Community Composition is Different at Forest Edges, but Carbon Storage Remains the Same

by Stephen Johnson

Forest fragmentation is one of the leading ways that humans alter natural habitat. Forests are frequently fragmented as land is cleared piecemeal for the expansion of agriculture, logging, and human settlement. Often, rather than clearing an entire forest, fragments of forest are left embedded in a matrix of agricultural and other habitats. As an increasing percentage of the world’s forests are fragmented, it is crucial to understand how forest fragments function. Fragments are subject to a variety of influences, most notably edge effects. Edge effects occur at the edges of two habitats, and include altered microclimate, reduced biodiversity, and vegetation changes. These edge effects can bring about altered species communities, which in turn could affect the amount of carbon that can be sequestered near forest edges. As forest fragmentation continues, a greater percentage of forest will be exposed to edge effects, potentially inhibiting forests’ ability to act as carbon sinks. To understand these effects, Ziter et al. (2014) examined how tree species composition and carbon storage capacity change with proximity to forest edge in large and small fragments. Using tree measurements and allometric data in the literature, they determined how much carbon was stored, and which species were present. Using linear mixed models and multidimensional scaling, they found that community composition shifts with proximity to the forest edge. Despite this shift, however, carbon storage did not decrease closer to the edge. Continue reading