An ecosystem that is altered or damaged in some way will be out of balance with the biome for that area. For example, if the local biome is forest, but the trees have been removed from one area, then the ecosystem is out of balance. The natural tendency is for plant species to move into that area, bringing the ecosystem back towards the biome state. The spread of a species into a new area is called colonisation. It can happen naturally only if there are ecologically healthy ecosystems nearby to provide plant seeds. Once the vegetation has started to recover, insects, birds and other animals will travel into the newly regenerated area. These processes of ecological colonisation can be supported by environmental ______________. For example, we are currently seeing important changes in the way agriculture is carried out in Britain. Rather than just maximising food production, farming is becoming more environmentally friendly, with the support of financial subsidies. This new approach increases biological diversity by conserving hedges and the wildflowers, insects, birds and other animals that live on the land. A proportion of agricultural land is left completely uncultivated so that species can gradually colonise it. This provides a habitat for a wider range of species. Leaving some farmland as set-aside is also a way to decrease overall production when that is economically desirable. Note that set-aside land is more permanent than fallow land, which is usually left for only a year. Colonisation is a slow process, taking place over years or even decades.
* biome: 생물군계 ** subsidy: 보조(금) *** fallow: 휴경