@article {KNZ002041, title = {Increasing effects of chronic nutrient enrichment on plant diversity loss and ecosystem productivity over time}, journal = {Ecology}, volume = {102}, year = {2021}, pages = {e03218}, abstract = {

Human activities are enriching many of Earth\’s ecosystems with biologically limiting mineral nutrients such as nitrogen (N) and phosphorus (P). In grasslands, this enrichment generally reduces plant diversity and increases productivity. The widely demonstrated positive effect of diversity on productivity suggests a potential negative feedback, whereby nutrient-induced declines in diversity reduce the initial gains in productivity arising from nutrient enrichment. In addition, plant productivity and diversity can be inhibited by accumulations of dead biomass, which may be altered by nutrient enrichment. Over longer timeframes, nutrient addition may increase soil fertility by increasing soil organic matter and nutrient pools. We examined the effects of 5-11 years of nutrient addition at 47 grasslands in twelve countries. Nutrient enrichment increased aboveground live biomass and reduced plant diversity at nearly all sites, and these effects became stronger over time. We did not find evidence that nutrient-induced losses of diversity reduced the positive effects of nutrients on biomass, however nutrient effects on live biomass increased more slowly at sites where litter was also increasing, regardless of plant diversity. This work suggests that short-term experiments may underestimate the long-term nutrient enrichment effects on global, grassland ecosystems.

}, keywords = {LTER-KNZ}, doi = {10.1002/ecy.3218}, url = {https://onlinelibrary.wiley.com/doi/10.1002/ecy.3218}, author = {Seabloom, E.W. and Adler, P.B. and Alberti, J. and Biederman, L. and Buckley, Y.M. and Cadotte, M.W. and S.L Collins and Dee, L. and Fay, P.A. and Firn, J. and Hagenah, N. and Harpole, W. S. and Hautier, Y. and Hector, A. and Hobbie, S.E. and Isbell, F. and Knops, J.M.H. and Kimberly J. Komatsu and Laungani, R. and MacDougall, A. and McCulley, R.L. and Moore, J.L. and Morgan, J.W. and Ohlert, T. and Prober, S.M. and Risch, A.C. and Schuetz, M. and Stevens, C.J. and Borer, E.T.} } @article {KNZ001965, title = {Global change effects on plant communities are magnified by time and the number of global change factors imposed}, journal = {Proceedings of the National Academy of Sciences}, volume = {116}, year = {2019}, pages = {17867-17873}, abstract = {

Global change drivers (GCDs) are expected to alter community structure and consequently, the services that ecosystems provide. Yet, few experimental investigations have examined effects of GCDs on plant community structure across multiple ecosystem types, and those that do exist present conflicting patterns. In an unprecedented global synthesis of over 100 experiments that manipulated factors linked to GCDs, we show that herbaceous plant community responses depend on experimental manipulation length and number of factors manipulated. We found that plant communities are fairly resistant to experimentally manipulated GCDs in the short term (\<10 y). In contrast, long-term (\≥10 y) experiments show increasing community divergence of treatments from control conditions. Surprisingly, these community responses occurred with similar frequency across the GCD types manipulated in our database. However, community responses were more common when 3 or more GCDs were simultaneously manipulated, suggesting the emergence of additive or synergistic effects of multiple drivers, particularly over long time periods. In half of the cases, GCD manipulations caused a difference in community composition without a corresponding species richness difference, indicating that species reordering or replacement is an important mechanism of community responses to GCDs and should be given greater consideration when examining consequences of GCDs for the biodiversity\–ecosystem function relationship. Human activities are currently driving unparalleled global changes worldwide. Our analyses provide the most comprehensive evidence to date that these human activities may have widespread impacts on plant community composition globally, which will increase in frequency over time and be greater in areas where communities face multiple GCDs simultaneously.

