Diameter Prediction for Correcting Continuous Forest Inventory Data
Permanent plot data are used in many studies. Trees are measured for diameter, height, and other characteristics at regular time intervals. Occasionally, errors in the diameter measurements result in a larger diameter reported at the time of the first measurement rather than the second, thus making some of the data apparently unusable. Currently there are at least two basic methods in use to compensate and estimate the growth on trees exhibiting illogical consecutive diameters. This study examines these two techniques in addition to a few others, and evaluates the advantages and disadvantages of each method. A 5% random sample was drawn from a data set void of obviously incorrect diameter measurements. For each tree in the sample, one of the two diameter measurements was assumed to be incorrect and was replaced by a predicted estimate from one of the candidate methods. The sample was then put back into the original data set and the estimated basal area plot growth was calculated for that time period. This was then compared to the true plot growth, and the resulting differences were examined. Based upon these differences, it was concluded that ordinary least squares or the introduced standard deviation technique will provide the best results if applied on a plot by plot basis. North. J. Appl. For. 8(2):76-82.
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Document Type: Journal Article
Affiliations: Department of Horticulture and Forestry, State University of Rutgers, P.O. Box 231, New Brunswick, NJ 08903
Publication date: 01 June 1991