Abstract:
The relationship between Leaf Area Index (LAI) and current stem-wood
production was examined in selected stands in eastern
Washington. Stands were sampled with an angle gauge (prism). LAI
was estimated from sapwood area; current stem-wood production from
DBH, height, and radial increment.
Maximum LAI attainable on a given site has been related to
qualities of the environment. Where stocking varies on a given site,
LAI is related to the degree of utilization of the available
resources.
The average leaf area per tree, relative to average tree size,
is a measure of stand vigor. To compare the relative sapwood area of
trees of different sizes, allometric regressions of sapwood area from
DBH were derived, for five species, from fully stocked stands.
In fully stocked stands with dominant Douglas-fir, current productivity
was more closely related to average LAI than to either Site
Index alone or predictions by Cochran (1979) based on Site Index,
basal area, and age. Within stands displaying a range of stocking on
a given site, wood production per unit of leaf area decreased as LAI
increased; nonetheless, productivity per hectare generally increased
up to the highest LAI observed in each stand. Both the pattern and
the scale of the relationship between LAI and productivity differed
among sites.