}, keywords = {LTER-KNZ}, doi = {10.1073/pnas.1819027116}, url = {https://www.pnas.org/content/early/2019/08/14/1819027116}, author = {Kimberly J. Komatsu and M.L. Avolio and Lemoine, Nathan P. and Isbell, Forest and Grman, Emily and Houseman, Gregory R. and Koerner, Sally E. and Johnson, D.S. and K.R. Wilcox and Juha M. Alatalo and Anderson, J.P. and Aerts, R. and S.G. Baer and Baldwin, Andrew H. and Bates, J. and Beierkuhnlein, C. and Belote, R.T. and John M. Blair and Bloor, J.M.G. and Bohlen, P.J. and Edward W. Bork and Elizabeth H. Boughton and W.D. Bowman and Britton, Andrea J. and Cahill, James F. and Chaneton, Enrique J. and Chiariello, N.R. and Cheng, Jimin. and Scott. L. Collins and Cornelissen, J.H.C. and G. Du and Eskelinen, Anu and Firn, Jennifer and Foster, B. and Gough, L. and Gross, K. and Hallett, L.M. and Han, X. and Harmens, H. and Hovenden, M.J. and Jagerbrand, A. and Jentsch, A. and Kern, Christel and Klanderud, Kari and Alan K. Knapp and Kreyling, Juergen and Li, W. and Luo, Yiqi and McCulley, R.L. and McLaren, Jennie R. and Megonigal, Patrick and J.W. Morgan and Onipchenko, Vladimir and Pennings, S.C. and Prev{\'e}y, J.S. and Price, Jodi N. and P.B. Reich and Robinson, Clare H. and Russell, L.F. and Sala, O.E. and Seabloom, E.W. and M.D. Smith and Soudzilovskaia, Nadejda A. and Souza, Lara and K.N. Suding and Suttle, B.K. and Svejcar, T. and Tilman, David and Tognetti, P. and Turkington, R. and White, S. and Xu, Zhuwen and Yahdjian, L. and Yu, Q. and Zhang, Pengfei and Zhang, Yunhai} } @article {KNZ001755, title = {Addition of multiple limiting resources reduces grassland diversity}, journal = {Nature}, volume = {537}, year = {2016}, pages = {93-96}, abstract = {

Niche dimensionality provides a general theoretical explanation for biodiversity\—more niches, defined by more limiting factors, allow for more ways that species can coexist1. Because plant species compete for the same set of limiting resources, theory predicts that addition of a limiting resource eliminates potential trade-offs, reducing the number of species that can coexist2. Multiple nutrient limitation of plant production is common and therefore fertilization may reduce diversity by reducing the number or dimensionality of belowground limiting factors. At the same time, nutrient addition, by increasing biomass, should ultimately shift competition from belowground nutrients towards a one-dimensional competitive trade-off for light3. Here we show that plant species diversity decreased when a greater number of limiting nutrients were added across 45 grassland sites from a multi-continent experimental network4. The number of added nutrients predicted diversity loss, even after controlling for effects of plant biomass, and even where biomass production was not nutrient-limited. We found that elevated resource supply reduced niche dimensionality and diversity and increased both productivity5 and compositional turnover. Our results point to the importance of understanding dimensionality in ecological systems that are undergoing diversity loss in response to multiple global change factors.

}, keywords = {LTER-KNZ}, doi = {10.1038/nature19324}, url = {https://www.nature.com/articles/nature19324}, author = {Harpole, W. S. and L.L. Sullivan and Lind, E.M. and Firn, J. and P. Adler and E.T. Borer and Chase, J. and Fay, P.A. and Hautier, Y. and Hillebrand, H. and MacDougall, A.S. and Seabloom, E.W. and Williams, R. and J.D. Bakker and Cadotte, M.W. and Chaneton, E.J. and Chu, C. and Cleland, E.E. and Antonio, C. and Davies, K.F. and Gruner, D.S. and Hagenah, N. and Kirkman, K. and Knops, J.M.H. and Kimberly J. La Pierre and McCulley, R.L. and Joslin L. Moore and J.W. Morgan and Prober, S.M. and A. Risch and Schuetz, M. and Stevens, C.J. and Wragg, P.D.} } @article {KNZ001747, title = {Climate modifies response of non-native and native species richness to nutrient enrichment}, journal = {Philosophical Transactions of the Royal Society B: Biological Sciences}, volume = {3719371}, year = {2016}, pages = {20150273}, abstract = {

Ecosystem eutrophication often increases domination by non-natives and causes displacement of native taxa. However, variation in environmental conditions may affect the outcome of interactions between native and non-native taxa in environments where nutrient supply is elevated. We examined the interactive effects of eutrophication, climate variability and climate average conditions on the success of native and non-native plant species using experimental nutrient manipulations replicated at 32 grassland sites on four continents. We hypothesized that effects of nutrient addition would be greatest where climate was stable and benign, owing to reduced niche partitioning. We found that the abundance of non-native species increased with nutrient addition independent of climate; however, nutrient addition increased non-native species richness and decreased native species richness, with these effects dampened in warmer or wetter sites. Eutrophication also altered the time scale in which grassland invasion responded to climate, decreasing the importance of long-term climate and increasing that of annual climate. Thus, climatic conditions mediate the responses of native and non-native flora to nutrient enrichment. Our results suggest that the negative effect of nutrient addition on native abundance is decoupled from its effect on richness, and reduces the time scale of the links between climate and compositional change.

