Biomass and primary productivity of an Alnus viridis stand -: a case study from the Schachental valley, Switzerland

Green alder (Alnus viridis) stands are spreading rapidly in the subalpine belt of the Swiss Alps. To understand this rapid colonisation, estimates of above ground biomass and net primary productivity were made in an old-growth pure stand of Alnus viridis in central Switzerland. A total above-ground biomass of 89.3 t ha(-1) was recorded. to which Alnus viridis contributed 97.8% and the understorey vegetation 2.2%. The annual above-ground production of A. viridis was estimated t be 6.18 t ha(-1) yr(-1). of which 61.5% were allocated to leaf production, 2.1.7% to stem (i.e. caudex) growth and 16.8% to increment of branch-wood. The above ground biomass and the annual production of A. viridis are high when compared with other subarctic or subalpine scrub-woodlands. This might be due to its high stem density, which is produced through clonal growth.