Biodiversity impacts of bioenergy crop production: a state-of-the-art review

The use of biomass as feedstock for energy is often associated with increased claims on land, competition with food production and impacts on other ecosystem services. Studies on sustainability aspects of bioenergy production often indicate biodiversity as a key concern. This article presents a first comprehensive review of published impacts of bioenergy crop production on biodiversity, evaluates the drivers and pressures of biodiversity change and summarizes current trends and impacts. The review provides insight into the types of biodiversity indicators applied under a range of conditions and the mitigating measures proposed to minimize negative impacts or realize biodiversity benefits. The 53 selected publications give diverse results that are explained by the various spatial scales, production systems and regions, time horizons, methodologies and biodiversity indicators used. Reported impacts depend on initial land use and are mostly negative, especially in tropical regions. The impacts of second generation bioenergy crops tend to be less negative than first generation ones, and are in some cases positive (at the field level), in particular in temperate regions. Land-use change appears as the key driver of biodiversity change, whereas the associated habitat loss, alterations in species richness and abundance are the main impacts addressed. Such changes are often paired with the (initiation of a) process of biological homogenization. The article confirms that concerns about the expansion of bioenergy crop production not only relate to the direct effects on biodiversity by replacing natural vegetation, but increasingly to indirect effects as well. These effects have, however, shown to be difficult to quantify. At the same time, the land sparing vs. land sharing debate receives growing attention, whereas little evidence exists in bioenergy literature on the impacts of large-scale application of these strategies on (agro)biodiversity. Following the findings of the review, the article finally provides recommendations for future research.