The fate of Amazonian forest fragments: A 34-year investigation
We synthesize key findings from the world’s largest and longest-running experimental study of habitat fragmentation, located in central Amazonia.
Over the past 34 years, Amazonian forest fragments ranging from 1 to 100 ha have experienced a wide array of ecological changes. Edge effects have been a dominant driver of fragment dynamics, strongly affecting forest microclimate, tree mortality, carbon storage, fauna, and other aspects of fragment ecology. However, edge-effect intensity varies markedly in space and time, and is influenced by factors such as edge age, the number of nearby edges, the matrix of modified vegetation surrounding fragments, and fragment size. In our study, the matrix has changed markedly over time (evolving from large cattle pastures to mosaics of abandoned pasture and regrowth forest) and in turn has strongly influenced fragment dynamics and faunal persistence. Rare weather events (e.g., windstorms and droughts), have further altered fragment ecology. In general, populations and communities of species in fragments are hyperdynamic relative to nearby intact forest. Fragmentation effects are likely to interact synergistically with other anthropogenic threats such as logging, hunting, fire, and climate change, creating an even greater peril for the Amazonian biota.