@article {KNZ001496, title = {Past, present, and future roles of long-term experiments in the LTER Network}, journal = {Bioscience}, volume = {62}, year = {2012}, pages = {377 -389}, abstract = {

The US National Science Foundation\–funded Long Term Ecological Research (LTER) Network supports a large (around 240) and diverse portfolio of long-term ecological experiments. Collectively, these long-term experiments have (a) provided unique insights into ecological patterns and processes, although such insight often became apparent only after many years of study; (b) influenced management and policy decisions; and (c) evolved into research platforms supporting studies and involving investigators who were not part of the original design. Furthermore, this suite of long-term experiments addresses, at the site level, all of the US National Research Council\&$\#$39;s Grand Challenges in Environmental Sciences. Despite these contributions, we argue that the scale and scope of global environmental change requires a more-coordinated multisite approach to long-term experiments. Ideally, such an approach would include a network of spatially extensive multifactor experiments, designed in collaboration with ecological modelers that would build on and extend the unique context provided by the LTER Network.

}, keywords = {LTER-KNZ, Climate change, global change, long-term research, LTER Network, multifactor experiments}, doi = {10.1525/bio.2012.62.4.9}, url = {https://academic.oup.com/bioscience/article/62/4/377/243762}, author = {Alan K. Knapp and M.D. Smith and Hobbie, S.E. and Scott. L. Collins and Fahey, T.J. and Hansen, G.J.A. and Landis, D.A. and Kimberly J. La Pierre and Melillo, J.M. and Seastedt, T.R. and Shaver, G.R. and Webster, J.R.} } @article {KNZ001232, title = {Impacts of management legacies on litter decomposition in response to reduced precipitation in a tallgrass prairie}, journal = {Applied Soil Ecology}, volume = {42}, year = {2009}, pages = {79 -85}, abstract = {

The response of ecosystem processes to current and future climatic events may be affected by historical disturbance regimes. Here, we address the interaction between reduced precipitation and the legacy effects of two contrasting long-term burn regimes in a tallgrass prairie (20 years of annual burning versus fire suppression). We examined rates of decomposition and the response of decomposition to reduced precipitation under rainout shelters in these two prairie types to assess potential interactions between legacy effects and reduced precipitation. To test the legacy effects of the different burn regimes, we placed experimental plots in each prairie type under a standardized management regime. In each plot, we ceased burning, mowed to maintain a standard canopy height, and maintained standard surface litter accumulation. We measured decay rates for surface litter, buried roots, and buried wooden dowels. While decomposition rates of substrates were reduced an average of approximately 29\% under reduced precipitation, we found no significant main effects of burn history on decomposition on any of the substrates. However, in the recovery period following 2 years of an experimentally imposed drought, we did find an effect of burn history on decomposition and this effect varied for different substrates. Historical effects of management or natural disturbances on ecosystem processes may often be subtle or negated by compensatory responses, and in this study few legacy effects on decomposition rate were detected.

