Drought events are projected to be more extreme and frequent in the future and have profound influences on the structure and functions of terrestrial ecosystems. Extreme drought can have severe impacts on terrestrial ecosystems, such as concurrently constraining vegetation growth and ecosystem carbon (C) uptake, having legacy effects on ecosystem productivity. Ecosystems usually become vulnerable after extreme drought and are sensitive to other environmental disturbances. The potential impacts of extreme drought will pose large uncertainty in the assessment of terrestrial C cycling and feedback to climate change. Thus, better understanding the mechanisms of ecosystem recovery from extreme drought will facilitate prediction of terrestrial ecosystem dynamics after disturbance of climate extremes.
Here, we performed a seven-year field precipitation experiment to examine recovery of a grassland ecosystem from different magnitudes of sustained drought, from slight to extreme. The ecosystem was exposed to precipitation treatments in the first three years (2010-2012) and recovered during the last four years (2013-2016) without precipitation treatments. Overall, large reductions of aboveground net primary productivity (ANPP, -43.3%) and perennial forb biomass (-83.1%) were observed in the 3rd year (2012) of extreme drought only. Nevertheless, ANPP fully recovered within one year after the drought treatments were terminated, and the rapid recovery was mainly due to increased soil total nitrogen and root biomass allocation after drought. Surprisingly, large increases of ANPP under the extreme drought treatment occurred during the recovery periods from 2013-2015 (+74.1, +88.5, and +119.8 g m-2 yr-1) compared to the control. The overcompensation offset the extreme drought-induced reduction of ANPP in the treatment years and was primarily ascribed to the enhanced biomass of perennial grasses. Higher resistance to drought and fast resource acquisition strategy might drive the rapid recovery and expansion of perennial grasses. Our findings revealed the rapid recovery of grasslands and the critical role of community overcompensation in maintaining grassland ecosystem function and stability under future climate change scenarios.
The paper entitled “Overcompensation of ecosystem productivity following sustained extreme drought in a semiarid grassland” was published in Ecology on Feb. 17, 2023. The first author of this paper is Jingyi Ru, a young researcher in the College of Life Sciences, and the corresponding author is Professor Shiqiang Wan. Hebei University is the first and corresponding Institute of the paper. The research was supported by the National Natural Science Foundation of China and Hebei Natural Science Foundation.
Figure 1. Changes in aboveground net primary productivity (ANPP, a) and aboveground biomass of perennial forbs (AGBPF, b), perennial grasses (AGBPG, c), and annuals and biennials (AGBAB, d) during 1-4 years post drought.