Precipitation amount and event size interact to reduce ecosystem functioning during dry years in a mesic grassland

Abstract

Ongoing intensification of the hydrological cycle is altering rainfall regimes by increasing the frequency of extreme wet and dry years and the size of individual rainfall events. Despite long‐standing recognition of the importance of precipitation amount and variability for most terrestrial ecosystem processes, we lack understanding of their interactive effects on ecosystem functioning. We quantified this interaction in native grassland by experimentally eliminating temporal variability in growing season rainfall over a wide range of precipitation amounts, from extreme wet to dry conditions. We contrasted the rain use efficiency (RUE) of above‐ground net primary productivity (ANPP) under conditions of experimentally reduced versus naturally high rainfall variability using a 32‐year precipitation–ANPP dataset from the same site as our experiment. We found that increased growing season rainfall variability can reduce RUE and thus ecosystem functioning by as much as 42% during dry years, but that such impacts weaken as years become wetter. During low precipitation years, RUE is lowest when rainfall event sizes are relatively large, and when a larger proportion of total rainfall is derived from large events. Thus, a shift towards precipitation regimes dominated by fewer but larger rainfall events, already documented over much of the globe, can be expected to reduce the functioning of mesic ecosystems primarily during drought, when ecosystem processes are already compromised by low water availability.

Effects of Water Addition on Reproductive Allocation of Dominant Plant Species in Inner Mongolia Steppe

“…Plant productivity was enhanced with increasing water availability, which is in line with the findings in previous studies (Li et al, 2003;Heisler-White et al, 2008;Fu et al, 2010). Note that more water addition could increase water losses via runoff, evaporation or deep soil water percolation (Knapp et al, 2008), and result in decreasing water resource utilization for plant productivity (Felton et al, 2019). High soil moisture can further prevent soil organic matter decomposition (Yang et al, 2002), as a result reducing production due to nutrients loss.…”

“…Extreme drought and rainfall events are predicted to vary spatially and temporally under climate change (IPCC, 2007;Benestad et al, 2012). The range of rainfall amount impacts terrestrial ecosystems as water limits plant growth, reproduction and productivity (Koerner et al, 2014;Estiarte et al, 2016;Felton et al, 2019). Biomass is an important variable that can be applied to explore the response of plants to the changes of rainfall.…”

Decreasing control of precipitation on grassland spring phenology in temperate China

“…The increased differences in temperature between years probably contributed to the larger variability in the SOS. Second, precipitation increased until the mid‐1990s for the whole study area (Lee & Sohn, 2011), which was probably related to the significant preseason increase in precipitation across the whole study area over the study period, reducing growth sensitivity to water availability in these arid and semi‐arid regions (Felton et al., 2019; Li et al., 2019; Shen et al., 2015). As a result, phenology dynamics might have become more related to temperature and variability therein.…”

Precipitation–productivity relationships and the duration of precipitation anomalies: An underappreciated dimension of climate change

“…Conducting these experiments in ecosystem with existing long‐term PPT–NPP datasets can yield additional insights (Felton et al, 2020; Knapp et al, 2018). Long‐term data adds historical context about past responses (Knapp et al, 2020) and are all‐inclusive in terms of drivers of NPP.…”