Enclosure increases nutrient resorption from senescing leaves in a subalpine pasture

Abstract

Aim: Nutrient resorption from senescing tissues is the most critical nutrient source for plants in degradation grasslands, playing critical roles to primary productivity and interspecies competitiveness. Hence within-species and among-species variation of nutrient resorption is one of the mechanisms explaining the increasing productivity and decreasing biodiversity after enclosure. Yet, the response of plant nutrient resorption to enclosure remains poorly documented. Methods: We conducted a 6-year manipulative field study to estimate the effects of enclosure on nutrient resorption efficiency in five dominant species in a degraded subalpine pasture. Results: Both soil, mature and senesced leaves showed significant increases in N, P, and K contents in response to enclosure. Despite some species-specific differences, enclosure generally increased the nutrient resorption in graminoids, but decreased in forbs (with the exception of phosphorus for Potentilla anserine), indicating an important difference in the adaptation of plant functional types to enclosure which may in turn strongly impact the productivity and structure of pasture vegetation under long-term enclosure. Conclusions: This study shows the positive effects of enclosure management on soil and plant nutrients accumulation, and our results highlight the importance of among-species and within-species variations in plant nutrient resorption to explain the effects of enclosure on biodiversity loss and productivity increase in a degraded ecosystem.