Assessing the Carbon Sequestration in Short Rotation Coppices of Robinia pseudoacacia L. on Marginal Sites in Northeast Germany

Abstract

The assessment of the carbon (C) sequestration potential of different land use systems is receiving increasing attention within the European Union forced by aspects of optimum humus content of soils and the debate on climate change. Short rotation coppice crops (SRC) emerge as a promising land use option both for bioenergy production and C sequestration. In this study, C storage in the biomass and the soil under four SRC systems of Robinia pseudoacacia L. was investigated. The plantations were established on reclamation sites in the mining district of Lower Lusatia in 1995, 2005, 2006, and 2007. Samples were collected in the winter of 2007 and 2009. Average aboveground dry matter (DM) production ranged from 0.04 to 9.5 Mg ha(-1) year(-1) for 1-14 years of growth, respectively. Total stocks of soil organic carbon (SOC) at 0-60 cm depth after 2 and 14 years of growth were 22.2 +/- 11.3 and 106.0 +/- 11.7 Mg ha(-1), respectively. Interpreting the data as a false chronosequence, the average rate of soil C sequestration in the 0-60 cm layer was 7.0 Mg ha(-1) year(-1). Hot water extractable carbon (HWC) that represents the labile fraction of SOC was highest in the oldest plantation (1.4 Mg ha(-1) for the 0-30 cm layer). The relative proportion of HWC in SOC, however, did not change substantially between different aged SRC, indicating that with time, because of increasing stocks, C became increasingly stabilized within the soils. Overall, plantations of R. pseudoacacia seem to be a promising land use option for post-mining areas due to their high capacity for sequestering C within biomass as well as a high potential to increase soil C stocks on marginal sites.