}, keywords = {LTER-KNZ, burning, decomposition, Drought, Legacy effects, Management regime, tallgrass prairie}, doi = {10.1016/j.apsoil.2009.01.009}, url = {https://www.sciencedirect.com/science/article/pii/S0929139309000274?via\%3Dihub}, author = {Reed, H.E. and John M. Blair and Wall, D. and Seastedt, T.R.} } @article {KNZ00946, title = {Ecological consequences of C4 grass invasion of a C4 grassland: A dilemma for management}, journal = {Ecological Applications}, volume = {15}, year = {2005}, pages = {1560 -1569}, abstract = {Many successful exotic invasive species are functionally distinct from the dominant native species they displace. Occasionally invasion occurs where the exotic species possesses functional traits relatively similar to those of the dominant native. We examined the ecological consequences of such an invasion within a mesic, temperate grassland at the Konza Prairie Long-Term Ecological Research site. We assessed potential changes in carbon (C) and nitrogen (N) cycling and plant diversity following the invasion of a C4 bunch grass species, Andropogon bladhii, into a tallgrass prairie dominated by the native C4 grass species, A. gerardii. In these prairies burning is an important management tool used to maintain native-species dominance. We determined how frequent spring fires affected the impacts of A. bladhii in this system. Over a two-year study our results show that burning regulated the effects that the invasive species has on the native prairie. Compared to the native species, A. bladhii exhibited significantly greater plant biomass, significantly lower pools of soil N, significantly lower rates of decay and C cycling, and higher foliar and root tissue C:N ratio in response to burning. Notable spatial heterogeneity in C and N cycling was evident in areas dominated by the invasive bunch grass. In addition to altered ecosystem processes, areas dominated by the invasive, A. bladhii, had significantly lower plant species diversity. In a grassland ecosystem where burning is an important management tool for controlling exotic-species establishment, maintaining native-species dominance, and increasing productivity, A. bladhii may be able to successfully out-compete the native C4 grass species by using traits typically used to explain the dominance of the native species. With frequent fire, the invasive species has the potential to decrease long-term fertility by lowering N inputs in litter and increasing erosion in non-vegetated soil between bunches, while also having a negative effect on plant diversity. By using fire to promote native C4 grasses and maintain these tallgrass prairies, the threat of invasion by nonnative C4 species may raise a dilemma for future management of these C4 grasslands.}, keywords = {LTER-KNZ}, doi = {10.1890/04-0407}, author = {Reed, H. and Seastedt, T.R. and John M. Blair} } @article {KNZ00875, title = {Relationships at the aboveground-belowground interface: Plants, soil biota, and soil processes}, journal = {Ecological Monographs}, volume = {73}, year = {2003}, pages = {377 -395}, abstract = {Interactions at the aboveground{\textendash}belowground interface provide important feedbacks that regulate ecosystem processes. Organisms within soil food webs are involved in processes of decomposition and nutrient mineralization, and their abundance and activity have been linked to plant ecophysiological traits such as species identity and the quality and quantity of plant tissue. We tested aboveground{\textendash}belowground diversity relationships in a naturally developed plant community of native tallgrass prairie by taking soil samples from beneath naturally established grass tillers of chosen characteristics (e.g., homogeneous vs. heterogeneous plant combinations or C4 vs. C3 photosynthetic pathway) without imposing any disturbances to existing plant{\textendash}soil relationships. The goal of this study was to elucidate the consequences, for soil microbiota (microflora phospholipid fatty acids, protozoa, and nematode functional groups) and for C and N mineralization, of plant community properties such as species richness, resource quality, resource heterogeneity, species identity, and presence of exotics. None of the biotic or abiotic soil variables was related to plant resource heterogeneity. Protozoa were not responsive to any of the plant community traits. Some bacterial and nematode groups were affected by plant characteristics specific to a particular plant species, but no uniform pattern emerged. Invasive and native plants generally were similar with respect to soil variables tested in this study. The lack of clear responses of soil variables to plant community traits indicates that idiosyncratic effects dominate both at the plant and soil biotic level and that generalized plant and soil diversity effects are hard to predict.}, keywords = {LTER-KNZ}, doi = {10.1890/0012-9615(2003)073[0377:RATAIP]2.0.CO;2}, author = {Porazinska, D.L. and Bardgett, R.D. and Blaauw, M.B. and Hunt, H.W. and Parsons, A.N. and Seastedt, T.R. and Wall, D.H.} } @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} } @article {KNZ00637, title = {Biotic interactions between grazers and plants: Relationships contributing to atmospheric boundary layer dynamics}, journal = {Journal of Atmospheric Sciences}, volume = {55}, year = {1998}, pages = {1247 -1259}, abstract = {During 1987 and 1988 First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE) studies conducted in the tallgrass prairie of central Kansas, variations in ungulate grazing intensity produced a patchy spatial and temporal distribution of remaining vegetation. Equally variable plant regrowth patterns contributed further to a broad array of total primary production that resulted in a pronounced mosaic of grazing impacts. This regrowth potential, derived from a relative growth rate (RGR) equation comparing ungrazed and grazed plants, determines much of the ecosystem dynamics within and among the grazed pastures and between years. Rates of change in new plant growth (DRGRg) ranged from 2100\% to 140\%; however, 78\% of the time in 1987 and 71\% in 1988, productivity increased as a function of grazing intensity. Since plant growth potential in ungrazed (RGRug) and grazed systems (RGRg) have inherently different attributes, interactions with the abiotic environment may develop many uncertainties. Thus, changes in growth rates in grazed areas compared to ungrazed areas (DRGRg) may impose major controls over system productivity and associated biological processes currently not accounted for in ecosystem models. Because FIFE microsite atmospheric boundary layer (ABL) studies did not directly incorporate grazing intensity into their design, Type I and Type II statistical errors may introduce significant uncertainties for understanding cause and effect in surface flux dynamics. As a consequence these uncertainties compromise the ability to extrapolate microsite ABL biophysical findings to other spatial and temporal scales.}, keywords = {LTER-KNZ}, url = {http://journals.ametsoc.org/doi/pdf/10.1175/1520-0469(1998)055\%3C1247\%3ABIBGAP\%3E2.0.CO\%3B2}, author = {Dyer, M.I. and Turner, C.L. and Seastedt, T.R.} } @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 {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 {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 {KNZ00579, title = {Effects of fire, mowing and nitrogen additions on root characteristics in tallgrass prairie}, journal = {Journal of Vegetation Science}, volume = {8}, year = {1997}, pages = {541 -546}, abstract = {Root harvests and root windows were used to study the influence of fire, mowing and nitrogen additions on root lengths, biomass, and nitrogen content in tall-grass prairie. Four years of nitrogen additions (10 g m2 yr-1) increased below-ground mass by 15 \% and nitrogen concentration in that mass by 77 \%. In general, live roots and rhizomes exhibited greater increases in nitrogen concentrations than detrital roots and rhizomes. After four years of treatment, live roots and rhizomes immobilized an additional 1.5 to 5 g/m2 of nitrogen, depending upon specific treatment, while dead roots and rhizomes immobilized an additional 3 to 3.5 g/m2. Average root growth parameters, as measured with root windows, were positively correlated with above-ground peak foliage biomass; however, the only significant correlation was between average new root growth and above-ground peak foliage biomass (r = 0.73, p <= 0.04). Root growth and decay, as measured by annual mean values for eight root windows over a four year interval, were insensitive to climatic and treatment effects.}, keywords = {LTER-KNZ, Below-ground Biomass, Rhizome, Root growth, Root window}, doi = {10.2307/3237205}, author = {Benning, T.L. and Seastedt, T.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.} } @inbook {KNZ00565, title = {Global grassland ecosystem modelling: development and test of ecosystem models for grassland systems}, booktitle = {Global Change: Effects on Coniferous Forests and Grasslands}, year = {1996}, pages = {229 -270}, publisher = {Wiley and Sons}, organization = {Wiley and Sons}, address = {Chichester}, keywords = {LTER-KNZ}, author = {Parton, W.J. and Coughenour, M.B. and Scurlock, J.M.O. and Ojima, D.S. and Gilmanov, T.G. and Scholes, R.J. and Schimel, D.S. and Kirchner, T.B. and Menaut, J.C. and Seastedt, T.R. and Moya, E.G. and Kamnalrut, A. and Kinyamario, J.I. and Hall, D.O.}, editor = {Breymeyer, A.I. and Hall, D.O. and Melillo, J.M. and Agren, G.I.} } @inbook {KNZ00563, title = {Impact of climate and atmospheric carbon dioxide changes on grasslands of the world}, booktitle = {Global Change: Effects on Coniferous Forests and Grasslands}, year = {1996}, pages = {271 -312}, publisher = {Wiley and Sons}, organization = {Wiley and Sons}, address = {Chichester}, keywords = {LTER-KNZ}, author = {Ojima, D.S. and Parton, W.J. and Coughenour, M.B. and Scurlock, J.M.O. and Kirchener, T.B. and Kittel, T.G.F. and Hall, D.O. and Schimel, D.S. and Moya, E.G. and Gilmanov, T.G. and Seastedt, T.R. and Kamnalrut, A. and Kinyamario, J.I. and Long, S.P. and Menaut, J.C. and Sala, O.E. and Scholes, R.J. and van Veen, J.A.}, editor = {Breymeyer, A.I. and Hall, D.O. and Melillo, J.M. and Agren, G.I.} } @article {KNZ00474, title = {Landscape-level interactions between topoedaphic features and nitrogen limitation in tallgrass prairie}, journal = {Landscape Ecology}, volume = {10}, year = {1995}, pages = {337 -348}, abstract = {Transects across watersheds with varying fire histories and remotely-sensed data were used to study vegetation-resource interactions in a tallgrass prairie in Kansas. Paired plots (fertilized, control) were established along these transects and sampled for grass and forb biomass during the 1989 and 1990 growing seasons. Fertilization resulted in significant production responses in grass and total biomass on the west slopes of the annually burned (ID) and infrequently burned (N4) watersheds for both years (p = 0.05). In 1989, fertilization also produced a significant increase in grass biomass on the west slope of the unburned transect (p = 0.05), however, total production was not significantly increased. East slopes were insensitive to nitrogen additions. Differences in production response along these transects were assessed by testing the interaction between fertilization response and slope position. Significant interactions occurred on both 1D and N4, but only in 1990. Production data for both years were also compared to Normalized Difference Vegetation Index (NDVI) values derived from thematic mapper (TM) images for 1989 and 1990. When differences among transects or watersheds were statistically different, a positive relationship between NDVI and biomass was observed. NDVI values accurately reflected the spatial patterns of production along these transects for both years although not necessarily the magnitude.}, keywords = {LTER-KNZ, fire, NDVI, nitrogen, transect, Watersheds}, doi = {10.1007/BF00130211}, author = {Benning, T.L. and Seastedt, T.R.} } @inbook {KNZ00485, title = {The relations of phytophagous invertebrates and rangeland plants}, booktitle = {Wildland Plants: Physiological Ecology and Developmental Morphology}, year = {1995}, pages = {580 -634}, publisher = {Society for Range Management}, organization = {Society for Range Management}, address = {Denver, CO}, keywords = {LTER-KNZ}, author = {Evans, E.W. and Seastedt, T.R.}, editor = {Bedunah, D.J. and Sosebee, R.E.} } @inbook {KNZ00516, title = {Soil systems and nutrient cycles of the North American Prairie}, booktitle = {The Changing Prairie}, year = {1995}, pages = {157 -174}, publisher = {Oxford University Press}, organization = {Oxford University Press}, keywords = {LTER-KNZ}, author = {Seastedt, T.R.}, editor = {Anthony Joern and Keeler, K.K.