Hybrid poplar spacing/productivity relations in short rotation intensive culture plantations

Abstract

It is often argued that in short rotation intensive culture plantations, biomass productivity increases with narrower tree spacings. Biomass productivity and tree spacing relations were studied for up to 16 years in northern Wisconsin hybrid poplar plantations. Maximum mean annual biomass increment was 12.8 Mg ha −1 yr −1 for Populus clone NE-41 planted at a l m 2 spacing. Productivity differences related to spacing were found to be minor. Productivity was influenced mainly by clone, irrigation and disease. A hypothesis is proposed that time to canopy closure is linearly related to time to maximum mean annual biomass productivity. Wide spacing and wide-crown trees that permit wider tree spacing allow longer rotations, which can lower costs and increase flexibility in management.