@article {KNZ002043, title = {Fire frequency, state change and hysteresis in tallgrass prairie}, journal = {Ecology Letters}, volume = {24}, year = {2021}, pages = {636-647}, abstract = {

Hysteresis is a fundamental characteristic of alternative stable state theory, yet evidence of hysteresis is rare. In mesic grasslands, fire frequency regulates transition from grass- to shrub-dominated system states. It is uncertain, however, if increasing fire frequency can reverse shrub expansion, or if grass-shrub dynamics exhibit hysteresis. We implemented annual burning in two infrequently burned grasslands and ceased burning in two grasslands burned annually. With annual fires, grassland composition converged on that of long-term annually burned vegetation due to rapid recovery of grass cover, although shrubs persisted. When annual burning ceased, shrub cover increased, but community composition did not converge with a long-term infrequently burned reference site because of stochastic and lagged dispersal by shrubs, reflecting hysteresis. Our results demonstrated that annual burning can slow, but not reverse, shrub encroachment. In addition, reversing fire frequencies resulted in hysteresis because vegetation trajectories from grassland to shrubland differed from those of shrubland to grassland.

}, keywords = {LTER-KNZ}, doi = {10.1111/ele.13676}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.13676}, author = {Collins, Scott L. and Nippert, J.B. and Blair, J. M. and J. M. Briggs and Blackmore, P. and Ratajczak, Zak} } @article {KNZ001806, title = {Complex variation in habitat selection strategies among individuals driven by extrinsic factors}, journal = {Ecology and Evolution}, volume = {7}, year = {2017}, pages = {1802-1822}, abstract = {

Understanding behavioral strategies employed by animals to maximize fitness in the face of environmental heterogeneity, variability, and uncertainty is a central aim of animal ecology. Flexibility in behavior may be key to how animals respond to climate and environmental change. Using a mechanistic modeling framework for simultaneously quantifying the effects of habitat preference and intrinsic movement on space use at the landscape scale, we investigate how movement and habitat selection vary among individuals and years in response to forage quality\–quantity tradeoffs, environmental conditions, and variable annual climate. We evaluated the association of dynamic, biotic forage resources and static, abiotic landscape features with large grazer movement decisions in an experimental landscape, where forage resources vary in response to prescribed burning, grazing by a native herbivore, the plains bison (Bison bison bison), and a continental climate. Our goal was to determine how biotic and abiotic factors mediate bison movement decisions in a nutritionally heterogeneous grassland. We integrated spatially explicit relocations of GPS-collared bison and extensive vegetation surveys to relate movement paths to grassland attributes over a time period spanning a regionwide drought and average weather conditions. Movement decisions were affected by foliar crude content and low stature forage biomass across years with substantial interannual variation in the magnitude of selection for forage quality and quantity. These differences were associated with interannual differences in climate and growing conditions from the previous year. Our results provide experimental evidence for understanding how the forage quality\–quantity tradeoff and fine-scale topography drives fine-scale movement decisions under varying environmental conditions.

}, keywords = {LTER-KNZ}, doi = {10.1002/ece3.2764}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.2764}, author = {Raynor, Edward J. and Beyer, Hawthorne L. and J. M. Briggs and Anthony Joern} } @article {KNZ001815, title = {Juniper invasions in grasslands: research needs and intervention strategies}, journal = {Rangelands}, volume = {39}, year = {2017}, pages = {64 - 72}, abstract = {{\textbullet} Despite prescribed fire programs, invasive juniper trees are increasing in the Great Plains. {\textbullet} Continued encroachment of junipers in the Great Plains, especially eastern redcedar and Ashe{\textquoteright}s juniper, is degrading grasslands and increasing health concerns through pollen production. {\textbullet} Biological and ecological research needs include effects on soil and water as well as restoration potential after a mature invasion is treated. {\textbullet} The interface of social science, ecology, economics, and policy may yield productive approaches to slowing the invasion.}, keywords = {LTER-KNZ}, doi = {10.1016/j.rala.2017.03.002}, url = {https://www.sciencedirect.com/science/article/pii/S0190052817300159?via\%3Dihub}, author = {Leis, Sherry A. and Blocksome, Carol E. and Twidwell, Dirac and Fuhlendorf, Sam D. and J. M. Briggs and Sanders, Larry D.} } @article {KNZ001800, title = {Temporal variability in large grazer space use in an experimental landscape}, journal = {Ecosphere}, volume = {8}, year = {2017}, abstract = {Land use, climate change, and their interaction each have great potential to affect grazing systems. With anticipated more frequent and extensive future drought, a more complete understanding of the mechanisms that determine large grazer landscape-level distribution under varying climatic conditions is integral to ecosystem management. Using an experimental setting with contrasting fire treatments, we describe the inter-annual variability of the effect of landscape topography and disturbance from prescribed spring fire on large grazer space use in years of variable resource availability. Using GPS telemetry, we investigated space use of plains bison (Bison bison bison) as they moved among watersheds managed with variable experimental burn treatments (1-, 2-, 4-, and 20-year burn intervals) during a seven-year period spanning years of average-to-above average forage production and severe drought. At the landscape scale, bison more strongly favored high-elevation and recently burned watersheds with watersheds burned for the first time in 2 or 4 yr consistently showing higher use relative to annually burned watersheds. In particular, watersheds burned for the first time in 4 yr were avoided to lesser extent than other more frequently burned watersheds during the dormant season. This management type also maintained coupling between bison space use and post-fire regrowth across post-drought growing season months, whereas watersheds with more frequent fire-return intervals attracted bison in only the first month post-fire. Hence, fire frequency played a role in maintaining the coupling of grazer and post-fire regrowth, the fire{\textendash}grazer interaction, in response to drought-induced reduction in fuel loads. Moreover, bison avoided upland habitat in poor forage production years, when forage regrowth is less likely to occur in upland than in lowland habitats. Such quantified responses of bison to landscape features can aid future conservation management efforts and planning to sustain fire{\textendash}grazer interactions and resulting spatial heterogeneity in grassland ecosystems.}, keywords = {LTER-KNZ}, doi = {10.1002/ecs2.1674}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.1674}, author = {Raynor, E.J. and Anthony Joern and Skibbe, A.M. and Sowers, M. and J. M. Briggs and Laws, A.N. and Goodin, D.G.} } @article {KNZ001721, title = {Assessing the potential for transitions from tallgrass prairie to woodlands: are we operating beyond critical transitions?}, journal = {Rangeland Ecology \& Management}, volume = {69}, year = {2016}, pages = {280{\textendash}287}, abstract = {

A growing body of evidence suggests humans are pushing ecosystems near or beyond key ecological thresholds, resulting in transitions to new, sometimes undesirable phases or states that are costly to reverse. We used remotely sensed fire data to assess if the Flint Hills\—a landscape of tallgrass prairie in the Central Great Plains, United States\—is operating beyond fire frequency thresholds. Long-term fire experiments and observational evidence suggests that applying prescribed fire at return intervals \> 3 yr can lead to transitions from grassland to shrubland. Fire return intervals \> 10 yr and complete fire suppression, in particular, can result in transitions to woodlands over 30 \− 50 yr. Once shrublands and woodlands are established, restoration back to grassland is difficult with prescribed fires. We applied these fire frequency cutoffs to remotely sensed fire data from 2000 to 2010 in the Flint Hills, identifying the extent of tallgrass prairie susceptible to shrub and tree expansion. We found that 56\% (15 620 km2) of grasslands in this region are burned less than every 3 yr and are therefore susceptible to conversion to shrub or tree dominance. The potential effects of this large-scale shift are greater risk for evergreen (Juniperus virginiana) woodland fires, reduced grazing potential, and increased abundance of woodland adapted species at the expense of the native grassland biota. Of the 12 127-km2 area likely to remain grassland, 43\% is burned approximately annually, contributing to vegetative homogenization and potential air-quality issues. While this synthesis forecasts a precarious future for tallgrass prairie conservation and their ecosystem services, increases in shrub or tree dominances are usually reversible until fire frequency has been reduced for more than 20 yr. This delay leaves a small window of opportunity to return fire to the landscape and avoid large-scale transformation of tallgrass prairie.

}, keywords = {LTER-KNZ, catastrophic shifts, forecasting, mesic grasslands, regime shifts, resilience, tipping points}, doi = {http://dx.doi.org/10.1016/j.rama.2016.03.004}, url = {https://www.sciencedirect.com/science/article/pii/S1550742416300021?via\%3Dihub}, author = {Z. Ratajczak and J. M. Briggs and Goodin, D.G. and Mohler, R. and Jesse B. Nippert and Obermeyer, B.K.} } @article {KNZ001728, title = {Ecohydrological and climate change studies at the Konza Prairie Biological Station}, journal = {Transactions of the Kansas Academy of Science}, volume = {119}, year = {2016}, pages = {5 - 11}, keywords = {LTER-KNZ}, issn = {0022-8443}, doi = {10.1660/062.119.0103}, url = {https://doi.org/10.1660/062.119.0103}, author = {J. M. Briggs and John M. Blair and Horne, E.A.} } @article {KNZ001753, title = {Foraging decisions underlying restricted space use: effects of fire and forage maturation on large herbivore nutrient uptake}, journal = {Ecology and Evolution}, volume = {6}, year = {2016}, pages = {5843{\textendash}5853 }, type = {Journal Articles}, abstract = {

Recent models suggest that herbivores optimize nutrient intake by selecting patches of low to intermediate vegetation biomass. We assessed the application of this hypothesis to plains bison (Bison bison) in an experimental grassland managed with fire by estimating daily rates of nutrient intake in relation to grass biomass and by measuring patch selection in experimental watersheds in which grass biomass was manipulated by prescribed burning. Digestible crude protein content of grass declined linearly with increasing biomass, and the mean digestible protein content relative to grass biomass was greater in burned watersheds than watersheds not burned that spring (intercept; F1,251 = 50.57, P \< 0.0001). Linking these values to published functional response parameters, ad libitum protein intake, and protein expenditure parameters, Fryxell\&$\#$39;s (Am. Nat., 1991, 138, 478) model predicted that the daily rate of protein intake should be highest when bison feed in grasslands with 400\–600 kg/ha. In burned grassland sites, where bison spend most of their time, availability of grass biomass ranged between 40 and 3650 kg/ha, bison selected foraging areas of roughly 690 kg/ha, close to the value for protein intake maximization predicted by the model. The seasonal net protein intake predicted for large grazers in this study suggest feeding in burned grassland can be more beneficial for nutrient uptake relative to unburned grassland as long as grass regrowth is possible. Foraging site selection for grass patches of low to intermediate biomass help explain patterns of uniform space use reported previously for large grazers in fire-prone systems.

