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How to model trade-offs between agricultural yield and biodiversity

Science for Environment Policy  │  Thematic Issue 57  │   June 2017

There is an inherent trade-off between increasing agricultural production and protection of biodiversity. This study models the effects of biodiversity conservation agri-environment schemes (AESs) and ecosystem service provider schemes, and shows that determining the aim of an agri-environment scheme is key to improving its efficiency. Such an optimisation could allow AES to be rolled out more generally to provide the backbone for both high yields and enhanced farmland biodiversity, say the researchers.

AES can use a variety of measures to try to reverse declines in farmland biodiversity, although the general principle is to reduce the intensity of farmland management. For example, the use of pesticides can be limited, or habitats with benefits for wildlife, such as hedgerows, can be created or maintained. AES can also promote more extensive agriculture by reducing the land available for crops or livestock or by restricting certain intensive management practices. However, it has also been argued that the consequent reduction in productivity could lead to increased pressure for agricultural land elsewhere, causing unintended negative impacts on biodiversity.

Researchers in this study suggest that AES can be broadly divided into those focusing on biodiversity conservation, and those focusing on ecosystem services. For example, a biodiversity conservation scheme might involve habitat protection for species of conservation concern, such as the protection of semi-natural, species-rich grassland for farmland birds. An ecosystem services scheme, on the other hand, might focus on more general, systematic goals related to environmental benefits and the provision of ecosystem services, such as improving water quality, or measures such as beetle banks or providing flowering strips to encourage crop predator or pollinator species. These schemes tend to target more common species.

Many existing schemes are not easily classified as one or the other; different AES may have synergistic effects or trade-offs between conservation of biodiversity versus the promotion of ecosystem-service providers — although the researchers suggest these effects have not been well explored. For example, biodiversity conservation schemes that focus on particular species may have synergistic effects for ecosystem-service providers through the conservation of suitable habitat. However, as a general rule, biodiversity conservation schemes focusing on rare species need to be implemented on large scales. This is to ensure the patchy distribution of the species is covered adequately, to maximise conservation success. Local ecosystem-service providers, such as natural enemies of pests and pollinators, need to be protected at a smaller scale, in comparison.

This study provides a framework to illustrate how biodiversity conservation or ecosystemservice schemes could be allocated depending on the specific needs of the agricultural landscape in question…

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SOURCE: EC – Science for Environment Policy