} } @article {KNZ00467, title = {Importance of photosynthetic pathways, management, and climate on plant production and soil carbon of semihumid temperate grasslands}, journal = {Ecological Applications}, volume = {4}, year = {1994}, pages = {344 -354}, abstract = {A modeling study evaluated the importance of photosynthetic pathways (C3, C4, or both) and management strategies to the foliage productivity and soil carbon characteristics of a semihumid temperate grassland subjected to various combinations of climate change. Model values for plant and soil characteristics were obtained at sites near Manhattan, Kansas, and the Manhattan climate record provided the nominal climatic drivers. Model runs used both actual monthly temperature and precipitation data for a 100{\textemdash}yr interval and average weather conditions generated from this record. Monthly temperatures were increased 2{\textdegree}C, left unchanged, or decreased 2{\textdegree}C; annual precipitation was increased 6 cm, left unchanged, or decreased 6 cm. All possible combinations of temperature and precipitation were then used in 100{\textemdash}yr simulations. Regardless of the specific climate scenario, plant production was lowest for C3 grasses and highest for the mixed C3{\textemdash}C4 community. The nominal seasonal pattern of precipitation favored an active C3 plant community in early to late spring, prior to the emergence of the C4 vegetation. However, the higher growth and water use efficiencies of C4 vegetation during summer contributed to the maximization response of the grasslands containing both C3 and C4 grasses. An analysis of variance of annual average values observed from 100{\textemdash}yr simulations was used to evaluate the relative importance of climate, photosynthetic pathways, and management activities (annually burned, burned every 4 yr, unburned, or lightly grazed) to plant production and soil carbon values. Photosynthetic pathway and precipitation were identified as the most significant single variables affecting foliage production; the interaction between photosynthetic and temperature was the most significant interaction term. Management treatments were by far the most important variables affecting soil carbon values, but 2{\textdegree}C warming did produce substantial soil carbon losses from C3 grasslands. Enhanced carbon fixation by the C4 and C3{\textemdash}C4 plant communities negated the losses of soil carbon caused by enhanced soil respiration at warmer temperatures.}, keywords = {LTER-KNZ}, doi = {10.2307/1941938}, author = {Seastedt, T.R. and Coxwell, C.C. and Ojima, D.S. and Parton, W.J.} } @article {KNZ00427, title = {Consequences of non-equilibrium resource availability across multiple time scales: the transient maxima hypothesis}, journal = {American Naturalist}, volume = {141}, year = {1993}, pages = {621 -633}, abstract = {Nonequilibrium biotic responses to changes in resource limitation dominate the behavior of tallgrass prairie ecosystems. Rates of leaf photosynthesis on a time scale of minutes, amounts of annual plant productivity, patterns in the productivity of certain consumer groups, and amounts of soil organic matter accumulation over millennia all reflect biotic responses to frequent and recurring shifts in limiting resources. Productivity is higher during a transition period when the relative importance of an essential resource is changing than during an equilibrium interval generated by single resource limitation. These "transient maxima" are both characteristic and easily measurable in the tallgrass prairie because of the unpredictable climate and ecological constraints such as grazing and recurrent fires that modify water, nitrogen, and light availability. Such diverse phenomena as overcompensation for herbivory, the intermediate disturbance hypothesis, maximum levels of productivity observed in successional ecosystems, and widespread nitrogen limitation in terrestrial and aquatic ecosystems can be explained by biotic response to shifts in limiting resources.}, keywords = {LTER-KNZ}, url = {http://www.jstor.org/stable/2462753}, author = {Seastedt, T.R. and Alan K. Knapp} } @article {KNZ00424, title = {Distinct Animal-Generated Edge Effects in a Tallgrass Prairie Community}, journal = {Ecology}, volume = {74}, year = {1993}, pages = {1281 -1285}, keywords = {LTER-KNZ}, doi = {10.2307/1940496}, author = {Reichman, O.J. and Benedix, J.H. and Seastedt, T.R.} } @article {KNZ00394, title = {Herbivory and its consequences}, journal = {Ecological Applications}, volume = {3}, year = {1993}, pages = {10 -16}, abstract = {We argue that herbivores often induce nonlinear or biphasic growth and development in plants. Collectively these individual responses translate into a system{\textemdash}level optimization curve wherein at low levels of herbivory overall community responses show increases in production potential, whereas extreme herbivory causes extreme reduction in productivity. The transition between these two states defines a point of optimal herbivory in respect to C and N processes.We present four case examples from the literature demonstrating such nonlinear responses, suggesting a widespread existence for this herbivore{\textemdash}plant phenomenon. The nonlinear responses appear to demonstrate temporal and spatial scale dependencies.}, keywords = {LTER-KNZ}, doi = {10.2307/1941781}, author = {Dyer, M.I. and Turner, C.L. and Seastedt, T.R.} } @article {KNZ00413, title = {Landscape patterns in soil-water relations and primary production in tallgrass prairie}, journal = {Ecology}, volume = {74}, year = {1993}, pages = {549 -560}, abstract = {Landscape variation in soil water relations, leaf xylem pressure potential ({\textdegree}) and leaf{\textemdash}level net photosynthesis (A) in Andropogon gerardii, and net primary production (NPP) were evaluated during the 1989 and 1990 growing seasons in a northeast Kansas (USA) tallgrass prairie. Landscape patterns were assessed along transects that spanned upland and lowland topographic positions in an annually burned and a long{\textemdash}term unburned watershed. Landscape variability in volumetric soil water content ({\textdegree}) was significantly greater in the unburned watershed (coefficient of variation [CV] = 0.425 and 0.479 for 0{\textemdash}15 and 0{\textemdash}30 cm soil depths in unburned prairie vs. 0.285 and 0.330 for similar depths in the burned watershed). In both watersheds, significantly higher {\textdegree} and total soil water content (0{\textemdash}30 cm) were measured in lowlands compared to uplands. Topographic anomalies, such as a lowland ridge, resulted in local, small{\textemdash}scale variation in soil moisture that equaled watershed variation. Variation across landscapes in predawn {\textdegree}, which was expected to reflect soil water content, was similar in both watersheds (CV = 0.312). Variation in midday @j was significantly greater across the burned than the unburned watershed in 1990 (maximum range in @j from uplands to lowlands was 0.708 MPa at predawn and 0.662 MPa at midday in the burned watershed). In both watersheds, variation in midday @j was much lower relative to {\textdegree}. Landscape patterns in leaf{\textemdash}level A in A. gerardii, the dominant species in this tallgrass prairie, were inconsistent when upland and lowland sites were compared. During an extended period of drought, A was significantly higher in plants in the unburned watershed. In both watersheds, NPP was strongly correlated with {\textdegree}. However, variability in NPP across topographic gradients in the unburned watershed was much less pronounced (CV = 0.224{\textemdash}0.245) than in the annually burned watershed (CV = 0.364{\textemdash}0.430). Moreover, the slope of the relationship between NPP and {\textdegree} was significantly greater in the annually burned watershed. We propose that relatively uniform energy limitations across topographic gradients in unburned tallgass prairie, caused by detrital accumulation that absorbs/reflects sunlight, reduced topographic variability in NPP in unburned watersheds. This pattern occurred in unburned watersheds despite greater landscape variation in {\textdegree} relative to burned watersheds. Analysis of long{\textemdash}term records of NPP from several watersheds supported the hypothesis that variability in NPP associated with topographic position is lower in unburned vs. burned watersheds. Variability in @j across watersheds and between years was muted by negative feedback of canopy leaf area (transpiring surface) on plant{\textemdash}soil water relations. We concluded that patterns in landscape variability in A and @j which may vary significantly over short time intervals, were not good predictors of seasonal carbon dioxide exchange or productivity in this tallgrass prairie. Nonetheless, interactions between A and @j, when combined with nitrogen and energy limitations to A. provide the mechanisms for integrated responses measured across these landscapes.}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/1939315}, author = {Alan K. Knapp and Fahnestock, J.T. and Hamburg, S.P. and Statland, L.J. and Seastedt, T.R. and Schimel, D.S.} } @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 {KNZ00429, title = {Maximization of aboveground grassland production: the role of defoliation frequency, intensity and history}, journal = {Ecological Applications}, volume = {3}, year = {1993}, pages = {175 -186}, abstract = {Production of tallgrass prairie vegetation was measured on experimental plots in which defoliation intensity and frequency were manipulated by mowing and using movable exclosures on areas chronically grazed by cattle. Defoliation history largely controlled whether or not defoliated plants overcompensated (exhibited enhanced production compared to undefoliated controls) for tissue removal. Plants on chronically grazed sites only compensated for foliage removed by grazers. Production on plots mowed prior to the year of measurement was similar to that on chronically grazed sites, while previously unmowed plots exhibited substantial aboveground overcompensation. Aboveground production was maximized by the most frequent mowing treatment and by intermediate mowing heights. Nitrogen and phosphorus concentrations and amounts in aboveground tissues were increased by mowing and grazing. Current mowing regime was more important than mowing history in determining nitrogen concentrations except very early in the growing season. Effects of grazing and mowing on belowground biomass were inconsistent, but frequent mowing appeared to limit accumulation of belowground N reserves and biomass. In North American grasslands, overcompensation is a nonequilibrium plant response to grazing. Photosynthate that would be stored as reserves and used for root growth and flower and seed production instead is used to replace lost leaf area, thereby resulting in higher foliage productivity. However, under chronic grazing or mowing, vegetation is prevented from maintaining high nutrient and water uptake capacity (large root biomass) and accumulating reserves that allow overcompensation responses.}, keywords = {LTER-KNZ}, doi = {10.2307/1941800}, author = {Turner, C.L. and Seastedt, T.R. and Dyer, M.I.} } @article {KNZ00418, title = {Observations and modeling of biomass and soil organic matter dynamics for the grassland biome worldwide}, journal = {Global Biogeochemical Cycles}, volume = {7}, year = {1993}, pages = {785 -809}, abstract = {Century is a model of terrestrial biogeochemistry based on relationships between climate, human management (fire, grazing), soil properties, plant productivity, and decomposition. The grassland version of the Century model was tested using observed data from 11 temperate and tropical grasslands around the world. The results show that soil C and N levels can be simulated to within {\textpm}25\% of the observed values (100 and 75\% of the time, respectively) for a diverse set of soils. Peak live biomass and plant production can be simulated within {\textpm} 25\% of the observed values (57 and 60\% of the time, respectively) for burned, fertilized, and irrigated grassland sites where precipitation ranged from 22 to over 150 cm. Live biomass can be generally predicted to within {\textpm}50\% of the observed values (57\% of the time). The model underestimated the live biomass in extremely high plant production years at two of the Russian sites. A comparison of Century model results with statistical models showed that the Century model had slightly higher r2 values than the statistical models. Data and calibrated model results from this study are useful for analysis and description of grassland carbon dynamics, and as a reference point for testing more physiologically based models prediction{\textquoteright}s of net primary production and biomass. Results indicate that prediction of plant and soil organic matter (C and N) dynamics requires knowledge of climate, soil texture, and N inputs.}, keywords = {LTER-KNZ}, doi = {10.1029/93GB02042}, author = {Parton, W.J. and Scurlock, J.M.O. and Ojima, D.S. and Gilmanov, T.G. and Scholes, R.J. and Schimel, D.S. and Kirchner, T. and Menaut, J.C. and Seastedt, T.R. and Moya, E.G. and Kamnalrut, A. and Kinyamario, J.I.} } @article {KNZ00383, title = {Effects of management and topography on the radiometric response of a tallgrass prairie}, journal = {Journal of Geophysical Research}, volume = {97}, year = {1992}, pages = {18855 -18666}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1029/92JD00654}, author = {Turner, C.L. and Seastedt, T.R. and Dyer, M.I. and Kittel, T.G.F. and Schimel, D.S.} } @proceedings {KNZ00375, title = {Effects of tallgrass prairie vegetation on the concentration and seasonality of nitrate\-nitrogen in soil water and streams}, year = {1992}, pages = {9 -12}, publisher = {University of Northern Iowa}, abstract = {

