Competition Indices for Mixed Species Northern Hardwoods

Abstract

Several competition indices are evaluated to determine their relationship with annual diameter growth in mixed species northern hardwood stands in upper Michigan. Indices are evaluated on four species with different shade tolerance. A new index which incorporates factors representing both root and crown competition is formulated and tested. Simple size ratio indices perform as well or better in their correlation with annual diameter growth than growing space, area overlap, and root/crown indices. Hegyi's index and several forms of the new root/crown index show the most consistent performance across study species. For. Sci. 37(5):1338-1349.