Leaf Litter Decomposition and Invertebrate Colonization in Alpine Environments Above the Tree Line: an Experimental Study

Abstract

ABSTRACT: Recent studies suggested a general warming trend in the Alps, resulting in a significant migration of forests to altitudes higher than the usual, regional tree line. As a consequence, some headwater streams will likely receive more allochthonous organic matter. For this reason, the dynamics of decomposition of terrestrial leaf detritus in stream reaches that naturally lacked this resource represents a subject of considerable interest, on which no information is currently available. The aim of this study was to analyse breakdown and macroinvertebrate colonisation of leaf bags in an Alpine headwater stream above the tree line. Results of this study indicate that decomposition of terrestrial leaves in a lotic alpine environment above the tree line takes place through a process similar to what happens at lower altitudes, but with some differences. The reduced rate of decomposition observed may be due to lower temperatures. At lower altitudes, tree cover provides a supply of organic material sufficie...