The Influence of Agricultural Abandonment and the Abiotic Environment on the Vegetation Communities of a Suburban Deciduous Forest


Daniel B. Breen

Additional Authors:

Vanessa B. Beauchamp Stephanie M. Koontz Roland P. Roberts


June 2015


Clustering analysis, invasive species, Piedmont physiographic province, secondary succession

ABSTRACT Length of time since agricultural abandonment, variations in topography and soil, and forest fragmentation associated with suburban development can influence dominant vegetation and foster exotic species invasion in a secondary successional forest. The Middle Patuxent Environmental Area (MPEA) in Maryland is a regrowth forest adjacent to suburban sprawl that was abandoned from agriculture at staggered rates. I surveyed vegetation throughout the MPEA to investigate how these interrelated factors have influenced species distribution and abundance. My predictions were that time since abandonment would explain the broader differences in forest succession, but that topography and an interface with suburbia would be the strongest determinants of smaller-scale species discrepancies within an area of similar abandonment history. I performed a hard noise clustering analysis using the R package vegclust to classify the MPEA into herbaceous, shrub, and tree communities each dominated by similar species. Tree communities differed distinctly in accordance with agricultural abandonment, proximity to suburban edges, and soil nutrients, with sun-tolerant Liriodendron tulipifera dominating in more recently reforested areas versus the shadetolerant Fagus grandifolia and Carpinus caroliniana in longer-forested sites. Shrub and herbaceous communities also displayed some pattern reflecting length of reforestation, but there was a greater dominance of invasive species in these strata. A prevalence of disturbance, and a resulting encroachment into the mature forest understory of invasive species such as the grass Microstegium vimineum, underscores the need for invasive species management in a suburban forest fragment to span various stages of succession.