Managed ecosystems: biodiversity and ecosystem functions in landscapes modified by human use

There is growing agreement that the long-term sustainability of terrestrial landscapes that provide ecosystem services, such as food, fibre, and timber, will be increased by the conservation of existing biodiversity and the adoption of biodiversitybased practices (Collins and Qualset 1999, Kates and Parris 2003). The broad concept of sustainability is characterized by a set of complementary goals: optimizing production of food, fibre, and forest products while protecting the resource base and social well-being. Biodiversity is increasingly recognized as a key component for the sustainability of managed ecosystems for future generations. For example, in the Millennium Ecosystem Assessment (MEA 2005), biodiversity is viewed as an important coping strategy against agricultural risks in an uncertain future. However, some would argue that this strategy should be viewed as ‘received wisdom’ rather than substantiated proof of process (Wood and Lenne 2005). Indeed, while humans have always relied on biodiversity for provisioning services within managed ecosystems, understanding how biodiversity influences the ecological functions that affect these services, such as pollination, pest control, nutrient cycling, and water purification, is incomplete. Yet with further research, the provision of multiple ecosystem functions (multifunctionality) by different sets of species (Hector and Bagchi 2007), may become one of the most viable tools for managing ecosystems that produce food, fibre, and a range of other ecosystem services (Jordan et al. 2007). Human utilization of the Earth’s ecosystems is progressing at a rapid rate (MEA 2005). This has resulted in enormous loss of biodiversity, both in ecosystems that are managed for provisioning services and in neighbouring unmanaged ecosystems that are impacted by these management activities (Bawa et al. 2007). For example, the increase in cropland (250 per cent) and pasture (440 per cent) in the last 300 years has resulted in the loss of approximately 30 per cent of forests and 40 per cent of steppe worldwide (Lambin et al. 2003) (Fig. 13.1). At present, 10 per cent of the world’s terrestrial land base is used for intensive, high-input agriculture, 15 per cent is associated with low-input agriculture, and 40 per cent is in agricultural mosaics used for other extractive purposes, such as grazing (Mooney et al. 2005, Wood et al. 2000). With the world’s population of 6.7 billion people projected to grow to 9 billion by 2050, increasing demand for resources will continue to lead to major changes in land use and conversion of natural biomes to managed ecosystems. Irrigated and pasture lands are both expected to double in area by 2050, with a net loss of 10 hectares of wildlands worldwide (FAO 2003), thereby increasing the global pressure on biodiversity in natural ecosystems. To keep pace with population growth, it is expected that more land will be converted to agriculture and further intensification of already converted land will increase through greater reliance on non-renewable,