Year-end Sale % OFF 
Abstract
Abstract. Although forest management is one of the instruments proposed to mitigate climate change, the relationship between forest management and canopy albedo has been ignored so far by climate models. Here we develop an approach that could be implemented in Earth system models. A stand-level forest gap model is combined with a canopy radiation transfer model and satellite-derived model parameters to quantify the effects of forest thinning on summertime canopy albedo. This approach reveals which parameter has the largest affect on summer canopy albedo: we examined the effects of three forest species (pine, beech, oak) and four thinning strategies with a constant forest floor albedo (light to intense thinning regimes) and five different solar zenith angles at five different sites (40° N 9° E–60° N 9° E). During stand establishment, summertime canopy albedo is driven by tree species. In the later stages of stand development, the effect of tree species on summertime canopy albedo decreases in favour of an increasing influence of forest thinning. These trends continue until the end of the rotation, where thinning explains up to 50% of the variance in near-infrared albedo and up to 70% of the variance in visible canopy albedo. The absolute summertime canopy albedo of all species ranges from 0.03 to 0.06 (visible) and 0.20 to 0.28 (near-infrared); thus the albedo needs to be parameterised at species level. In addition, Earth system models need to account for forest management in such a way that structural changes in the canopy are described by changes in leaf area index and crown volume (maximum change of 0.02 visible and 0.05 near-infrared albedo) and that the expression of albedo depends on the solar zenith angle (maximum change of 0.02 visible and 0.05 near-infrared albedo). Earth system models taking into account these parameters would not only be able to examine the spatial effects of forest management but also the total effects of forest management on climate.
Highlights
Albedo is the fraction of solar energy reflected from a surface back to the atmosphere; it is controlled by the characteristics of the surface, cloudiness and the position of the sun
Given that MODIS albedo was used to derive the parameters of the radiation transfer model, this comparison only validates the effective leaf area index (LAI) simulated by ForGEM and the ray-tracing approach
That the gap fraction is excluded as a major cause of the deviation between simulations and observations, too high near-infrared single scattering albedo values for pine, as obtained from the Joint Research Centre Twostream Inversion Package (JRC-TIP) product, are left as the most likely cause
Summary
Albedo is the fraction of solar energy reflected from a surface back to the atmosphere; it is controlled by the characteristics of the surface, cloudiness and the position of the sun. The size of the land surface albedo is a major factor controlling the energy budget of the Earth and albedo is a key parameter in the Earth’s climate system. Of the main vegetated land surface types, i.e. trees, grasses and crops, trees generally have the lowest albedo, trapping more solar radiation than shorter vegetation The differences in albedo between broad vegetation classes, i.e. evergreen and deciduous forest, and among other vegetation types are reasonably well established, as are the climate effects that follow a change in albedo (Anderson et al, 2011; Bala et al, 2007; Bathiany et al, 2010; Betts, 2000; Pielke et al, 1998; Schwaiger and Bird, 2010)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