}, keywords = {LTER-KNZ}, issn = {0962-8436}, doi = {10.1098/rstb.2015.0273}, url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2015.0273}, author = {Flores-Moreno, H. and P.B. Reich and Lind, E.M. and L.L. Sullivan and Seabloom, E.W. and Yahdjian, L. and MacDougall, A.S. and Reichmann, L.G. and J. Alberti and B{\'a}ez, S. and J.D. Bakker and Cadotte, M.W. and Caldeira, M.C. and Chaneton, E.J. and D{\textquoteright}Antonio, C.M. and Fay, P.A. and Firn, J. and Hagenah, N. and Harpole, W. S. and Iribarne, O. and Kirkman, K.P. and Knops, J.M. H. and Kimberly J. La Pierre and Laungani, R. and Leakey, A.D. B. and McCulley, R.L. and Joslin L. Moore and Pascual, J. and E.T. Borer} } @article {KNZ001698, title = {Anthropogenic nitrogen deposition predicts local grassland primary production worldwide}, journal = {Ecology}, volume = {96}, year = {2015}, pages = {1459 -1465}, abstract = {

Humans dominate many important Earth system processes including the nitrogen (N) cycle. Atmospheric N deposition affects fundamental processes such as carbon cycling, climate regulation, and biodiversity, and could result in changes to fundamental Earth system processes such as primary production. Both modelling and experimentation have suggested a role for anthropogenically altered N deposition in increasing productivity, nevertheless, current understanding of the relative strength of N deposition with respect to other controls on production such as edaphic conditions and climate is limited. Here we use an international multiscale data set to show that atmospheric N deposition is positively correlated to aboveground net primary production (ANPP) observed at the 1-m2 level across a wide range of herbaceous ecosystems. N deposition was a better predictor than climatic drivers and local soil conditions, explaining 16\% of observed variation in ANPP globally with an increase of 1 kg N\·ha\−1\·yr\−1 increasing ANPP by 3\%. Soil pH explained 8\% of observed variation in ANPP while climatic drivers showed no significant relationship. Our results illustrate that the incorporation of global N deposition patterns in Earth system models are likely to substantially improve estimates of primary production in herbaceous systems. In herbaceous systems across the world, humans appear to be partially driving local ANPP through impacts on the N cycle.

}, keywords = {LTER-KNZ}, doi = {http://dx.doi.org/10.1890/14-1902.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/14-1902.1}, author = {Stevens, C.J. and Lind, E.M. and Hautier, Y. and Harpole, W.S. and E.T. Borer and Hobbie, S. and Seabloom, E.Q. and L. Ladwig and J.D. Bakker and Chu, C. and Scott. L. Collins and Davies, K.F. and Firn, J. and Hillebrand, H. and Kimberly J. La Pierre and MacDougall, A.S. and Melbourne, B.A. and McCulley, R.L. and J.W. Morgan and Orrock, J.L. and Prober, S.M. and A. Risch and Schultz, M. and Wragg, P.D.} } @article {KNZ001789, title = {Consistent responses of soil microbial communities to elevated nutrient inputs in grasslands across the globe}, journal = {Proceedings of the National Academy of Sciences}, volume = {112}, year = {2015}, pages = {10967 - 10972}, abstract = {

Soil microorganisms are critical to ecosystem functioning and the maintenance of soil fertility. However, despite global increases in the inputs of nitrogen (N) and phosphorus (P) to ecosystems due to human activities, we lack a predictive understanding of how microbial communities respond to elevated nutrient inputs across environmental gradients. Here we used high-throughput sequencing of marker genes to elucidate the responses of soil fungal, archaeal, and bacterial communities using an N and P addition experiment replicated at 25 globally distributed grassland sites. We also sequenced metagenomes from a subset of the sites to determine how the functional attributes of bacterial communities change in response to elevated nutrients. Despite strong compositional differences across sites, microbial communities shifted in a consistent manner with N or P additions, and the magnitude of these shifts was related to the magnitude of plant community responses to nutrient inputs. Mycorrhizal fungi and methanogenic archaea decreased in relative abundance with nutrient additions, as did the relative abundances of oligotrophic bacterial taxa. The metagenomic data provided additional evidence for this shift in bacterial life history strategies because nutrient additions decreased the average genome sizes of the bacterial community members and elicited changes in the relative abundances of representative functional genes. Our results suggest that elevated N and P inputs lead to predictable shifts in the taxonomic and functional traits of soil microbial communities, including increases in the relative abundances of faster-growing, copiotrophic bacterial taxa, with these shifts likely to impact belowground ecosystems worldwide.

