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.
Subject(s)
Conservation of Natural Resources , Water Supply , Wetlands , Australia , Climate , Humans , Lakes , New ZealandABSTRACT
Pollen records of deglacial sequences from northwest Nelson, New Zealand, demonstrate that there was no significant temperature decline associated with the Younger Dryas in New Zealand. Records of glacial advances at this time were either the product of increased snow accumulation under enhanced precipitation regimes or random variation rather than the result of a regional thermal decline. This finding supports those models of Younger Dryas initiation that require neither enhanced westerly circulation nor significant thermal decline in the Southern Hemisphere.