}, keywords = {LTER-KNZ}, doi = {10.1002/ece3.2304}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.2304}, author = {Raynor, E.J. and Anthony Joern and Jesse B. Nippert and J. M. Briggs} } @article {KNZ001679, title = {Bison foraging responds to fire frequency in nutritionally heterogeneous grassland}, journal = {Ecology}, volume = {96}, year = {2015}, pages = {1586 -1597}, abstract = {

Foraging decisions by native grazers in fire-dependent landscapes modulate the fire\–grazing interaction. Uncovering the behavioral mechanisms associated with the attraction of grazers to recently burned areas requires understanding at multiple spatial scales in the ecological foraging hierarchy. This study focused on feeding in the area between steps in a foraging bout, the feeding station, as forage chemistry and vegetation architecture play central roles in these fine-scale, feeding-station decisions. The forage maturation hypothesis (FMH) uses the temporal dynamics of forage quality and quantity in grasslands to explain the distribution of large herbivores, but does not address herbivore responses to inter-patch variation caused by fire-induced nutrient increases of forage quality. Using an experimental setting with contrasting fire treatments we describe the effects of variable burn history on foraging kinetics by bison at Konza Prairie Biological Station (KPBS). We assessed the potential to link the FMH in a complementary fashion to the transient maxima hypothesis (TMH) to explain temporal variation in bison responses to grassland forage quality and quantity in response to burning at different temporal frequencies. Forage attributes met predictions of the TMH that allowed us to investigate how forage maturation affects feeding station foraging behavior across watersheds with varying burn frequency. At sites burned in the spring after several years without burning, both bite mass and intake rate increased with increasing biomass at a greater rate during the growing season than during the transitional midsummer seasonal period. In these infrequently burned watersheds, early growing season bite mass (0.6 \± 0.05 g; mean \± SE), bite rate (38 \± 1.5 bites/min), and intake rate (21 \± 2.3 g/min) was reduced by ~15\%, 13\%, and 29\% during the midsummer transitional period. A behavioral response in foraging kinetics at the feeding station occurred where a nonequilibrial pulse of high-quality resource was made available and then retained by repeated grazing over the growing season. Our results provide the first experimental evidence for demonstrating the fine-scale behavioral response of a large grazer to fire-induced changes in forage attributes, while linking two prominent hypotheses proposed to explain spatial variation in forage quality and quantity at local and landscape scales.

}, keywords = {LTER-KNZ}, doi = {10.1890/14-2027.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/14-2027.1}, author = {Raynor, E.J. and Anthony Joern and J. M. Briggs} } @phdthesis {KNZ001732, title = {Ecological hierarchy of foraging in a large herbivore: the plains bison perspective in tallgrass prairie}, volume = {PhD. Dissertation}, year = {2015}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS}, abstract = {

Foraging decisions by native grazers in fire-dependent landscapes reflect fire-grazing interactions. I assessed behavioral responses associated with the attraction of grazers to recently burned areas at multiple spatial scales. (a) I focused on feeding in the area between steps in a foraging bout \– the feeding station \– where forage quality and vegetation architecture underlie these fine-scale decisions. The \‘forage maturation hypothesis\’ (FMH) predicts the distribution of large herbivores based on the temporal dynamics of forage quality and quantity, but does not address herbivore responses to inter-patch variation caused by fire-induced increases of forage quality. The \‘transient maxima hypothesis\’ (TMH) also predicts variable forage quality and quantity, but in response to intermittent disturbance from fire. I described the effects of variable spring burn history to bison foraging and their spatio-temporal distribution at Konza Prairie. Forage attributes met predictions of the TMH to explain how forage maturation affects foraging behavior across watersheds with varying burn frequency. At sites burned in the spring after several years without burning, intake rate increased with increasing vegetation biomass at a greater rate during the early growing season than during the transitional mid-summer period. This foraging behavior occurred in response to a non-equilibrial pulse of high quality resource that set the stage in the burned area, and was then retained by repeated grazing over the growing season. Thus, bison responded increased forage resource availability resulting from transient maxima in infrequently-burned watersheds burned that spring and they intensely used these areas until forage availability and forage regrowth was not possible. (b) At the patch scale, bison selected areas of low-to-moderate grass cover in which to feed and avoided areas of high forb cover in the growing season. During the dormant season, however, bison selected feeding-sites with uniformly high canopy cover in watersheds that were not burned. (c) At the landscape-scale, infrequently burned watersheds (compared to watersheds that were not burned) provided the strongest significant predictor of bison space use in all early growing- and transitional-season months. (d) The probability of habitat selection was driven by availability of high foliar, protein and low-to-intermediate herbaceous biomass throughout the growing season. These results explain the hierarchy of foraging by a dominant consumer in an experimental landscape by linking two prominent hypotheses, TMH-FMH, proposed to explain spatial variation in forage quality and quantity at local and landscape scales.

}, keywords = {LTER-KNZ, Bison; Foraging Behavior; Forage Maturation; Movement; Space Use; Transient Maxima}, url = {http://krex.k-state.edu/dspace/bitstream/handle/2097/20348/EdwardRaynor2015.pdf?sequence=1\&isAllowed=y}, author = {Raynor, E.J.} } @article {KNZ001627, title = {Fire dynamics distinguish grasslands, shrublands, and woodlands as alternative attractors in the Central Great Plains of North America}, journal = {Journal of Ecology}, volume = {102}, year = {2014}, pages = {1374 -1385}, abstract = {

Grasslands are threatened globally due to the expansion of woody plants. The few remaining headwater streams within tallgrass prairies are becoming more like typical forested streams due to rapid conversion of riparian zones from grassy to wooded. Forestation can alter stream hydrology and biogeochemistry. We estimated the rate of riparian woody plant expansion within a 30 m buffer zone surrounding the stream bed across whole watersheds at Konza Prairie Biological Station over 25 years from aerial photographs. Watersheds varied with respect to experimentally-controlled fire and bison grazing. Fire frequency, presence or absence of grazing bison, and the historical presence of woody vegetation prior to the study time period (a proxy for proximity of propagule sources) were used as independent variables to predict the rate of riparian woody plant expansion between 1985 and 2010. Water yield was estimated across these years for a subset of watersheds. Riparian woody encroachment rates increased as burning became less frequent than every two years. However, a higher fire frequency (1\–2 years) did not reverse riparian woody encroachment regardless of whether woody vegetation was present or not before burning regimes were initiated. Although riparian woody vegetation cover increased over time, annual total precipitation and average annual temperature were variable. So, water yield over 4 watersheds under differing burn frequencies was quite variable and with no statistically significant detected temporal trends. Overall, burning regimes with a frequency of every 1\–2 years will slow the conversion of tallgrass prairie stream ecosystems to forested ones, yet over long time periods, riparian woody plant encroachment may not be prevented by fire alone, regardless of fire frequency.

}, keywords = {LTER-KNZ, bison, Ecosystems, Forests, Grasslands, Grazing, Linear regression analysis, Trees, Watersheds}, doi = {10.1111/1365-2745.12311}, url = {https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2745.12311}, author = {Z. Ratajczak and Jesse B. Nippert and J. M. Briggs and John M. Blair} } @inbook {KNZ001656, title = {Grassland Ecology}, booktitle = {Plant Sciences - Ecology and the Environment}, volume = {8}, number = {Springer Reference Series}, year = {2014}, pages = {389-423}, publisher = {Springer-Verlag Berlin Heidelberg}, organization = {Springer-Verlag Berlin Heidelberg}, keywords = {LTER-KNZ}, author = {John M. Blair and Jesse B. Nippert and J. M. Briggs}, editor = {Monson, R} } @article {KNZ001528, title = {Genetic variation and mating success in managed American plains bison}, journal = {Journal of Heredity}, volume = {104}, year = {2013}, pages = {182 -191}, abstract = {

The American plains bison (Bison bison) was pushed to the brink of extinction in the late 1800s but has since rebounded. Less than 5\% of animals currently exist in conservation herds that are critical for maintaining genetic variability. Here, we use 25 microsatellite loci to assess genetic diversity and patterns of mating success over a 3-year period in a managed conservation herd at Konza Prairie Biological Station, Kansas (total number of individuals genotyped = 587). Heterozygosity was comparable to and allelic diversity higher than that in 11 other wild and managed herds for which similar estimates are available. Parentage analyses revealed that males within the oldest age classes (5\–7 years) sired \>90\% of calves over the study period, consistent with a polygynous breeding system. Asymmetries in siring success also were observed within age classes, with the same males enjoying high siring success over multiple seasons. Empirical results of paternity will facilitate future modeling and empirical efforts to determine how demographic factors, population size, and variation in siring success interact to determine the retention (or loss) of genetic diversity in natural and managed herds, thus allowing informed recommendations for management practices and conservation efforts of this symbolic North American species.

}, keywords = {LTER-KNZ}, doi = {10.1093/jhered/ess095}, url = {https://academic.oup.com/jhered/article/104/2/182/802105}, author = {Ungerer, M.C. and Weitekamp, C.A. and Anthony Joern and Towne, G. and J. M. Briggs} } @article {KNZ001514, title = {Community stability does not preclude ecosystem sensitivity to chronic resource alteration}, journal = {Functional Ecology}, volume = {26}, year = {2012}, pages = {1231 -1233}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-2435.2012.02053.x}, url = {https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2435.2012.02053.x}, author = {Alan K. Knapp and J. M. Briggs and M.D. Smith} } @mastersthesis {KNZ001515, title = {Mechanisms driving woody encroachment in the tallgrass prairie: an analysis of fire behavior and physiological integration}, volume = {MS Thesis}, year = {2012}, pages = {1 -72}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS}, abstract = {

Woody encroachment has altered the vegetative structure of grasslands worldwide and represents a potentially irreversible shift in grassland dynamics and biodiversity. Clonal woody species appear to be one of the greatest contributors to the shift from graminoid to woody dominance in the tallgrass prairie. Part of the high success rate of clonal species may be attributed to an ability to circumvent recruitment filters through the integration of environmental heterogeneity and acropetal translocation of resources from mother to daughter ramets. The clonal shrub Cornus drummondii persists in a tension zone of the graminoid-dominated tallgrass prairie, where the dominance structure is primarily maintained through the direct and indirect effects of fire. The competitive displacement of native herbaceous vegetation associated with the establishment and expansion of C. drummondii causes a major alteration in the fuel dynamics responsible for the propagation and sustainment of fire, potentially contributing to biofeedback mechanisms that facilitate shrub expansion. The goal of this research was to quantify fire behavior parameters (temperature, intensity, rate of spread, and heat flux) in relation to C. drummondii invasions and to test physiological integration as a mechanism driving encroachment, using manipulation experiments at the Konza Prairie Biological Station. We observed a significant decrease in fireline intensity associated with the encroachment of C. drummondii, which was amplified by the effects of stem density and shrub island area. This alteration in fire behavior also led to reduced heat flux at stems within shrub islands, reducing the likelihood of tissue necrosis and top-kill. With additional fuel, temperatures and fire intensities were higher, similar to open grasslands. In severing rhizomes, and effectively severing the integration of clonal ramets, we observed a higher risk of mortality of daughter ramets. These rhizome severed ramets were more water stressed, had lower photosynthetic rates, and lower woody and foliar biomass production. These results indicate that C. drummondii significantly alters fire behavior, releasing ramets from the fire trap of successive top-killing, while the integration of intraclonal ramets allows daughter ramets to survive mid-summer drought and increases the likelihood of successful establishment and further clonal reproduction.

}, keywords = {LTER-KNZ, Cornus drummondii, Fire behavior, Physiological integration, woody encroachment}, url = {http://hdl.handle.net/2097/14197}, author = {Killian, P.D.} } @inbook {KNZ001114, title = {Ecological consequences of the replacement of native grassland by Juniperus virginiana and other woody plants}, booktitle = {Ecological Studies Vol. 196, Western North American Juniperus communities: A dynamic vegetation type}, year = {2008}, pages = {156 -169}, publisher = {Springer-Verlag, NY}, organization = {Springer-Verlag, NY}, abstract = {

Although grasslands have been altered by humans for thousands of years (Wedel 1961; Bond et al. 2003), the loss of grassland as a result of anthropogenic activities has increased dramatically over the past 150 years. When Europeans first settled the Midwest and Great Plains, the greatest threat to native grasslands was the conversion of the most highly productive of these ecosystems to row-crop agriculture (Samson and Knopf 1994). Later, with improvements in soil moisture management and irrigation technology, even low-productivity grasslands were plowed. Today, those remnants of the most productive grasslands that escaped the plow are threatened, as are most of Earth\’s ecosystems, by a variety of global change phenomena (Vitousek et al. 1997), with the invasion and expansion of woody species into grasslands one of the greatest of these threats. The replacement of grasslands by shrubland, woodland, and forest is a concern not only in the United States but worldwide (Archer et al. 1988; Van Auken 2000; Roques et al. 2001; Silva et al. 2001). Species of woody plants that invade grasslands may include both native plants which previously existed as more minor components of the ecosystem as well as alien species (Bragg and Hulbert 1976; Harcombe et al. 1993).