}, keywords = {LTER-KNZ, Fertilization, shotgun metagenomics, Soil bacteria, Soil ecology, Soil fungi}, doi = {10.1073/pnas.1508382112}, url = {https://www.pnas.org/content/112/35/10967}, author = {Leff, J.W. and Jones, S.E. and Prober, S.M. and Barber{\'a}n, A. and E.T. Borer and Firn, J.L. and Harpole, W.S. and Hobbie, S.E. and Hofmockel, K.S. and Knops, J.M.H. and McCulley, R.L. and Kimberly J. La Pierre and A. Risch and Seabloom, E.W. and Sch{\"u}tz, Martin and Steenbock, C. and Stevens, C.J. and Fierer, N.} } @article {KNZ001788, title = {Grassland productivity limited by multiple nutrients}, journal = {Nature Plants}, volume = {1}, year = {2015}, pages = {15080}, abstract = {

Terrestrial ecosystem productivity is widely accepted to be nutrient limited1. Although nitrogen (N) is deemed a key determinant of aboveground net primary production (ANPP)2,3, the prevalence of co-limitation by N and phosphorus (P) is increasingly recognized4,​5,​6,​7,​8. However, the extent to which terrestrial productivity is co-limited by nutrients other than N and P has remained unclear. Here, we report results from a standardized factorial nutrient addition experiment, in which we added N, P and potassium (K) combined with a selection of micronutrients (K+μ), alone or in concert, to 42 grassland sites spanning five continents, and monitored ANPP. Nutrient availability limited productivity at 31 of the 42 grassland sites. And pairwise combinations of N, P, and K+μ co-limited ANPP at 29 of the sites. Nitrogen limitation peaked in cool, high latitude sites. Our findings highlight the importance of less studied nutrients, such as K and micronutrients, for grassland productivity, and point to significant variations in the type and degree of nutrient limitation. We suggest that multiple-nutrient constraints must be considered when assessing the ecosystem-scale consequences of nutrient enrichment.

}, keywords = {LTER-KNZ}, doi = {10.1038/nplants.2015.80}, url = {https://www.nature.com/articles/nplants201580}, author = {Fay, P.A. and Prober, S.M. and Harpole, W.S. and Knops, J.M.H. and J.D. Bakker and E.T. Borer and Lind, E.M. and MacDougall, A.S. and Seabloom, E.W. and Wragg, P.D. and P. Adler and D.M. Blumenthal and Buckley, Y.M. and Chu, C. and Cleland, E.E. and Scott. L. Collins and Davies, K.F. and G. Du and Feng, X. and Firn, J. and Gruner, D.S. and Hagenah, N. and Hautier, Y. and Heckman, R.W. and Jin, V.L. and Kirkman, K.P. and Klein, J. and L. Ladwig and Li, Q. and McCulley, R.L. and Melbourne, B.A. and Mitchell, C.E. and Joslin L. Moore and J.W. Morgan and A. Risch and sch{\"u}tz, M. and Stevens, C.J. and Wedin, D.A. and Yang, L.H.} } @article {KNZ001678, title = {Plant diversity predicts beta but not alpha diversity of soil microbes across grasslands worldwide}, journal = {Ecology Letters}, volume = {18}, year = {2015}, pages = {85 -95}, abstract = {

Aboveground\–belowground interactions exert critical controls on the composition and function of terrestrial ecosystems, yet the fundamental relationships between plant diversity and soil microbial diversity remain elusive. Theory predicts predominantly positive associations but tests within single sites have shown variable relationships, and associations between plant and microbial diversity across broad spatial scales remain largely unexplored. We compared the diversity of plant, bacterial, archaeal and fungal communities in one hundred and forty-five 1 m2 plots across 25 temperate grassland sites from four continents. Across sites, the plant alpha diversity patterns were poorly related to those observed for any soil microbial group. However, plant beta diversity (compositional dissimilarity between sites) was significantly correlated with the beta diversity of bacterial and fungal communities, even after controlling for environmental factors. Thus, across a global range of temperate grasslands, plant diversity can predict patterns in the composition of soil microbial communities, but not patterns in alpha diversity.

