Obtaining volume estimates from CASI images of a thinning and fertilization trial

The potential for estimating per hectare values of total stem volume from C ASI images (pixel size similar to 60 x 60 cm) taken over a 49 year old thin ning and fertilization trial with Douglas-fir at Shawnigan Lake, Vancouver Island, British Columbia was explored. Canopy structures, stem densities an d volumes varied considerably among 42 square 20m trial plots which made th e site ideal for testing the assumption that volume could be predicted from a vegetation index (NDVI) and the "uniformity" of the image as portrayed t hrough spatial autocorrelations and variances of pixel values. A combinatio n of NDVI, variances, and coefficients of spatial autocorrelation were used as predictors of plot total stem volume per hectare. Results were encourag ing, the coefficient of determination was 0.60 and the mean standard error of prediction was 10%. Wavelet analyses did not suggest any tangible improv ement in the predictions.