Population dynamics of willow coppice systems and their implications for management of short-rotation forests

Spacing, length of rotation and clonal composition of Salix coppice systems determine the degree of within-stand competition and thereby the dynamics of the populations. Three general effects of competition are identified and their dependence on planting design and management is illustrated. (1) The dependence of yield on initial planting density disappears at higher densities and becomes weaker at low densities in later rotations. (2) The development of a competitive hierarchy between stools is reflected by a temporal increase of skewness and relative variation in weight frequency distributions. (3) Mortality of stools due to self-thinning is enhanced by high planting density and longer cutting cycles. Furthermore, the relative performance of clones in a mixture cannot be predicted from their performance in pure stands. Key words: Biomass production, Clone mixture, Competition, Rotation length, Salix, Self-thinning, Spacing, Willow coppice