Spatial dispersion of woody regeneration in an old-growth forest

Spatial pattern and density for woody regeneration were examined in relation to canopy structure for an old-growth forest in east-central Indiana. All woody stems @>2 cm diameter at 1.37 m were recorded by species and diameter on a 4-ha area gridded into 10 x 10 m quadrats. Canopy structure was inventoried using a 5 x 5 m grid. Canopy structure was divided into three classes: canopy gaps, secondary canopy, and primary canopy. The nonparametric dispersion index was used to examine spatial patterns of woody species and the Clark-Evans nearest neighbor index was used to examine spatial pattern of canopy gaps. Canopy gaps covered 9.0% of the 4 ha area, averaged 52.4 m^2 in area, and were randomly dispersed. Most species were aggregated at scales >400 m^2. While overall regeneration density did not vary significantly with canopy structure, densities for some individual species were significantly different under different canopy structures. The current disturbance regime of this forest, primarily single-tree gaps, has created a canopy structure which favors the regeneration of shade-tolerant species.