The decomposition of branch-wood in the canopy and floor of a mixed deciduous woodland.

The pattern of decomposition of branch-wood greater than 2 cm diameter is described for a one hectare site at Meathop Wood, Cumbria, based on studies carried out as part of the IBP between 1967 and 1972. Three phases of decomposition are recognised. Following the death of branches in the canopy and their colonisation by fungi, decomposition proceeded at an average annual loss rate of about 8.4%. Wood at branch-fall had on average lost about 40% of its original dry weight. On the forest floor the average annual rate of weight lost to decomposition was 17.1%. This could be divided into two phases; fungi were predominant initially but shortly after branch-fall invasion by wood-boring animals occurred. The average annual branch-fall between 1967 and 1971 was 31.5 g·m-2. The standing crop of dead branch-wood on the forest floor was estimated in 1971 to be 203.3 g·m-2. Assuming steady state this implies an annual turnover of 15.5% of the standing crop which is in good agreement with the observed decomposition rate.Considerable differences in the rates of decay were observed between individual branches. No significant differences were found between branches of the four main "species" of tree investigated (Quercus robur pluspetraea, Fraxinus excelsior, Betula pendula pluspubescens, Corylus avellana).