Simulation of environmental impact scores within the life cycle of mixed wood chips from alternative short rotation coppice systems in Flanders (Belgium)

The expansion of Short Rotation Coppice (SRC) practices is mainly driven by the viability of SRC wood as an alternative to other renewable and non-renewable fuels in energy production, but also to the capacity of increasing biodiversity and the supply of ecosystem services locally. To delve into these environmental synergies and possible trade-offs, the Life Cycle Assessment method was applied to seven SRC experimental sites recently implemented in Flanders (Belgium). These have differing land use objectives and, thus, present different species proportions and plantation density. For instance, most sites are either planted with willow and poplar clones, or with a mix of the two with local tree species in order to activate temporary unused industrial lands or enhance the local ecosystem functionality. A regular 3 to 7-year rotation was simulated up to year 2033 using CO2FIX given that trees were yet to be harvested at the time of the assessment. Yields were first estimated over time: SRC systems composed by mixed species presented the highest productivity and also the best environmental performance profiles. Overall, the highest environmental impacts were due to consumption of diesel during the cyclic harvests, but also to fertilization activities. Uncertainty distribution ranges were determined for the most critical parameters and a Monte Carlo analysis was performed to obtain average impact scores with variability ranges. While replacing hardwood with wood from SRC chips was not found to be advantageous because of e.g. larger metal, fossil and ozone depletion potentials, benefits were observed for land use reduction and climate change mitigation. Due to frequent rotations, the beneficial trends for the latter seem sufficient to compensate the negative effects of the other impacts on human health and ecosystems quality.