Plant traits and soil fertility mediate productivity losses under extreme drought in C₃ grasslands

Abstract

Extreme drought decreases aboveground net primary production (ANPP) in most grasslands, but the magnitude of ANPP reductions varies especially in C3‐dominated grasslands. Because the mechanisms underlying such differential ecosystem responses to drought are not well resolved, we experimentally imposed an extreme 4‐yr drought (2015–2018) in two C3 grasslands that differed in aridity. These sites had similar annual precipitation and dominant grass species (Leymus chinensis) but different annual temperatures and thus water availability. Drought treatments differentially affected these two semiarid grasslands, with ANPP of the drier site reduced more than at the wetter site. Structural equation modeling revealed that community‐weighted means for some traits modified relationships between soil moisture and ANPP, often due to intraspecific variation. Specifically, drought reduced community mean plant height at both sites, resulting in a reduction in ANPP beyond that attributable to reduced soil moisture alone. Higher community mean leaf carbon content enhanced the negative effects of drought on ANPP at the drier site, and ANPP–soil‐moisture relationships were influenced by soil C:N ratio at the wetter site. Importantly, neither species richness nor functional dispersion were significantly correlated with ANPP at either site. Overall, as expected, soil moisture was a dominant, direct driver of ANPP response to drought, but differential sensitivity to drought in these two grasslands was also related to soil fertility and plant traits.

Effect of Nitrogen Application on the Sensitivity of Desert Shrub Community Productivity to Precipitation in Central Asia

“…Plant height is a trait associated with plant growth ability, so community productivity usually increases with plant height (Moles et al, 2009 ; Luo et al, 2021 ). However, in our study area, winds are strong in the growing season, and gales above force 7 are frequent and occur for over 80 days annually, which leads to plants widespread dwarfing (Zhang et al, 2013 ; Xu et al, 2017 ).…”

“…The mechanism governing the impact of precipitation and N content on ANPP is not yet well-understood (Weltzin et al, 2003 ; Ogle and Reynolds, 2004 ; Luo et al, 2021 ; Guo et al, 2022 ). Generally, the changes in precipitation determine the changes in ANPP by triggering physiological responses of individual plants and based on community attributes (plant density, height, species richness, etc.)…”

Stability response of alpine meadow communities to temperature and precipitation changes on the Northern Tibetan Plateau

“…The paths of SEMs were modified according to p values of Fisher's C statistic and AIC (Luo et al, 2021). The stability of nondominant functional groups was not considered in the SEM, as it did not effectively improve the fit of the model.…”

“…The piecewiseSEMs were constructed based on a priori knowledge from the literature (Zhou et al, 2019) and the causal relationships found in multiple regression (Table 2) and correlation analysis (Figure ) of effects on community biomass stability. The paths of SEMs were modified according to p values of Fisher's C statistic and AIC (Luo et al, 2021). The stability of nondominant functional groups was not considered in the SEM, as it did not effectively improve the fit of the model.…”

Land Use and Climate Change Altered the Ecological Quality in the Luanhe River Basin

“…According to the land use in the LHRB, grasslands and cultivated lands are the main land use types in the north. Previous studies reported that drought would lead to plant trait losses [70], and drought conditions are severe in the north LHRB [71]. Thus, it is possible that the drought in the north LHRB causes the EQ of grasslands and cultivated lands to be as low as that of construction lands (Figure 9).…”