}, keywords = {LTER-KNZ}, doi = {10.1111/ele.12381}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.12381}, author = {Prober, S.M. and Leff, J.W. and Bates, S.T. and E.T. Borer and Firn, J. and Harpole, W.S. and Lind, E.M. and Seabloom, E.W. and P. Adler and J.D. Bakker and E.E Cleland and DeCrappeo, N.M. and DeLorenze, E. and Hagenah, N. and Hautier, Y. and Hofmockel, K.S. and Kirkman, K.P. and Knops, J.M.H. and Kimberly J. La Pierre and MacDougall, A.S. and McCulley, R.L. and Mitchell, C.E. and A. Risch and Schuetz, M. and Stevens, C.J. and Williams, R.J. and Fierer, N.} } @article {KNZ001632, title = {Eutrophication weakens stabilizing effects of diversity in natural grasslands}, journal = {Nature}, volume = {508}, year = {2014}, pages = {521 -525}, abstract = {

Studies of experimental grassland communities1, 2, 3, 4, 5, 6, 7 have demonstrated that plant diversity can stabilize productivity through species asynchrony, in which decreases in the biomass of some species are compensated for by increases in others1, 2. However, it remains unknown whether these findings are relevant to natural ecosystems, especially those for which species diversity is threatened by anthropogenic global change8, 9, 10, 11. Here we analyse diversity\–stability relationships from 41 grasslands on five continents and examine how these relationships are affected by chronic fertilization, one of the strongest drivers of species loss globally8. Unmanipulated communities with more species had greater species asynchrony, resulting in more stable biomass production, generalizing a result from biodiversity experiments to real-world grasslands. However, fertilization weakened the positive effect of diversity on stability. Contrary to expectations, this was not due to species loss after eutrophication but rather to an increase in the temporal variation of productivity in combination with a decrease in species asynchrony in diverse communities. Our results demonstrate separate and synergistic effects of diversity and eutrophication on stability, emphasizing the need to understand how drivers of global change interactively affect the reliable provisioning of ecosystem services in real-world systems.

}, keywords = {LTER-KNZ, Biodiversity, Community ecology, Grassland ecology}, doi = {10.1038/nature13014}, url = {https://www.nature.com/articles/nature13014}, author = {Hautier, Y. and Seabloom, E.W. and E.T. Borer and P. Adler and Harpole, W.S. and Hillebrand, H. and Lind, E.M. and MacDougall, A.S. and Stevens, C.J. and J.D. Bakker and Buckley, Y.M. and Chu, C. and Scott. L. Collins and Daleo, P. and Damschen, E.I. and Davies, K.F. and Fay, P.A. and Firn, J. and Gruner, D.S. and Jin, V.L. and Klein, J.A. and Knops, J.M.H. and Kimberly J. La Pierre and Li, W. and McCulley, R.L. and Melbourne, B.A. and Joslin L. Moore and O{\textquoteright}Halloran, L.R. and Prober, S.M. and A. Risch and Sankaran, M. and Schuetz, M. and Hector, A.} } @article {KNZ001793, title = {Herbivores and nutrients control grassland plant diversity via light limitation}, journal = {Nature}, volume = {508}, year = {2014}, pages = {517 - 520}, keywords = {LTER-KNZ}, doi = {10.1038/nature13144}, url = {https://www.nature.com/articles/nature13144}, author = {E.T. Borer and Seabloom, E.W. and Gruner, D.S. and Harpole, W.S and Hillebrand, H. and Lind, E.M. and P. Adler and J. Alberti and Anderson, T.M. and J.D. Bakker and L.A. Biederman and D.M. Blumenthal and C.S. Brown and Brudvig, L.A. and Buckley, Y.M. and Cadotte, M. and Chu, C. and Cleland, E.E. and Crawley, M.J. and Daleo, P. and Damschen, E.I. and Davies, K.F. and DeCrappeo, N.M. and G. Du and Firn, J. and Hautier, Y. and Heckman, R.W. and Hector, A. and HilleRisLambers, J. and Iribarne, Oscar and Klein, J.A. and Knops, J.M.H. and Kimberly J. La Pierre and Leakey, A.D.B. and Li, W. and MacDougall, A.S. and McCulley, R.L. and Melbourne, B.A. and Mitchell, C.E. and Joslin L. Moore and Mortensen, B. and O{\textquoteright}Halloran, L.R. and Orrock, J.L. and Pascual, J. and Prober, S.M. and Pyke, D.A. and A. Risch and Schuetz, M. and M.D. Smith and Stevens, C.J. and L.L. Sullivan and Williams, R.J. and Wragg, P.D. and Wright, J.P. and Yang, L.H.} } @article {KNZ001448, title = {Productivity is a poor predictor of plant species richness}, journal = {Science}, volume = {333}, year = {2011}, pages = {1750 -1753}, abstract = {

