Litter input, litter decomposition and the evolution of carbon dioxide in a beech woodland-Wytham woods, Oxford

Abstract

Tree litter fall was measured from May 1969 to April 1973 and varied between 205 and 388 g m^-2a^-1. Peak standing crops of the ground flora were determined between September 1969 and October 1972 and fell in the range 17.3 to 20.9 g m^-2 a^-1. Litter losses due to wind action had a net value of 8 g m^-2 a^-1 and the mean above ground litter input to the soil was 235 g m^-2 a^-1.Between February 1971 and January 1973 above ground litter loss due to decomposition was calculated from litter standing crop depletions and litter turnover times. It was estimated to be 235.8 g m^-2 a^-1. Steady state conditions were thus assumed for this woodland.The contribution to litter from dying roots was estimated at 92 g m^-2 a^-1 and hence the total input of dead organic matter to the site was 327 g m^-2 a^-1.Soil metabolism, measured as carbon dioxide evolution, showed a significant correlation with temperature and during 1973-1974 had a dry matter equivalent of 342 g m^-2 a^-1. The difference between the above ground litter input (235 g m^-2 a^-1) and the dry matter equivalent of soil metabolism (342 g m^-2 a ^-1) was attributed to the decomposition of root litter, root respiration and the respiratory activity of fungal mycorrhizae. Total organic matter decomposition accounted for 95% of total soil metabolism whilst the contributions by root and mycorrhizal respiration approximated 4 and 1%, respectively.