Habitat fragmentation, variable edge effects, and the landscape-divergence hypothesis

• Published in: PloS one Vol. 2; no. 10; p. e1017
• Main Authors: Laurance, William F, Nascimento, Henrique E M, Laurance, Susan G, Andrade, Ana, Ewers, Robert M, Harms, Kyle E, Luizão, Regina C C, Ribeiro, José E
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 10.10.2007; Public Library of Science (PLoS)
• Subjects: Beef cattle; Biodiversity; Biodiversity conservation; Brazil; Carbon sequestration; Carbon storage; Cattle; Community composition; Conservation; Conservation of Natural Resources; Divergence; Drought; Dynamics; Ecology; Ecology/Community Ecology and Biodiversity; Ecology/Conservation and Restoration Ecology; Ecology/Spatial and Landscape Ecology; Ecosystem; Ecosystems; Environment; Environmental changes; Forests; Fragmentation; Fragments; Geography; Habitat destruction; Habitat fragmentation; Habitats; Hypotheses; Landscape; Linear Models; Old-growth forests; Plant communities; Population Dynamics; Rainforests; Reproducibility of Results; Spatial variability; Species composition; Species Specificity; Standard deviation; Studies; Temporal variability; Time Factors; Trees; Tropical Climate; Variability; Variables; Wildlife conservation; Brazil
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0001017

Edge effects are major drivers of change in many fragmented landscapes, but are often highly variable in space and time. Here we assess variability in edge effects altering Amazon forest dynamics, plant community composition, invading species, and carbon storage, in the world's largest and longest-running experimental study of habitat fragmentation. Despite detailed knowledge of local landscape conditions, spatial variability in edge effects was only partially foreseeable: relatively predictable effects were caused by the differing proximity of plots to forest edge and varying matrix vegetation, but windstorms generated much random variability. Temporal variability in edge phenomena was also only partially predictable: forest dynamics varied somewhat with fragment age, but also fluctuated markedly over time, evidently because of sporadic droughts and windstorms. Given the acute sensitivity of habitat fragments to local landscape and weather dynamics, we predict that fragments within the same landscape will tend to converge in species composition, whereas those in different landscapes will diverge in composition. This 'landscape-divergence hypothesis', if generally valid, will have key implications for biodiversity-conservation strategies and for understanding the dynamics of fragmented ecosystems.