Spatial patterns of weeds along a gradient of landscape complexity
Résumé
Processes that drive spatial patterning among plant species are of ongoing interest, mostly because these patterns have implications for the structure and function of plant communities. We investigated the spatial strategies of weeds focusing on how spatial patterns of weeds are mediated by agricultural landscape complexity and species life-history attributes. We quantified the spatial distribution of 110 weed species using data collected in ten landscapes in central western France along a gradient of landscape complexity, from structurally complex (numerous small fields) to structurally simple (few large fields). We then related differences observed in species' distribution patterns to ecological attributes of species for resource exploitation and dispersion. Our study reveals that weeds were spatially aggregated at the landscape scale. Their spatial patterns are related to the frequency of occurrence of weeds but surprisingly not directly to the seed dispersal type, nor to the degree of habitat specialization. We show that landscape complexity had no direct effect on the spatial patterning of weeds but through interactions with species attributes. Our results point to the importance of interactions between landscape complexity and species attributes in the spatial patterning of weed species even in intensively managed fields. These patterns appear to be a consequence of the spatial arrangement of landscape elements as well as the result of landscape filtering on species attributes.