Predictions of individual-tree and whole-stand attributes for loblolly pine plantations

In this study, a new approach was developed for constraining an individual-tree model such that it provides reasonable tree- and stand-level predictions of survival and growth. Data from 100 plots randomly selected from the Southwide Seed Source Study of loblolly pine (Pinus taeda L.) were used to fit the equations. Another 100 plots, randomly selected from the remaining plots, were used for validation. Results showed that the new approach produced results that were comparable to those from the same tree model constrained with number of trees and basal area in each diameter-class. Both of these two constrained tree models were slightly better than the unconstrained tree model in predicting tree and stand attributes. All of the above methods, however, were outperformed by the disaggregative model, in which outputs from the individual-tree model were adjusted with stand growth predictions from a whole-stand model. The disaggregative approach provided the best predictions of tree- and stand-level survival and growth. It bridges the gaps between individual-tree models and whole-stand models and should be seriously considered as an alternative to the constrained modeling approach.