关键词: 大量元素, 微量元素, 种内性状变异, 物种周转, 温带草原

Abstract: Litter plays a critical role in biogeochemical cycling, yet how its multi-element traits respond to concurrent global changes, such as extreme drought, nitrogen deposition and snowpack changes and their combinations, remains poorly understood. To address this gap, we established a multifactorial manipulative experiment in a temperate grassland, where drought, nitrogen deposition and snowmelt delay and all their combinations were simulated. We measured the concentrations of a suite of primary macronutrients (C, N, P, K), secondary macronutrients (Ca, Mg) and micronutrients (Mn, Fe, Cu, Zn) of plant litter. Afterwards, we examined the individual and combined effects of N addition, drought, and snowmelt delay on the concentrations of community-level litter elements, and quantified the relative contributions of intraspecific trait variation (ITV) and species turnover. The results showed that the element concentrations of leaf litter were primarily shaped by drought and N addition, with limited response to snowmelt delay. Community-level litter element responses were largely driven by ITV, which increased the concentrations of elements such as N, K, Mn, and Zn, and concurrently decreased the concentration of Mg. In contrast, species turnover was the dominant mechanism responsible for reducing litter Ca concentration under all conditions and for increasing litter C concentration under N addition, and it weakened the community-level response to environmental change by offsetting the ITV-driven increase in Mn. Our results demonstrate that ITV acts as the dominant mechanism, working in concert with species turnover to drive the responses of litter multi- element traits in the temperate grassland to multiple global change factors.

Key words: global change, macronutrients, micronutrients, intraspecific trait variation, species turnover, temperate grassland