Towards a predictive description of forest canopies from litter properties.

摘要

Specific leaf area (SLA), carbon isotope ratio (delta13C) and leaf nitrogen content (N) were measured in litter in 1993 and in the litter layer and canopy in 1996 in a pedunculate oak (Quercus robur) wood at Wytham, Oxford, UK. The frequency distribution of SLA of leaves falling through the late summer and autumn of 1993 changed with a greater contribution of leaves of high SLA earlier in the period. For the same SLA, leaves falling earlier in the season had less negative delta13C and higher N content than leaves falling later. The frequency distribution of SLA of litter leaves was similar in both years but litter leaves had lower N and less negative delta13C in 1996. In the canopy, there was a highly significant negative relationship between height in the canopy and SLA in green and senescent leaves. The relationship between SLA and both delta13C ratio and leaf N was different between green, senescent and litter leaves. The frequency distribution of foliage in the canopy estimated from the frequency of SLA in the litter and the vertical pattern of SLA in the canopy was similar to the distribution measured by the 'drop-line' method.