摘要 : Forests are the earth's largest, most productive ecosystems, playing one of the biggest roles in the development of human societies. Covering about 21% of the geographical area of India, they have been essential in mankind's well-... 展开 Forests are the earth's largest, most productive ecosystems, playing one of the biggest roles in the development of human societies. Covering about 21% of the geographical area of India, they have been essential in mankind's well-being not only as a large part of the economy, but also by providing basic necessities to local communities. With forest cover shrinking, the current demand for forest products may exceed the limits of sustainable consumption. To meet the growing demand, exotic tree species are often planted. The exotics are generally fast growing, more productive per unit area as compared to indigenous species. In order to introduce the exotic species, factors like edaphic, climatic, forest types, etc. should be taken into consideration. There are a number of potential fast growing exotic tree genera like Populus, Eucalyptus, Leucaena, Salix, Robinia, Cryptomeria, Prosopis, Sesbania, Casuarina, Acacia, etc., which have the potential to take intensive pressure of the natural forests. There is a huge scope for exotic trees in agroforestry, energy plantations, industrial plantation, wasteland plantation and strip plantation. Various researchers have reported success stories of exotic plants in increasing the net returns from agriculture fields, reclaiming saline and alkali soils, afforestation in opencast coal mines, etc. Apart from these advantages, there are various negative impacts of exotic trees viz., allelopathy, liable to attack by pests and disease, use of excess water and effect on soil and invasive nature. These risks can be reduced by taking some precautions before introduction of an exotic species viz., introducing material through proper evaluation before mass plantation, keeping wide genetic base, etc. Thus, exotics have very high potential in every aspect of forestry. 收起