To promote the positive effects and mitigate the negative impacts of agricultural systems and practices on biological diversity in agro-ecosystems and their interface with other ecosystems.
The agricultural sectors are heavily influenced by varying degrees of government intervention, employing measures that have often led to levels of commodity production and the adoption of farming practices that have not been conducive to sustainability, or have discouraged more sustainable practices. The increase in productivity is being achieved in many cases at the cost of degrading natural capital (fertile soil, clean water, natural and semi-natural ecosystems). In addition, the factors behind the decline of biodiversity can be understood by considering the incentives and disincentives facing a country or an individual farmer with regard to sustainable use of genetic resources.
The Royal Society for the Protection for Birds in the UK estimates that recreating 160,000 ha of a range of habitats by 2020 would cost an additional £20 million per year on top of current nature conservation expenditure - which is less than 1% of current agricultural subsidies.
In a study to assess the effectiveness of agri-environment in the Netherlands, 78 pairs of fields (pairs comprising one field with a management scheme, and one field managed conventionally) were compared. Most Dutch management agreements support wading bird populations by delaying agricultural activities. Surprisingly, fields with management agreements had lower densities of these species, perhaps because the farmers applied only one third of the usual amount of fertilizer, resulting in lower plant densities and therefore lower densities of soil invertebrates, on which these birds feed. However, this study did not measure the breeding success of the birds and it is possible (or even likely) that the birds are more successful on sites with a management agreement.
Another major agri-environment scheme in the Netherlands is to conserve botanically rich grassland by reducing fertilizer inputs and/or delaying the date at which grazing or mowing starts. However, no difference in botanical diversity was found between fields with management agreements under this scheme and conventionally managed fields. Furthermore, there was no tendency for botanical diversity to increase with the age or number of years that the field had been under a management agreement. One reason might be that fertility takes a long time to respond to the change in management scheme, and that the scheme had been running for too short a timescale. Fields with management agreements did show some increase in diversity of hover flies and bees, although the management agreements seemed to have little effect on botanical diversity on working farms in spite of well-designed initial experiments.
There are many opportunities to reverse some of the loss of natural habitat to farmland in a strategic targeted manner that might also result in benefits to the local economy (e.g. tourism) and wider economy (e.g. flood protection, carbon sequestration and water-quality protection).
Extensive restoration and habitat improvement is obviously insufficient on its own to solve current rural problems, but, combined with other measures, it might help to restore trust and respect between the farming community and the public, and thus help revitalize agriculture.
Conventionally managed farms might act as ecological traps, with birds attracted to sites that result in lower breeding success and ignoring sites in which they might do better. If this is the case, areas need to be created that are both of good quality and are perceived by birds as being such.
Whilst carefully targeted and tested agro-environment schemes might be beneficial, the most cost-effective approach is still likely to be to combine this with large-scale habitat restoration in carefully selected areas.
The key, but usually unasked question, is whether, on its own, the alteration of farming methods is sufficiently effective. Measures such as making grants dependent on, for example, hedgerow planting and maintenance or establishing unsprayed strips along field boundaries, can often be inefficient if applied universally over the landscape. Furthermore, if applied on a broad scale, such measures require extensive monitoring, might be bureaucratic, can cause resentment and are likely to be insufficient to reverse declines in the landscape and biodiversity.