Inorganic nitrogen concentrations in tallgrass prairie soils and streams exhibit a sinusoidal seasonal pattern; nitrate levels are relatively high in winter and low in summer. The pattern is not observed in either rainfall or canopy drip (throughfall). Thus, the pattern is created by plant root-microbial interactions; when roots are not active, nitrates accumulate and can be leached from the soil. We used nitrogen fertilizer and herbicide in a factorial experiment to test the strength of root uptake activities on soil water nitrogen. Soil-water nitrate concentrations were 10 times higher when prairie roots were deactivated by application of a foliar herbicide. Ammonium nitrogen concentrations were unaffected. When fertilizer was added, nitrate levels of soil water beneath herbicide-treated vegetation were double that of untreated prairie. Mineralization of nitragen from herbicide-treated roots was not believed to be the source of the increased nitrate. These and previous studies at Konza Prairie emphasize the importance of plant cover in maintaining low nitrate concentrations of streams

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Ramundo, R.A. and Tate, C.M. and Seastedt, T.R.}, editor = {Smith, D.A. and Jacobs, C.A.} } @article {KNZ00377, title = {Mass loss and nitrogen dynamics of decaying litter of grasslands: the apparent low nitrogen immobilization potential of root detritus}, journal = {Canadian Journal of Botany}, volume = {70}, year = {1992}, pages = {384 -391}, abstract = {

Litter-bag studies and simulation modeling were used to examine the relationship between mass loss and nitrogen content of decaying prairie foliage and root litter. In contrast with forest studies, grassland roots were low in lignin and nitrogen, decayed more rapidly than foliage, and demonstrated very low nitrogen immobilization potentials. Our findings agree with reports indicating that buried substrates with high C:N ratios do not immobilize substantial amounts of nitrogen-limited environments induce steeper slopes in the mass loss-nitrogen concentration relationship. However, results suggesting rapid nitrogen mineralization contradict our own studies demonstrating reduced inorganic nitrogen availability in soils of frequently burned prairie. Simulation of observed patterns using the CENTURY grassland model indicated that these results could not occur without creating soil organic matter with unrealistically high C:N ratios. Litter-bag studies of buried substrates therefore may provide an incomplete perspective on the mass loss and nitrogen dynamics of buried litter in grassland and agroecosystem soils. key words: Andropogon gerardii, C:N ratio, decomposition, immobilization, mineralization, nitrogen

}, keywords = {LTER-KNZ}, doi = {10.1139/b92-052}, author = {Seastedt, T.R. and Parton, W.J. and Ojima, D.S.} } @article {KNZ00382, title = {Soil invertebrate and plant responses to mowing and Carbofuran application in a North American tallgrass prairie}, journal = {Plant and Soil}, volume = {144}, year = {1992}, pages = {117 -124}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1007/BF00018852}, author = {Todd, T.C. and James, S.W. and Seastedt, T.R.} } @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 {KNZ00336, title = {Fire, mowing and insecticide effects on soil Sternorrhyncha (Homoptera) densities in tallgrass prairie}, journal = {Journal of the Kansas Entomological Society}, volume = {64}, year = {1991}, pages = {238 -242}, abstract = {

Densities of soil-dwelling Sternorrhyncha (Aphidoidea + Coccoidea) in tallgrass prairie significantly increased in response to application of a foliar insecticide (carbaryl). Densities of these soil homopterans also increased in response to mowing of vegetation. Spring burning of vegetation to enhance grass production did not have a strong affect on total populations. Resource abundance of cool season grasses, as mediated by competition from other herbivores, best explain these patterns

