Patterns of spatial autocorrelation in the distribution and diversity of carabid beetles and spiders along Alpine glacier forelands

Spatial autocorrelation is a common feature of ecological data and can be found in the distribution pattern of many species or in the diversity of many species assemblages. The presence of spatial autocorrelation in species distribution along primary successions on recently deglaciated terrains has been largely overlooked until now, despite its potential consequences for comparisons between glacier forelands. Here, we investigated the occurrence of spatial autocorrelation at different spatial scales in the distribution and diversity of ground beetles and spiders along glacier forelands. We found positive spatial autocorrelation in patterns of occurrence of most species and in patterns of species assemblages diversity at spatial scales representing single (< 3 km) or adjacent valleys (< 7 km), whereas at a larger spatial scales (0-30 km) such positive spatial autocorrelation disappeared. We concluded that spatial autocorrelation could be a key issue for studies investigating distribution of arthropods, including in glacier forelands, in order to perform more robust analysis and to avoid misinterpretation of species distribution in relation to the glacier retreat and other environmental characteristics.