Bioclimatic Concept for Assessment of Atmosphere and Forest Land-Cover Coupling at a Regional Scale

Abstract: A biophysical model for quantitative description of mountain forest cover in relation to environmental features (climate, relief, growing season) is developed. It is based on the climatoligical approach of Budyko and accounts for the long-term coupling between the forest functioning and atmosphere. Approximations of heat- and water-balances of mountain natural vegetation environment are framed in a bi-dimensional biosphere-atmosphere equilibrium scheme that defines forest-cover classes as Forest Functional Types (FFTs). The index of dryness of Budyko and potential evapotranspiration (net radiation estimates) during the growing season are used as bioclimatic indicators of the bi-dimensional framework to define the limits of FFTs stable equilibrium. Forest-vegetated land cover of South and South-eastern Bulgaria is considered. Modelling is run for the present-day climate by using meteorological data, which cover space- and altitudinal- environmental differences of the region. Human-induced land cover change is simulated and the potential impacts due to the ‘albedo effects ’ through forest-atmosphere feedbacks are evaluated