Abstract
This paper aims to assess the importance of environmental and management factors determining the weed species composition along a strong elevation gradient. A total of 76 cereal fields (39 low input and 37 intensively managed) were sampled along an elevation gradient in central Italy. Explanatory variables were recorded for each field to elucidate the role of large-scale spatial trends, of site-specific abiotic environmental conditions and of field management characters. Redundancy analysis was used to assess the relative importance of each environmental variable in explaining the variation in species composition. Our results indicate that variation in weed species composition is strongly determined by altitude, mean annual precipitation, mean annual temperature and also by soil characteristics. However, the level of intensification proved to be the most influential variable. There was a significant difference in species richness and composition between low-input and intensively managed fields. Intensification leads to considerable species loss at both lower and higher elevations. Low-input fields had 296 species in total, while intensively managed fields had only 196.
Acknowledgements
This work was supported by the Erasmus Teaching Staff Mobility between the University of Pécs (Hungary) and the University of Camerino (Italy) and the Carpathes Nature Conservation Foundation. The authors are grateful to the Italian farmers for the permission to access their land. They would like to thank Domenico Lucarini (University of Camerino) for his help in solving taxonomical difficulties and to Emily Rauschert (The Pennsylvania State University) for useful comments and linguistic improvement of the text.