中欧社会论坛 - China Europa Forum

Eve Veromann, Estonian University of Life Sciences

juin 2010

The notion that agriculture has to become more sustainable is incorporated in local, regional, national, European and global policies and instruments. Biodiversity is the basis for agricultural production. On the one hand, it is the origin of all crops and domestic livestock and the variety within them. On the other hand, components of wild biodiversity in agricultural and associated landscapes provide and maintain ecosystem services that are essential to agriculture, for example pollination. Knowledge is being increasingly accumulated on how biodiversity can be mobilized to make agriculture sustainable, both in ecological and economic terms. Functional agrobiodiversity is a concept that is gaining more and more ground.

The European Learning Network on Functional AgroBiodiversity defines functional agrobiodiversity as follows:

Biodiversity on the scale of agricultural fields or landscapes, which provides ecosystem services that support sustainable agricultural production and can also have a positive spin-off to the regional and global environment and society as a whole.

Functional biodiversity is concentrated on selectively enhanced diversity, on the functional groups that provide ecosystem services. For that purpose, it is necessary to provide prescriptions for landscape management that effectively support target functional groups. One important tool of functional agrobiodiversity is management of field margins.

In recent years, increasingly more attention has been paid to the positive role which field margins, hedges, and ponds can play on farmland. These reflect agricultural, environmental, recreational, cultural and conservation interests. Furthermore, new approaches to creating and managing these areas have shown how they can deliver greater benefits for the environment and farmers.

Non-crop vegetation in agricultural landscapes can provide a range of important ecological services, including conservation of native flora and fauna, agronomical services such as the enhancement of biological pest control and pollinators as well as reduction of soil erosion, runoff and pesticide drift.

In agricultural landscapes dominated by large monocultures, many arthropod species tend to suffer from lack of nectar and pollen sources, shelter and hibernation, mating and nesting sites. The scarcity of floral resources in modern horticultural and arable systems severely constrains predator survival, limiting the effectiveness of biological pest control. It has been well-established that many biological control agents depend on flowering vegetation as a source of nectar and pollen. For example, adult parasitoids depend on nectar as a food source. If the field margins are supplied with plants with suitable floral resources for parasitoids, their lifespan will be significantly elongated and this can have a significant influence on the number of pests attacked by parasitoids.

Flowering field margins can also be a crucial element in the diversion or interception of pest insects (for example in using the trap cropping systems). Further, field margins are also known to be important over-wintering habitat or refuge for many beneficial arthropods (i.e. spiders, ground beetles, hoverflies, ladybirds etc.) that move into adjacent arable crops and can help to reduce the threat of insect pest species building up. It has been shown that the abundance and number of species of parasitoids and predatory insects (such as carabids) are greater in field margins compared with the field centre. However, the effectiveness of field margins in delivering pest control services strongly depends on various characteristics such as their botanical composition, the complex interactions between fauna and flora, the proportions of cropped and non-cropped areas, semi-natural habit and crops, landscape features, cropping systems etc.

In addition to pest control services, the importance of field margins and hedges as habitat and food sources suppliers for farmland birds has been highlighted. It has been shown that modification of field margin management that has been made specifically to help target species of farmland birds (or mammals) that are in decline may help in their conservation. Field margins enriched with flowering perennial plants support larger insect populations which leads to a higher number of invertebrates that provides food for farmland birds and small mammals such as bats, hedgehogs, shrew-mice etc.

For using the ecosystem services that environment offers and implementing them on the common agriculture practice, a wider knowledge transfer between scientists, farmers, policy makers, and all other stakeholders is needed.

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