ESTIMATING CONDITION AREAS AND BOUNDARY LENGTHS IN SAMPLE PLOTS WITH MAPPED DESIGNS

Currently the U.S. Forest Service is implementing different versions o f sampling a mapped cluster of subplots on the ground for estimating f orest parameters. Biased estimators of lengths of boundaries between f orest conditions and unbiased but inefficient estimators of areas in t hese conditions are available. Improved estimators are given for these ecological parameters for each subplot (and hence for the population) by measuring some additional distances to the boundary and then using either easily implemented triangulation approximation techniques, gri d counting, and line transect sampling, or importance sampling. The tr iangulation approximation techniques are preferred at this time for op erational surveys such as those conducted by the U.S. Forest Service. Boundary lengths and areas and the co-location frequency of various fo rest conditions, ecotones, or transition zones have traditionally not been of interest in forest surveys but can now be objectively and reli ably estimated with the new mapped designs.