}, keywords = {LTER-KNZ}, doi = {10.1007/978-0-387-34003-6_8}, url = {https://link.springer.com/chapter/10.1007\%2F978-0-387-34003-6_8}, author = {Alan K. Knapp and McCarron, J.K. and Silletti, A.M. and Hoch, G.A. and Heisler, J.L. and Lett, M.S. and John M. Blair and J. M. Briggs and M.D. Smith}, editor = {Van Auken, O.W.} } @article {KNZ001149, title = {Shrub encroachment in North American grasslands: Shifts in growth form dominance rapidly alters control of ecosystem carbon inputs}, journal = {Global Change Biology}, volume = {14}, year = {2008}, pages = {615 -623}, abstract = {

Shrub encroachment into grass-dominated biomes is occurring globally due to a variety of anthropogenic activities, but the consequences for carbon (C) inputs, storage and cycling remain unclear. We studied eight North American graminoid-dominated ecosystems invaded by shrubs, from arctic tundra to Atlantic coastal dunes, to quantify patterns and controls of C inputs via aboveground net primary production (ANPP). Across a fourfold range in mean annual precipitation (MAP), a key regulator of ecosystem C input at the continental scale, shrub invasion decreased ANPP in xeric sites, but dramatically increased ANPP (\>1000 g m\−2) at high MAP, where shrub patches maintained extraordinarily high leaf area. Concurrently, the relationship between MAP and ANPP shifted from being nonlinear in grasslands to linear in shrublands. Thus, relatively abrupt (\<50 years) shifts in growth form dominance, without changes in resource quantity, can fundamentally alter continental-scale pattern of C inputs and their control by MAP in ways that exceed the direct effects of climate change alone.

}, keywords = {LTER-KNZ}, doi = {10.1111/j.1365-2486.2007.01512.x}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2007.01512.x}, author = {Alan K. Knapp and J. M. Briggs and Scott. L. Collins and S.R. Archer and Bret-Harte, M.S. and Ewers, B.E. and Peters, D.P. and Young, D.R. and Shaver, G.R. and Pendall, E. and Cleary, M.B.} } @inbook {KNZ001125, title = {Estimating aboveground net primary production in grassland and herbaceous dominated ecosystems}, booktitle = {Principles and Standards for Measuring Net Primary Production}, year = {2007}, pages = {27 -48}, publisher = {Oxford University Press, NY}, organization = {Oxford University Press, NY}, abstract = {This paper reviews past and currently accepted methods of estimating aboveground net primary production (NPP) in grass and herb-dominated ecosystems, provides some guiding principles and recommendations to facilitate accurate determination of aboveground NPP, and discusses biases and errors and sampling adequacy. }, keywords = {LTER-KNZ}, author = {Alan K. Knapp and J. M. Briggs and Childers, D.L. and Sala, O.E.} } @proceedings {KNZ001208, title = {Fire and resource availability influence carbon and water relations of the C3 shrub Cornus drummondii in a mesic grassland}, journal = {Proceedings of the 23rd Tall Timbers Fire Ecology Conference: Fire in Grassland and Shrubland Ecosystems}, year = {2007}, pages = {86 -93}, address = {Tall Timbers Research Station, Tallahassee, Florida, USA}, abstract = {

A dramatic increase in cover by woody vegetation has been observed in grasslands worldwide, due to independent and interacting global changes. In the C4-dominated mesic tallgrass prairie of North America, the most proximate factor driving this shift in growth-form dominance is fire exclusion. In 2001, we reintroduced annual fire into a C4-dominated mesic grassland where it had been excluded for 10 y, and evaluated changes in stem density and ecophysiology of an increasingly abundant C3 woody plant, roughleaf dogwood(Cornus drummondii). Our primary objective was to quantify the impacts of fire-induced aboveground mortality and resource constraints on the persistence of roughleaf dogwood in this ecosystem.

In both years of the study (2001\–2002), burned shrubs suffered a complete loss of aboveground biomass due to top-kill from spring fire but persisted via resprouting. A considerable reduction in total growing-season precipitation in 2002, as compared to 2001, revealed that resprouts had lower mortality with reduced soil moisture, were less vulnerable to reductions in soil moisture availability, and maintained higher predawn xylem pressure potentials and rates of photosynthesis than did unburned shrubs. Additionally, enrich-ment of13Cleaf in burned shrubs in 2002 was indicative of greater water use efficiency of resprouting stems. During the drought that occurred in the second growing season, mortality of stems within unburned shrub islands increased and was nearly 9 times more than in burned shrub islands. Thus, resprouting shrubs\—with their characteristics of reduced leaf tissue, taller stems, and greater stem densities\—are efficient in rapidly reoccupying post-fire environments, even with the added stress of below-average precipitation during the growing season. The results of this study suggest that within this grassland, reintroduction of fire will not eliminate rough leaf dogwood in the short term because of its ability to resprout vigorously and persist, even under stressful moisture conditions. Given that North American grasslands are important both economically and ecologically, fire management plans should therefore emphasize frequent fire to prevent shrub establishment

