Influence of environment, history and vegetative interactions on stand dynamics in a Connecticut forest

We examined the changing influence of environmental factors and land use history on the composition of the canopy tree, shrub, herb and tree seedling strata of a Connecticut forest over 45 years. The many herb and shrub species initially found in post-agricultural areas of this site declined or disappeared as the forest canopy closed. Tsuga canadensis ([L.] Carriere) increased in importance in the forest canopy until the introduction of the hemlock woolly adelgid (Adelges tsugae Annand). Shade-intolerant understory species are now increasing in abundance as the death of large T. canadensis opens gaps in the canopy. Mantel path analysis, a multivariate technique that allows examination of indirect and direct relationships among variables, was used to quantify the complex network of relationships among environment, land use history and plant community composition. Overall environmental variability was uncorrelated with vegetation, except within the shrub stratum. Slope and drainage were the most important individual environmental factors measured. Land use history was strongly correlated with all four strata, and the strength of this relationship decreased over time. The composition of the tree seedling stratum was highly variable through time; other strata showed more self-similarity between sample dates. Land use history appears to impact the vegetation so strongly as to conceal any effects of environmental variation on this site.

Duke Scholars

Author Norman L. Christensen Environmental Sciences and Policy

Author Dean L. Urban Environmental Sciences and Policy