (Michx.) Nash, Pascopyrum smithii (Rydb.) {\'A}.L{\"o}ve) and two invasive (Bothriochloa ischaemum (L.) Keng, Bromus inermis Leyss.) grass species subjected to increased temperature and decreased soil water availability. Regardless of temperature or soil moisture, the invasive grasses in our study displayed greater seedling growth as compared with paired native species. Invasive grasses were also generally characterized by greater intra-radical colonization by AM fungi, compared with native species. Our data suggest that invasive grasses will continue to be problematic and successfully out-compete native grasses following increased temperatures and reduced water availability, as projected by climate-change models.

}, keywords = {LTER-KNZ, Bothriochloa ischaemum, Bromus imermis, Climate change, Invasive species, Pascopyrum smithii, Schizachyrium scoparium}, doi = {10.1139/cjb-2015-0238}, url = {http://www.nrcresearchpress.com/doi/10.1139/cjb-2015-0238}, author = {E.B. Duell and G.T. Wilson and Hickman, K.R.} } @mastersthesis {KNZ001874, title = {Soil characteristics and ecosystem-level effects of woody species encroachment in tallgrass prairie}, volume = {MS Thesis}, year = {2016}, school = {Oklahoma State University}, type = {M.S. Thesis}, address = {Stillwater, OK}, keywords = {LTER-KNZ}, url = {https://shareok.org/handle/11244/54571}, author = {Mino, L.A.} } @mastersthesis {KNZ001769, title = {Elevated temperatures and drought favor invasive grasses over native species}, volume = {MS Thesis}, year = {2015}, school = {Oklahoma State University}, type = {M.S. Thesis}, address = {Stillwater, OK}, keywords = {LTER-KNZ}, url = {https://shareok.org/handle/11244/45161}, author = {E.B. Duell} } @article {KNZ001663, title = {Experimental evidence that invasive grasses use allelopathic biochemicals as a potential mechanism for invasion: Chemical warfare in nature}, journal = {Plant and Soil}, volume = {385}, year = {2014}, pages = {165 -179}, abstract = {

Background and aims Bothriochloa spp. are non-native warm-season grasses invading native grasslands of the southern and central Great Plains, altering ecological services these grasslands supply. Our study investigated potential allelopathic effects of the invasive grass species B. ischaemum on native grass germination, growth, and survival. Methods Leachate or litter from Andropogon gerardii (native) or B. ischaemum were applied to two native grass species (A. gerardii; Schizachyrium scoparium). Leachate and litter were also added to B. ischaemum and a water control was included. Germination, above- and belowground biomass, and survival were determined. Results Application of B. ischaemum leachate or litter significantly reduced the germination, growth, and survival of both A. gerardii and S. scoparium but had no conspecific effects, while A. gerardii treatments had no effect on any species. Conclusions Bothriochloa spp. may gain a competitive advantage through allelopathic biochemicals. It is unclear if these allelopathic effects directly hinder competitors or indirectly hinder them through alterations in soil microbial communities, however, reductions in germination of native seeds strongly support direct allelopathic effects. Greater phenolic content in native grass leachates suggest allelopathic biochemical production may not be unique to non-native species and may be a mechanism for maintenance of plant species biodiversity in native systems.

}, keywords = {LTER-KNZ, Allelopathy, Bothriochloa spp, Invasive species, Leachate, Leaf litter, Yellow bluestem}, doi = {10.1007/s11104-014-2209-3}, url = {https://link.springer.com/article/10.1007\%2Fs11104-014-2209-3}, author = {Greer, M.J. and G.T. Wilson and Hickman, K.R. and Wilson, S.} } @phdthesis {KNZ001669, title = {Grassland invasion by non-native grass species: ecological issues of multiple species at multiple trophic levels}, volume = {PhD. Dissertation}, year = {2013}, school = {Oklahoma State University}, type = {Ph.D. Thesis}, address = {Stillwater, OK}, abstract = {

