Leaf Area of Mature Northwestern Coniferous Forests: Relation to Site Water Balance

Leaf area of nature coniferous forest communities of western Oregon appears to be related primarily to site H 2 O balance rather than characteristics of tree species composing the community. Leaf areas were determined for stands in communities ranked along measured gradients of precipitation and evaporative potential. Nine coniferous and 1 deciduous tree species were found in the various stands along these gradients. Leaf areas of these stands were linearly correlated with a simple site H 2 O balance index computed from measurements of growing season precipitation, open pan evaporation, and estimates of soil H 2 O storage. Species composition had no apparent influence on the relation between community leaf area and site H 2 O balance.