Effect of landscape structure on agrobiodiversity in western Iran (Gilan-E Gharb)

摘要

The widespread transition into intensive agroecosystems has led to a considerable decline in plant biodiversity especially for organisms in the field boundaries. The aim of this study was to survey the vegetation of fields and field boundary types located in an agricultural landscape. We provided the structural map of the landscape and classified it into field boundary types nested in three main groups of natural and seminatural elements. Species recorded in all habitat types were categorized into two emergent groups based on their response to land use intensification: 1) agrotolerant species (AT) and 2) high nature-value species (NV). We analyzed the effect of landscape structure and soil physicochemical properties on species richness of these groups. We found both landscape structure and soil properties significant in explaining variation among AT and NV species richness both at 2-m-x-2-m and landscape scales. The most overall species richness was recorded for agricultural fields (43 species) followed by non-crop field edges (37). Woody green veins and permanent ditches were the elements providing high NV species richness clearly, while fields and other field boundary types were mostly supporters of AT species richness. Diversity of AT species increased along nitrogen and clay content gradients of the soil, while NV species benefited where phosphorus and soil moisture content were high. We recommend agricultural landscapes to be more specified with (semi-)natural habitats which embed high a proportion of rare weeds as nature-value plant species.