For more than 30 years, the relationship between net primary productivity and species richness has generated intense debate in ecology about the processes regulating local diversity. The original view, which is still widely accepted, holds that the relationship is hump-shaped, with richness first rising and then declining with increasing productivity. Although recent meta-analyses questioned the generality of hump-shaped patterns, these syntheses have been criticized for failing to account for methodological differences among studies. We addressed such concerns by conducting standardized sampling in 48 herbaceous-dominated plant communities on five continents. We found no clear relationship between productivity and fine-scale (meters\−2) richness within sites, within regions, or across the globe. Ecologists should focus on fresh, mechanistic approaches to understanding the multivariate links between productivity and richness.

}, keywords = {LTER-KNZ}, doi = {10.1126/science.1204498}, url = {http://science.sciencemag.org/content/333/6050/1750}, author = {P. Adler and Seabloom, E.W. and E.T. Borer and Hillebrand, H. and Hautier, Y. and Hector, A. and Harpole, W.S. and O{\textquoteright}Halloran, L.R. and Grace, J.B. and Anderson, T.M. and J.D. Bakker and L.A. Biederman and C.S. Brown and Buckley, Y.M. and Calabrese, L.B. and Chu, C.J. and Cleland, E.E. and Scott. L. Collins and Cottingham, K.L. and Crawley, M.J. and Damschen, E.I. and Davies, K.F. and DeCrappeo, N.M. and Fay, P.A. and Firn, J. and Frater, P. and Gasarch, E.I. and Gruner, D.S. and Hagenah, N. and HilleRisLambers, J. and Humphries, H.C. and Jin, V.L. and Kay, A. and Kirkman, K.P. and Klein, J.A. and Knops, J.M.H. and Kimberly J. La Pierre and Lambrinos, J.G. and Li, W. and MacDougall, A.S. and McCulley, R.L. and Melbourne, B.A. and Mitchell, C.E. and Joslin L. Moore} } @article {KNZ001301, title = {Phosphorus biogeochemistry across a precipitation gradient in grasslands of central North America}, journal = {Journal of Arid Environments}, volume = {74}, year = {2010}, pages = {954 -961}, abstract = {

Soil P transformations and distribution studies under water limited conditions that characterize many grasslands may provide further insight into the importance of abiotic and biotic P controls within grass-dominated ecosystems. We assessed transformations between P pools across four sites spanning the shortgrass steppe, mixed grass prairie, and tallgrass prairie along a 400-mm precipitation gradient across the central Great Plains. Pedon total elemental and constituent mass balance analyses reflected a pattern of increased chemical weathering from the more arid shortgrass steppe to the more mesic tallgrass prairie. Soil surface A horizon P accumulation was likely related to increased biocycling and biological mining. Soluble P, a small fraction of total P in surface A horizons, was greatest at the mixed grass sites. The distribution of secondary soil P fractions across the gradient suggested decreasing Ca-bound P and increasing amounts of occluded P with increasing precipitation. Surface A horizons contained evidence of Ca-bound P in the absence of CaCO3, while in subsurface horizons the Ca-bound P was associated with increasing CaCO3 content. Calcium-bound P, which dominates in water-limited systems, forms under different sets of soil chemical conditions in different climatic regimes, demonstrating the importance of carbonate regulation of P in semi-arid ecosystems.

}, keywords = {LTER-KNZ, Grassland ecosystems, Phosphorus biogeochemistry, Sequential phosphorus extraction, Soil weathering}, doi = {10.1016/j.jaridenv.2010.01.003}, url = {https://www.sciencedirect.com/science/article/abs/pii/S014019631000011X?via\%3Dihub}, author = {Ippolito, J.A. and Blecker, S.W. and Freeman, C.L. and McCulley, R.L. and John M. Blair and Kelly, E.F.} } @article {KNZ001242, title = {Conservation of nitrogen increases with precipitation across a major grassland gradient in the Central Great Plains of North America}, journal = {Oecologia}, volume = {159}, year = {2009}, pages = {571 -581}, abstract = {

