Crops and pastures of non-uniform height and density, and weed patches within them support a diversity of insects, which in turn support spiders, birds and other predators. But crop rotations have been simplified, and improved crop and pasture breeding and more efficient agri-chemical use have allowed growing and grazing times to be extended. Crop rotation replaced by same crop each year, reduces diversity of invertebrates including butterflies and birds. This leaves large areas managed in the same way at the same time. Improved grassland sowing techniques have also cut species diversity by killing weeds, and re-seeding with palatable competitive grass species, problems with converting permanent pasture to temporary lay is that it reduces diversity of vegetation, reduce the amount of earthworms and other invertebrates, also birds such as skylarks, lapwings, thrushes, gulls and golden plovers.
Another way of increasing intensive food production areas is hedge row removal, this increase sizes of fields but also causes decline in small mammals such as owls, over wintering predatory invertebrates, it also decreases to availability of berry and nut food source for winter thrushes and other birds. The use for hedges is that they are used as stock-proof fences, for shelter and game conservation, easily managed by laying, cutting, and coppicing an annual trimming.
Intensive, industrial-scale farming may be damaging one of the very natural resources that successful crops require: pollinating bees. A study by Princeton scientists found that native bee populations decline dramatically as agricultural intensity goes up.
In farms studied in around California, concentrated farming appeared to reduce bee populations by eliminating natural habitats and poisoning them with pesticides. The expansion of intensive agriculture is threatening more than one third of Europe’s most important bird habitats, Britain’s Royal society for the Protection of Birds (RSPB) warned “ It reduces the diversity of landscape, hedges and ditches and as a result it is no longer possible for open country species to nest, like skylarks, partridges and lapwings.”
Despite the inevitable conflicts between production and conservation, it has also been noted that some farming practices can actually lead to a generally increase and improvement in biodiversity.
In conclusion statistics on soil erosion, declining in fish stocks, deforestation, nitrate pollination (eutrophication) and genetic diversity are raising fears for future stock, and further reduction of species.
