Evaluating the Value of Information Concerning Different Methods of Forest Sampling

Abstract

Forest inventory is essential for estimating stand value and assists with making informed management decisions. However, the compromise made between the cost of sampling methods during inventory, and the accuracy of the information gathered has not been fully recognized. This study evaluates the value of information across multiple sampling methods and intensities. The objectives focus on 1) evaluating measurement and travel time across multiple plot sizes, 2) comparing absolute present value errors across sampling intensities, 3) evaluating the impact of timber markets on absolute present value error, and 4) determining how sampling intensity affects the absolute harvest age error. Stands of a thinned loblolly pine plantation in Charlotte State Forest, Virginia were sampled using fixed-radius plots to inform a simulation study. An intensive sample was designated as the true optimal value during the comparison of absolute error values from the sample data. All inventory data were analyzed to compare accuracy across multiple sampling methods. The intensity of samples significantly influenced sampling error. Smaller plot sizes with decreased intensities increased error in estimates of absolute present value error and absolute harvest age error. Larger plots required fewer samples to obtain decreased error, but the cost associated with larger sample sizes increases the total inventory cost. The results confirm that as sample size and intensity increase, sampling error will decrease. However, in a management setting, mid-sized plots offer a balance between accuracy, cost, and time that provide reliable estimates without diminishing inventory costs. Forest managers can use the methodology presented in our study for their own management objectives and circumstances to determine a sampling design that is most suitable and efficient under their conditions.