}, keywords = {LTER-KNZ}, url = {http://talltimbers.org/wp-content/uploads/2014/03/Heisleretal2007_op.pdf}, author = {Heisler, J.L. and Alan K. Knapp and J. M. Briggs} } @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 {KNZ00960, title = {An ecosystem in transition: causes and consequences of the conversion of mesic grassland to shrubland}, journal = {BioScience}, volume = {55}, year = {2005}, pages = {243 -254}, abstract = {Woody plant expansion is one of the greatest contemporary threats to mesic grasslands of the central United States. In this article, we synthesize more than 20 years of research to elucidate the causes and consequences of the ongoing transition of C4-dominated grasslands to savanna-like ecosystems codominated by grasses and woody plants. This transition is contingent on fire-free intervals, which provide the opportunity for recruitment both of new individuals and of additional shrub and tree species into this grassland. Once shrubs establish, their cover increases regardless of fire frequency, and infrequent fires accelerate the spread of some shrub species. This process has resulted in a new dynamic state of shrub{\textendash}grass coexistence in the mesic grasslands of North America. Important consequences of this shift in plant life-form abundance include alterations in plant productivity, species diversity, and carbon storage. Without drastic measures such as mechanical removal of shrubs, it is unlikely that management of fire and grazing regimes alone will be sufficient to restore historic grass dominance in these ecosystems.}, keywords = {LTER-KNZ, fire, Grasslands, Grazing, tallgrass prairie, woody vegetation}, doi = {10.1641/0006-3568(2005)055[0243:AEITCA]2.0.CO;2}, author = {J. M. Briggs and Alan K. Knapp and John M. Blair and Heisler, J.L. and Hoch, G.A. and Lett, M.S. and McCarron, J.K.} } @article {KNZ00891, title = {Direct and indirect effects of fire on shrub density and aboveground productivity in a mesic grassland}, journal = {Ecology}, volume = {85}, year = {2004}, pages = {2245 -2257}, abstract = {Determinants of the balance between grass and woody vegetation in grasslands and savannas have received considerable attention because of the potential for dramatic shifts in ecosystem structure and function as one growth form replaces the other. We studied a mesic grassland where recently established {\textquotedblleft}shrub islands{\textquotedblright} are increasing in abundance due to fire suppression. Our objective was to assess the role of the direct effects of fire vs. indirect alterations in resource availability (N and light), as mechanisms that may constrain/facilitate shrub (Cornus drummondii) encroachment. The direct effects of fire in 2001 and 2002 were 100\% aboveground mortality of C. drummondii shoots and removal of the detrital layer. Post-fire resprouting resulted in \~{}600\% increase in stem density compared to a 200\% increase in shrub islands protected from fire. In burned shrub islands with an added detrital layer, temperature and light penetration to the soil surface were reduced (by 6.5{\textdegree}C and to <3\% of full sunlight), but stem density still increased by \~{}400\%. Thus, both the direct effects of fire and the indirect effect on the energy environment increased C. drummondii stem densities. In contrast, N additions did not influence new stem production or aboveground net primary productivity (ANPP; grams per square meter per year), suggesting that N availability did not constrain shrub growth during this study. While fire did not impact total ANPP, it did shift the relative abundance of growth forms. Grass productivity (360.7 {\textpm} 20.1 g/m2 [mean {\textpm} 1 se]) was stimulated (an increase of \~{}30\%) by the high light conditions of the post-fire environment, while C. drummondii ANPP (34.2 {\textpm} 2.4 g/m2) was reduced by \~{}30\%. In shrub islands protected from fire, C. drummondii ANPP was greatest (50.4 {\textpm} 2.2 g/m2), whereas lower graminoid ANPP (282.5 {\textpm} 19.9 g/m2) was observed. The persistence of woody vegetation, despite two successive fires, along with a significant reduction in grass ANPP (\~{}30\%) suggests that once established, C. drummondii can persist and exclude C4 grasses. Thus, restoring fire to mesic grasslands may prevent further conversion to shrub/woodland, but the abundance of shrubs is likely to remain unchanged with community structure co-dominated by multiple growth forms.}, keywords = {LTER-KNZ}, doi = {10.1890/03-0574}, author = {Heisler, J.L. and J. M. Briggs and Alan K. Knapp and John M. Blair and Seery, A.} } @article {KNZ00892, title = {Influence of shrub encroachment on aboveground net primary productivity and carbon and nitrogen pools in a mesic grassland}, journal = {Canadian Journal of Botany}, volume = {82}, year = {2004}, pages = {1363 -1370}, abstract = {The clonal shrub Cornus drummondii C.A. Mey. is rapidly increasing in cover and displacing mesic grassland species in the central USA as a consequence of fire suppression. We assessed the impact of C. drummondii on carbon (C) and nitrogen (N) pools and C fluxes in a tallgrass prairie in eastern Kansas, USA, through a comparison of both burned and unburned C. drummondii islands with open grassland areas. Allometric equations relating C. drum mondii foliage and wood biomass to basal stem diameter were developed to estimate aboveground biomass and net primary productivity (ANPP) of C. drummondii. Within C. drummondii islands, ANPP was 496 {\textpm} 45 g C{\textperiodcentered}m–2{\textperiodcentered}year–1, nearly three times that within open grassland (167 {\textpm} 13 g C{\textperiodcentered}m–2{\textperiodcentered}year–1). As a result of greater aboveground biomass, aboveground C and N storage within shrub islands (3270 {\textpm} 466 g C{\textperiodcentered}m–2, 37.9 {\textpm} 5.3 g N{\textperiodcentered}m–2) was substantially greater than that within open grassland (241 {\textpm} 33 g C{\textperiodcentered}m–2, 6.1 {\textpm} 0.8 g N{\textperiodcentered}m–2). No change in soil organic C or total N to 10-cm depth was evident; however, soil CO2 flux was significantly reduced in C. drummondii islands relative to the open grassland. The storage of C in aboveground biomass of C. drummondii represents a significant short-term increase in C storage relative to open grassland. However, potential alterations in belowground processes must be quantified before the long-term net effect of shrub encroachment on C and N pools within this mesic grassland can be determined.Key words: aboveground biomass, Cornus drummondii, net primary productivity, shrub encroachment, tallgrass prairie.}, keywords = {LTER-KNZ}, doi = {10.1139/b04-088}, author = {Lett, M.S. and Alan K. Knapp and J. M. Briggs and John M. Blair} } @article {KNZ00830, title = {Long-term patterns of shrub expansion in a C4-dominated grassland: fire frequency and the dynamics of shrub cover and abundance}, journal = {American Journal of Botany}, volume = {90}, year = {2003}, pages = {423 -428}, abstract = {Worldwide, grassland ecosystems have experienced a major shift in growth-form dominance as woody plant species have expanded and replaced native grasses. In the C4-dominated grasslands of central North America, a reduction in fire frequency is the most cited cause of this shift in growth forms as fire both enhances grass productivity and constrains the establishment and expansion of native woody vegetation. Using an 18-yr plant species composition data set, we quantified patterns of change in shrub cover, frequency, and species richness associated with three distinct fire regimes. During the study period (1983{\textendash}2000), shrub cover increased most dramatically in sites in which the frequency of fire was once every 4 yr (intermediate frequency; 28.6\%) followed by sites in which fire occurred only once during the 18-yr period (low frequency; 23.7\%). Annual fire effectively prevented the recruitment of new woody species, but even with this high fire frequency, shrub cover increased slightly (3.7\%). Comparatively, shrub species richness increased by three and six, respectively, in the intermediate- and low-frequency fire sites. These data indicate that within this grassland, periods without fire are necessary for recruitment of both new individuals and additional shrub species; however, once established, shrub cover will increase regardless of fire frequency and even annual fire will not reduce shrub abundance.}, keywords = {LTER-KNZ, C4 grassland, Fire frequency, growth form substitution, Shrubs, woody encroachment}, doi = {10.3732/ajb.90.3.423}, author = {Heisler, J.L. and J. M. Briggs and Alan K. Knapp} } @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 {KNZ0011, title = {Assessing the rate, mechanism and consequences of conversion of tallgrass prairie to Juniperus virginiana forest}, journal = {Ecosystems}, volume = {5}, year = {2002}, pages = {578 -586}, abstract = {We assessed the determinants and consequences of the expansion of Juniperus virginiana L. (red cedar) populations into central US grasslands using historical aerial photos and field measurements of forest extent, tree growth, fire-induced mortality, and responses in herbaceous species diversity and productivity. Photos from northeast Kansas dating back to 1956 indicate that native tallgrass prairie can be converted to closed-canopy red cedar forest in as little as 40 years (a 2.3\% increase in forest cover per year). Mean tree density in 21 forested sites ranged from 130 to 3500 trees/ha, with most sites at more than 800 trees/ha. In younger stands, maximum growth rates of individual red cedar trees exceeded 20 cm/y in height. Land management practices were critical to the establishment and growth of red cedar forest. Grazing reduced the fuel loads by more than 30\% in tallgrass prairie. Based on measurements of mortality for more than 1800 red cedar trees, fire-induced mortality in grazed areas averaged 31.6\% versus more than 90\% at ungrazed sites. When tallgrass prairie was converted to red cedar forest, herbaceous species diversity and productivity were drastically reduced, and most grassland species were virtually eliminated. Consequently, community structure shifted from dominance by herbaceous C4 species to evergreen woody C3 species; this shift is likely to be accompanied by alterations in carbon storage and other ecosystem processes in a relatively short time period. Here we present a conceptual model that integrates the ecological and socioeconomic factors that underlie the conversion of grassland to red cedar forest.}, keywords = {LTER-KNZ, fire, forest expansion, Grazing, Juniperus virginiana, land-cover change, land-use change, red cedar, tallgrass prairie}, doi = {10.1007/s10021-002-0187-4}, author = {Hoch, G.A. and J. M. Briggs and Johnson, L.C.} } @article {KNZ00821, title = {Effect of local and regional processes on plant species richness in tallgrass prairie}, journal = {Oikos}, volume = {99}, year = {2002}, pages = {571 -579}, abstract = {Historically, diversity in a community was often believed to result primarily from local processes, but recent evidence suggests that regional diversity may strongly influence local diversity as well. We used experimental and observational vegetation data from Konza Prairie, Kansas, USA, to determine if: (1) there is a relationship between local and regional richness in tallgrass prairie vegetation; (2) local dominance reduces local species richness; and (3) reducing local dominance increases local and regional species richness. We found a positive relationship between regional and local richness; however, this relationship varied with grazing, topography and fire frequency. The decline in variance explained in the grazed vegetation, in particular, suggested that local processes associated with grazing pressure on the dominant grasses strongly influenced local species richness. Experimental removal of one of the dominant grasses, Andropogon scoparius, from replicate plots resulted in a significant increase in local species richness compared to adjacent reference plots. Overall all sites, species richness was higher in grazed (192 spp.) compared to ungrazed (158 spp.) areas. Across the Konza Prairie landscape, however, there were no significant differences in the frequency distribution of species occurrences, or in the relationship between the number of sites occupied and average abundance in grazed compared to ungrazed areas. Thus, local processes strongly influenced local richness in this tallgrass prairie, but local processes did not produce different landscape-scale patterns in species distribution and abundance. Because richness was enhanced at all spatial scales by reducing the abundance of dominant species, we suggest that species richness in tallgrass prairie results from feedbacks between, and interactions among, processes operating at multiple scales in space and time.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1034/j.1600-0706.2002.12112.x}, author = {Scott. L. Collins and Glenn, S.M. and J. M. Briggs} } @article {KNZ002, title = {Expansion of woody plants in tallgrass prairie: a 15 year study of fire and fire-grazing interactions}, journal = {The American Midland Naturalist}, volume = {147}, year = {2002}, pages = {287 -294}, abstract = {Temporal changes in the abundance of trees and a common shrub, Cornus drummondii, were quantified for 15 y (1981{\textendash}1996) in seven tallgrass prairie watersheds in Northeast Kansas. Woody plant responses to different fire frequencies and grazing were assessed with a data set that included >9000 individuals. Although 15 tree species were included in this data set, only four (Juniperus virginiana, Celtis occidentalis, Gleditsia triacanthos and Ulmus americana) were sufficiently abundant for detailed analysis. Over the 15 y study tree density increased by two- to 10-fold, except in watersheds burned annually where woody plants remained almost completely absent throughout the study. Although increased woody plant abundance was expected in watersheds protected from fire, tree and shrub density also increased substantially in watersheds burned only once in 4 y. An intermediate fire frequency (burned every 3{\textendash}5 y) actually increased the abundance of C. drummondii relative to a low fire frequency (burned only once in 15 y). Moreover, a severe wildfire in 1991, which affected all watersheds, did not markedly reverse this pattern of increase in abundance in most tree species. Four years after the addition of native herbivores (Bos bison) to three of the long-term experimental watersheds (infrequently and annually burned) woody plant abundance increased by four- and 40-fold, respectively, compared to corresponding ungrazed watersheds. Thus, the presence of large ungulate grazers in tallgrass prairie resulted in a significant increase in woody plant abundance. The most parsimonious explanation for this phenomenon is that fire intensity and extent was reduced in grazed grasslands allowing greater success of woody species.}, keywords = {LTER-KNZ, tallgrass prairie, woody plant}, doi = {10.1674/0003-0031(2002)147[0287:EOWPIT]2.0.CO;2}, author = {J. M. Briggs and Alan K. Knapp and B. Brock} } @article {KNZ00801, title = {White-tailed deer browsing on six shrub species of tallgrass prairie}, journal = {Great Plains Research}, volume = {12}, year = {2002}, pages = {141 -156}, abstract = {Native grasses and forbs were once dominant in tallgrass prairies, but nonnative plants have largely replaced natives in most grassland of Illinois. Ample evidence indicates that white-tailed deer (Odocoileus virginianus) have a strong impact on native forests and prairie, but we know little about their impact on nonnative grasslands. This study tested the hypothesis that foraging by deer on native forbs and woody plants increases the dominance of introduced grasses as succession proceeds in old fields of central Illinois. We tested that hypothesis using fencing that excluded deer, but not other herbivores, from replicated plots in three old fields at different successional stages. The composition of the plant community changed rapidly in early succession and showed relatively little effect of deer, other than slowing the invasion by woody plants. In mid- and late successional fields, however, fenced plots had higher relative abundance of native forbs, particularly goldenrod (Solidago spp.), and lower relative abundance of introduced perennial grasses than did control plots. Thus, deer facilitated introduced perennial grasses and inhibited native forbs and woody plants in old fields, thereby delaying succession to deciduous forest.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1674/0003-0031-170.2.323}, author = {Van Der Hoek, D.J. and Alan K. Knapp and J. M. Briggs and Bokdam, J.} } @article {KNZ00756, title = {Determinants of C3 forb growth and production in a C4 dominated grassland}, journal = {Plant Ecology}, volume = {152}, year = {2001}, pages = {93 -100}, abstract = {Forbs are the most abundant species within the vascular flora of tallgrass prairie and they make the greatest contribution to biodiversity of all growth forms. However, little is known about the factors that determine their productivity and growth rates. The objective of this study was to assess the controls of forb growth (absolute and relative) and production in tallgrass prairie from a long-term burning experiment at the Konza Prairie in NE Kansas. Over the 14-year study, forbs comprised 9\% of the total biomass production on sites with a high fire frequency vs. 29\% on the low fire frequency site, with gramminoids accounting for the remainder. Although interannual variations in peak biomass of the grasses was strongly correlated with environmental variables related to water availability, there were no similar relationships for forbs, suggesting that production of forbs and grasses responded to interannual variations in climate in different ways. Multivariate analysis of climatic controls on growth rates of grasses and forbs yielded similar results. Although forbs had low biomass and absolute growth per unit ground area in frequently burned prairie, their relative growth rates were highest in such sites. Thus, it appears that reduced growth rates of individual forbs per se do not limit forb success in annually burned prairie. Instead, direct negative effects of fire on forbs (increased mortality) may be responsible. Determinants of forb growth and productivity in unburned prairie remain unresolved.}, keywords = {LTER-KNZ, aboveground net primary production, Biodiversity, fire, forbs, Graminoids, Relative growth rates, tallgrass prairie}, doi = {10.1023/A:1011400101014}, author = {J. M. Briggs and Alan K. Knapp} } @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 {KNZ00803, title = {Species, season, and density of buried seeds surviving fox squirrel depredation}, journal = {Prairie Naturalist}, volume = {33}, year = {2001}, pages = {197 -208}, keywords = {LTER-KNZ}, author = {Smith, C.C. and J. M. Briggs} } @proceedings {KNZ00693, title = {Expansion of eastern red cedar in the northern Flint Hills, Kansas}, year = {1999}, pages = {9 -15}, publisher = {University of Nebraska at Kearney}, address = {Kearney, NE}, keywords = {LTER-KNZ}, author = {Hoch, G.A. and J. M. Briggs}, editor = {Springer, J.T.} } @article {KNZ00697, title = {The keystone role of bison in North American tallgrass prairie}, journal = {BioScience}, volume = {49}, year = {1999}, pages = {39 -50}, keywords = {LTER-KNZ}, url = {http://www.jstor.org/stable/10.1525/bisi.1999.49.1.39}, author = {Alan K. Knapp and John M. Blair and J. M. Briggs and Scott. L. Collins and D.C. Hartnett and Johnson, L.C. and Towne, E.G.} } @article {KNZ00704, title = {Managing Data from Multiple Disciplines, Scales, and Sites to Support Synthesis and Modeling}, journal = {Remote Sensing Environment}, volume = {70}, year = {1999}, pages = {99 -107}, abstract = {The synthesis and modeling of ecological processes at multiple spatial and temporal scales involves bringing together and sharing data from numerous sources. This article describes a data and information system model that facilitates assembling, managing, and sharing diverse data from multiple disciplines, scales, and sites to support integrated ecological studies. Cross-site scientific-domain working groups coordinate the development of data associated with their particular scientific working group, including decisions about data requirements, data to be compiled, data formats, derived data products, and schedules across the sites. The Web-based data and information system consists of nodes for each working group plus a central node that provides data access, project information, data query, and other functionality. The approach incorporates scientists and computer experts in the working groups and provides incentives for individuals to submit documented data to the data and information system.}, keywords = {LTER-KNZ}, doi = {10.1016/S0034-4257(99)00060-7}, author = {Olson, R.J. and J. M. Briggs and Porter, J.H. and Mah, G.R. and Stafford, S.G.} } @article {KNZ00717, title = {Relationships between leaf area index and Landsat TM spectral vegetation indices across three temperate zone sites}, journal = {Remote Sensing of the Environment}, volume = {70}, year = {1999}, pages = {52 -68}, abstract = {Mapping and monitoring of leaf area index (LAI) is important for spatially distributed modeling of vegetation productivity, evapotranspiration, and surface energy balance. Global LAI surfaces will be an early product of the MODIS Land Science Team, and the requirements for LAI validation at selected sites have prompted interest in accurate LAI mapping at a more local scale. While spectral vegetation indices (SVIs) derived from satellite remote sensing have been used to map LAI, vegetation type, and related optical properties, and effects of Sun{\textendash}surface{\textendash}sensor geometry, background reflectance, and atmospheric quality can limit the strength and generality of empirical LAI{\textendash}SVI relationships. In the interest of a preliminary assessment of the variability in LAI{\textendash}SVI relationships across vegetation types, we compared Landsat 5 Thematic Mapper imagery from three temperate zone sites with on-site LAI measurements. The sites differed widely in location, vegetation physiognomy (grass, shrubs, hardwood forest, and conifer forest), and topographic complexity. Comparisons were made using three different red and near-infrared-based SVIs (NDVI, SR, SAVI). Several derivations of the SVIs were examined, including those based on raw digital numbers (DN), radiance, top of the atmosphere reflectance, and atmospherically corrected reflectance. For one of the sites, which had extreme topographic complexity, additional corrections were made for Sun{\textendash}surface{\textendash}sensor geometry. Across all sites, a strong general relationship was preserved, with SVIs increasing up to LAI values of 3 to 5. For all but the coniferous forest site, sensitivity of the SVIs was low at LAI values above 5. In coniferous forests, the SVIs decreased at the highest LAI values because of decreasing near-infrared reflectance associated with the complex canopy in these mature to old-growth stands. The cross-site LAI{\textendash}SVI relationships based on atmospherically corrected imagery were stronger than those based on DN, radiance, or top of atmosphere reflectance. Topographic corrections at the conifer site altered the SVIs in some cases but had little effect on the LAI{\textendash}SVI relationships. Significant effects of vegetation properties on SVIs, which were independent of LAI, were evident. The variability between and around the best fit LAI{\textendash}SVI relationships for this dataset suggests that for local accuracy in development of LAI surfaces it will be desirable to stratify by land cover classes (e.g., physiognomic type and successional stage) and to vary the SVI.}, keywords = {LTER-KNZ}, doi = {10.1016/S0034-4257(99)00057-7}, author = {Turner, D.P. and Cohen, W.B. and Kennedy, R.E. and Fassnacht, K.S. and J. M. Briggs} } @inbook {KNZ00649, title = {Animal populations and communities}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {113 -139}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {D.W. Kaufman and Kaufman, G.A. and Fay, P.A. and Zimmerman, J.L. and Evans, E.W.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00661, title = {Belowground biology and processes}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {244 -264}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {C. W. Rice and Todd, T.C. and John M. Blair and Seastedt, T.R. and Ramundo, R.A. and G.T. Wilson}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00665, title = {Climate change, elevated CO2 and predictive modeling: Past and future climate change scenarios for the tallgrass prairie}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {283 -300}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, url = {http://www.colostate.edu/Depts/GDPE/Distinguished_Ecologists/2005/Hayden/grassland\%20dynamics\%20ch16.pdf}, author = {Seastedt, T.R. and Hayden, B.P. and Owensby, C.E. and Alan K. Knapp}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00623, title = {Data entry}, booktitle = {Data and Information Management in the Ecological Sciences: A Resource Guide}, year = {1998}, publisher = {Long-Term Ecological Research Network Office, University of New Mexico}, organization = {Long-Term Ecological Research Network Office, University of New Mexico}, address = {Albuquerque}, abstract = {One of the many issues that an information management specialist must consider is the need to convert data into a usable electronic format. This frequently means converting data collected in the field, usually on paper, into an electronic form that can then be used in a statistical or graphical package by the researcher. The purpose of this paper is to present guidelines that we have found useful in making this conversion as quick and error-free as possible.