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {http://www.jstor.org/stable/25085278}, author = {Seastedt, T.R. and Reddy, V.M.} } @article {KNZ00313, title = {Influence of mowing and fertilization on biomass, productivity and spectral reflectance in Bromus inermis plots}, journal = {Ecological Applications}, volume = {1}, year = {1991}, pages = {443 -452}, keywords = {LTER-KNZ}, doi = {10.2307/1941901}, author = {Dyer, M.I. and Turner, C.L. and Seastedt, T.R.} } @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 {KNZ00335, title = {Physiological interactions along resource gradients in a tallgrass prairie}, journal = {Ecology}, volume = {72}, year = {1991}, pages = {672 -684}, abstract = {

Spatial variability in availability of resources that limit photosynthesis (water and N) leads to variation in rates of atmosphere- biosphere exchange. N content and allocation are canopy properties that link ecosystem, physiological, and biophysical processes and that vary in space at scales relevant to atmosphere-biosphere interaction. We studied landscape-scale variation in these and related canopy properties in Kansas Tallgrass Prairie (USA). The tallgrass ecosystem was suited to this investigation because primary production in the prairie is constrained by N availability. This work was designed to aid in interpertation and spatial extrapolation of gas exchange measurements made using aerodynamic techniques as part of FIFE (First ISLSCP Field Experiment), a NASA- supported study. We collected data on spatial disrtibution of biomass, leaf area index (LAI), canopy N mass. N concentration ([N]), and gas exchange along topographic and management gradients. We also measured height distribution of N, light interception, and gas exchange within canopies as a function of position in the landscape. Substantial variation in biomass, LAI, N accumulation, and N allocation occurred over time, with topography, and as a result of previous burning. The verticle gradient of [N] and photosynthetic capacity within canopies were correlated, in space and time, with biomass and canopy light interception. The gradients were steper in high biomass sites than in low biomass sites. In addition, proportional N allocation to the upper layer increased with time (12\% in June, 32\% in August) as biomass increased. As nutrient uptake increased within the tallgrass landscape, biomass increased and light limitation in the lower canopy was induced. As this light limitation increased with increasing biomass, or with accumulation of dead vegetation, allocation of N to the upper canopy increased. Height distribution of photosyntheticd capicity paralleled within-canopy N allocation and light interception. As resource ratios (light, water and nitrogen) varied in the landscape, so did rates of gas exchange. This work suggests that in interactions between light extinction, N allocation, and photosynthesis that have been proposed for monospecific stands apply to the multispecies, but structurally simple, canopy of the tallgrass prairie. Models of plant performance based on evolutionary arguments may provide a powerful basis for spatial extarapolation of atmosphere-ecosystem exchange rates from sites to landscape and larger regions. Key words: atmosphere-ecosystem exchange, FIFE; Konza Prairie Long-Term Ecological Research site; leaf area index; light interception; nitrogen allocation; photosynthetic capacity; photosynthetically active radiation; remote sensing; toposequences

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/2937207}, author = {Schimel, D.S. and Kittel, T.G.F. and Alan K. Knapp and Seastedt, T.R. and Parton, W.J. and Brown, V.B.} } @article {KNZ00314, title = {Remote sensing measurements of production processes in grazing lands: the need for new methodologies}, journal = {Agriculture, Ecosystems and Environment}, volume = {34}, year = {1991}, pages = {495 -505}, abstract = {

Remote sensing of grazinglands to obtain estimates of productivity relies entirely upon absorption and reflectance properties of the vegetation and its background to provide accurate qualitative and quantitative values. Interpretations of these signals are highly dependent on vegetation responses to perturbations, such as grazing or alterations in nutrient cycles. If remote sensing models of grassland growth ignore feedbacks derived from grazing animals, or only negative feedbacks are assumed, there is a likelihood of errors developing during model validation. We review fundamental assumptions made when using remote sensing data from grazing systems and give examples of the problems involved

}, keywords = {LTER-KNZ}, doi = {10.1016/0167-8809(91)90132-H}, author = {Dyer, M.I. and Turner, C.L. and Seastedt, T.R.} } @article {KNZ00294, title = {Field bioassessment for selecting test systems to evaluate military training lands in tallgrass prairie}, journal = {Ecosystem Health.V.1 Environmental Management}, volume = {14}, year = {1990}, pages = {81 -93}, abstract = {

Ecosystems responses to physical or chemical stress may vary from changes in single organisms to alteration of the structure and function of the ecosystem. These responses to stress cannot be predicted exactly. Ecosystems repeatedly exposed to physical and/or chemical stress can be used to study the separate and combined environmental effects of stress. Such studies also allow the development of procedures to select test systems for the analysis of stress in ecosystems. A preliminary field survey of six military training sites at Fort Riley, Kansas, USA, was conducted to identify and verify ecological test systems for evaluating ecosystem responses to physical and/or chemical stress. Comparisons of these data with data collected concurrently from Konza Prairie Research Natural Area reference sites showed that soil microarthropods, some species of macroarthropods, small mammals, and native earthworm species were negatively affected by stress. In contrast, plant species diversity, plant foliage biomass, soil mycorrhizae, and many soil characteristics were within the boundaries of nominal variations observed on \"pristine\" Konza Prairie. Introduced European earthworms appeared to be positively affected by training activities. This study provided a test of systematic procedures to support impact analysis, ecological toxicology, and ecosystem risk assessment

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1007/BF02394022}, author = {Schaeffer, D.J. and Seastedt, T.R. and D.J. Gibson and D.C. Hartnett and Hetrick, B.A.D. and James, S.W. and D.W. Kaufman and Schwab, A.P. and Herricks, E.E. and Novak, E.W.} } @inbook {KNZ00295, title = {The influence of fire on belowground processes of tallgrass prairies}, booktitle = {Fire in North American Tallgrass Prairie}, year = {1990}, pages = {99 -117}, publisher = {University of Oklahoma Press}, organization = {University of Oklahoma Press}, address = {Norman, OK}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Seastedt, T.R. and Ramundo, R.A.}, editor = {Scott. L. Collins and Wallace, L.L.} } @article {KNZ00293, title = {Site-specific underestimation of wetfall NH+4 using NADP data}, journal = {Atmospheric Environment}, volume = {24A}, year = {1990}, pages = {3093 -3095}, abstract = {

Estimates of NH4+ in weekly composited wetfall samples were measured by two laboratories, one at Kansas State University and that operated by the National Atmospheric Deposition Program (NADP) in Illinois. NH4+ samples were lower in the NADP estimates and exhibited a strong seasonal difference in concentrations. Losses were likely not due to volatilization; microbial immobilization of NH4+ likely occurred during transport of samples. Differences in estimates of annual ammonium ion deposition were larger than those observed for average weekly concentrations because of seasonal rainfall patterns. NADP values will require site-specific corrections for models describing or predicting regional or national patterns of nitrogen inputs in wetfall. Key words: Ammonium, NADP, nitrate, wetfall

}, keywords = {LTER-KNZ}, doi = {10.1016/0960-1686(90)90489-A}, author = {Ramundo, R.A. and Seastedt, T.R.} } @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} } @proceedings {KNZ00250, title = {Effects of manipulation on foliage characteristics of Andropgon gerardii Vitman}, year = {1989}, pages = {143 -146}, publisher = {University of Nebraska Press}, address = {Lincoln, NE}, abstract = {

