Environmental and hygienic aspects of willow coppice in Sweden

Willow coppice of various Salix spp. has been shown to be a good alternative to fossil fuels both environmentally and economically. Willow stands have also been shown to be adaptable as vegetation filters in order to purify waters and soils. The purification efficiency of willow vegetation filters has been demonstrated in several countries, e.g. Sweden, Poland, Denmark, and Estonia. However, there are still many questions to be answered: for example, what are the mechanisms behind the uptake and allocation of heavy metals and recalcitrant organic constituents, which maximum doses are possible in a particular situation without risks for leakage, and how are hygienic aspects influenced when using vegetation filters. The aim of this paper is to point out some relevant facts concerning willow coppice in general and willow vegetation filters in particular. More specifically, the paper presents and discusses the direct and indirect factors that are improved in such a way that there is a clear benefit of short-rotation forestry. For example, willow cultivations enhance biodiversity compared with conventional agricultural crops and monospecific conifer plantations. They have a pronounced capacity to take up nutrients and heavy metals (including cadmium). The economy is favourable regardless whether the coppice is used as biofuel or as a vegetation filter. The conclusion is that the growing and use of willow coppice is beneficial for the environment and may come to play an important role in a society based on recycling principles. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.