Tree crown condition has been visually assessed under forest health monitoring programs in many countries, but the assessments suffer from observer bias and lack of information on the relationship with actual foliage biomass (FM). It is hypothesized here that the image analysis measure DSO, based on fractal analysis of tree crown images taken from the ground, is closely related to actual FM and stem growth and would help to interpret the results of visual assessments. Thirty-two Japanese cypress (Chamaecyparis obtusa Endl.) in two even-aged stands (22 and 39 years old) were felled and photographed. DSO values of crown images were calculated and FM, crown size and current stem volume increment (VI) were measured. It was found that, by pooling data from both stands, foliage biomass density (FMD) (dry weight of foliage, FM, divided by crown surface area, CSA) showed a strong linear relation to DSO (r2 = 0.973) and FM showed strong proportionality to the product of CSA and DSO (CSA x DSO) (r2 = 0.990). Stem VI also had a strong linear relationship with CSA x DSO, with the slopes of the fitted curves of the two stands being significantly different. The image analysis measure DSO could be useful in non-destructively estimating actual FMD and, when coupled with measurements of crown size and stem growth, actual FM and growth efficiency.
All Science Journal Classification (ASJC) codes
- Nature and Landscape Conservation
- Management, Monitoring, Policy and Law