The effects of burning, mowing, and nitrogen fertilizer on the chlorophyll, nitrogen, and phosphorus content of big bluestem were measured using a factorial experimental design at Konza Prairie Research Natural Area. While spring burning usually increased foliage production, burning had no effect on mid-season chlorophyll or nitrogen concentrations. Chlorophyll concentrations were significantly increased by fertilizer and mowing treatments. Nitrogen concentrations of foliage were higher on fertilized and mowed plots. Mowing also increased phosphorous concentrations of foliage, but nitrogen fertilizer significantly reduced phosphorus concentrations. These results support other research indicating that 1) nitrogen use efficiency (grams biomass produced per gram of foliage nitrogen) is higher on burned prairie, 2) removal of foliage by mowing results in more nutrient-rich regrowth, and 3) the amount of phosphorus available to big bluestem foliage is limited. The dilution of phosphorus caused by added nitrogen was a consequence of increased productivity on these plots and suggessts phosphorus uptake in excess of requirements for maximum growth. The relationships between burning, mowing, and nitrogen on the spectral reflectance patterns of vegetation indicated that chlorophyll (or nitrogen) concentrations of foliage appeared to more strongly affect indices of greenness and plant vigor than did the amount of plant biomass. Key words: biomass, burning, mowing, big bluestem, Andropogon gerardii, chlorophyll, nitrogen, phosphorus, Kansas

}, keywords = {LTER-KNZ, burning}, author = {Ramundo, R.A. and Shapley, T.D. and Turner, C.L. and Dyer, M.I. and Seastedt, T.R.}, editor = {Bragg, T.B. and Stubbendieck, J.} } @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 {KNZ00251, title = {Microarthropods in decaying wood from temperate coniferous and deciduous forests}, journal = {Pedobiologia}, volume = {33}, year = {1989}, pages = {69 -77}, abstract = {

Microarthropod population densities in large woody debris increase the decay process. Maximum densities were about 2 X 106 individuals per m3 of wood, but remained 2-10 times lower than population densities found in an equivalent amount of litter and soil from either coniferous or deciduous forests. Oribatid mites are the most abundant microarthropods in wood. Species diversity of all microarthropod groups is lower in decaying wood compared with species numbers in litter and soil. The dominant species in wood appear to be mycophagous; the number of wood-feeding microarthropods composes a small minority of both species and numbers of fauna found in decaying boles. Key words: coniferous forest, decay, decidous forest, population density, microarthropods, mites, Oribatids, species diversity, wood

}, keywords = {LTER-KNZ}, author = {Seastedt, T.R. and Reddy, M.V. and Cline, S.P.} } @article {KNZ00231, title = {Nitrogen dynamics of soil water in burned and unburned tallgrass prairie}, journal = {Soil Biology \& Biochemistry}, volume = {21}, year = {1989}, pages = {1003 -1007}, abstract = {

Porous cup lysimeters were used to study the effects of spring burning for 5 yr on soil water N dynamics of tallgrass prairie. NO3--N concentration within the the rooting zone (20 cm depth) were unaffected by burning and averaged 27 {\ae}g 1-1. Concentrations at 80 cm were also similar for burned and unburned prairie and averaged 13 {\ae}g 1-1. Organic N was the dominant form of N in soil water, and showed a strong effect of treatment and depth. Oraganic N concentration averaged 409 {\ae}g 1-1 at 20 cm depth on unburned watersheds versus 295 {\ae}g 1-1 on burned watersheds (P\< 0.05). Values were not influenced by burning at 80 cm depths but were 30-50\% lower than those observed at 20 cm. Soil water N concentrations averaged \< 30\% of those observed in bulk precipitation inputs, and while fire is responsible for the maintenance of the tallgreass prairie flora, fire does not appear to be an important factor affecting groundwater export of N in this biome. Total N concentrations increased from an average of ca.200 {\ae}g 1-1 in 1982 to an average of ca.400 {\ae}g 1-1 during 1986, while lysimeter volumes declined from \> 400 to ca.200 sample-1. These changes were not related to precipitation, and suggests that the soil environment sampled by the lysimeters changes through time

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1016/0038-0717(89)90036-9}, author = {Hayes, D.C. and Seastedt, T.R.} } @proceedings {KNZ00252, title = {Silica, nitrogen and phosphorus dynamics of tallgrass prairie}, year = {1989}, pages = {205 -209}, publisher = {University of Nebraska Press}, address = {Lincoln, NE}, abstract = {

Experiments were conducted on big bluestem (Andropogon gerardii Vitman) in the greenhouse and on a tallgrass site on Konza Prairie to evaluate the effects of simulated grazing on the cycling of silica (SiO2), nitrogen, and phosphorus. Concentrations of all elements increased in vegetation that had been clipped or pruned. The absolute amount of nitrogen obtained by plants in the greenhouse experiment was increased by clipping foliage. Phosphorous exhibited only neutral or negative responses, while the absolute amount of silica declined in all but one experiment involving root pruning. In that experiment, the absolute amount of silica in roots was increased by 25\% by cutting a portion of the root system. These results suggest that the direct effects of clipping or pruning on the absolute amounts of elements cycled through vegetation are usually neutral or negative. Increased silicification or grazed foliage is suggested to be a consequence of delayed senescence and reduced leaf area. This interpretation provides a proximate reason why silicification is an \"inducible defense\" against herbivores. Key words: big bluestem, Andropogon gerardii, simulated grazing, nutrients, productivity, roots, Kansas

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Seastedt, T.R. and Ramundo, R.A. and Hayes, D.C.}, editor = {Bragg, T.B. and Stubbendieck, J.} } @article {KNZ00204, title = {Factors influencing nitrogen concentrations in soil and water in a North American tallgrass prairie}, journal = {Soil Biology \& Biochemistry}, volume = {20}, year = {1988}, pages = {725 -729}, abstract = {

The influence of roots, soil fauna and microbes on nitrogen concentrations in soil water in annually-burned tallgrass prairie were evaluated using porous cup lysimeters and a series of manipulations involving an insecticide, clipping of the vegetation, and C and N additions to the soil surface. An organophosphate insecticide (isofenphos), which significantly reduced densities of certain nematode and arthropod groups, resulted in small but statistically significant declines in soil water NO3- concentrations during 2 of 3 yr of study. Organic N, the dominant form of soil water N, was unaffected by treatment. Clipping the foliage weekly during the spring resulted in significant reductions in annual foliage production, but failed to change concentrations of soil water NO3- or organic N. Nitrogen additions (10 g N m-2 as NH4NO3) greatly increased soil water NO3- concentrations; however, when 250 g C sucrose m-2 were concurrently added to plots, there was a significant reduction in soil water NO3- concentrations. Soil water NH4+ concentrations were unaffected by treatment. These studies emphasize the importance of microbes as the dominant factor affecting soil water N concentrations in carbon-rich soils. Plants, soil fauna and nitrogen fertilizers do affect N. dynamics, but, under annually-burned conditions in the tallgrass prairie, these effects are obscured by microbial processes

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1016/0038-0717(88)90158-7}, author = {Seastedt, T.R. and Hayes, D.C.} } @article {KNZ00206, title = {Interactions among soil invertebrates, microbes and plant growth in tallgrass prairie}, journal = {Agriculture, Ecosystems, and Environment}, volume = {24}, year = {1988}, pages = {219 -228}, abstract = {

The tallgrass prairie of North American contains a diverse and abundant soil fauna well represented by earthworms, macro- and microarthopods and nematodes. A portion of this fauna representing a large fraction of the animal biomass has been introduced in the last 200 years, and functional roles and regulatory mechanisms may have been altered because of these introductions. Four years of experimental manipulations of plant and fauna variables have failed to establish a definitive net effect of the soil fauna on primary productivity. However, measurable effects of the fauna on nutrient dynamics of the grassland ecosystem have been observed. Experimental manipulations of plant root dynamics and addition of inorganic nitrogen and fixed carbon have demonstrated that both resources quality and resource quantity are factors limiting the size of soil fauna populations

