Changes in above and belowground biodiversity mediate soil respiration response to nutrient enrichment in a Tibetan alpine steppe

Abstract:

Biodiversity loss induced by anthropogenic nitrogen (N) input could exert profound effects on ecosystem functions. However, limited studies have considered the joint effects of plant species richness, plant functional diversity and soil biodiversity on the dynamics of soil respiration and its components (autotrophic and heterotrophic respiration) under extra N input. Here, we quantified the interactive effects of above/belowground biodiversity and traditional factors (environmental variables, plant and microbial properties) on soil autotrophic and heterotrophic respiration based a N-manipulation experiment in a Tibetan alpine steppe. Our results demonstrated that that above/belowground biodiversity loss explained more variance in autotrophic and heterotrophic respiration than traditional factors. The decreased plant functional diversity triggered by N input resulted in the lower autotrophic respiration under high N addition levels. Likewise, the loss of soil biodiversity together with the decreased plant functional diversity led to the decline of heterotrophic respiration along the experimental N gradient. These findings highlight that the indirect regulation of N enrichment on ecosystem function through both above and belowground biodiversity loss should be considered for better understanding the responses of terrestrial ecosystems to atmospheric N deposition.