Organic layers favor phosphorus storage and uptake by young beech trees (Fagus sylvatica L.) at nutrient poor ecosystems

Abstract

The accumulation of organic layers in forests is linked to decreasing nutrient availability. Organic layers might represent a source of phosphorus (P) nutrition of trees in forests. Our aims were i) to test if the fate of P in a tree sapling-soil system differs between nutrient-poor and nutrient-rich sites, and ii) to assess the influence of organic layers on the fate of P in a tree sapling-soil system at either site. We conducted a 33P labeling experiment of mesocosms of beech (Fagus sylvatica) saplings. Recovery of 33P in the organic layer was greater under nutrient-poor than under nutrient-rich conditions likely caused by the abundance of microorganisms and roots. Under nutrient-poor conditions, we found that the mobilization of P followed by efficient uptake promoted tree sapling growth if the organic layer was present. The presence of organic layers did not significantly influence P uptake by beech saplings under nutrient-rich conditions suggesting mechanisms of P mobilization in addition to organic matter mineralization. Our results highlight the importance of organic layers for P nutrition of young beech trees growing on nutrient-poor soils in temperate forest ecosystems. The role of organic layers should be considered for sustainable forest management.