The Ecological Citizen: Confronting human supremacy

What is habitat fragmentation? (A definition)

Habitat fragmentation refers to a reduction in the total area of habitat and its division into smaller patches, which become isolated within a surrounding matrix of unsuitable habitat. Fragmentation is a major consequence of human-caused habitat destruction and land-use change, predominantly urban development and agricultural expansion.

As a core area becomes fragmented the proportion of edge increases, causing microclimatic changes in light, temperature and wind. Although these conditions can boost biodiversity in some contexts, for example by favouring hardier generalists, many interior species typically associated with long-established ecosystems, such as semi-natural ancient woodland, are often outcompeted, predated upon, and exposed to disease-bearing domestic animals.

At a larger scale, the dissection and diminishment of habitats drives biodiversity loss by reducing a region's overall biomass, disrupting nutrient cycling and impeding species dispersal. Moreover, the isolation of patches exacerbates genetic drift and inbreeding, preventing gene flow and making populations less adaptable to environmental fluctuations and ultimately more susceptible to extinction.

It is generally accepted that large unfragmented habitats provide more stability, ensuring improved biodiversity and genetic diversity in the long term. Thus, rather than thinking in terms of localised and piecemeal conservation, we must take a wider view. This can be achieved theoretically by understanding the interactions of organisms and physical processes at the landscape scale to discern spatial patterns. Practical measures may also be taken, including establishing wildlife corridors and increasing the permeability of the landscape through wildlife-friendly farming and agroforestry initiatives.

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For further reading, see: Lindenmayer DB and Fischer J (2006) Habitat Fragmentation and Landscape Change: An Ecological and Conservation Synthesis, Island Press

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The Ecological Citizen: Confronting human supremacy

What is habitat fragmentation? (A definition)

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