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The role of intensive agriculture in mediterranean woody crops as regards the conservation of reptiles

Abstract:

The progressive expansion and intensification of agriculture poses an increasing threat to farmland-inhabiting wildlife, principally as the result of a deterioration in habitat quality. Reptiles constitute one of the most threatened wildlife groups, and their populations have undergone a significant decrease in farmland landscapes, regardless of which they have been studied to a far lesser extent than other vertebrate taxa. This situation is of particular concern in Mediterranean areas, in which woody crops such as olive groves or vineyards have undergone a high degree of intensification and mechanisation. In this chapter, we assess the peer-reviewed literature concerning the effects of agricultural intensification on the conservation status of reptiles in Mediterranean woody crops. The aim of this chapter is to synthesize the knowledge regarding the ecological effects that current agriculture management in intensive Mediterranean woody crops has on reptiles, paying particular attention to olive groves and vineyards, which have been the principal woody crops in the Mediterranean Basin since Roman times. This intensification has led to a loss of habitat complexity owing to the shortening of the productive lives of the crops, since older trees trees/vineyards provide more shelter than young plants. Moreover, crop intensification involves the massive use of agrochemicals, such as pesticides and fertilizers, in addition to certain practices like tillage, which also contribute to the total elimination of herbaceous cover. Intensive management in its entirety leads to a dramatic simplification of the habitat, and consequently a loss of reptile diversity. In summary, the impacts on the reptilian community are caused principally by the direct toxicity of pesticides and the loss of food and shelter that results from the loss of vegetation and habitat simplification, which are also caused by pesticide use and/or continuous tillage. Several recent works have reported the negative impacts of intensive and super-intensive olive groves and those of trellised vineyards on bird species, which could also affect reptile communities. Some agri-environmental measures, such as the maintenance of natural vegetation, hedges and boundaries, or the establishment of cover crops among the grapevines and olives, may be suitable means to improve the status of reptilian communities in woody crops. The role of the surrounding landscape is also crucial, as it could cushion the effects of intensive cropping on ecosystems. Long term studies carried out on a larger spatial scale are required in order to accurately determine the impact of agricultural intensification systems on reptiles and to compare them with more traditional environmentally friendly management.