}, keywords = {LTER-KNZ}, url = {http://www.ecoinformatics.org/pubs/guide/briggs2.fv2.htm}, author = {J. M. Briggs and Benson, B.J. and Hartman, M. and Ingersoll, R.}, editor = {Michener, W.K. and Porter, J.H. and Stafford, S.G.} } @inbook {KNZ00625, title = {Data management at a long-term ecological research site}, booktitle = {Long-Term Ecological Research in the East Asia-Pacific Region: Biodiversity and Conservation of Terrestrial and Freshwater Ecosystems}, year = {1998}, pages = {52 -57}, publisher = {Center for Global Environmental Research National Institute for Environmental Studies}, organization = {Center for Global Environmental Research National Institute for Environmental Studies}, address = {Tsukuba, Japan}, keywords = {LTER-KNZ}, author = {J. M. Briggs}, editor = {Iwakuma, T.} } @inbook {KNZ00633, title = {Disturbance, diversity and species interactions in tallgrass prairie}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {140 -156}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Scott. L. Collins and Steinauer, E.M.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00648, title = {Diversity of terrestrial macrofauna}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {101 -112}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {D.W. Kaufman and Fay, P.A. and Kaufman, G.A. and Zimmerman, J.L.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00632, title = {The dynamic tallgrass prairie: Synthesis and research opportunities}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {301 -315}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Scott. L. Collins and Alan K. Knapp and D.C. Hartnett and J. M. Briggs}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00624, title = {Evolution of the Konza Prairie LTER Information Management System}, booktitle = {Data and Information Management in the Ecological Sciences: A Resource Guide}, year = {1998}, publisher = {Long-Term Ecological Research Network Office, University of New Mexico}, organization = {Long-Term Ecological Research Network Office, University of New Mexico}, address = {Albuquerque}, keywords = {LTER-KNZ}, url = {http://www.ecoinformatics.org/pubs/guide/briggsk.fv2.htm}, author = {J. M. Briggs}, editor = {Michener, W.K. and Porter, J.H. and Stafford, S.G.} } @inbook {KNZ00639, title = {The flora of Konza Prairie: A historical review and contemporary patterns}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {69 -80}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Freeman, C.C.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00657, title = {Geomorphology of the Konza Prairie}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {35 -47}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Oviatt, C.G.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @book {KNZ001010, title = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {364 -364}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00652, title = {Grasslands, Konza Prairie and long-term ecological Research}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {3 -15}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Alan K. Knapp and Seastedt, T.R.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00642, title = {Hydrology and aquatic chemistry}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {159 -176}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Gray, L.J. and G. L. Macpherson and Koelliker, J.K. and W. K. Dodds}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00626, title = {A landscape perspective of patterns and processes in tallgrass prairie}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {265 -279}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {J. M. Briggs and Nellis, M.D. and Turner, C.L. and Henebry, G.M. and Su, H.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00650, title = {Long-term ecological consequences of varying fire frequency in a humid grassland}, booktitle = {Fire in Ecosystem Management: Shifting The Paradigm From Suppression to Prescription}, year = {1998}, pages = {173 -178}, publisher = {Tall Timbers Research Station}, organization = {Tall Timbers Research Station}, address = {Tallahassee, FL}, keywords = {LTER-KNZ, fire}, author = {Alan K. Knapp and John M. Blair and J. M. Briggs}, editor = {Pruden, T.L. and Brennan, L.A.} } @article {KNZ00631, title = {Modulation of diversity by grazing and mowing in native tallgrass prairie}, journal = {Science}, volume = {280}, year = {1998}, pages = {745 -747}, abstract = {Species diversity has declined in ecosystems worldwide as a result of habitat fragmentation, eutrophication, and land-use change. If such decline is to be halted ecological mechanisms that restore or maintain biodiversity are needed. Two long-term field experiments were performed in native grassland to assess the effects of fire, nitrogen addition, and grazing or mowing on plant species diversity. In one experiment, richness declined on burned and fertilized treatments, whereas mowing maintained diversity under these conditions. In the second experiment, loss of species diversity due to frequent burning was reversed by bison, a keystone herbivore in North American grasslands. Thus, mowing or the reestablishment of grazing in anthropogenically stressed grasslands enhanced biodiversity.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1126/science.280.5364.745}, author = {Scott. L. Collins and Alan K. Knapp and J. M. Briggs and John M. Blair and Steinauer, E.M.} } @inbook {KNZ00651, title = {Patterns and controls of aboveground net primary production in tallgrass prairie}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {193 -221}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Alan K. Knapp and J. M. Briggs and John M. Blair and Turner, C.L.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00645, title = {Plant populations: Patterns and processes}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {81 -100}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {D.C. Hartnett and Fay, P.A.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00646, title = {Regional climate and the distribution of tallgrass prairie}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {19 -34}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, url = {http://www.colostate.edu/Depts/GDPE/Distinguished_Ecologists/2005/Hayden/grassland\%20dynamics\%20ch2.pdf}, author = {Hayden, B.P.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00660, title = {Soils and soil biota}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {48 -66}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Ransom, M.D. and C. W. Rice and Todd, T.C. and Wehmueller, W.A.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00643, title = {Structure and dynamics of aquatic communities}, booktitle = {Grassland Dynamics: Long-Term Ecological Research in Tallgrass Prairie}, year = {1998}, pages = {177 -189}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Gray, L.J. and W. K. Dodds}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @inbook {KNZ00620, title = {Terrestrial nutrient cycling in tallgrass prairie}, booktitle = {Grassland Dynamics: Long-term Ecological Research}, year = {1998}, pages = {222 -243}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-KNZ, tallgrass prairie}, author = {John M. Blair and Seastedt, T.R. and C. W. Rice and Ramundo, R.A.}, editor = {Alan K. Knapp and J. M. Briggs and D.C. Hartnett and Scott. L. Collins} } @article {KNZ00605, title = {Modelling impact of bison on tallgrass prairie}, journal = {Transactions Kansas Academy of Science}, volume = {100}, year = {1997}, pages = {3 -9}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Nellis, M.D. and J. M. Briggs} } @article {KNZ00581, title = {Spatial and temporal patterns of vegetation in the Flint Hills}, journal = {Transactions Kansas Academy of Science}, volume = {100}, year = {1997}, pages = {10 -20}, abstract = {In tallgrass prairie, complex interactions among multiple limiting resources in combination with a variety of land use practices can lead to a heterogeneous landscape. Remote-sensing data (AVHRR) were coupled with abiotic factors to explore spatial and temporal vegetation patterns of the Flint Hills in Kansas and Oklahoma. This information should enable the detection of both natural (e.g., interannual variation in precipitation and temperature) and anthropogenic (e.g., climate change, over-grazing, land-use practices) stresses on this grassland ecosystem. Shifts in the spatial and temporal patterns of vegetation (as measured from NDVI by AVHRR) have been correlated with meteorological data (from 117 weather stations) to identify key abiotic variables that determined vegetation patterns across this region. In 4 years, the combination of annual precipitation and growing degree days was useful to detect spatial and temporal vegetation patterns of the Flint Hills. However, it is imperative that land-use patterns are known in order to assess adequately spatial and temporal patterns of vegetation in this area.}, keywords = {LTER-KNZ}, doi = {10.2307/3628435}, author = {J. M. Briggs and Rieck, D.R. and Turner, C.L. and Henebry, G.M. and Goodin, D.G. and Nellis, M.D.} } @article {KNZ00570, title = {Detecting spatial and temporal patterns of aboveground production in a tallgrass prairie using remotely-sensed data}, year = {1996}, pages = {2361 -2365}, abstract = {Spatial and temporal patterns of aboveground production in a tallgrass prairie ecosystem constitute one of the important spatial components associated with ecological processes and biophysical resources (e.g., water and nutrients). This study addresses the effects of disturbance, topography, and climate on the spatial and temporal patterns of North American tallgrass prairie at a landscape level by using high resolution satellite data. Spatial heterogeneity (SH) derived from the satellite data was related to the impacts of the disturbance of fire and grazing, topographical gradient, and amount of precipitation during the growing season. The result suggests that ecological processes and biophysical resources can be quantified with high resolution satellite data for tallgrass prairie management}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1109/IGARSS.1996.516987}, author = {Su, H. and J. M. Briggs and Alan K. Knapp and John M. Blair and Krummel, J.R.} } @article {KNZ00561, title = {Fire and topographic effects on decomposition rates and nitrogen dynamics of buried wood in tallgrass prairie}, journal = {Soil Biology \& Biochemistry}, volume = {28}, year = {1996}, pages = {323 -329}, abstract = {Decay rates and N dynamics of wood in soils of annually burned and unburned tallgrass prairie were measured over a 3-y period. Wooden dowels were placed at upland, mid-slope and lowland sites in two annually burned and two unburned watersheds. After 3 y, an average of only 15\% of initial wood mass remained in burned watersheds, while 34\% remained in unburned watersheds. Topographic position also significantly affected decay rates, with dowels decaying faster in the shallow-soil, upland sites and slope sites than in the deep-soil, lowland sites. This pattern is opposite of that generally observed for plant productivity (i.e. greater at lowland sites compared to uplands), and suggests that the controls of belowground decomposition and plant productivity are dissimilar. Dowels in both burned and unburned watersheds showed significant increases in N concentration over 3 y. Topographic position did not affect N concentration in the residual dowel material. Burn treatment, however, did affect N concentration, with dowels decomposing in burned watersheds having a higher average N concentration (0.5\% after 3 y exposure) than dowels in unburned watersheds (0.43\%). Relatively rapid decay rates resulted in net release of N, despite increased N concentration in the residual material. Faster net N release on the annually burned watershed was due to faster mass loss, since there were no differences in the rate of increase in N concentration per unit mass lost. Surface soil temperatures on burned prairie following spring fire usually exceed those on unburned prairie. However, average monthly summer soil temperatures (May{\textendash}August) at a 10 cm depth in burned and unburned plots during the study were not statistically different and could not explain decay rate differences. Additionally, one of our unburned watersheds was accidentally burned during the first year of the study. Surprisingly, there were no significant differences in rates of wood decay between that watershed and the other unburned watershed. This suggests that indirect effects of annual fire (i.e. changes in the composition of soil flora and fauna) may override the short-term effects of fire (i.e. changes in soil temperature and moisture) on belowground decomposition in tallgrass prairie.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1016/0038-0717(95)00138-7}, author = {O{\textquoteright}Lear, H.A. and Seastedt, T.R. and J. M. Briggs and John M. Blair and Ramundo, R.A.} } @article {KNZ00478, title = {Interannual variability in primary production in tallgrass prairie: climate, soil moisture, topographic position and fire as determinants of aboveground biomass}, journal = {American Journal of Botany}, volume = {82}, year = {1995}, pages = {1024 -1030}, abstract = {From 1975 to 1993, aboveground net primary production (NPP) at the Konza Prairie Research Natural Area in NE Kansas varied from 179 g/m2 to 756 g/m2. Across a variety of sites, NPP was significantly related to precipitation (r2 = 0.37), but much variability was unexplained. Thus, we evaluated the relationship between NPP with meteorological variables and soil moisture measurements in tallgrass prairie sites that varied in fire frequency and topographic position. Annually burned lowland sites had significantly higher NPP than either annually burned upland or unburned sites. NPP in burned sites was more strongly related to meteorological variables and soil moisture when compared to unburned sites. The lack of significant correlation between soil moisture with NPP on unburned sites suggests that factors other than water availability limit production in these sites. When NPP data were analyzed separately by life forms, interannual variability in forb NPP was not correlated with any meteorological variables, but was negatively correlated with grass NPP (r = -0.49). The inability of a single factor, such as precipitation to explain a large portion of the interannual variability in NPP is consistent with the concept that patterns of NPP in tallgrass prairie are a product of spatial and temporal variability in light, water, and nutrients, driven by a combination of topography, fire history, and climate.}, keywords = {LTER-KNZ, tallgrass prairie}, url = {~http://www.jstor.org/stable/2446232}, author = {J. M. Briggs and Alan K. Knapp} } @proceedings {KNZ00436, title = {Aboveground biomass in tallgrass prairie: effect of time since last fire}, year = {1994}, pages = {165 -170}, keywords = {LTER-KNZ, tallgrass prairie}, url = {http://images.library.wisc.edu/EcoNatRes/EFacs/NAPC/NAPC13/reference/econatres.napc13.jbriggs.pdf}, author = {J. M. Briggs and Fahnestock, J.T. and Ward, L. and Alan K. Knapp}, editor = {Wickett, R.G. and Lewis, P.D. and Woodliffe, A. and Pratt, P.} } @inbook {KNZ00435, title = {Development and refinement of the Konza Prairie LTER Research Information Management Program}, booktitle = {Environmental Information Management and Analysis: Ecosystem to Global Scales}, year = {1994}, pages = {87 -100}, publisher = {Taylor and Francis Ltd}, organization = {Taylor and Francis Ltd}, address = {London}, keywords = {LTER-KNZ}, author = {J. M. Briggs and Su, H.}, editor = {Michener, W.K. and Brunt, J.W. and Stafford, S.G.} } @inbook {KNZ00469, title = {Effects of topography and fire on spatial and temporal distribution of soil moisture in a tallgrass prairie}, booktitle = {Time Domain Reflectometry in Environmental, Infrastructure and Mining Applications}, year = {1994}, pages = {154 -162}, publisher = {United States Department of Interior Bureau of Mines}, organization = {United States Department of Interior Bureau of Mines}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Su, H. and Alan K. Knapp and J. M. Briggs} } @article {KNZ00457, title = {Expansion of gallery forest on Konza Prairie Research Natural Area, Kansas}, journal = {Landscape Ecology}, volume = {9}, year = {1994}, pages = {117 -125}, abstract = {To determine the dynamics of the spatial extent of gallery forest on Konza Prairie Research Natural Area (KPRNA), aerial photographs taken over a 46 year time frame were digitized into an ARC-INFO Geographic Information System (GIS). A Global Positioning System (GPS) was used to collect ground control points to co-register the photographs for each year. Gallery forest areas for the three major drainage boundaries (Kings Creek, Shane Creek, and White Pasture) were analyzed to assess the uniformity of change in the landscape system. Results indicated that the total gallery forest area on KPRNA has increased in area from 157 ha in 1939 to over 241 ha in 1985. During this time, there was an increase in the total number of patches and a decrease in the mean size of forest patches. However, the rate of increase was not consistent over this time period, nor was it uniform from one drainage basin or stream order to another. Detailed spatial analysis of the forested area with a geomorphology and digital elevation model of Konza Prairie showed that in 1985, 58\% of the forest was on alluvial/colluvial soil, yet only 15\% of that soil type was forested. In addition, over 70\% of the forest was on the 0{\textendash}15\% slope interval, but only 15{\textendash}20\% of that slope interval was forested. These results may be attributed to a variety of factors such as changing management practices (i.e., frequency of fires and herbicide spraying) and the temporal constraints on extent to which the gallery forest can expand across the landscape.}, keywords = {LTER-KNZ, burning, gallery forest, GIS, historical landuse, tallgrass prairie}, doi = {10.1007/BF00124378}, url = {http://link.springer.com/article/10.1007/BF00124378}, author = {Knight, C.L. and J. M. Briggs and Nellis, M.D.} } @inbook {KNZ00434, title = {Impact of El Nino on Konza Prairie Research Natural Area}, booktitle = {El Nino \& Long-Term Ecological Research (LTER) Sites}, year = {1994}, pages = {46 -47}, keywords = {LTER-KNZ}, author = {J. M. Briggs}, editor = {Greenland, D.} } @article {KNZ00458, title = {Odor as a factor in nut discovery by fox squirrels}, journal = {Transactions of the Kansas Academy of Science}, volume = {97}, year = {1994}, pages = {1 -3}, abstract = {Walnuts and bur oak acorns were buried in alternate positions in a 10-{\texttimes}-10 grid in a riparian forest with 10-m spacing between nuts. Bur oak acorns soaked in walnut extract and walnuts were buried in a second grid of similar spacing. Fox squirrels removed walnuts fastest and at the same rate in both grids, whereas acorns soaked in walnut extract were removed faster than unsoaked acorns but slower than walnuts. In the light of earlier studies, these observations are interpreted as showing that squirrels can smell buried walnuts from a greater distance than buried acorns.}, keywords = {LTER-KNZ}, doi = {10.2307/3628246}, url = {http://www.jstor.org/stable/3628246}, author = {Luft, J. and Malinowski, J. and J. M. Briggs and Smith, C.C.} } @proceedings {KNZ00463, title = {Space shuttle photography for monitoring global change}, year = {1994}, pages = {532 -534}, keywords = {LTER-KNZ}, author = {Nellis, M.D. and Lulla, K. and J. M. Briggs} } @proceedings {KNZ00433, title = {Using remote sensing to determine heterogeneity in tallgrass prairie}, year = {1994}, pages = {113 -119}, keywords = {LTER-KNZ, tallgrass prairie}, author = {J. M. Briggs and Scott. L. Collins} } @proceedings {KNZ00456, title = {Water relations and biomass responses to irrigation across a topographic gradient in tallgrass prairie}, year = {1994}, pages = {215 -220}, keywords = {LTER-KNZ, Water relations}, url = {http://images.library.wisc.edu/EcoNatRes/EFacs/NAPC/NAPC13/reference/econatres.napc13.aknapp.pdf}, author = {Alan K. Knapp and Koelliker, J.K. and Fahnestock, J.T. and J. M. Briggs}, editor = {Wickett, R.G. and Lewis, P.D. and Woodliffe, A. and Pratt, P.} } @article {KNZ00391, title = {Comparative water relations of seedling and adult Quercus species during gallery forest expansion in tallgrass prairie}, journal = {Forest Ecology and Management}, volume = {56}, year = {1993}, pages = {29 -41}, abstract = {Seasonal patterns in xylem pressure potential (ψ) and stomatal conductance to water vapor (g) were compared between seedlings (1{\textendash}5 years old) invading tallgrass prairie and adult trees of Quercus macrocarpa (Bur oak) and Quercus muehlenbergii (Chinquapin oak) in adjacent gallery forest. Water is often limiting to productivity in the Flint Hills of NE Kansas, thus, we hypothesized that seedlings invading a grassland would have lower ψ and g compared with adult trees, reflecting competitive interactions for water between seedlings and the dominant grasses. We found that ψ was usually lower in adult trees than in older seedlings, but in the very smallest seedlings ψ was significantly reduced compared with mature (greater than 50 years) individuals. Adult and 1- to 2-year-old seedlings had similar g during the season with highest g occurring in older (4- to 5-year-old) seedlings. In general, Q. muehlenbergii had higher ψ and lower g than Q. macrocarpa consistent with reports that Q. muehlenbergii is more drought tolerant. Rapid and extensive root growth characteristic of Quercus seedlings reduced the period of time when seedlings invading prairie must compete with the grasses for water, although water stress may still be an important factor affecting first-year seedlings in this ecosystem. In contrast, strong intraspecific competition for water within mature gallery forests may have reduced ψ and g in forest trees. Thus, the potential for water stress to impact Quercus survival and growth in this drought-prone ecosystem is greatest during establishment and then after forest development is complete. Older seedlings (greater than 4{\textendash}5 years old), saplings and isolated trees within the prairie may experience the least water stress due to a reduction in both inter- and intraspecific competition for water. These data suggest that in the absence of severe fire or drought occurring during the growing season, gallery forests will continye to expand into tallgrass prairie.}, keywords = {LTER-KNZ, Water relations}, doi = {10.1016/0378-1127(93)90101-R}, author = {Bragg, W.K. and Alan K. Knapp and J. M. Briggs} } @article {KNZ00430, title = {The interactive effects of fire, bison (Bison bison) grazing and plant community composition in tallgrass prairie}, journal = {American Midland Naturalist}, volume = {129}, year = {1993}, pages = {10 -18}, abstract = {Fire and native large herbivore grazing were two important influences on the structure and function of North American grasslands. In 1988 and 1989 the influence of fire regime on grazing patterns of North American bison (Bison bison) was studied on the Konza Prairie in northeastern Kansas. Bison grazing was spatially and temporally nonrandom and was influenced by fire regime and local plant community composition. During the growing season, bison were observed up to 3 x more frequently than expected on watersheds burned in the spring. Summer grazing was concentrated in large watershed areas (79-119 ha) dominated by warm-season, perennial, C4 grasses. During the autumn and winter, bison grazed both burned and unburned watersheds more uniformly but grazed most intensively in areas with large stands of cool-season, C3 grasses. On a smaller spatial scale (5-10 m2), bison selected patches during the growing season with low forb cover dominated by the perennial C4 grass, Andropogon gerardii. Grazed patches were larger on frequently burned than on infrequently burned watersheds. The importance of fire history in determining patterns of bison grazing over the landscape indicates that interactions between bison grazing and fire regime may be important to the composition and spatial heterogeneity of tallgrass prairie vegetation.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/2426430}, author = {Vinton, M.A. and D.C. Hartnett and Finck, E.J. and J. M. Briggs} } @article {KNZ00400, title = {Management practices in tallgrass prairie: Large- and small-scale experimental effects on species composition}, journal = {Journal of Applied Ecology}, volume = {30}, year = {1993}, pages = {247 -255}, abstract = {Many studies from grasslands have reported how differing management techniques affect production levels and species composition (e.g., Ehrenreich \& Aikman 1963; Wells 1980; Parr \& Way 1988). In most studies the main emphasis has been on a single treatment (e.g., mowing, grazing or burning) under either highly controlled small-scale, experimental conditions (Hover \& Bragg 1981; Collins 1987; Cox 1988) or less rigorous large-scale descriptive field studies (e.g., Abrams \& Hulbert 1987; Gibson \& Hulbert 1987). There are inherent strengths and weaknesses to both these approaches. Experimental studies, usually carried out at only one site or in small plots, may reflect local conditions; conversely, large-scale field observations usually lack statistical rigour (Hurlbert 1984) and treatment effects may be obscured by large-scale landscape heterogeneity (e.g. Gibson 1988a).}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1007/978-1-4612-4018-1_12}, author = {D.J. Gibson and Seastedt, T.R. and J. M. Briggs} } @article {KNZ00348, title = {Effects of fire on tree spatial patterns in a tallgrass prairie landscape}, journal = {Bulletin of Torrey Botanical Club}, volume = {119}, year = {1992}, pages = {300 -307}, abstract = {

