Habitat Fragmentation: A Multi-Scale Approach detailing its lasting impact on Earth’s ecosystems

Scale is an most important factor to consider as it effects all processes. The same process when viewed at different scales can appear to have conflicting results. That is why this study, which considers multiple spatial and temporal scales, presents a very clear and compelling argument that destruction and degradation of natural ecosystems are the primary cause of global declines in biodiversity. Conservation efforts are needed worldwide.

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The large transdisciplinary team of authors analyzed both a broad spatial scale covering 5 continents and a temporal scale looking back 35 years. They zoomed in to analyze small forest patches and found that 70% of the world’s forests fall within 1 km of the forest’s edge and 20% of the world’s forest is found within 100m of an edge. This configuration of the remaining forest fragments has profound effects on the nature and quality of remaining forest patches- as edges are exposed to different biotic and abiotic conditions than the interior forest. Equally significant to remaining forest configuration is patch size, which the authors show impair key ecosystem functions by decreasing biomass and altering nutrient cycles. They determined that these impacts on ecosystem functions were greatest in the smallest and most isolated forest patches.

The power of this paper comes from combining GIS analysis of global forest cover with a series of long running field experiments on fragmentation. Here they were able to synthesize global trends with the results from empirically manipulated fragmentation experiments, which allows them to make claims on both structure and function of these landscapes. These fragmentation experiments are some of the oldest and longest running experiments in ecology, and pairing them with new technologies able to calculate the global magnitude of forest fragmentation show sobering estimates of our current world. Conservation of the remaining largely intact forests should be of highest concern as well as restoration and conservation of smaller parcels to preserve local biodiversity.

Map showing the Mean distance to forest edge for forested pixels within each 1-km cell. Tables breakdown Proportion of the world’s forest at each distance to the forest edge for the Brazilian Amazon (C) and Atlantic Forests (E) and the number of fragments in the Brazilian Amazon (D) and Atlantic Forests (F). Source: Haddad el al., 2015.

Map showing the Mean distance to forest edge for forested pixels within each 1-km cell. Tables breakdown Proportion of the world’s forest at each distance to the forest edge for the Brazilian Amazon (C) and Atlantic Forests (E) and the number of fragments in the Brazilian Amazon (D) and Atlantic Forests (F). Source: Haddad el al., 2015.

Reference

Haddad, Nick M, Lars A Brudvig, Jean Clobert, Kendi F Davies, Andrew Gonzalez, Robert D Holt, Thomas E Lovejoy, et al. “Habitat Fragmentation and Its Lasting Impact on Earth’s Ecosystems.” JOUR. Science Advances 1, no. 2 (March 20, 2015). http://advances.sciencemag.org/content/1/2/e1500052.abstract.

Article by Amy S. Gage

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