@article {KNZ001885, title = {Legacy effects of a regional drought on aboveground net primary production in six central US grasslands}, journal = {Plant Ecology}, volume = {219}, year = {2018}, pages = {505 - 515}, abstract = {

Global climate models predict increases in the frequency and severity of drought worldwide, directly affecting most ecosystem types. Consequently, drought legacy effects (drought-induced alterations in ecosystem function postdrought) are expected to become more common in ecosystems varying from deserts to grasslands to forests. Drought legacies in grasslands are usually negative and reduce ecosystem function, particularly after extended drought. Moreover, ecosystems that respond strongly to drought (high sensitivity) might be expected to exhibit the largest legacy effects the next year, but this relationship has not been established. We quantified legacy effects of a severe regional drought in 2012 on postdrought (2013) aboveground net primary productivity (ANPP) in six central US grasslands. We predicted that (1) the magnitude of drought legacy effects measured in 2013 would be positively related to the sensitivity of ANPP to the 2012 drought, and (2) drought legacy effects would be negative (reducing 2013 ANPP relative to that expected given normal precipitation amounts). The magnitude of legacy effects measured in 2013 was strongly related (r2\ =\ 0.88) to the sensitivity of ANPP to the 2012 drought across these six grasslands. However, contrary to expectations, positive legacy effects (greater than expected ANPP) were more commonly observed than negative legacy effects. Thus, while the sensitivity of ANPP to drought may be a useful predictor of the magnitude of legacy effects, short-term (1-year) severe droughts may cause legacy effects that are more variable than those observed after multiyear droughts.

}, keywords = {LTER-KNZ}, issn = {1385-0237}, doi = {10.1007/s11258-018-0813-7}, url = {http://link.springer.com/10.1007/s11258-018-0813-7.pdf}, author = {Griffin-Nolan, Robert J. and Carroll, Charles J. W. and Denton, Elsie M. and Johnston, Melissa K. and Scott. L. Collins and M.D. Smith and Alan K. Knapp} } @article {KNZ001802, title = {Drought timing differentially affects above- and belowground productivity in a mesic grassland}, journal = {Plant Ecology}, volume = {218}, year = {2017}, pages = {317 - 328}, abstract = {

Climate models forecast an intensification of the global hydrological cycle with droughts becoming more frequent and severe, and shifting to times when they have been historically uncommon. Droughts, or prolonged periods of precipitation deficiency, are characteristic of most temperate grasslands, yet few experiments have explored how variation in the seasonal timing of drought may impact ecosystem function. We investigated the response of above- and belowground net primary production (ANPP \& BNPP) to altered drought timing in a mesic grassland in NE Kansas. Moderate drought treatments (25\% reduction from the mean growing season precipitation [GSP]) were imposed by erecting rainout shelters in late spring (LSP), early summer (ESM), and mid-summer (MSM, n = 10 plots/treatment). These treatments were compared to two controls (long-term average GSP [LTA] and ambient GSP [AMB]) and a wet treatment (+30\% of the long-term average GSP [WET]). We found that LSP drought did not significantly reduce ANPP relative to control plots while the ESM and MSM drought did despite equivalent reductions in soil moisture. In contrast, the WET treatment did not affect ANPP. Neither the WET nor the drought treatments altered BNPP as compared to the controls. Our results suggest that forecasts of ecosystem responses to climate change will be improved if both the seasonal timing of alterations in precipitation as well as differential responses of above- and belowground productivity to drought are incorporated into models.

}, keywords = {LTER-KNZ}, doi = {10.1007/s11258-016-0690-x}, url = {https://link.springer.com/article/10.1007\%2Fs11258-016-0690-x}, author = {Denton, Elsie M. and Dietrich, John D. and M.D. Smith and Alan K. Knapp} }