Is there any ecotone effect on species number in fragmented agricultural landscapes?
|Popis||Fragmentation of agricultural landscapes can cause biodiversity decline, but it also generates ecotones, which could theoretically compensate for its negative effect, because ecotones are believed to be zones with increased biodiversity. However, the notion of increased biodiversity in the ecotones is controversial. We asked whether ecotones in an agricultural landscape contain more species of vascular plant species or of their subgroups (archaeophytes, neophytes or endangered species) than patches of homogeneous habitats. We also tested whether the more structurally diverse ecotones are more species-rich than the less structurally diverse ecotones. In the agricultural landscape of southern Moravia, Czech Republic, vegetation plots were recorded in all ecotones and habitat patches encountered along five 1-km transects. Total species numbers in ecotones were similar to those in neighbouring open-land habitat patches. Species numbers within species groups were not significantly different between ecotones and any adjacent habitat. Species numbers in forest/scrub-open land ecotones did not differ from species numbers in ecotones between two open-land patches, indicating that even increased structural heterogeneity did not increase species numbers in ecotones. Based on our own results and various published case studies, we suggest that contrary to the widespread belief repeated in ecological textbooks, higher species number is not a general feature of ecotones, at least not for vascular plants in the central European agricultural landscape. Ecotones therefore cannot counteract the negative effects of fragmentation. They probably do not serve as refugia of red-listed species, but at the same time they do not host increased number of neophytes.|