@article {KNZ002034, title = {Is a drought a drought in grasslands? Productivity responses to different types of drought}, journal = {Oecologia}, year = {2021}, keywords = {LTER-KNZ}, doi = {10.1007/s00442-020-04793-8}, url = {https://link.springer.com/article/10.1007/s00442-020-04793-8}, author = {Carroll, C.J.W. and Slette, I.J. and Griffin-Nolan, R.J. and Baur, L.E. and Hoffman, A.M. and Denton, E.M. and Gray, J.E. and Post, A.K. and Johnston, M.K. and Yu, Q. and Collins, S.L. and Luo, Y. and Smith, M.D. and Knapp, A.K.} } @article {KNZ002001, title = {Mass ratio effects underlie ecosystem responses to environmental change}, journal = {Journal of Ecology}, volume = {108}, year = {2020}, pages = {855-864}, abstract = {

1. Random species loss has been shown experimentally to reduce ecosystem function, sometimes more than other anthropogenic environmental changes. Yet, controversy surrounds the importance of this finding for natural systems where species loss is non-random.
2. We compiled data from 16 multi-year experiments located at a single native tallgrass prairie site. These experiments included responses to 11 anthropogenic environmental changes, as well as non-random biodiversity loss either the removal of uncommon/rare plant species or the most common (dominant) species.
3. As predicted by the mass ratio hypothesis, loss of a dominant species had large impacts on productivity that were comparable to other anthropogenic drivers. In contrast, the loss of uncommon/rare species had small effects on productivity despite having the largest effects on species richness.
4. The anthropogenic drivers that had the largest effects on productivity nitrogen, irrigation, and fire experienced not only loss of species but also significant changes in the abundance and identity of dominant species.
5. Synthesis. These results suggest that mass ratio effects, rather than species loss per se, are an important determinant of ecosystem function with environmental change.

}, keywords = {LTER-KNZ}, doi = {10.1111/1365-2745.13330}, url = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.13330}, author = {M.D. Smith and Koerner, S.E. and Alan K. Knapp and M.L. Avolio and Chaves, F.A. and Denton, E.M. and Dietrich, J. and Gibson, D.J. and Gray, J. and Hoffman, A.M. and Hoover, D.L. and Kimberly J. Komatsu and Silletti, A. and K.R. Wilcox and Yu, Q. and John M. Blair} } @article {KNZ001887, title = {A reality check for climate change experiments: Do they reflect the real world?}, journal = {Ecology}, volume = {99}, year = {2018}, pages = {2145-2151}, abstract = {

Experiments are widely used in ecology, particularly for assessing global change impacts on ecosystem function. However, results from experiments often are inconsistent with observations made under natural conditions, suggesting the need for rigorous comparisons of experimental and observational studies. We conducted such a \“reality check\” for a grassland ecosystem by compiling results from nine independently conducted climate change experiments. Each experiment manipulated growing season precipitation (GSP) and measured responses in aboveground net primary production (ANPP). We compared results from experiments with long-term (33-yr) annual precipitation and ANPP records to ask if collectively (n\ =\ 44 experiment-years) experiments yielded estimates of ANPP, rain-use efficiency (RUE, grams per square meter ANPP per mm precipitation), and the relationship between GSP and ANPP comparable to observations. We found that mean ANPP and RUE from experiments did not deviate from observations. Experiments and observational data also yielded similar functional relationships between ANPP and GSP, but only within the range of historically observed GSP. Fewer experiments imposed extreme levels of GSP (outside the observed 33-yr record), but when these were included, they altered the GSP\–ANPP relationship. This result underscores the need for more experiments imposing extreme precipitation levels to resolve how forecast changes in climate regimes will affect ecosystem function in the future.

}, keywords = {LTER-KNZ}, doi = {10.1002/ecy.2474}, url = {https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecy.2474}, author = {Alan K. Knapp and Carroll, C.J.W. and Griffin-Nolan, R.J. and Slette, I.J. and Chavez, F.A. and Baur, L. and Felton, A.J. and Gray, J. and Hoffman, A.M. and Lemoine, N.P. and Mao, W. and Post, A. and M.D. Smith} } @article {KNZ001869, title = {Gene expression patterns of two dominant tallgrass prairie species differ in response to warming and altered precipitation}, journal = {Scientific Reports}, volume = {6}, year = {2016}, pages = {25522}, abstract = {

To better understand the mechanisms underlying plant species responses to climate change, we compared transcriptional profiles of the co-dominant C4 grasses, Andropogon gerardii Vitman and Sorghastrum nutans (L.) Nash, in response to increased temperatures and more variable precipitation regimes in a long-term field experiment in native tallgrass prairie. We used microarray probing of a closely related model species (Zea mays) to assess correlations in leaf temperature (Tleaf) and leaf water potential (LWP) and abundance changes of ~10,000 transcripts in leaf tissue collected from individuals of both species. A greater number of transcripts were found to significantly change in abundance levels with Tleaf and LWP in S. nutans than in A. gerardii. S. nutans also was more responsive to short-term drought recovery than A. gerardii. Water flow regulating transcripts associated with stress avoidance (e.g., aquaporins), as well as those involved in the prevention and repair of damage (e.g., antioxidant enzymes, HSPs), were uniquely more abundant in response to increasing Tleaf in S. nutans. The differential transcriptomic responses of the co-dominant C4 grasses suggest that these species may cope with and respond to temperature and water stress at the molecular level in distinct ways, with implications for tallgrass prairie ecosystem function.

}, keywords = {LTER-KNZ}, doi = {10.1038/srep25522}, url = {https://www.nature.com/articles/srep25522}, author = {M.D. Smith and Hoffman, A.M. and M.L. Avolio} }