Shoot mortality and dynamics of live and dead biomass in a stand of Salix viminalis

Abstract

Cumulative shoot mortality in a dense, productive stand of coppiced Salix viminalis amounted to nearly 90% of the initial shoot number after three years following a single cut. The decline in shoot number per area and the increase of stem dry weight per area indicated that mortality was due to self-thinning. Death occurred mainly among the smallest shoots. Although the proportion of living stems decreased drastically, the living biomass constantly accounted for almost 90% of the total standing biomass. Shoots of Salix viminalis lost about 25% of their biomass per year during the first two years after death. Weight loss was by loss of distal parts, which turned into litter, and through decrease of wood density. Cumulative weight loss as a percentage of cumulative biomass increased from 3.1% after the first season to 10.4% after the third season. For a rotation period of four years it is predicted that the proportion of standing dead and live biomass (0.1 and 0.9, respectively) would remain approximately constant, while the cumulative weight loss as a percentage of total biomass is expected to stay below 14%.