Willow Production Related to Climatic Variations in Southern Sweden

The aim of this study is to quantify the variations of energy forestry production at different locations in south Sweden that can be expected because of variations in climate only. The growth of first-year shoots of willow (Salix viminalis) is simulated by means of a model based on photosynthesis. The production is examined over a 15-year period and at 13 different locations. The mean yearly stem production ranged between 10.0 tonnes of dry matter per hectare and year at Helsingborg and 6.5 tonnes per hectare and year at Hagshult. The yearly variation was within +/- 25% for sites located in the inland areas while those at the coast generally showed variations within +/- 15%. On a regional basis, Skane had the highest mean production with 9.4 tonnes per hectare and year while the production of the Malardalen region was about 13% lower. The difference in production between Malardalen and Ostergotland was about 2%. A sensitivity analysis showed that the growth response of clones to temperature might be an important selection criterion when aiming at increasing the production.