ESTIMATION OF TREE REPLACEMENT PATTERNS IN AN APPALACHIAN PICEA-ABIESFOREST

Patterns of tree species replacement in a Picea-Abies forest, determin ed by several different methods, are compared and the methods are asse ssed. Methods are grouped as either understory-based or gap-based esti mates of replacement. The understory-based methods characterize canopy understory interactions with spatial statistics, sapling density meas urement, sapling frequency measurement, and successor sapling identifi cation beneath live canopy trees. The gap-based methods include saplin g density measurement, sapling frequency measurement, and successor sa pling identification in tree-fall gaps. Methods except those based on frequency indicate a strong trend of replacement of all canopy species by Abies. Understory-based methods may underestimate canopy recruitme nt of intolerant trees, while gap-based methods relying on sapling den sity or frequency may overestimate recruitment of intolerant trees. Es timates based on the selection of successor saplings in the understory or in gaps are reliable. Gap successor estimates consider the process of gap capture and are useful in analyses of forest dynamics.