MANAGEMENT OF FOREST SOILS CONSIDERING WATER EROSION AS A CONTROL FACTOR

In Mediterranean regions, water erosion is strongly linked to desertification and relates mainly to constraints of land use. Soil and water play very important roles as production factors in agriculture and forest crops, so they are of almost importance in the management of forest soils for sustainable productivity. The density of plants, the amount of water available and the soil properties are aspects to take in account in the management of forestlands. The lower stage canopies of bushes and herbs established in forest lands compete for water with the trees, but are important in the maintenance of ecosystems and absorbing the energy of rainfall and throughfall, thus reducing soil erosion. For the assessment of the available water and the rainfall erosion it is necessary to know the hydrologic behaviour of tree canopies and, mainly, the role of the leaves. The major aim of this study is to present and analyse the role of the leaves in what concerns canopy interception, retention and throughfall and to present values for the leaves' retention and throughfall erosivity, obtained experimentally. Typical conditions, in Southern Portugal, are presented for mixed stands of cork and evergreen oaks, with cereals or pasture covers, and for eucalyptus. Proper management attitudes are necessary to ensure productivity, environment stability (i.e. avoiding desertification) and, consequently, improve homeland and global security.