ESTIMATING SALAD LEAF-AREA INDEX AND LEAF BIOMASS FROM DIFFUSE LIGHT ATTENUATION

Gaultheria shallon leaf area index and leaf biomass were estimated from 13 stands dominated by Douglas-fir Pseudotsuga menziesii on E Vancouver Island, British Columbia. Leaf area index and biomass were predicted from a Beer's Law light attenuation model using diffuse photosynthetically active radiation (400-700 nm wavelength). The extinction coefficients, determined using reduced major axis maximum likelihood, were 0.8055 m2/m2 for leaf area index and 0.0069 g/m2 for leaf biomass. Salal leaf area index and biomass were then predicted for any convenient height in the understory canopy using a cumulative Weibull model based on dominant salal height per quadrat. The models are of use for objectively assessing the amount of Columbian black-tailed deer Odocoileus hemionus columbianus winter browse and to quantify competitive leaf area. -Authors