Species–area relationships and minimum area in citrus grove weed communities

Field surveys were carried out in the Catania plain (eastern Sicily, Italy) on winter–spring weed communities in citrus groves, an economical and traditional crop of the Mediterranean area. The aim of this study was to define species–area relationships and to derive information on the minimum sampling area in citrus groves, taking into consideration the ecological, botanical and agronomical implications. Weed flora was composed of 63 taxa belonging to 25 botanical families (42% of taxa included in the families Poaceae, Asteraceae and Brassicaceae). The dominance of therophytes and species with a wide distribution was related to the high degree of artificiality induced by human pressure. The species richness per survey was rather low, ranging from 8 to 22 species, in a surface area of 256 m2. Species–area analyses showed that the minimum sampling area that fully expressed the specific characteristics of plant communities in these citrus groves ranged from 33 to 56 m2. As a result, this methodology can be an appropriate decision support system for sustainable weed management strategies, with a more rational use of herbicides.