Silicon fertilization reinforces community temporal stability via increasing species asynchrony under long-term nitrogen fertilization in alpine meadow

There is a lot of empirical evidence pointing towards nitrogen (N) fertilization having adverse effects, but silicon (Si) fertilization having beneficial effects, on biodiversity in grassland. However, despite N and Si fertilization having been widely applied in grassland management, relatively little is known about how their influences on biodiversity can shape community temporal stability, which is of practical importance in guaranteeing the performance of multiple ecosystem functions. Here, a nine-year field experiment was conducted to test the mechanisms contributing to community temporal stability in relation to net primary productivity and species richness, including species dominance, species asynchrony, dominant species stability, and population stability, under N and Si fertilization in an alpine meadow ecosystem. We found that N fertilization increased the aboveground net primary productivity but decreased the species richness and species asynchrony. This meant that the community temporal stability was weakened through the reduced species asynchrony and increase in species dominance, which led to a less stable ecosystem. Meanwhile, Si fertilization increased community temporal stability directly, and indirectly via the positive influence on species asynchrony, indicating that compensatory growth is the main mechanism driving community temporal stability. Overall, Si fertilization was able to modulate the response of community temporal stability to N fertilization. These results highlight the different mechanisms driving community temporal stability under different types of nutrient fertilization, such as N and Si, which provides scientific support for alpine meadow management.