STUDIES ON THE DECOMPOSITION OF CONIFEROUS LEAF LITTER¹

Abstract

Summary An investigation of some aspects of the rate and type of decomposition of leaf litter of Abies grandis Lindley, Picea sitchensis (Bongard) Carrière, and Pinus sylvestris L. in a mixed coniferous plantation near Bangor was carried out. Leaf litter was exposed on the surface of the litter layer and at the humus/mineral soil interface, at different distances from the base of selected trees, each type of litter being laid out only under its own tree species. Seasonal changes in the rate and type of decomposition were investigated by exposing litter in June 1959, October 1959, and April 1960. The moisture content of the experimental litter showed a good correlation with rainfall. In all three tree species there was a high positive correlation between leaf length and dry weight, and this was used to determine the progressive losses in dry weight of the litter. There was a rapid initial loss in dry weight, and thereafter Abies continued to lose weight most rapidly, and Pinus more slowly, whereas Picea showed little change. There was usually little change in N content, although in one case this decreased by about 50 per cent in the first two months after exposure. The C content either decreased for the first six months after exposure or showed little change. The C/N ratio generally showed either a consistent slow decrease or little variation, although in the June 1959 exposure there was a very rapid decrease in C/N ratio during the first two months. The quantity of extractable polyphenols decreased very rapidly after the litter had been exposed, and thereafter there was usually little change. There was some evidence that addition of polyphenol from external sources could occur.