Lower forest density enhances snow retention in regions with warmer winters: A global framework developed from plot-scale observations and modeling

Abstract

[1] Many regions of the world are dependent on snow cover for frost protection and summer water supplies. These same regions are predominantly forested, with forests highly vulnerable to change. Here we combine a meta-analysis of observational studies across the globe with modeling to show that in regions with average December-January-February (DJF) temperatures greater than À1 C, forest cover reduces snow duration by 1-2 weeks compared to adjacent open areas. This occurs because the dominant effect of forest cover shifts from slowing snowmelt by shading the snow and blocking the wind to accelerating snowmelt from increasing longwave radiation. In many locations, midwinter melt removes forest snow before solar radiation is great enough for forest shading to matter, and with warming temperatures, midwinter melt is likely to become more widespread. This temperature-effect in forest-snow-climate interactions must be considered in representations of the combined ecohydrological system and can be used advantageously in forest management strategies.

Canopy structure and topography effects on snow distribution at a catchment scale: Application of multivariate approaches

“…However, this effect decreases with increasing snow accumulations. The differences between snow storages accumulated in open areas and in forests with different structure were reported from many other world's areas (Lundquist et al, 2013;Revuelto et al, 2016).…”

“…Additionally, the forest influences turbulent fluxes (Pohl et al, 2006) and reduces the amount of short-wave solar radiation and thus snowmelt rates (Pomeroy et al, 2012;Schnorbus and Alila, 2013). The proportion of longwave and shortwave radiation varies depending on yearly climatic conditions and thermal regime of the study site (Lundquist et al, 2013). The longwave radiation under forest canopy is relatively more important than incoming shortwave radiation especially in mid-winter because it causes faster snowmelt compared to adjacent open area.…”

“…The longwave radiation under forest canopy is relatively more important than incoming shortwave radiation especially in mid-winter because it causes faster snowmelt compared to adjacent open area. This occurs because the efficiency of forest to reduce incoming shortwave radiation is most important during spring when the shortwave radiation is high enough (Lundquist et al, 2013;Schnorbus and Alila, 2013).…”

The vulnerability of Pyrenean ski resorts to climate-induced changes in the snowpack

“…This variability results from complex interaction between mesoscale meteorology, local topography and weather factors. Aspect, slope or wind-blown effects (Green and Pickering 2009) or forest density (Lundquist et al 2013) are crucial factors that affect the spatial distribution of snow. For example, due to the complex topography of mountain areas, slope angle and aspect are also very likely to influence the sensitivity of snowpack to temperature change (Uhlmann et al 2009).…”

Modeling the distributed effects of forest thinning on the long-term water balance and streamflow extremes for a semi-arid basin in the southwestern US

“…Most of these studies have identified immediate increases in runoff and sediment production (Bosch and Hewlett, 1982;Brown et al, 2005;Hibbert, 1983;Hornbeck et al, 1993;Sahin and Hall, 1996). However, in basins where water yield depends mainly on snow accumulation and melt, researchers have reported high variability and uncertainty tied to site-specific topography, forest structure and microclimatic conditions (Cline et al, 1977;Lundquist et al, 2013;Schelker et al, 2013;Stottlemyer and Troendle, 2001;Troendle and Reuss, 1997;Venkatarama, 2014;Woods et al, 2006). Multiple authors have found a direct relationship between thinning, snow interception reduction and ablation increase (Link and Marks, 1999;Lundquist et al, 2013;Varhola et al, 2010;Venkatarama, 2014).…”