Invasion of native grasslands by non-native grasses is of great economic and ecologic concern. Non-native grasses have potential to alter ecosystem functions, habitat quality, disturbance regimes, and feedback loops. These alterations can have bottom-up or top-down effects that may negatively influence grasslands at multiple trophic levels. I conducted three integrated studies to assess non-native grass invasion: 1) on the competitive interactions between native vs. non-native grass species with community-level implications; 2) possible utilization of allelopathic biochemicals as an invasion mechanism; and 3) possible alterations in the small mammal communities with implications for ecosystem-level function. My first study indicated that both invasive and native species varied in mycorrhizal dependency along a continuum from obligately to facultatively dependent. Native species biomass production was consistently reduced when planted into \&$\#$39;away\&$\#$39; soil, as compared to \&$\#$39;home\&$\#$39; soil. Increased biomass production of native grasses was consistently observed following additions of native prairie soil to steam-pasteurized soil from the invaded sites, indicating invasive feedbacks may occur through alterations in biotic communities. My second study indicated that Bothriochloa spp. may gain a competitive advantage through the use of allelopathic biochemicals. However, it is unclear if these allelopathic effects directly hinder competitors, or indirectly hinder competitors through alterations of soil microbial communities. Determination of allelopathic biochemicals was not definitive. Data from my third study indicate that invasion of B. ischaemum into the native grasslands lowered all abundance metrics for deer mice (Peromyscus maniculatus), while increasing all abundance metrics for hispid cotton rats (Sigmodon hispidus), as compared to native grassland controls. Species-specific models show cotton rats select vegetation that supplies aerial predator avoidance and deer mice select habitat that increases foraging efficency. Alterations in these small mammal communities may have profound effects on ecosystem functioning. Our research indicates non-native grass invasion alters native communities on multiple trophic levels. I propose management practices for restoration may be most successful if determined on a species-specific and site-specific basis, as different species appear to use different mechanisms for successful invasion into native prairies.

}, keywords = {LTER-KNZ}, url = {https://shareok.org/handle/11244/14859}, author = {Greer, M.J.} } @phdthesis {KNZ001567, title = {Bud bank demography: Density of native grass meristems as a predictor of rangeland invasibility}, volume = {PhD Dissertations}, year = {2012}, school = {Oklahoma State University}, type = {Ph.D. Thesis}, address = {Stillwater, OK}, keywords = {LTER-KNZ}, url = {https://shareok.org/handle/11244/6850}, author = {West, R.} } @article {KNZ001490, title = {Invasive warm-season grasses reduce mycorrhizal root colonization and biomass production of native prairie grasses}, journal = {Mycorrhiza}, volume = {22}, year = {2012}, pages = {327 -336}, abstract = {

Soil organisms play important roles in regulating ecosystem-level processes and the association of arbuscular mycorrhizal (AM) fungi with a plant species can be a central force shaping plant species\’ ecology. Understanding how mycorrhizal associations are affected by plant invasions may be a critical aspect of the conservation and restoration of native ecosystems. We examined the competitive ability of old world bluestem, a non-native grass (Caucasian bluestem [Bothriochloa bladhii]), and the influence of B. bladhii competition on AM root colonization of native warm-season prairie grasses (Andropogon gerardii or Schizachyrium scoparium), using a substitutive design greenhouse competition experiment. Competition by the non-native resulted in significantly reduced biomass production and AM colonization of the native grasses. To assess plant\–soil feedbacks of B. bladhii and Bothriochloa ischaemum, we conducted a second greenhouse study which examined soil alterations indirectly by assessing biomass production and AM colonization of native warm-season grasses planted into soil collected beneath Bothriochloa spp. This study was conducted using soil from four replicate prairie sites throughout Kansas and Oklahoma, USA. Our results indicate that a major mechanism in plant growth suppression following invasion by Bothriochloa spp. is the alteration in soil microbial communities. Plant growth was tightly correlated with AM root colonization demonstrating that mycorrhizae play an important role in the invasion of these systems by Bothriochloa spp. and indicating that the restoration of native AM fungal communities may be a fundamental consideration for the successful establishment of native grasses into invaded sites.

