Agroforestry for Mine-Land Reclamation in Germany: Capitalizing on Carbon Sequestration and Bioenergy Production

Abstract

Surface mining operations generate significant and large-scale landscape disturbances. As a consequence, effective reclamation management is required to ensure the establishment of a sustainably productive, ecologically valuable, and economically attractive post-mining landscape. In the post-surface-mining landscape of Lower Lusatia (northeast Germany), a new land-use option during reclamation is the establishment of alley cropping systems (ACSs) producing food and woody biomass for obtaining bioenergy. The established multi-row tree strips are typically managed as short rotation coppices (SRC), for which black locust (Robinia pseudoacacia L.) is the most frequently used tree species. The alley cropping systems are promising land-use systems for mine-site reclamation because they provide a multitude of ecological and economic benefits; furthermore, within these plantations, significant amounts of carbon (C) can be accumulated in the biomass and the soil. The results of field studies on C sequestration in R. pseudoacacia stands on reclaimed mine sites within the Lusatian region indicate an average shoot dry matter (DM) production of R. pseudoacacia between 3 and 10 Mg DM ha−1 year−1 depending on the plantation age and rotation period. The DM yields for foliage biomass ranged between 12 and 32 % of the shoot biomass for 2- and 4-year-old trees. Estimates of the C storage within the soil are up to 7 Mg C ha−1 year−1 within 0--60 cm depth. In summary, the results support the hypothesis that ACS of R. pseudoacacia may be in many respects a beneficial land-use system for marginal, post-mining landscapes, with a significant C sequestration potential above- and belowground.