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Site Index Models for Tree Species in the Northeastern United States

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Forest Science


Quantitative measures of site productivity provide critical information for management of forests. In this study, models were developed to predict site index (the average height of dominant/codominant trees at a specified base age) using data that encompassed the entire northeastern United States and a wide range of stand conditions. Regression analyses were conducted for 22 tree species/groups, with models utilizing breast-height age being presented. For 15 remaining species/groups having relatively low frequency of occurrence, empirical evaluations were performed to determine which of the 22 sets of model coefficients provided the best predictions. Comparisons with site index models currently being used in the region indicated a smaller range of site index values using the models developed in this study, primarily due to higher predicted values for poorer sites. Thus, replacement of existing models with the models presented here will produce different results in data processing and growth projection systems that use site index as an input variable. However, because of the recency and breadth of the underlying data, the models developed in this study should more accurately reflect the site productivity of forest stands across the region.


dominant height; forest inventory; base-age invariant; mixed models


Westfall, James A.; Hatfield, Mark A.; Sowers, Paul A.; O'Connell, Barbara M. 2017. Site Index Models for Tree Species in the Northeastern United States. Forest Science. 63(3): 283-290.

Last updated on: March 17, 2022