Regional analyses and biogeochemical models predict that ecosystem N pools and N cycling rates must increase from the semi-arid shortgrass steppe to the sub-humid tallgrass prairie of the Central Great Plains, yet few field data exist to evaluate these predictions. In this paper, we measured rates of net N mineralization, N in above- and belowground primary production, total soil organic matter N pools, soil inorganic N pools and capture in resin bags, decomposition rates, foliar 15N, and N use efficiency (NUE) across a precipitation gradient. We found that net N mineralization did not increase across the gradient, despite more N generally being found in plant production, suggesting higher N uptake, in the wetter areas. NUE of plants increased with precipitation, and δ15N foliar values and resin-captured N in soils decreased, all of which are consistent with the hypothesis that N cycling is tighter at the wet end of the gradient. Litter decomposition appeared to play a role in maintaining this regional N cycling trend: litter decomposed more slowly and released less N at the wet end of the gradient. These results suggest that immobilization of N within the plant\–soil system increases from semi-arid shortgrass steppe to sub-humid tallgrass prairie. Despite the fact that N pools increase along a bio-climatic gradient from shortgrass steppe to mixed grass and tallgrass prairie, this element becomes relatively more limiting and is therefore more tightly conserved at the wettest end of the gradient. Similar to findings from forested systems, our results suggest that grassland N cycling becomes more open to N loss with increasing aridity.