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1016/0167-8809(88)90067-9}, author = {Seastedt, T.R. and James, S.W. and Todd, T.C.} } @article {KNZ00203, title = {Mass, nitrogen, and phosphorus dynamics in foliage and root detritus of annually burned and unburned tallgrass prairie}, journal = {Ecology}, volume = {69}, year = {1988}, pages = {59 -65}, abstract = {

Mass, nitrogen, and phosphorus of litterfall were measured for 4 yr on annually burned and unburned tallgrass prairie near Manhattan, Kansas. Decomposition and mineralization rates of foliage, flowering stem, and roots were concurrently studied with a series of litterbag and tethered litter experiments. Amounts of nitrogen and phosphorus in living and dead foliage and roots were measured for 2 yr on an annually burned site. Litterfall exhibited seasonal peaks on all sites, with most of the annualy litter deposition occurring in autumn. An average of 52 g.m-2.yr-1 of litter was deposited on the soil of the annual burned watersheds, while 142 g.m-2.yr-1 was collected on unburned sites. Nitrogen and phosphorus amounts were 0.53 and 0.07 g.m-2.yr-1, respectively, from burned sites and 1.94 and 0.19 g.m-2.yr-1 on unburned sites. Litterfall on unburned sites averaged approximately 35\% of aboveground maximum biomass estimates. Litter decay rates varied from a minimum of approximately 10\%/yr for flowering stems in the canopy to a maximum of approximately 50\%/yr for roots. Foliage and stems act as nitrogen and phosphorus sinks during the first 2 yr of decomposition. Dead roots and rhizomes also act as temporary nitrogen sinks, but unlike foliage, roots appear to mineralize significant amounts of phosphorus during the 1st yr of decay. Root nitrogen to phosphorus ratios may provide a proximate explanation for nitrogen limitation in tallgrass prairies. Key words: decomposition, litterfall, nitrogen, phosphorus, roots, tallgrass prairie

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/1943160}, author = {Seastedt, T.R.} } @article {KNZ00205, title = {Maximization of densities of soil animals by foliage herbivory: empirical evidence, graphical and conceptual models}, journal = {Oikos}, volume = {51}, year = {1988}, pages = {243 -248}, abstract = {

Feeding by consumers on one portion of a plant resource often results in benefits to consumer feeding on other portions of the same resource. Moderate grazing of foliage often increases densities and biomass of belowground herbivores and detritivores in spite of a neutral or reduced root growth response to foliage removal. Graphical and conceptual models are presented to describe these responses and suggest causal relationships. Empirical data and the models indicate that the positive numerical response of soil animals to foliage herbivory results from increased quality (nitrogen concentration) of roots and changes in consumer assimilation efficiencies. Root growth and senescence and acquisition of soil inorganic nitrogen by microbes colonizing senescent roots are hypothesized as additional causal agents for the soil animal response

}, keywords = {LTER-KNZ}, doi = {10.2307/3565649}, author = {Seastedt, T.R. and Ramundo, R.A. and Hayes, D.C.} } @article {KNZ00142, title = {Canopy rainfall interception and throughfall in burned and unburned tallgrass prairie}, journal = {The Southwestern Naturalist}, volume = {32}, year = {1987}, pages = {267 -271}, abstract = {

Interception of precipitation by grass canopies in annually burned and unburned tallgrass prairie was measured for individual precipitation events from 1983 to 1984. Seasonal patterns of interception closely reflected differences in grass canopy development throughout the growing season in burned but not unburned prairie. Mean interception for the study period was 38 and 19\% for unburned and burned prairie, respectively, indicating tht througfall volume in burned prairie was approximately 1.3 times that of unburned prairie on an annual basis. Thus, water availability for plant uptake may be initally higher in burned prairie, especially early in the growing season

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/3671570}, author = {Gilliam, F.S. and Seastedt, T.R. and Alan K. Knapp} } @article {KNZ00161, title = {Experimental manipulations of soil arthropod, nematode, and earthworm communities in a North American tallgrass prairie}, journal = {Pedobiologia}, volume = {30}, year = {1987}, pages = {9 -17}, abstract = {An insecticide was applied to foliage and an insecticide-nematicide was applied to the soil surface of a North American tallgrass prairie site in an attempt to manipulate population densities of invertebrate consumers. The objectives of this study included 1) measurement of impacts of the dominant root herbivores, June beetle larvae (Phyllophaga spp.: Scarabaeidae) on plant root biomass and production; 2) to evaluate nematode and earthworm response to the chemicals and to correlate changes in these groups with changes in living or dead plant mass, and 3) to test if differences in densities of aboveground invertebrate consumer groups directly or indirectly affected population densities of the belowground groups. The last question resulted from an observation by Seastedt (1985) that moderate aboveground herbivory appears to increase population densities of soil nematodes and certain arthropod groups}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Seastedt, T.R. and Todd, T.C. and James, S.J.} } @article {KNZ00144, title = {Root dynamics of tallgrass prairie in wet and dry years}, journal = {Canadian Journal of Botany}, volume = {65}, year = {1987}, pages = {787 -791}, abstract = {

Root dynamics were studied using root windows at Konza Prairie, a tallgrass prairie in north central Kansas, during dry (1984) and wet (1985) years. Amounts, production, and disappearance of root lengths decreased during drought but increased when rains resumed; however, standing crop remained low. The 1985 root lengths increased throughout the growing season, while production and disappearance remained constant. Yearly summaries of amounts, productivity and decomposition by 10-cm increments in soil depth show that the effect of drought on these variables decreased with increasing soil depth. Turnover rates of root length averaged 564 in the dry year versus 389\% in the wet year, with the largest difference noted in the 0 to 10 cm depth (800 in 1984 versus 540\% in 1985). Production and decay patterns observed using root windows were also noted in root biomass data (obtained from soil cores). The average total root biomass turnover rate was 31\%. Failure to sort belowground materials into tissue types (rhizome, roots) and live versus dead status result in reduced estimates of biomass turnover rates. The greatest possible separation of plant components presents the most comprehensive picture of (belowground) growth dynamics

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1139/b87-105}, author = {Hayes, D.C. and Seastedt, T.R.} } @article {KNZ00121, title = {Detritus accumulation limits productivity of tallgrass prairie}, journal = {BioScience}, volume = {36}, year = {1986}, pages = {662 -668}, abstract = {

A number of ecosystems in North American are maintained by fire, and other systems such as the Serengetti grasslands and taiga forest decline in productivity when fire or grazing is excluded. We believe, however, that the tallgrass prairie is unique among the North American biomes because of the strong negative impacts of plant ligtter production on subsequent ecosystem function. These deleterious effects on plant litter include: a reduction in available light energy to the system; an alteration of the microclimate and physiology of emerging shoots such that carbon dioxide uptake is reduced; a conversion of immediately usable inorganic notrogen in rainwater to less readily available organic nitrogen in microbial biomass; an inhibition of nitrogen fixation by free living microbes and blue-green algae as a result of phosphorus and/or light limitation; and a reduction in soil temperatures, which diminishes root productivity, invertebrate activities, and probably microbial activities as well. Fire and grazing therefore become necessary, integral ecosystem processes that maintain productivity of tallgrass prairie by the removal of standing and fallen litter

