Effects of dry grassland management on spider (Arachnida: Araneae) communities on the Swiss occidental plateau

The spider communities of dry grassland are diverse and very sensitive to habitat conditions. This paper shows that variation in the composition of spider communities can be related to (i) management practices (mainly pasture and prevention of shrub growth); (ii) broad-scale natural conditions (altitude, humidity); and (iii) spatial variation of unknown origin. Using partial canonical correspondence analysis, we show that the three groups of variables statistically explain distinct parts of the variation of species abundances, with management contributing almost half of the explained variation. This study is consistent with the hypothesis that different sources of variation (spatial, environment and management) influence community structure in distinct ways, and that these must all be taken into account when devising habitat conservation strategies.