Discrimination between agricultural management and the hedge effect in pear orchards (south-eastern France)

The arthropod populations in five pear orchards were sampled by beating branches twice a month during the year 2003 in the Provence region of south-eastern France. Multivariate analyses linking the matrix of species with a certain number of environmental variables (distance from the hedge, type of agricultural practices in the orchard, year effect, etc.) were performed to identify the most explanatory variables in terms of composition and structure (richness and equitability) of different arthropod populations. Univariate analyses were performed on descriptive population variables (numbers, diversity and richness) to highlight intrasite or intersite differences. These analyses revealed significant differences in the composition of orchard populations. The variance revealed by all environmental variables explained 28.7% of population composition. The variance revealed by hedge variables only explained 2.2% of population composition, while that revealed by variables concerning management practices explained 12.4%.