Importance of (semi)natural vegetation on farms for achieving multiple objectives: A conceptual model based on temperate southern Australia

CONTEXT: Agriculture provides food, fibre and other resources for people throughout the world, but clearing of native vegetation for agriculture has led to profound losses of biodiversity and changes to ecosystem function. There is growing recognition of the need to retain and restore (semi)natural vegetation in farmland for biodiversity conservation. However, managing such vegetation is complicated by trade-offs between different objectives, and knowledge to guide management is dispersed across multiple fields. OBJECTIVE: We integrate knowledge on the benefits and disbenefits of (semi)natural vegetation on farms for achieving six objectives, including biodiversity, farm production, carbon stocks, soil health, local water cycle, and amenity/human wellbeing. METHODS: Drawing on scientific literature from temperate southern Australia as a case study region, we develop a conceptual model of the relationships between these objectives and seven common types of native and restored vegetation on farms. RESULTS AND CONCLUSIONS: From 224 peer-reviewed empirical studies, we identified 19 'causal pathways' by which (semi)natural vegetation provides benefits or disbenefits for the identified objectives. More pathways result in benefits than disbenefits, and generally there is greater support for the benefits provided by native than restored vegetation. Nonetheless, farm-level restoration (revegetation) contributes towards reversing the negative consequences of vegetation loss but this process takes time. Various 'moderating factors' serve to alter the outcome of most pathways. For example, restoration age affects the benefits that revegetation provides biodiversity, carbon stores, soil health and water cycling. Many moderating factors are related to management practices (e.g. stock grazing, use of fertilisers), highlighting opportunities to enhance the benefits of (semi) natural vegetation in farmland. Relatively little is known about the value of (semi)natural vegetation for amenity/human wellbeing, or the outcomes resulting from natural regeneration. SIGNIFICANCE: The conceptual model and causal pathways identified here contribute towards a more comprehensive understanding of the diverse benefits of (semi)natural vegetation on farms, which is essential effective management and the sustainability of agricultural landscapes worldwide.