}, keywords = {LTER-KNZ, Arbuscular mycorrhizas, Big bluestemm, Bothriochloa bladhii, Bothriochloa ischaemum, Little bluestem, Old world bluestems, plant{\textendash}soil feedback, tallgrass prairie, Warm-season grasses}, doi = {10.1007/s00572-011-0407-x}, url = {https://link.springer.com/article/10.1007\%2Fs00572-011-0407-x}, author = {G.T. Wilson and Hickman, K.R. and Williamson, M.M.} } @mastersthesis {KNZ001346, title = {Bud bank density regulates invasion by exotic plants}, volume = {MS Thesis}, year = {2010}, school = {Oklahoma State University}, type = {M.S. Thesis}, address = {Stillwater, OK. 65 pp}, abstract = {

Grasslands and savannas, which cover as much as 30-50\% of the earth\&$\#$39;s ice-free land area, are affected by global environmental changes including biological invasions. To test the role of bud banks, an important feature of native prairie communities, in regulating invasion by exotic plants under three levels of simulated grazing (no clipping, 28 day clipping interval, and 14 day clipping interval) I conducted a greenhouse microcosm study. Using native rhizomes planted into native prairie soil, I established bud bank densities of 0, 30, 60, and 100\% of mean tallgrass prairie bud bank density. Seeds of three exotic species were sown into each microcosm. The number of emerging and established exotic plants in each microcosm was counted every 14 days. I measured the aboveground biomass of each species at the end of the growing season (22 weeks). Assessments of exotic plant emergence, establishment, survivorship, reproduction, and biomass based on these measurements were compared using analysis of variance. The effects of the bud bank on exotic plant emergence, establishment, and survivorship were inconsistent and relatively weak. However, reproduction and biomass of exotic species were strongly influenced by bud bank density. In the absence of clipping, the biomass of exotic species was 675\% higher at the lowest bud bank density than at the highest density. Furthermore, I found evidence for an invasibility threshold between 0-30\% of mean field bud bank density in tallgrass prairie. These findings improve our understanding of plant invasion and suggest that restoring and maintaining bud banks should be a priority for land managers seeking to prevent and limit plant invasions.

}, keywords = {LTER-KNZ}, url = {http://hdl.handle.net/11244/9198}, author = {Sprinkle, J.W.} } @article {KNZ00879, title = {Grazing management effects on plant species diversity in tallgrass prairie}, journal = {Journal of Range Management}, volume = {57}, year = {2004}, pages = {58 -65}, abstract = {A 6-year study was conducted in tallgrass prairie to assess the effects of grazing management (cattle stocking densities and grazing systems) on plant community composition and diversity. Treatments included sites grazed season-long (May to October) at 3 stocking densities (3.8, 2.8, and 1.8 hectares per animal unit), ungrazed control sites, and sites under a late-season rest rotation grazing system at this same range of stocking densities. Plant communities were sampled twice each season using a nearest-point procedure. Native plant species diversity, species richness, and growth form diversity were significantly higher in grazed compared to ungrazed prairie, and diversity was greatest at the highest stocking density. This enhancement of plant species diversity under grazing was not a result of increased frequency of weedy/exotic species. There were no significant effects of grazing system on plant diversity, nor any significant stocking density {\texttimes} grazing system interactions, indicating that animal density is a key management variable influencing plant species diversity and composition in tallgrass prairie and that effects of animal density override effects of grazing systems. Increasing cattle stocking densities decreased the abundance of the dominant perennial tall grasses, and increased abundance of the C4 perennial mid-grasses. The frequency of perennial forbs was relatively stable across grazing treatments. Abundance of annual forbs varied among years and grazing treatments. In half of the years sampled, annual forbs showed the highest frequency under intermediate stocking density. Patterns of responses among plant groups suggest that some species may respond principally to direct effects of grazers and others may respond to indirect effects of grazers on competitive relationships or on the spatial patterns of fuel loads and fires. Thus, this study suggests that large grazer densities, fire, and annual climatic variability interact to influence patterns of plant community composition and diversity in tallgrass prairie. Effects of varying management such as stocking densities and grazing systems on plant species diversity and the relative abundances of different plant growth forms or functional groups may have important consequences for grassland community stability and ecosystem function.}, keywords = {LTER-KNZ, Biodiversity, cattle grazing, Flint Hills, grazing systems, plant ecology, range management, stocking rates}, doi = {10.2111/1551-5028(2004)057[0058:GMEOPS]2.0.CO;2}, author = {Hickman, K.R. and D.C. Hartnett and Cochran, R.C. and Owensby, C.E.} } @article {KNZ009, title = {Effects of grazing intensity on growth, reproduction, and abundances of three palatable forbs in Kansas tallgrass prairie}, journal = {Plant Ecology}, volume = {159}, year = {2002}, pages = {23 -33}, abstract = {

