Crop mosaic composition and configuration differentially affect vegetation diversity in farmland
Résumé
Landscape heterogeneity is widely recognized as a key determinant of biodiversity. Complex landscapes have been reported to benefit weed species richness at both local and landscape scales. But landscape heterogeneity was mainly associated with the proportion of semi-natural areas. Little is known about the effects of the crop mosaic heterogenity itself. Moreover, local environmental heterogeneity, partly created by different disturbance regimes, may also affect spatial variation of plant species composition. Our aims were to (i) analyze the independent effect of crop mosaic composition and configuration on vegetation richness and composition, (ii) examine whether changes occurred in vegetation richness and composition according to the field position (field centre vs field edge) and (iii) determine whether crop mosaic composition and configuration gradients modulate vegetation changes between field centre and edge. As part of the Farmland project, we sampled weeds in crop fields within 30 1km x 1km agricultural landscapes, in Brittany, France. We showed that landscapes with higher diversity in crop mosaic composition had higher vegetation diversity. Field edges had noticeably higher richness than field centres. Beta diversity between field centre and edge was positively related to crop mosaic heterogeneity supporting the role of spatial heterogeneity in maintaining plant diversity in agro-ecosystems.