Plot Size and Prediction Model Form Effects on Stand Diameter Distribution Recovery MethodsJosh Bankston, a forestry student, looked at various impacts on the accuracy of growth and yield models. Diameter distribution information of a forest stand provides insights in to the stand's value. In whole stand forest growth and yield systems, the future diameter distribution of a stand gets predicted by use of models that predict the stand's diameter moments and/or percentiles in conjunction with a mathematical system to recover the diameter distribution from the predicted moments and/or percentiles. For industry applications, it is important to know which combination of plot size, recovery method used, and moment/percentile equation form yields the most precise prediction of future stand diameter distribution. Being able to more accurately predict future stand diameter distribution can give better financial insight and aid in management making decisions associated with sampled forest stand. This research examined how various plot sizes which data were recorded from, recovery methods used to obtain predicted diameter distribution, and how different forms of moment/percentile prediction equations affect the precision of model development. Data used for this analysis were collected from 202 quarter-acre measurement plots that were located within 56 loblolly pine stands across Alabama, Arkansas, Louisiana, and Mississippi. The data were collected by the Mississippi State University Loblolly Pine Cooperative between 1981 and 1989. A total of 336 measurement observations were accounted for. Results indicated that precision is generally lower for smaller plot sizes. Changes in precision rank for the different recovery methods may occur as plot size increases. This result falls in line with our hypothesis of larger plot sizes yielding more precise results. Trends also show that distribution recovery methods are also less accurate in thinned stands. This trend is most likely due to disruption of the normal distribution when a stand undergoes a thinning operation. The quarter-acre plot size was shown to yield the most accurate results, but the slight increase in precision may not prove to be worth the extra money when a smaller plot size can be used and yield similar results.
News / Recognition
Undergraduate Research Symposium
Katherine Abell, a wildlife, fisheries, and aquaculture major, and Zachary Senneff, a forestry major, were among the winners of the 2014 MSU Undergraduate Research Symposium. Abell placed first in the community engagement and social sciences categories and Senneff placed second in the biological sciences and engineering category.