A global review on hydrological responses to forest change across multiple spatial scales: Importance of scale, climate, forest type and hydrological regime

Abstract

Despite extensive studies on hydrological responses to forest cover change in small watersheds, the hydrological responses to forest change and associated mechanisms across multiple spatial scales have not been fully understood. This review thus examined about 312 watersheds worldwide to provide a generalized framework to evaluate hydrological responses to forest cover change and to identify the contribution of spatial scale, climate, forest type and hydrological regime in determining the intensity of forest change related hydrological responses in small (<1000 km 2) and large watersheds (≥1000 km 2). Key findings include: 1) the increase in annual runoff associated with forest cover loss is statistically significant at multiple spatial scales whereas the effect of forest cover gain is statistically inconsistent; 2) the sensitivity of annual runoff to forest cover change tends to attenuate as watershed size increases only in large watersheds; 3) annual runoff is more sensitive to forest cover change in water-limited watersheds than in energy-limited watersheds across all spatial scales; and 4) small mixed forest-dominated watersheds or large snow-dominated watersheds are more hydrologically resilient to forest cover change. These findings improve the understanding of hydrological response to forest cover change at different spatial scales and provide a scientific underpinning to future watershed management in the context of climate change and increasing anthropogenic disturbances.

Global synthesis of forest cover effects on long-term water balance partitioning in large basins

“…precipitation recycling). Both views are supported by observational and modelling studies (Ellison et al, 2012;Zhang et al, 2016). For instance, previous studies have reported that forest cover reduction in large basins can result in both increased (Wei and Zhang, 2010) or decreased (Coe et al, 2009) mean river flows.…”

“…variations in the water balance partitioning) to forest cover change is to exclude the effect of non-forest drivers on runoff (Renner et al, 2014). This can be even more challenging 25 for large basins with various confounding factors including artificial reservoirs and associated water resources schemes (Zhang et al, 2016). Although more-detailed studies are essential to understand water balance partitioning dynamics in different basins, as well as to characterize the influence of forest and non-forest drivers, our observation-based analysis allows to infer that variations in water balance partitioning patterns are related to variations in forest cover.…”

Topography significantly influencing low flows in snow-dominated watersheds

“…Moreover, hydrological responses are compounded by the spatially diverse effects of climate, vegetation, soil, and topography (Li et al, 2017;Zhang et al, 2017). For example, several hydrological models have been applied to test the effect of the spatial distribution of a hydrological variable (e.g.…”

Scaling properties reveal regulation of river flows in the Amazon through a forest reservoir

“…Mean and extreme river flows are global-change-sensitive components of river flow regimes that are determinant for many 10 ecological and societal processes (Sterling et al, 2013;Piao et al, 2007;Coe et al, 2009;Mahe et al, 2005;Lima et al, 2014;Zhang et al, 2016). Landscape and climate alterations foreshadow shifts of precipitation and river flow regimes (Botter et al, 2013;Boers et al, 2017;Hirota et al, 2011;Davidson et al, 2012;Khanna et al, 2017;Lawrence and Vandecar, 2015;Zemp et al, 2017;Sampaio et al, 2007).…”

“…This is a key reason why findings from small river basins about the hydrological effects of forest loss (e.g. from paired catchment studies) cannot be extrapolated to large river basins (Zhang et al, 2016;Ellison et al, 2012;Zhou et al, 2015).…”