Environmental consequences when growing short rotation forests in Sweden

As a perennial crop with good root penetration into the soil, high water use and efficient nutrient uptake over a long growing season, short rotation forests with willows have an influence on the environment that differs from the influence of annual farm crops. Also the landscape is affected differently by the dense willow stand, with a height of 7 m before harvest. There is usually less use of herbicides in the perennial woody crop. Due to larger amounts of litter from the willow plantation and no tillage, there is, with time, an increase of the humus content in the soil. In relation to this, the soil fauna, using organic material for food, prosper in the short rotation forest. Considerably more cadmium is taken up by the willows than by conventional annual crops. This could be used to clean the soil of cadmium, but more knowledge is needed for the optimisation of this procedure. Willows are usually efficient in taking up nutrients, including nitrogen, but when used as vegetation filters it is important to assess the actual ability of a stand to take up N. This ability varies considerably with the developmental stage of the plantation and also with site conditions. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.