The effects of different intensities of cattle grazing on the aboveground growth, reproduction, and abundances of three palatable forbs were studied in native tallgrass prairie. Populations of Aster ericoides, Ruellia humilis, and Amorpha canescens were sampled at peak flowering during the 1993-1995 growing seasons in four annually-burned sites varying in cattle stocking density [ungrazed, low, moderate, high]. The three forbs exhibitedreduced shoot growth and/or reproduction under moderate to heavy grazing, and in no case did grazing increase any measure of plant performance. Ruellia showed reduced shoot height and biomass, percentage of stemsflowering, and reproductive biomass in response to grazing. Aster showed decreases in shoot biomass and height with grazing. Amorpha showed no change in shoot or reproductive biomass, but a decrease in percent of flowering stems and in reproductive allocation with grazing. Patterns in the percentage of stems grazed indicated generally high but variable palatability among these species. By contrast, the three species showedinconsistent population response to grazing. Abundance (frequency) of all three species indicated no short-term change between years in response to grazing intensity. Responses of these species differ considerably from those of most other perennial tallgrass prairie forbs that are unpalatable, unconsumed, and increase in performance (e.g. size, abundance) due to release from competition from the dominant grasses under ungulate grazing. The results demonstrate that immediate aboveground growth and reproductiveresponses of established adults to grazing are not good predictors of grazer effects on population abundances in tallgrass prairie.