Spatial patterns of trees invading a tallgrass prairie in NE Kansas, USA were examined using a Geographical Information System. Without burning and with adequate moisture levels, the number of trees increased over a five year period by over 60\%, while in an area burned annually the number of trees decreased. Under a variety of burning regimes, Juniperus virginiana and Celtis occidentalis were significantly more uniform in their distribution pattern than Populus deltoides and Gleditsia triacanthos. In addition, three tree species (G. triacanthos, J. virginiana and U. americana) had a significant increase in the degree of aggregation with increasing tree height, while C. occidentalis showed no relationship between aggregation and tree height. There were significant associations between adult and juvenile trees at various scales, with bird dispersed J. virginiana having a higher critical distance (39 m) than wind dispersed G. triacanthos and U. americana. The spatial pattern of tree species appears to be affected by the means of dispersion; trees with wind-dispersed seeds had clumped distributions, whereas most trees with bird-dispersed seeds were regular to random in their dispersion patterns. The spatial pattern of trees invading tallgrass prairie is a function of the burning regime, dispersal vectors, habitat availability, and reproductive mode. Key words: tallgrass prairie, spatial patterns, trees, Geographical Information System

}, keywords = {LTER-KNZ, Wind}, doi = {10.2307/2996761}, author = {J. M. Briggs and D.J. Gibson} } @article {KNZ00372, title = {Geographic information systems for modeling bison impact on Konza Prairie, Kansas}, journal = {GIS/LIS Proceedings}, volume = {2}, year = {1992}, pages = {618 -623}, keywords = {LTER-KNZ, Information Systems}, author = {Nellis, M.D. and J.D. Bathgate and J. M. Briggs} } @article {KNZ00373, title = {Growth and transition: Remote sensing and geographic information systems at Kansas State University}, journal = {Photogrammetric Engineering and Remote Sensing}, volume = {58}, year = {1992}, pages = {1159 -1161}, abstract = {

