Trees as bioindicators of environmental pollution

Forests, as natural ecosystems, have a significant contribution to environmental protection. Under injurious action of the environmental factors (soil erosion, soil acidification, pollutants, climate, nutritive resources depletion), the degree of trees damage increases. All processes which occur in the. vegetal systems (plants, trees) react sensitively to such action by some alterations. The environmental factors have a synergistic action and may finally cause trees death. It is very difficult to distinguish the specific influence of each factor mentioned above. There are many literature data related to this subject, most of them focusing on the influence of abiotic, factors (pollutants) upon trees growth and development.