Monday, 30 July 2012

Biodiversity in the Vineyards - who needs it?

See my previous post on biodiversity in the vineyards for definitions of terms, some background and details of a specific project in the Loire.

There are two strands to the arguments about why biodiversity is important and why we should preserve it. The first are the economic aspects such as its potential to improve the production of agricultural commodities; its role in the regulation of soil fertility and the physical and chemical cycles of the Earth; and the possibilities for the tourist industry. The second is ethical and cultural - our moral duty to future generations and the need to maintain the potential of living organisms.

Grass between the rows.
Biodiversity is the key to sustainability and to reducing the high input style of farming where artificial fertilizers and phyto-pharmaceuticals are routinely used. The French scientists based at INRA are leading the way on the research into the benefits of biodiversity for farming.

Viticulture is an intensive monoculture resulting in a homogeneous landscape with low levels of biodiversity. If we want to challenge this approach to winemaking the attack must be two pronged. Chemical inputs and landscape homogeneity must be tackled simultaneously.

Vines surround a patch of woodland.
Vineyards and annual crops have the lowest levels of biodiversity in agriculture (pasture has the highest levels and forestry falls between the two). The use of biocontrols is now well established, but best practice today is to manage the landscape for conservation biocontrol so that natural predators and pollinators build up sufficient numbers to be sustainable and have a real beneficial impact. This includes creating a mosaic of habitats to provide shelter and food year round (for example, planting hedges).

A landscape scale approach allows the monitoring of both changes in the landscape such as the creation of hedges and crop margins to shelter predators, and the changes in the pest population. The main insect pests in the vineyards are leafhoppers, who suck leaves dry and spread diseases, and moths, who's caterpillars eat the grape flowers and the forming fruit.

Lots of groundcover, and woodland behind.
Ideally, no parcel of vines should be more than 400m from a patch of woodland. In order to reduce the isolation between semi-natural habitats, low hedges can be planted, which allow the insect meta-populations to flow, but also fit the requirements of a commercial grape growing operation. There is still a lot to learn about managing biodiversity for agriculture though. For instance, it turns out that the moth pests thrive in a monoculture and so landscape changes work well to control them. The leafhoppers, on the other hand, use all the available habitats and are not discouraged by having the vines broken up by hedges or crop margins. It seems the entomologists at INRA will be kept busy for a while yet.


Source: Protection des Paysages Viticoles, a paper by G. Pain et al, 2010, Mission Val de Loire.


Autolycus said...

Another argument for biodiversity is the simple precautionary principle, or as I like to call it, the Joni Mitchell principle:

Don't it always seem to go
That you don't know what you've got till it's gone

Susan said...

Auty: I think this is a subset of 'duty to future generations'.

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