A set of simple linear regression models for predicting diameter at breast height (dbh) from crown diameter and a set of similar models for predicting crown diameter from dbh were developed for four species groups in Hardin County, TN. Data were obtained from 557 trees measured during the 1989 USDA Southern Forest Experiment Station survey of the forests of Tennessee, with supplemental aerial photographic observations. Estimates of individual tree crown diameter were obtained from ground measurements and from measurements made on 9 X 9 in. color aerial photographs (with nominal scale of 1:4,800) taken during the fall color season. In practice, users of aerial photographs can estimate dbh by measuring crown diameter, converting it to feet using the photo scale, and applying the appropriate equation. Similarly, crown diameter can be estimated from a ground measurement of dbh. This procedure may be useful in reducing the time required for field measurements. It may also be used to calculate crown diameters for datasets that include dbh but no direct measurement of crown attributes. South. J. Appl. For. 19(4):177-181.
Data from Forest Inventory and Analysis (FIA) units of the USDA Forest Service were used to compare average annual stand-level basal area accretion onto survivor pines in naturally regenerated pine stands throughout Alabama and Georgia. Growth rates measured between 1972-82 were compared to growth rates during the previous 10-year survey cycle in each state. Separate analyses were conducted for loblolly (Pinus taeda), longleaf (P. palustris), shortleaf (P. echinata), and slash (P. elliottii) pine cover types. The unadjusted average stand-level growth rates for survivor pines 1.0 in. diameter and greater at breast height were notably lower for all cover types during the latter survey in Georgia, while only the average unadjusted growth of shortleaf was substantially lower during this period in Alabama. However, when growth rates were adjusted with regression models to account for differences in initial stand structure (stand size class, stand density, site quality class, hardwood competition, and mortality) between the two survey periods, reductions in average adjusted basal area growth ranged from 3% to 31% during the later cycle in both states. The reductions were statistically significant in almost every case. The agents causing the growth differences were not identified, but it is unlikely that stand dynamics are responsible. The observational nature of the FIA dataset precludes further resolution of causal relationships. South. J. Appl. For. 15(2):73-79.
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