Remote sensing and geographic information systems education and research at Kansas State University have grown tremendously in the past decade. Dramatic improvements in hardware and software have enhanced offerings in a wide range of spatial analysis (including remote sensing) courses. Success in extramural funding through such agencies as the U.S. Agency for International Development and the National Science Foundation have created a major research thrust in Kansas State University\&$\#$39;s Geography and Biology programs relative to the application of remote sensing and geographic information systems for natural resource assessment and landscape ecology. The State of Kansas initatives have also enhanced Kansas State University\&$\#$39;s role in providing a significant contribution in remote sensing/geographic information systems research and education

}, keywords = {LTER-KNZ, Information Systems}, author = {Nellis, M.D. and J. M. Briggs and Seyler, H.L.} } @article {KNZ00371, title = {Transformed vegetation index for measuring spatial variation in drought impacted biomass on Konza Prairie, Kansas}, journal = {Transactions of the Kansas Academy of Science}, volume = {95}, year = {1992}, pages = {93 -99}, keywords = {LTER-KNZ}, doi = {10.2307/3628024}, author = {Nellis, M.D. and J. M. Briggs} } @article {KNZ00337, title = {Controls of nitrogen limitation in tallgrass prairie}, journal = {Oecologia}, volume = {87}, year = {1991}, pages = {72 -79}, abstract = {

The relationship between fire frequency and N limitation to foliage production in tallgrass prairie was studied with a series of fire and N addition experiments. Results indicated that fire history affected the magnitude of the vegetation response to fire and to N additions. Sites not burned for over 15 years averaged only a 9\% increase in foliage biomass in response to N enrichment. In contrast, foliage production increased an average of 68\% in response to N additions on annually burned sites, while infrequencly burned sites, burned in the year of the study, averaged a 45\% increase. These findings are consistent with reports indicating that reduced plant growth on unburned prairie is due to shading and lower soil temperatures, while foliage production on frequently burned areas is constrained by N availability. Infrequent burning of unfertilized prairie therefore results in maximum production response in the year of burning relative to either annually burned or long-term unburned sites. Foliage biomass of tallgrass prairie is dominated by C4 grasses; however, forb species exhibited stronger production responses to nitrogen additions than did the grasses. After four years of annual N additions, forb biomass exceeded that of grass biomass on unburned plots, and grasses exhibited a negative response to fertilizer, probably due to competition from the forbs. The dominant C4 grasses may out-compete forbs under frequent fire conditions not only because they are better adapted to direct effects of burning, but because they can grow better under low available N regimes created by frequent fire. Key words: Andropogon gerardii, fire, nitrogen, prairie, productivity

}, keywords = {LTER-KNZ, fire;soil temperature;tallgrass prairie}, doi = {10.1007/BF00323782}, author = {Seastedt, T.R. and J. M. Briggs and D.J. Gibson} } @article {KNZ00307, title = {Estimating aboveground biomass in tallgrass prairie with the harvest method: determining proper sample size using jackknifing and Monte Carlo simulations}, journal = {The Southwestern Naturalist}, volume = {36}, year = {1991}, pages = {1 -6}, abstract = {

Sample adequacy for estimating aboveground biomass in the Flint Hills (Kansas) tallgrass prairie was determined by using a combination of jackknifing and Monte Carlo simulations. Based on this analysis, we concluded that 14 and 16 0.1 -m2 (20 by 50 cm) quadrats should be harvested in burned and unburned sites, respectively, when estimating total, live graminoid and previous years dead biomass. However, 20 quadrats should be harvested to detect at least a 20\% difference in production between sites due to treatments such as fire. Due to high variability in forb biomass, other measurements (cover or density) may be more appropriate for detecting fire effects on this group of plants

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/3672110}, author = {J. M. Briggs and Alan K. Knapp} } @inbook {KNZ00338, title = {Longterm ecological questions and considerations for taking longterm measurements: Lessons from the LTER and FIFE programs on tallgrass prairie}, booktitle = {Long-term Ecological Research: An International Perspective (SCOPE Vol. 47)}, year = {1991}, pages = {153 -172}, publisher = {John Wiley \& Sons}, organization = {John Wiley \& Sons}, address = {Chichester}, abstract = {

