Changes in forest canopy structure along a site quality gradient in southern Wisconsin.

Ordination of foliage-height profiles yielded a continuum in vertical structure paralleling a continuous change in species composition and soil moisture status. The profiles were used to test hypotheses on canopy structure relating to net energy capture under different levels of moisture stress. Canopies on the mesic end of the moisture gradient showed the hypothesized shift from multilayer to monolayer with increasing moisture availability. Stands on the xeric end of the gradient included a significant shrub layer which caused a divergence from the hypothesized trends leading essentially to a double layer structure.-from Authors