The Influence of Changes in Vegetation Type on the Surface Energy Budget

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The influence of changes in vegetation type on the surface energy budget

The influence of changes in vegetation type on the surface energy budget was studied using the Simple Biosphere Model (SiB) of Sellers et al. (1986). The modeled energy budget response to the conversion of forest to short vegeta-tion or bare soil (deforestation) was investigated with SiB forced by three time-series of atmospheric boundary condi-tions collected at three different climatic sites: an Amazonian tropical forest, a. U.S. Great Plains grassland, and a cen-tral Wales spruce forest. The results show that SiB can simulate realistic surface energy budgets and surface tempera-tures, and that deforestation may have a significant influence on the local surface energy budget and surface weather. The influence is especially prominent at the Amazonian and U.S. Great Plains sites, and greater in summer than in other seasons.It was found that atmospheric boundary conditions play a dominant role in determining the degree of changes in the surface fluxes and temperature induced by deforestation; the largest change in latent heat flux appeared at the Amazon site, the largest change in sensible heat flux appeared at the Spruce forest site, and the largest change in sur-face temperature appeared at the Great Plains site. The Bowen ratios of the SiB sensitivity integrations for each site are comparable with observations. The values of the Bowen ratio and the ratio of latent heat flux to net radiation vary distinctly from site to site, implying that local atmospheric conditions limit the range of changes caused by the vegeta-tion change.