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {http://www.jstor.org/stable/1310387}, author = {Alan K. Knapp and Seastedt, T.R.} } @proceedings {KNZ00125, title = {Effects of vegetation, burning and mowing on soil macroarthropods of tallgrass prairie}, year = {1986}, pages = {99 -102}, publisher = {North Dakota State University: Tri-College Center for Environmental Study}, address = {Fargo, ND}, abstract = {

Tallgrass prairie was burned annually, mowed and raked three times yearly, or left undisturbed for two years, and soil anthropods were censused after the first and second years of treatment. Total arthropod densities increased from about 75 individuals/m2 to 132 individuals /m2 and arthropod biomass increased from about 24 kg/ha to 43 kg/ha from November 1981 to March 1983. These increases were associated with increased productivity of prairie vegetation during the initial year of the study. Annual burning resulted in increased biomass of root xylem feeders (cicada nymphs), mowing and raking resulted in increased biomass of root chewing insects (white grubs). Smaller herivores (mostly chrysomelid larvae), predaceous beetle larvae and insect detritivores were most abundant on unburned plots. Overall, arthropod biomass was highest on burned plots; however, densities of arthropods were not significantly different among treatments. Of the arthropods found to be abundant in tallgrass prairie soil, only the white grubs are known to adversely affect plant productivity. Results from this study suggest that drought or land use practices that stress the vegetation will increase densities of these pest insects

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Seastedt, T.R. and Hayes, D.C. and Petersen, N.J.}, editor = {Clambey, G.K. and Pemble, R.H.} } @article {KNZ00116, title = {Nitrogen mineralization by native and introduced earthworms: effects on big bluestem growth}, journal = {Ecology}, volume = {67}, year = {1986}, pages = {1094 -1097}, abstract = {

The presence, in the tallgrass prairie of North America, of an introduced European earthworm, Aporrectodea turgida Eisen (Lumbricidae) and native worms of the genus Diplocardia (Acanthodrilidae) led us to ask how the two groups compare with regard to mineralization of nitrogen and stimulation of plant growth in this ecosystem. Our working hypothesis was that earthworm- caused increases in N mineralization would be detected in leachates from pot cultures and reflected in increased plant growth and N uptake by Andropogon gerardii Vitman, a tallgrass dominant. The magnitude of both of these effects was expected to be greater in pots containing A. turgida, because these worms are larger and appear to be more active. Gut analysis was also performed to assess potential differences in feeding habits of the Diplocardias and A. turgida

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/1939833}, author = {James, S.W. and Seastedt, T.R.} } @article {KNZ0099, title = {Canopy interception of nitrogen in bulk precipitation by annually burned and unburned tallgrass prairie}, journal = {Oecologia}, volume = {66}, year = {1985}, pages = {88 -92}, abstract = {

Nitrogen content of bulk precipitation and throughfall (canopy leachates) was measured on annually burned and unburned tallgrass prairie during a 20 month period. Throughfall amounts averages 58\% of precipitation on unburned prairie while throughfall on annually burned sites averaged 76\% of precipitation inputs. Stemflow was measured in late summer and autumn. Volumes were correlated with stem density; maximum stemflow volumes measured in this study averaged about 50\% of throughfall volumes. Bulk precipitation averages 530, 456, and 420 micrograms/l of nitrate, ammonium and organic nitrogen, respectively. Throughfall on burned sites averaged 345, 344, and 980 micrograms/l of nitrate, ammonium and organic nitrogen, and throughfall on unburned sites averaged 258, 196, and 1701 micrograms/l of nitrate ammonium and organic nitrogen. Microbes on standing dead vegetation and litter of the unburned sites were estimated to remove more inorganic nitrogen from bulk precipitation than did foliage on burned sites. Only a portion of the inorganic nitrogen in bulk precipitation is immediately available for plant use, and this availability is influenced by the amount of detritus present on the prairie

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1007/BF00378557}, author = {Seastedt, T.R.} } @article {KNZ0098, title = {Maximization of primary and secondary productivity by grazers}, journal = {The American Naturalist}, volume = {126}, year = {1985}, pages = {559 -564}, abstract = {

Not only have consumers coevolved with their food resources, but they have coevolved with them as these resources have been modified by other herbivores and detritivores. Current theory states that most plants respond to herbivory by producing chemical that adversely affect the growth or survivorship of the herbivores. Certain consumers, however, may exhibit positive growth responses when these changes in plant chemistry occur. Increased growth is predicted whenever herbivory increases the quality of the food resource via plant stress or when it removes chemicals having a negative effect on the palatability or assimilation of the resource. I suggest that these positive responses are more widespread than is currently acknowledged

}, keywords = {LTER-KNZ, graze, primary, productivity}, doi = {http://www.jstor.org/stable/2461537}, author = {Seastedt, T.R.} } @article {KNZ0071, title = {Belowground macroarthropods of annually burned and unburned tallgrass prairie}, journal = {American Midland Naturalist}, volume = {111}, year = {1984}, pages = {405 -408}, abstract = {

Biomass of macroarthopods averaged 4.2 g/m2 in the top 20 cm of soil from annually burned tallgrass prairie vs. 2.7 g/m2 from unburned sites. Change in scarab beetle larvae and adult biomass (mostly Phyllophaga spp.) was responsible for this difference and averaged 3.4 g/m2 on burned sites vs. 1.7 g/m2 on unburned sites. Causal relationships between burning and increased scarab abundance remain speculative. The standing crop of belowground arthropod biomass of tallgrass prairie is 2- 10 times larger than that of aboveground arthropods

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Seastedt, T.R.} } @article {KNZ0072, title = {Microarthropods of burned and unburned tallgrass prairie}, journal = {Journal of the Kansas Entomological Society}, volume = {57}, year = {1984}, pages = {468 -476}, abstract = {

Microarthropod densities in the top 5 cm of soil of tallgrass prairie averaged 47,700 individuals/m2 on burned sites versus 73,800 individuals/m2 on sites not burned for the last 5 years. Oribatid mites, mesostigmatid mites and collembolans were more numerous on unburned sites while prostigamatid mite numbers were not affected by burning. Densities of microarthropods in the uppermost 5 cm of soil were correlated with the amount of litterfall at various sites, but were not correlated with indices of plant productivity. Numbers of microarthropods at the 5-10 cm layer of soil were not different on burned and unburned sites and averaged 20,200 individuals/m2. A preliminary survey of the mites (Acari) on Konza Prairie indicated a minimum of 81 species. The mite fauna appears as diverse as other temperate ecosystems

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {http://www.jstor.org/stable/25084545}, author = {Seastedt, T.R.} } @article {KNZ0050, title = {The rhinoceros beetle, Xyloryctes jamaicensis Drury (Coleoptera, Scarabaeidae):a locally abundant detritivore of a Kansas riparian forest}, journal = {Journal of the Kansas Entomological Society}, volume = {56}, year = {1983}, pages = {543 -546}, abstract = {

Third stage larvae of the rhinoceros beetle, Xyloryctes jamaicensis Drury (Coleoptera, Scarabaeidae), were abundant during autumn 1981 in litter and upper soil horizons of a bur oak- hackberry forest near Manhattan, Kansas. Densities of larvae ranged from 0 to 3.7 individuals/m2 within forest transects, while amounts of fecal pellets of these larvae ranged from 28.2 to 463.1 g/m2 along these same transects. No third stage larvae were present the following autumn, suggesting that the population is dominated by a particular brood. Fecal pellets exhibited slow decay rates (10\%/yr), and the amount of pellets on the forest floor represents the relative abundance of several generations of larvae

}, keywords = {LTER-KNZ, beetle, prairie, tallgrass}, doi = {http://www.jstor.org/stable/25084458}, author = {Seastedt, T.R.} }