}, keywords = {LTER-KNZ, Grasslands, Net nitrogen mineralization, Nitrogen pools, Nitrogen use efficiency, Regional trends}, doi = {10.1007/s00442-008-1229-1}, url = {https://link.springer.com/article/10.1007\%2Fs00442-008-1229-1}, author = {McCulley, R.L. and Burke, I.C. and Lauenroth, W.K.} } @article {KNZ001155, title = {Biologic cycling of silica across a grassland bioclimosequence}, journal = {Global Biogeochemical Cycles}, volume = {20}, year = {2006}, abstract = {[1] The dynamics of biologic Si cycling in grassland ecosystems are largely unknown and likely to impact mineral weathering rates regionally and diatom productivity globally; key regulatory processes in the global Si cycle are closely tied to the global carbon cycle. Across a bioclimatic sequence spanning major grassland ecosystems in the Great Plains, soil biogenic silica depth distributions are similar to that of soil organic carbon; however, unlike soil organic carbon, quantities of soil biogenic silica decrease with increasing precipitation, despite an increase in annual biogenic inputs through litterfall across the same gradient. Though comprising only 1{\textendash}3\% of the total Si pool, faster turnover of biogenic Si and annual cycling by grasses should positively impact mineral dissolution. Our results suggest that the largest reservoir of biogenic Si in terrestrial ecosystems resides in soils, and emphasize the potential significance of grasslands in the global biogeochemical cycle of Si.}, keywords = {LTER-KNZ}, doi = {10.1029/2006GB002690}, author = {Blecker, S.W. and McCulley, R.L. and Chadwick, O.A. and Kelly, E.F.} } @article {KNZ00893, title = {Regional patterns in carbon cycling across the Great Plains of North America}, journal = {Ecosystems}, volume = {8}, year = {2005}, pages = {106 -121}, abstract = {The large organic carbon (C) pools found in noncultivated grassland soils suggest that historically these ecosystems have had high rates of C sequestration. Changes in the soil C pool over time are a function of alterations in C input and output rates. Across the Great Plains and at individual sites through time, inputs of C (via aboveground production) are correlated with precipitation; however, regional trends in C outputs and the sensitivity of these C fluxes to annual variability in precipitation are less well known. To address the role of precipitation in controlling grassland C fluxes, and thereby soil C sequestration rates, we measured aboveground and belowground net primary production (ANPP-C and BNPP-C), soil respiration (SR-C), and litter decomposition rates for 2 years, a relatively dry year followed by a year of average precipitation, at five sites spanning a precipitation gradient in the Great Plains. ANPP-C, SR-C, and litter decomposition increased from shortgrass steppe (36, 454, and 24 g C m-2 y-1) to tallgrass prairie (180, 1221, and 208 g C m-2 y-1 for ANPP-C, SR-C, and litter decomposition, respectively). No significant regional trend in BNPP-C was found. Increasing precipitation between years increased rates of ANPP-C, BNPP-C, SR-C, and litter decomposition at most sites. However, regional patterns of the sensitivity of ANPP-C, BNPP-C, SR-C, and litter decomposition to between-year differences in precipitation varied. BNPP-C was more sensitive to between-year differences in precipitation than were the other C fluxes, and shortgrass steppe was more responsive than were mixed grass and tallgrass prairie.}, keywords = {LTER-KNZ, grassland, Great Plains, litter decomposition, Net primary production, Precipitation, Regional trends, soil respiration}, doi = {10.1007/s10021-004-0117-8}, author = {McCulley, R.L. and Burke, I.C. and Nelson, J.A. and Lauenroth, W.K. and Alan K. Knapp and Kelly, E.F.} } @article {KNZ001145, title = {Microbial community composition across the Great Plains: Landscape versus regional variability}, journal = {Soil Science Society of America Journal}, volume = {68}, year = {2004}, pages = {106 -115}, abstract = {Rates of nutrient cycling vary across landscape and regional scales. This biogeochemical variability can be partially attributed to patterns in plant community characteristics and abiotic and edaphic conditions across topographic gradients at the landscape-scale or across regional climatic gradients. However, it is also possible that concomitant changes in the microbial communities performing these biogeochemical processes occur across the same spatial scales and may therefore contribute to the observed biogeochemical trends. To assess patterns of microbial community composition across regional and landscape scales, we sampled upland and lowland topographic positions at three grassland communities spanning a 500-mm regional precipitation gradient across the central Great Plains. Soil microbial community composition and biomass were determined using phospholipid fatty acid (PLFA) analysis. Microbial biomass increased across the regional gradient, and different microbial communities were associated with the different grassland community types. The relative abundance of fungi decreased while gram-negative anaerobic bacteria increased from shortgrass steppe to tallgrass prairie. There were no differences in microbial biomass at the landscape-scale, and the only alteration in microbial community composition between upland and lowland landscape positions was a shift toward more nonspecific bacteria in lowlands. The fact that the trends in microbial biomass and community composition at the landscape-scale were less pronounced suggests that variability in microbial community composition is larger regionally across the Great Plains than landscape variability associated with topographical features at any particular site. Alterations in the microbial community may play a role in determining the biogeochemical patterns of grasslands in the Great Plains region.}, keywords = {LTER-KNZ}, doi = {10.2136/sssaj2004.1060}, author = {McCulley, R.L. and Burke, I.C.} } @phdthesis {KNZ00857, title = {Biogeochemical response of U.S. Great Plains grasslands to regional and interannual variability in precipitation}, volume = {PhD Dissertation}, year = {2002}, pages = {1 -151}, school = {Colorado State University}, type = {Ph.D. Thesis}, address = {Fort Collins, CO}, keywords = {LTER-KNZ}, url = {https://mountainscholar.org/handle/10217/82139}, author = {McCulley, R.L.} } @article {KNZ00841, title = {Influence of climate variability on plant production and N-mineralization in Central US grasslands}, journal = {Journal of Vegetation Science}, volume = {13}, year = {2002}, pages = {383 -394}, abstract = {We assessed the influence of annual and seasonal climate variability over soil organic matter (SOM), above-ground net primary production (ANPP) and in situ net nitrogen (N) mineralization in a regional field study across the International Geosphere Biosphere Programme (IGBP) North American mid-latitude transect (Koch et al. 1995). We hypothesized that while trends in SOM are strongly correlated with mean climatic parameters, ANPP and net N-mineralization are more strongly influenced by annual and seasonal climate because they are dynamic processes sensitive to short-term variation in temperature and water availability. Seasonal and monthly deviations from long-term climatic means, particularly precipitation, were greatest at the semi-arid end of the transect. ANPP is sensitive to this climatic variability, but is also strongly correlated with mean annual climate parameters. In situ net N-mineralization and nitrification were weakly influenced by soil water content and temperature during the incubation and were less sensitive to seasonal climatic variables than ANPP, probably because microbial transformations of N in the soil are mediated over even finer temporal scales. We found no relationship between ANPP and in situ net N-mineralization. These results suggests that methods used to estimate in situ net N-mineralization are inadequate to represent N-availability across gradients where microbial biomass, N-immobilization or competition among plants and microbes vary.}, keywords = {LTER-KNZ, Annual variation, ANPP, Central Grasslands region, Environmental gradient, IGBP Transect, Mineralization, Nitrogen flux, Seasonal variation}, doi = {10.1111/j.1654-1103.2002.tb02062.x}, author = {Barrett, J.E. and McCulley, R.L. and Lane, D.R. and Burke, I.C. and Lauenroth, W.K.} }