Divergent responses of above‐ and belowground ecosystem functioning to shrub encroachment in the Tibetan semi‐arid alpine steppes

Abstract

AbstractSemi‐arid alpine ecosystems on the Tibetan Plateau are experiencing rapid climate change and extensive anthropogenic activity, concomitant with the encroachment of shrubs. Shrub encroachment will lead to changes in both the ecosystem structure and functioning of the semi‐arid alpine steppes. Yet, the encroaching impacts of shrubs on the above‐ and belowground ecosystem functioning of the semi‐arid alpine steppes remain uncertain. To quantify shrub encroachment impacts on ecosystem functioning of the semi‐arid alpine steppes, two alpine steppe sites encroached by shrub species are investigated, with one site encroached by leguminous shrub species (Caragana spinifera) and another site encroached by non‐leguminous shrub species (Dasiphora fruticosa). Results shows that the individual ecosystem functions and the ecosystem multifunctionality (EMF) of alpine steppes are significantly enhanced following both leguminous and non‐leguminous shrubs encroachment. We conclude that shrub encroachment tends to facilitate the belowground EMF (BEMF) but has neutral effects on the aboveground EMF (AEMF) in alpine steppes. Our findings also highlight that soil nutrients play critical roles in driving ecosystem functioning responses to shrubs encroachment. These findings further our understanding of shrub encroachment impacts on the ecosystem functioning of the semi‐arid alpine steppes.