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The hydrological legacy of deforestation on global wetlands

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Science  14 Nov 2014:
Vol. 346, Issue 6211, pp. 844-847
DOI: 10.1126/science.1260510

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Abstract

Increased catchment erosion and nutrient loading are commonly recognized impacts of deforestation on global wetlands. In contrast, an increase in water availability in deforested catchments is well known in modern studies but is rarely considered when evaluating past human impacts. We used a Budyko water balance approach, a meta-analysis of global wetland response to deforestation, and paleoecological studies from Australasia to explore this issue. After complete deforestation, we demonstrated that water available to wetlands increases by up to 15% of annual precipitation. This can convert ephemeral swamps to permanent lakes or even create new wetlands. This effect is globally significant, with 9 to 12% of wetlands affected, including 20 to 40% of Ramsar wetlands, but is widely unrecognized because human impact studies rarely test for it.

Impacts of deforestation on wetlands

Deforestation worldwide may be causing an increase in the extent of wetlands. Using a combination of different approaches, Woodward et al. show that ancient and more recent deforestation has resulted in major changes in global wetland hydrology. For example, in Australia and New Zealand, deforestation has created new wetlands or increased the water level in existing wetlands. Recognition of this effect has implications for landscape management: Reforestation programs in wetland catchments may have unintended consequences for vulnerable wetlands.

Science, this issue p. 844

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