Starting with the description of meteorological variables in forest canopies and its parameter variations, a numerical three-dimentional model is developed. Its applicability is demonstrated, first, by wind sheltering effects of hedges and, second, by the effects of deforestation on local climate in complex terrain. Scientists in ecology, agricultural botany and meteorology, but also urban and regional lanners will profit from this study finding the most effective solution for their specific problems.

1 Introduction.- 2 Distribution of Meteorological Variables in Forest Canopies.- 2.1 Forest Structure and Utilization.- 2.2 Variation of Meteorological Parameters Within a Stand.- 2.3 Methods of Investigation.- 3 Air Flow Around and Through Individual Trees.- 3.1 The Numerical Model.- 3.2 Investigations on Single Trees.- 3.3 Studies on Groups of Trees.- 3.4 Investigations of Wind Shelter Hedges.- 4 Air Flow Through and Above Stands.- 4.1 Improvement of the Numerical Model.- 4.2 Investigations in a Horizontally Homogeneous Stand.- 4.3 Investigations in a Horizontally Inhomogeneous Stand.- 5 Concluding Remarks.- References.- Symbols.