Environmental Consequences of Land use Changes for Bioenergy Crop Production at a Regional Scale

Abstract

Sustainability has become a focus of global bioenergy (especially biofuel) policy and research over the past few years. Due to the rapid expansion of demand for global bioenergy and increased sustainability requirements, land use change associated with bioenergy crops (hereafter referred to as ‘bioenergy-driven land use change’) has emerged as an important research topic. The use of degraded land, marginal and abandoned agricultural lands (hereafter referred to as ‘underutilised agricultural land’) has been proposed for non-food and lignocellulosic crop production. However, the implications and consequences of the use of these lands remain highly uncertain. This was a study to evaluate the regional environmental effects of the use of underutilised agricultural land for bioenergy production using a spatial modelling approach and land use change scenarios in a case study region—the Burnett River catchment, Australia. The aim of this research was to evaluate whether land use change scenarios that involve bioenergy crop production on underutilised agricultural land can enhance regional-scale environmental outcomes when compared with current land uses, and to provide recommendations and suggestions for future land use options. The scenarios assessed in this research, including the selection of bioenergy crops (and the associated management practices) and land use change pathways, were developed to minimise potential environmental impacts. In line with four research objectives based on the aim, a review of past studies relating to bioenergy-driven land use changes was conducted to better understand their dynamics and their effects both in the past, and in future projections(Objective 1, Chapter 2). A spatially explicit evaluation framework was developed to evaluate regional scale environmental consequences associated with land use changes (Objective 2, Chapter 3). The evaluation framework focused on the issues of water quantity and quality (and soil erosion), and terrestrial biodiversity, the impacts of which are commonly experienced regardless of geographical region. It was tested in a case study region in subtropical Queensland, Australia (Objective 3, Chapter 5), and then applied to six bioenergy-driven land use change scenarios to quantify the impacts and compare the results with a baseline (2005/06) and with other scenarios(Objective 4, Chapter 6). The findings from the evaluation were synthesised as recommendations for future bioenergy sustainability research community and policy, and also as a basis for decision making concerning sustainable land use options for future bioenergy production (Chapter 6 and 7).TThe results of the land use change scenario evaluation indicated that bioenergy crop scenarios could benefit regional environmental quality in the case study region only when: (i) open grazing areas (pastures) were used as the plantation site, (ii) native woody perennial bioenergy crops were used (e.g. Pongamia [Millettia pinnata] or Short Rotation Coppice [SRC] eucalyptus species), and (iii) the new plantations were under low intensity management (similar to conventional forested grazing areas or conventional forestry). The results also suggested that current bioenergy policy — simply limiting crop production to underutilised agricultural land — will not necessarily enhance environmental sustainability in bioenergy production. They also indicated that future policy could address more detailed prescriptions including very careful site planning and management strategies. These included: (i) selection of the most suitable crops and site locations (i.e. the land use change pathway most suited to a region); (ii) stringent control of native vegetation clearing and consideration of the local ecology when deciding on a location (e.g. appropriate distance from watercourses and conservation areas, spatial configuration of native vegetation and local ecology); and (iii) identification and implementation of the optimum management intensity. These are perhaps the most significant findings of the study and they have added important knowledge to current bioenergy research and policy. Another important contribution of this research was the evaluation framework that offers a methodology potentially applicable to various regions for land use change scenario evaluation and could support for decision making on bioenergy land use at the regional scale. The need for such an evaluation framework is becoming more important, as there is an increasing need worldwide for decision making related to land use change for bioenergy crops. While land use change scenarios vary significantly between countries and regions, the evaluation framework could be tailored to specific regions in future applications. Future development of the framework could also be undertaken in accordance with the development of sustainability indicators by accredited certification organisations/initiatives. A well-planned and integrated bioenergy industry can have major environmental, economic and social benefits for a region.