On the unique value of forests for water: Hydrologic impacts of forest disturbances, conversion, and restoration

We need empirical evidence on the impacts of land-use change on hydrological processes to guide policies and land management decisions. Based on a global meta-analysis of 287 primary studies covering 1049 data points in 58 countries and across 12 biomes, we review hydrologic process changes resulting from native forest disturbances and conversions to other land-use types. Infiltration rates consistently fell over 50%, overland flow increased and evapotranspiration as a share of rainfall declined when native forests were disturbed or converted. Changes in total evapotranspiration, interception, and streamflow were less consistent in direction, while restored native forests returned infiltration function rates to pre-conversion levels. Forests, and perhaps especially native forests, have a unique value in supporting and regulating hydrologic processes, as they can reduce erosion, improve water infiltration, and potentially enhance water supply, including in downwind locations. We thus underscore global calls for increasing the proportion of reforested areas with native species in landscape restoration planned for this decade.