Nitrogen deposition magnifies the sensitivity of desert steppe plant communities to large changes in precipitation

Abstract

Precipitation alteration and nitrogen (N) deposition caused by anthropogenic activities could profoundly affect the structure and functioning of plant communities in arid ecosystems. However, the plant community impacts conferred by large temporal changes in precipitation, especially with a concurrent increase in N deposition, remain unclear. To address this uncertainty, from 2016 to 2017, an in situ field experiment was conducted to examine the effects of five precipitation levels, two N levels and their interaction on the plant community function and composition in a desert steppe in northern China. Above‐ground net primary production (ANPP) and plant community‐weighted mean (CWM) height significantly increased with increasing precipitation, and both were well fitted with a positive linear model, but with a higher slope under N addition. The ANPP increase was primarily driven by the increase in Artemisia capillaris, a companion forb sensitive to precipitation variation. The plant community composition shifted with precipitation enhancement—from a community dominated by Stipa tianschanica, a perennial grass, to a community dominated by Artemisia capillaris. Synthesis. The findings imply that the ecosystem sensitivity to future changes in precipitation variability will be mediated by two potential mechanisms: concurrent N deposition and plant community‐level change. It is suggested that we should consider the vegetation compositional shift and multiple resource colimitation in assessing the sensitivity of terrestrial ecosystems to climate change.

Functional diversity response to geographic and experimental precipitation gradients varies with plant community type

“…Here, we show that the shifts of CWM of plant height, SLA and LT in grassland communities with increasing precipitation are consistent between the experimental and natural gradients. This suggests that CWMs of plant height, SLA and LT are good predictor for short-or long-term responses of grass communities to precipitation changes, which is supported by the other studies in desert steppe (Ma et al, 2019). Similarly, the CWM of LCC, FDvar of LT and LCC and FDis are good predictors for short-or long-term responses of shrub communities to precipitation changes.…”

Symbiotic soil fungi enhance resistance and resilience of an experimental grassland to drought and nitrogen deposition

“…Moreover, anthropogenic activities have doubled nitrogen (N) inputs to terrestrial ecosystems via atmospheric deposition (Galloway et al., 2008). Various studies have now shown that these global changes can strongly threaten the temporal stability (Isbell et al., 2009; Tilman & Downing, 1994) and functioning of terrestrial ecosystems (Ma et al., 2019; Rillig et al., 2019; de Vries et al., 2012). The core components of ecosystem stability are well‐defined as resistance, that is, the ability of ecosystems to withstand perturbations, and as resilience, that is, the ability of ecosystems to return to their original state after subsequent recovery (Mariotte et al., 2013; Standish et al., 2014).…”

Precipitation and nitrogen addition enhance biomass allocation to aboveground in an alpine steppe

“…As water and N are the most important factors that determine the growth and survival of plant and limit the production of grassland ecosystems (Bobbink et al, ; Greaver et al, ), the altered Precip and enhanced N deposition affect grassland ecosystem functions and services that are essential for well‐being of humanity (Basto et al, ; Liu et al, ). Despite numerous reports on the effects of altered Precip and enhanced N deposition grassland ecosystems (Liu et al, ; Ma et al, ; Tian et al, ; Yang et al, ), less is known with respect to how altered Precip, enhanced N deposition, and their interaction in the alpine steppe will influence aboveground and belowground biomass allocation, especially at different soil layer (Liu et al, ).…”