The earth, with its global problems of overpopulation, over-use and abuse of fossil fuel and nuclear energy, and production of toxic wastes, has often been compared to a sick patient. Illness is recognized as a significant deviation from known, long-term trends. Long-term monitoring represents a minimal activity for responsible individuals and agencies interested in placing current environmental problems into perspective. Long-term measurements are directed at questions involving phenomena not interpretable or perhaps not useful when viewed over short (annual or less) time scales, but are related to the long-term \"health\" or functioning of the system. At a minimum, the Long-term Ecological Research (LTER) data therefore provide the context in which short-term observational or experimental results can be interpreted (Magnuson, 1990). A much more interesting, albeit potentially less relevant, use of LTER data involves the study of a set of complex questions that cannot be resolved with short-term studies. The juxtaposition of basic and applied science within the context of a single research effort is a strength of the LTER program. This chapter attempts to identify a set of long-term ecological questions that are useful to a national or international network of research sites. While there exists a nearly infinite list of interesting questions that could be addressed with long-term studies, a realistic and goal-oriented list of measurements is presented. The criteria for selecting these questions involved identiying variables that 1) are useful for intersite comparisons, 2) are not strongly biased by spatial scaling factors, and 3) can provide the necessary linkages between atmospheric/climatological variables and biological measurements. \"Focused studies of the interactions between the atmosphere and the biosphere that regulate trace gases can improve both our understanding of terrestrial ecosystems and our ability to predict regional- and global-scale changes in atmospheric chemistry\". The list of proposed variables for study was devvelpoped from the \"core LTER measurements\", a guideling used since the inception of the LTER effort from recommendations suggested in Earth System Science, and from practical experience with the recent NASA- ISLSCP (International Surface Land Climatology Project) conducted on the Konza Prairie LTER site. While appropriate examples are taken from many systems, particular emphasis has been given to questions that have interested researchers studying grasslands. We build on the work of Strayer et al. (1986). Their extensive overview of long-term studies provided useful definitions of research productivity, of what constitutes \"long- term research\", and reasons for the \"successes\" of previous and existing long-term research efforts. Their findings emphasized that individual scientists and not specific research protocols or experimental designs were largely responsible for successful long-term research efforts. Here, however, we suggest that certain constraints on research designs are important if a goal of the research is to benefit directly a regional or global network

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Seastedt, T.R. and J. M. Briggs}, editor = {Risser, P.J.} } @article {KNZ00308, title = {Seasonal variation of heterogeneity in tallgrass prairie: a quantitative measure using remote sensing}, journal = {Photogrammetric Engineering and Remote Sensing}, volume = {57}, year = {1991}, pages = {407 -411}, abstract = {

Remote sensing may be a tool to quantitatively measure the change in heterogeneity that takes place in a landscape over a growing season. Seven different SPOT satellite scenes of the Konza Prairie Research Natural Area were analyzed to assess the potential of using textural algorithms as a quantitative measure of seasonal variation in heterogeneity. Unburned watersheds usually have greater heterogeneity than annually burned watersheds. However, the greatest amount of heterogeneity as measured by textural analysis occurs in those area with a mixture of forest and upland tallgrass prairie. Results suggest that remote sensing textural algorithms, in combination with normalized vegetation difference indices, can provide insight regarding both temporal changes that occur seasonally and the influences of periodic spring fires and management practices on the tallgrass prairie ecosystem

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {J. M. Briggs and Nellis, M.D.} } @article {KNZ00216, title = {Comparative analysis of temporal and spatial variability in aboveground production in a deciduous forest and prairie}, journal = {Holarctic Ecology}, volume = {12}, year = {1989}, pages = {130 -136}, abstract = {

Production patterns of tallgrass prairie and adjacent eastern deciduous forest were summarized for a five to seven year period. Each system responded differentially to annual or growing season rainfall and solar energy (measured by pan water evaporation). Overall, forest productivity was negatively correlated with annual precipitation; the prairie exhibited no relationship with precipitation. These differences probably reflect the lack of water limitation of the forest and the \"downstream\" position of the forest. Wood and seed production in the forest were the most variable components measured in our study. Neither variable was related to forest foliage production. Seed production in the prairie was also variable within and between years but was related to prairie foliage production. Prairie seed production was not correlated with seed production of the forest. The two ecosystems respond differentially and independently of each other within the range of climatic variation observed here. Such differences have potential significance to consumers who use both systems for habitat or resources

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1111/j.1600-0587.1989.tb00831.x}, author = {J. M. Briggs and Seastedt, T.R. and D.J. Gibson} } @article {KNZ00247, title = {The effects of spatial scale on Konza landscape classification using textural analysis}, journal = {Landscape Ecology}, volume = {2}, year = {1989}, pages = {93 -100}, abstract = {

Spatial scale is inherent in the definition of landscape hererogeneity and diversity. For example, a landscape may appear heterogenous at one scale but not quite homogeneous at another scale. In assessing the impact of burning and grazing on the Konza Prairie Research Natural Area (a tallgrass prairie), spatial scale is extremely important. Textural contrast algorithms were applied to various scales of remote sensing data and related to landscape units for assessment of heterogeneity under a variety of burning treatments. Acquired data sets included Landsat multispectral scanner (MSS), with 80 m resolution, Landsat thematic mapper (TM), with 30 m resolution, and high resolution density sliced aerial photography (with a 5 m resolution). Results suggest that heterogeneous areas of dense patchiness (e.g., unburned areas) must be analyzed at a finer scale than more homogeneous areas which are burned at least every four years. Key words: spatial scale, textural analysis, tallgrass prairie, remote sensing, landscape ecology, Kansas

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1007/BF00137153}, author = {Nellis, M.D. and J. M. Briggs} } @proceedings {KNZ00224, title = {Is fire a disturbance in grasslands?}, year = {1989}, pages = {159 -161}, publisher = {University of Nebraska Press}, address = {Lincoln, NE}, abstract = {

Many grasslands, and in particular the tallgrass prairies of North America, are generally thought to be maintained by periodic fire. Semantic disagreement among researchers, however, threatens to hamper discussion of fire as an ecological force in grassland ecosystems. Some authors emphasize that fires are disturbances (or perturbations) since these fires disrupt or alter ecosystem states, trends and dynamics (e.g., accumulating nitrogen is volatilized, plant and animal communities change in composition). Other researchers point out that, because these fire-induced disruptions and alterations can maintain the status quo of the ecosystem (e.g., prevent it from becoming woodland), it is the lack of fire rather than fire itself that should be considered a disturbance. We argue that, since both points of view are useful, there is little to be gained by labeling loosely either fire or lack thereof as a \"disturbance\" in grassland ecosystems. Key Words: disturbance, fire, grasslands, perturbation, prairie, Kansas

}, keywords = {LTER-KNZ, fire}, author = {Evans, E.W. and Finck, E.J. and J. M. Briggs and D.J. Gibson and James, S.W. and D.W. Kaufman and Seastedt, T.R.}, editor = {Bragg, T.B. and Stubbendieck, J.} } @article {KNZ00215, title = {Influence of habitat on acorn selection by Peromyscus leucopus}, journal = {Journal of Mammalogy}, volume = {70}, year = {1989}, pages = {35 -43}, abstract = {

Acorn selection by white-footed mice (Peromyscus leucopus) was tested with mice from four different habitats and acorns from six species of oaks (Quercus). Three mice captured in white-oak (subgenus Lepidobalanus) forests in northwestern Arkansas selected acorns from the white-oak group (post [Q. stellata] and white [Q. alba] oaks) over those from the red-oak (subgenus Erthrobalanus) group (pin [Q. palustris], willow [Q. phellos], and black [Q. velutine] oaks). These mice were able to subsist for more than two months on a diet of only acorns, provided that acorns from post oaks were available. These mice developed signs of tannin poisoning when maintained on acorns only from the red-oak group. Eleven mice captured in white-oak forests in eastern Kansas also consumed more acorns from the white-oak (post, bur [Q. macrocarpa], and chinquapin [Q. muehlengergii] oaks) than from the red-oak group (black, norther red [Q. rubra], and pin oaks). However, seven mice captured in red-oak group forest in eastern Kansas consumed more acorns from the red-oak group than from the white-oak group and showed no signs of tannin poisoning. Five mice captured in habitats without oaks consumed equal amounts of acorns from the two subgenera. These results suggest that exposure to acorns may determine acorn selection by P. leucopus independent of fat, protein, or tannin content of the acorns. Acorn selection may be labile, as seven mice captured in white-oak forests in eastern Kansas consumed equal amounts of bur and black oak acorns after being given only red-oak acorns for 9 days

}, keywords = {LTER-KNZ}, doi = {10.2307/1381667~}, author = {J. M. Briggs and Smith, K.G.} } @proceedings {KNZ00217, title = {Landsat thematic mapper digital data for predicting aboveground biomass in a tallgrass prairie ecosystem}, year = {1989}, pages = {53 -55}, publisher = {University of Nebraska Press}, address = {Lincoln, NE}, abstract = {

Landstat thematic mapper digital data was found to offer an excellent potential for regular monitoring of the tallgrass prairie ecosystem by providing estimates of aboveground biomass production. Data from several channels of a May thematic mapper scene were analyzed individually and in various combinations using stepwise regression in Statistical Analysis System (SAS). These procedures were used to determine the most appropriate multiple regression equation for estimating production of 1) total live aboveground biomass, 2) grasses, 3) forbs, 4) previous years dead, and 5) current years dead. Regression equations were based on satellite-derived estimates relative to ground level biomass values for watersheds on Konza Prairie Research Natural Area under a variety of burning treatments. Results suggest that multiple channel equations were most appropriate for measuring production of forbs and total live aboveground biomass. Channel one (0.45 to 0.52 {\ae}meters) and channel four (0.76 to 0.90 {\ae}meters) were applicable to estimate production of grass and levels of previous years litter, respectively. However, none of the channels were accurate in predicting current years dead. Further plans involve using thematic mapper data to estimate aboveground biomass over an entire growing season on Konza and exploring the potential of using satellite data to monitor grassland production across the Great Plains. Key Words: tallgrass prairie, remote sensing, aboveground biomass, Landstat, thematic mapper, monitoring, Konza Prairie, Kansas

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {J. M. Briggs and Nellis, M.D.}, editor = {Bragg, T.B. and Stubbendieck, J.} } @article {KNZ00199, title = {SPOT satellite data for pattern recognition on the North American tall-grass prairie Long-term Ecological Research Site}, journal = {Geocarto International}, volume = {3}, year = {1988}, pages = {37 -40}, abstract = {

The cluster routine uses a two-pass sequential clustering algorithm. In the first pass, the program reads through the entire data set, and sequentially builds clusters (groups of points in spectral space) based on parameters selected by the user, and computes the mean value for each cluster. These clusters become the signatures used to assign classes in the output GIS file. The second pass classifies each pixel in the data set according to a minimum distance classifier. The algorithm calculates the spectral distance between the candidate pixel and the mean value for every cluster, using the mean values that were computed in the first pass

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1080/10106048809354174}, author = {Nellis, D.M. and J. M. Briggs} } @article {KNZ00152, title = {Micro-based Landsat TM data processing for tallgrass prairie monitoring in the Konza Prairie Research Natural Area, Kansas}, journal = {Papers and Proceedings of the Applied Geography Conference}, volume = {10}, year = {1987}, pages = {76 -80}, abstract = {

Despite the large amount of evidence supporting the important role that burning and frequency of burning have on grassland resources, information on the spatial extent of burning in the Flint Hills of Kansas has not been developed. This is primarily due to the massive data requirements needed to access burning on a regional scale. This study assesses the regional potential for monitoring burning practices in the Flint Hills of Kansas using satellite data. The specific objective of this study was to ascertain the utility of Landsat thematic mapper digital data for delineating the spatial characteristics of burning in the Konza Prairie Research Natural Area. The Konza Prairie is an area exceeding 8,000 acres owned by Nature Conservancy and leased to Kansas State University for long-term ecological research. The management objectives of the research area are based on the efforts of periodic fire and grazing on a tall grass prairie ecosystem

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Nellis, M.D. and J. M. Briggs} }