Enhancing biodiversity persistence in intensively used agricultural landscapes: A synthesis of 30 years of research in the Western Australian wheatbelt

Meeting the global challenge to conserve biodiversity in intensively used agricultural landscapes is dependent on understanding and overcoming the limits to persistence of constituent species and ecological communities. This review synthesizes nearly 30 years of ecological research towards enhancing biodiversity persistence in the Western Australian (WA) wheatbelt, a 14 million ha intensively used agricultural region within a global biodiversity hotspot. Outcomes for a range of taxonomic groups and ecological processes are integrated at a range of scales, and evaluated in the context of agricultural landscapes worldwide. Impacts of six major anthropogenic causes of biodiversity decline in the WA wheatbelt (vegetation clearing, livestock grazing, exotic species introductions, soil cultivation and fertilization, and altered fire management) are discussed, and associated with changes to underlying ecological processes that continue to limit biodiversity persistence even after primary interventions have ceased. At the general level, these limits reflect changes to ubiquitous drivers of species diversity and community composition that are observed in agricultural landscapes worldwide. On the other hand, the unique features of the WA wheatbelt, including the ancient landscapes and low nutrient status of its soils, the lack of large native predators and ungulate grazers, and its relatively recent development for agriculture, contribute to differences among limits to biodiversity persistence across regions. Indicators and thresholds associated with these limits are identified, and practical options for enhancing biodiversity persistence are evaluated. To conclude, we acknowledge that biodiversity outcomes in the WA wheatbelt are constrained by the sheer extent of intervention required, and propose four key directions through which ecological research might best improve the efficiency of on-ground conservation investments in agricultural landscapes: (1) stronger scientific engagement in active adaptive management to close ‘general–local knowledge gaps’; (2) representation of species guilds with respect to landscape parameters as a framework for integrating studies of optimal landscape configurations; (3) introduction of the concept of ‘conservation intensification’ for focusing development and implementation of restoration strategies; and (4) greater application of the concepts of ecological resistance and resilience to the search for integrated and innovative restoration solutions, especially under climate change.