. Estimating productivity on sites with a low stocking capacity. Forests and forestry Mensuration; Forest site quality. footnote 3) for determining plant commu- nity, even when disturbance has destroyed the climax vegetation. In addition, he estimated the average basal area and site index associated with each plant commu- nity from measurements in undisturbed stands. Hall's data indicated that six plant communities grew on sites incapable of supporting "normal" levels of stocking (fig. 5). The ratio of Hall's basal area data to equivalent normal yield table data provided a basis for
. Estimating productivity on sites with a low stocking capacity. Forests and forestry Mensuration; Forest site quality. footnote 3) for determining plant commu- nity, even when disturbance has destroyed the climax vegetation. In addition, he estimated the average basal area and site index associated with each plant commu- nity from measurements in undisturbed stands. Hall's data indicated that six plant communities grew on sites incapable of supporting "normal" levels of stocking (fig. 5). The ratio of Hall's basal area data to equivalent normal yield table data provided a basis for discounting normal- yield-table-derived stocking standards and productivity estimates as follows: Plant community Percent of normal Pine/wheatgrass 20 Pine/bitterbrush/fescue or sedge 54 Pine/bitterbrush/stipa 59 Pine/fescue 59 Pine/elk sedge 74 Pine/shrub/elk sedge 79 In addition, nonstockable land was treated as 0 percent of normal (fig. 6). Seven other plant communities were iden- tified but not discounted as no stocking problem appeared to exist. Forest Survey field plots sample approximately an acre with a cluster of 10 points. In eastern Oregon, each stock- able point on each commercial forest plot was placed in one of the 13 plant commu- nities. On spots where the soil was too shallow to support tree growth, we found grasses and herbs that identified nonforest habitat types in Hall's key. Points falling on such spots were classed as nonstockable, as were those falling on bare rock, water, or any other nonstockable condition. The 10 discount factors—one for each point in the 10-point cluster—were then aver- aged to provide a discount factor for the entire plot. Productivity was estimated for the plot by obtaining the mean annual. Lgure 5.—This uncut ponderosa pine stand, near Bend, Oregon, is growing in a pine/bitter- brush/fescue plant community. Although the site index is 70, basal area per acre is only 85 square feet—about 42 percent of "; The
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