In my post yesterday, I discussed managing the cutting of hay fields to preserve butterfly habitat. Livestock grazing is another agricultural impact on butterflies. When livestock are in high density and allowed to forage an entire field, then much of the forage that is not eaten is trampled and otherwise made less suitable for caterpillars and butterflies.
A group of French Scientists have developed an Alternative Rotational Stocking (ARS) strategy. The strategy is to create refuge areas by fencing the livestock out of the refuge during the main flowering period and simultaneously, increasing the density of livestock in non-refuge areas. This strategy produces a mosaic of refuge areas containing tall flowers and a lot of nectar where butterflies thrive, among the larger heavily grazed areas that are less suitable habitat for butterflies.
Farruggia and colleagues compared the ARS strategy to standard livestock grazing practicies. The ARS strategy greatly increased butterfly diversity without decreasing livestock production. The ARS strategy can help manage pastures to eliminate certain undesirable plants. To preserve butterfly diversity, about 20 percent of the grazing area would need to be maintained grazing free during the period of flowering. This would make it possible to rotate areas on a 5 year basis.
Agricultural production requires large areas of land. How that land is managed can have important affects on the larger ecosystem. People are looking for creative ways to maintain biodiversity and at the same time produce enough food to feed the world.