Vegetation cover on the surface of the Earth has changed considerably due to human activities, mainly through the conversion of natural vegetation to croplands and pastures. These changes have altered regional and global climates through biophysical and biogeochemical processes. In this work, the effects of the conversion of natural caatinga to croplands and to degraded caatinga on the land surface processes in the semiarid region of Brazil are analysed using the Integrated Biosphere Simulator (IBIS) model. Through these land cover changes, the biophysical and morphological characteristics of the vegetation have been modified and therefore, these changes have affected the exchange of energy, water and carbon between the atmosphere and land surface. Results of a simulated conversion from caatinga cover to cropland and degraded caatinga show that surface albedo (in wet and dry season) increased, consequently the energy balance was altered. In addition, roughness length and stomatal conductance changes corroborate the variations in turbulent exchanges between the surface and atmosphere. Regarding the components of carbon balance, when caatinga is replaced by cropland, the net ecosystem exchange (NEE) and net primary productivity (NPP) increases. The opposite effects are found when caatinga is replaced by degraded caatinga. It indicates that the metabolic activity of the ecosystem decreases and this land cover (degraded caatinga) is acting as a source of CO2 to the atmosphere, however with low rates. The present work has important implications for land use management issues in the semiarid region of Brazil, including efforts to restore and preserve the natural ecosystem.
Land change cover; land surface processes; semiarid
