Ecological Indicators (Dec 2022)
Plant species diversity is driven by soil base cations under acid deposition in desert coal-mining region in northwestern China
Abstract
Given that the rate of acid deposition tends to be stable or even decline in most regions of China, the rapid development of the coal industry accelerated the rates of S and N deposition in Northwest China. Although desert plants are sparse, they play an essential role in maintaining ecosystem functions. However, few studies have evaluated whether and how acid deposition affects plant species diversity in deserts, especially those with moderate and severe alkalinity. In this study, three coal-fired power plants located at the Ningdong Energy and Chemical Industry Base in Northwest China were selected as the monitoring sites. From 2019 to 2021, we analyzed the chemical compositions of the bulk deposition of rainfall and dustfall, plant species diversity, and the main factors influencing plant diversity along a 2000 m sampling distance gradient. There were no apparent trends in annual deposition of SO42− (19.67–82.28 kg ha−1 yr−1), NO3− (2.83–11.42 kg ha−1 yr−1), NH4+ (1.91–5.20 kg ha−1 yr−1), and inorganic N (4.91–16.11 kg ha−1 yr−1) along the sampling gradient. The SO42− deposition was lower than the S deposition critical load in the study area, whereas the N deposition exceeded the acceptable N deposition of soils. The base cation (BC) neutralized the input acidity of the bulk deposition, in which Ca2+ played a key role. There were no significant differences in the Patrick richness index (2–8), Shannon-Wiener diversity index (0.45–1.73), and Pielou evenness index (0.56–0.99) along the sampling gradient, whereas an increasing trend was observed in the Simpson dominance index (0.13–0.72). C:N:P ecological stoichiometry in plant–microbe-soil could not highly explain the variation in plant diversity. S, N, and BC deposition had minor direct effects on plant diversity. However, S and BC deposition could indirectly influence plant diversity through their influence on soil BCs and bulk deposition pH. The results indicate that S deposition increases bulk deposition acidity, reduces soil BC concentration, and improves soil alkaline environments, thus enhancing plant diversity in the studied deserts. Current N deposition does not greatly affect plant diversity. However, long-term observations are still required to thoroughly evaluate the effect of N deposition..
