Edge Influence on Forest Structure and Composition in Fragmented Landscapes

Abstract

Although forest edges have been studied extensively as an important consequence of fragmentation, a unifying theory of edge influence has yet to be developed. Our objective was to take steps toward the development of such a theory by (1) synthesizing the current knowledge of patterns of forest structure and composition at anthropogenically created forest edges, (2) developing hypotheses about the magnitude and distance of edge influence that consider the ecological processes influencing these patterns, and (3) identifying needs for future research. We compiled data from 44 published studies on edge influence on forest structure and composition in boreal, temperate, and tropical forests. Abiotic and biotic gradients near created forest edges generate a set of primary responses to edge creation. Indirect effects from these primary responses and the original edge gradient perpetuate edge influence, leading to secondary responses. Further changes in vegetation affect the edge environment, resulting in ongoing edge dynamics. We suggest that the magnitude and distance of edge influence are a direct function of the contrast in structure and composition between adjacent communities on either side of the edge. Local factors such as climate, edge characteristics, stand attributes, and biotic factors affect patch contrast. Regional factors define the context within which to assess the ecological significance of edge influence (the degree to which the edge habitat differs from interior forest habitat). Our hypotheses will help predict edge influence on structure and composition in forested ecosystems, an important consideration for conservation. For future research on forest edges in fragmented landscapes, we encourage the testing of our hypotheses, the use of standardized methodology, complete descriptions of study sites, studies on other types of edges, synthesis of edge influence on different components of the ecosystem, and investigations of edges in a landscape context. Harper et al. Edge Influence in Fragmented Landscapes 769 Resumen: Aunque los bordes de bosque han sido extensivamente estudiados como una importante consecuencia de la fragmentación, aún no se ha desarrollado una teoría unificadora de la influencia del borde. Nuestros objetivos fueron acercarnos al desarrollo de tal teoría mediante (1) la síntesis del conocimiento actual de los patrones de estructura y composición del bosque en bordes de bosque creados antropogénicamente; (2) el desarrollo de hipótesis relacionadas con la magnitud y distancia de la influencia del borde considerando procesos ecológicos que influyen sobre esos patrones; y (3) la identificación de futuras necesidades de investigación. Recopilamos datos de 44 estudios publicados sobre la influencia del borde sobre la estructura y composición de bosques boreales, templados y tropicales. Los gradientes bióticos y abióticos creados cerca de los bordes de bosque generan una serie de respuestas primarias a la creación del borde. Los efectos indirectos de estas respuestas primarias y el borde ori...

Edge effect on vascular epiphytes in a subtropical Atlantic Forest

“…The edge, as an environment with higher light intensity, dryer air and moderately strong wind blowing through the branches, sustained approximately 4.6 times less biomass than the 60-m transect and 3.3 times less than did the 10-m and 30-m transects, a result that agrees with the findings of Williams-Linera (1990), who reported that the most significant changes occur at 2.5-15 m in from the edge of the fragment.. Biomass is related to primary production, niches diversity and the carrying capacity of the ecosystems (Cardinale et al 2006). In the present study, two factors contributed to this: large species occurred less frequently at the edge; and the individuals at the edge tended to be smaller than those of the same species in inner transects what somehow agrees with other studies (Harper et al 2005) that described greater growth and recruitment of some species but reduced growth or increased mortality of others.…”

Efeito De Borda Em Remanescentes De Floresta Atlântica Na Bacia Do Rio Tapacurá, Pernambuco

“…Ainda nas áreas de borda são observadas alterações a níveis de temperatura; de velocidade e turbulência do vento; e de umidade relativa do ar, bem como de umidade do solo, os quais estão relacionados às mudanças e perdas que ocorrem na composição e estrutura da vegetação (FRANCESCHINELLI et al, 2003;HARPER et al, 2005;OLIVEIRA et al, 2004). Com isso, objetivou-se neste trabalho, avaliar efeito de borda sobre o componente arbóreo, adulto e regenerante, em dois fragmentos de Floresta Atlântica, na Bacia do Rio Tapacurá -PE.…”

Effects of traditional coppice practices and microsite conditions on tree health in a European beech forest at its southernmost range

“…In particular, the shallow soils (siliceous, rocky and skeletal) and the effects of strong winds, such as increased evapotranspiration and air turbulence (Harper et al 2005) are among the most limiting environmental factors. Aridity and wind speeds are expected to be higher in these marginal sites, affecting tree health through drought and mechanical damage (Barbeta et al 2011).…”

“…Indeed, Mediterranean mountain beech stands located on ridges or steep slopes, as well as those that are in fragmented stands or near edges, are negatively affected by the increased exposure to wind, turbulence, warmer air and higher soil temperatures (Harper et al 2005, Heithecker & Halpern 2007, Barbeta et al 2011.…”