// INTRODUCTION //

In recent decades, biodiversity decline due to land-use changes in agricultural landscapes is a central theme across the globe, which has been reported in many taxa (e.g., birds, insects, mammals, plants). However, most studies are pattern based and little known about what factors cause the decline. This study purpose is clarify mechanisms of causal correlation between biodiversity loss and plant community changes.

// METHODS //

This study conducted at 31 fields at semi-natural grasslands of paddy fields in southeast area of Hyogo prefecture, western Japan. Recently, in some of these areas, have been changing to land-use intensive or abandoned fields due to human management. We surveyed diversity of butterflies, grasshoppers and plants as well as environment variables ( vegetation height and aboveground biomass). This study scheme is to compare diversity of plants and herbivorous insects among three types of habitats: Traditional fields (N=13), Intensive fields (N=10) and Abandoned fields (N=8).

// RESULTS //

We found that perennial species diversity at traditional fields was the highest, and high perennial diversity contributes herbivorous insects diversity. Our study revealed mechanisms of biodiversity decline caused by land-use change that has negative effect on　high perennial species diversity maintaining herbivorous insect diversity.