}, keywords = {LTER-KNZ, flowering}, doi = {10.1023/A:1015534721939}, url = {http://ipsapp008.lwwonline.com/content/getfile/5220/57/6/fulltext.pdf}, author = {Hickman, K.R. and D.C. Hartnett} } @inbook {KNZ00591, title = {Comparative ecology of native and introduced ungulates}, booktitle = {Ecology and Conservation of Great Plains Vertebrates}, year = {1997}, pages = {72 -101}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {New York}, abstract = {The defining period of coevolution among Great Plains plant and ungulate species occurred during the past 12,000 years (Mack and Thompson 1982, Axelrod 1985). In the late Pleistocene and early Holocene, a diverse array of large grazers and browsers were reduced to a much smaller group of ungulate species represented by bison (Bison bison), pronghorn (Antilocapra americana), deer (Odocoileus hemionus and O. virginianus), and elk (Cervus canadensis). These changes occurred in the presence of nomadic humans from the Asian steppe who were immigrating to the Great Plains during the same time. The landscape was characterized by gently rolling interfluvial surfaces covered with perennial herbaceous vegetation. These exposed grasslands were periodically interrupted by more protected wetland, riparian woodland, or scarp woodland habitats. Although wetlands and woodlands occupied less than 7 and less than 3\% of the Great Plains, respectively (National Wetlands Inventory, and Nebraska Natural Heritage Program data bases), the heterogeneity that they created at landscape scales played a major role in determining the distribution and abundance of native ungulates. Extreme cold and heat, drought, flood, fire, wind, and countless biotic interactions caused locally short-term fluctuations in ungulate populations and long-term shifts in landscape features. These dynamic temporal changes were overlayed on a multi-scale spatial mosaic. Native ungulates were adapted to this landscape.}, keywords = {LTER-KNZ}, doi = {10.1007/978-1-4757-2703-6_4}, author = {D.C. Hartnett and Steuter, A.A. and Hickman, K.R.}, editor = {Knopf, F.L. and Samson, F.B.} } @article {KNZ00547, title = {Effects of bison grazing, fire and topography on floristic diversity in tallgrass prairie}, journal = {Journal of Range Management}, volume = {49}, year = {1996}, pages = {413 -420}, abstract = {Grazed and ungrazed sites subjected to different fire frequencies were sampled on the Konza Prairie Research Natural Area in northeast Kansas after 4 years of bison grazing (1987-1991). The objective was to study effects of bison grazing on plant species composition and diversity components (plant species richness, equitability, and spatial heterogeneity) in sites of contrasting fire frequency. Cover and frequency of cool-season graminoids (e.g. Poa pratensis L., Agropyron smithii Rydb., Carex spp.) and some forbs (e.g. Aster ericoides [A. Gray] Howell, and Oxalis stricta L.) were consistently higher in sites grazed by bison than in ungrazed exclosures, whereas the dominant warm-season grasses (Andropogon gerardii Vitman, Sorghastrum nutans [L.] Nash, Panicum virgatum L., Schizachyrium scoparium [Michx.] Nash) and other forbs (e.g. Solidago missouriensis Nutt.) decreased in response to bison. Plant species diversity (H') and spatial heterogeneity in all areas sampled were significantly increased by bison. Increased heterogeneity and mean species richness in grazed prairie (40 species per sample site) compared to ungrazed prairie (29 species per site) were likely a result of greater microsite diversity generated by bison, whereas preferential grazing of the dominant grasses and concomitant increases in subordinate species resulted in an increase in equitability of species abundances. Species/area relationships indicated greater effects of bison on plant species richness with increasing sample area. Increases in plant diversity components associated with bison grazing were generally greater in annually burned than in 4-year burned sites. Effects of ungulate grazers on floristic diversity have important implications given recent evidence that plant species diversity and the compositional and production stability of grassland plant communities are positively related.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/4002922}, author = {D.C. Hartnett and Hickman, K.R. and Walter, L.E.F.} } @proceedings {KNZ00548, title = {Effects of bison grazing on plant species diversity in tallgrass prairie}, year = {1996}, pages = {215 -216}, keywords = {LTER-KNZ, tallgrass prairie}, author = {D.C. Hartnett and Hickman, K.R. and Walter, L.E.F.}, editor = {West, N.E.} } @proceedings {KNZ00551, title = {Effects of grazing systems and stocking rates on plant species diversity in Kansas tallgrass prairie}, year = {1996}, pages = {228 -229}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Hickman, K.R. and D.C. Hartnett and Cochran, R.C.}, editor = {West, N.E.} } @phdthesis {KNZ00552, title = {Effects of large ungulate herbivory on tallgrass prairie plant population and community structure}, volume = {PhD Dissertation}, year = {1996}, pages = {1 -105}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Hickman, K.R.} } @proceedings {KNZ00493, title = {Effects of bison grazing, on floristic diversity in tallgrass prairie}, year = {1995}, pages = {215 -216}, keywords = {LTER-KNZ, tallgrass prairie}, author = {D.C. Hartnett and Hickman, K.R. and Walter, L.E.F.} }