Estimating salal leaf area index and leaf biomass from diffuse light attenuation

Abstract
Salal (Gaultheriashallon Pursh) leaf area index and leaf biomass were estimated from 37 quadrat samples in 13 stands dominated by Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) on eastern 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 (Odocoileushemionuscolumbianus Richardson) winter browse and to quantify competitive leaf area.