Is a drought a drought in grasslands? Productivity responses to different types of drought

文献类型： 外文期刊

第一作者： Carroll, Charles J. W.

作者： Carroll, Charles J. W.;Slette, Ingrid J.;Gray, Jesse E.;Post, Alison K.;Smith, Melinda D.;Knapp, Alan K.;Carroll, Charles J. W.;Slette, Ingrid J.;Gray, Jesse E.;Post, Alison K.;Smith, Melinda D.;Knapp, Alan K.;Griffin-Nolan, Robert J.;Baur, Lauren E.;Collins, Scott L.;Hoffman, Ava M.;Denton, Elsie M.;Johnston, Melissa K.;Yu, Qiang;Luo, Yiqi

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关键词： Drought; Grasslands; Drought attributes; Biomass

期刊名称：OECOLOGIA （ 影响因子：3.225； 五年影响因子：3.665 ）

ISSN： 0029-8549

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收录情况： SCI

摘要： Drought, defined as a marked deficiency of precipitation relative to normal, occurs as periods of below-average precipitation or complete failure of precipitation inputs, and can be limited to a single season or prolonged over multiple years. Grasslands are typically quite sensitive to drought, but there can be substantial variability in the magnitude of loss of ecosystem function. We hypothesized that differences in how drought occurs may contribute to this variability. In four native Great Plains grasslands (three C-4- and one C-3-dominated) spanning a similar to 500-mm precipitation gradient, we imposed drought for four consecutive years by (1) reducing each rainfall event by 66% during the growing season (chronic drought) or (2) completely excluding rainfall during a shorter portion of the growing season (intense drought). The drought treatments were similar in magnitude but differed in the following characteristics: event number, event size and length of dry periods. We observed consistent drought-induced reductions (28-37%) in aboveground net primary production (ANPP) only in the C-4-dominated grasslands. In general, intense drought reduced ANPP more than chronic drought, with little evidence that drought duration altered this pattern. Conversely, belowground net primary production (BNPP) was reduced by drought in all grasslands (32-64%), with BNPP reductions greater in intense vs. chronic drought treatments in the most mesic grassland. We conclude that grassland productivity responses to drought did not strongly differ between these two types of drought, but when differences existed, intense drought consistently reduced function more than chronic drought.

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