Tree-tree allelopathic interactions in middle European Forests

The allelopathy (mutual interactions between the organisms through the excretion of matters in to the environment) plays an important role in forest ecosystems. We have observed various tree-tree allelopathic interactions in middle European Forests during the different development phases of trees. We have studied the (a) forest regeneration in old stand, (b) mutual influence of young plants on the growth of each other and (c) the mutual influence of tree species in mixed plantations and in rotations. The influence of one tree spp. on another tree varies from positive through neutral and even to negative. We have conducted experiments to find the influence of water macerates from vegetative organs of grown-up trees on seed germination and seedlings growth of young forest trees. Other workers studied the effects of leaf extracts of woody species on seed germination and seedlings growth of plants. The results show that germination energy or vigour was more affected than the germination. In all ecosystems, the plants produce biomass, whose quantity and rate of production depends on plant type, age, health, site conditions and other factors. The allelopathic influences of one tree on another may increase or decrease the biomass production of each other e.g. European beech is harmful to Scotch pine and completely killed its trees.