Ten-year biomass production and stand structure of Salix ‘aquatica’ energy forest plantation in Southern Finland

The biomass production and stand structure of Salix ‘Aquatica’ planted on abandoned farmland and harvested after 3 and 7 year rotations was studied in southern Finland for 10 years. Coppicing doubled the stand density to 3.5 × 105 shoots ha−1. Self-thinning began during the first growing season and shoot mortality amounted to 13%–20% at the end of the first growing season. Cumulative shoot mortality of the initial sprout number at the end of the first rotation (3 years) was 60%; the corresponding figure at the end of the second rotation (7 years) was 87%. The diameter distribution at the beginning of self-thinning resembled a bidomal distribution. The second self-thinning phase began at the age of four years. The mean annual leafless above-ground biomass production was higher during the second (7.7 t ha−1) than during the first rotation (5.1 t ha−1). The annual increment varied highly depending on the temperature sum and losses caused by pathogens. The leaf area index of 1–3 year old sprouts varied between 4.9 and 6.4 m2 m−2.