Black locust (Robinia pseudoacacia L.) Short-Rotation Crops under Marginal Site Conditions

The improvement of the reliability of renewable resources and the decline in reserves of fossile raw material in the coming decades will lead to increasing demands for wood material and consequently to a greater role of short rotation forestry (SRF). Particular efforts have been made in Europe to substitute fossils with renewables, in this context the proportion of renewable energy should be increased to 20% by 2020. SRF can be provide relatively high dendromass (biomass) increment rates if the short rotation tree plantations are grown under favourable site conditions and for an optimum rotation length. However, in many countries only so-called marginal sites are available for setting up tree plantations for energy purpose. For SRF under marginal site conditions black locust (Robinia pseudoacacia L.) can be considered as one of the most promising tree species thanks to its favourable growing characteristics. According to a case study presented in the paper black locust can produce a Mean Annual Increment (MAI) of 2.9 to 9.7 oven-dry tons ha–1 yr–1 at ages between 3 and 7 years using a stocking density of 6667 stems ha–1. On the base of the presented results and according to international literature the expected dendromass volume shows great variation, depending upon site, species, their cultivars, initial spacing and length of rotation cycle.