Abstract:

The extensive planting of single crop for extended time periods in agricultural landscapes has led to a decrease in species diversity. Natural and semi-natural habitats within agricultural landscapes, as well as the associated plant and small animal (especially ground arthropod) communities, are of vital importance for preserving biodiversity in agro-ecosystems. It is crucial to study the relationship of regional agricultural landscape heterogeneity and biodiversity for maintaining ecosystem services and stability. In this study, Fengqiu County of Henan Province, a typical agricultural region in the lower reaches of the Yellow River, was taken as the study area for investigating the diversity of semi-natural habitat plants in agricultural landscape and ground arthropods in comparison to cropland of this agricultural ecosystem. The analysis of the relationship between plant diversity in semi-natural habitat and landscape variables was repeated for four different spatial scales (100 m, 250 m, 400 m, 550 m) and for artificial forest, hedgerow, and ditch environments to determine the optimal spatial scale of analysis for plant diversity in agricultural landscape. The relationship between ground arthropods diversity and semi-natural habitat variables was also analyzed at the local habitat scale. All analyses were conducted using generalized linear models (GLM) in R statistical software. The results show that: (1) Plant diversity was highest in artificial forest. The abundance and species richness of ground arthropods in semi-natural habitats were significantly higher than that in farmland; (2) The relationships between richness of plant species and diversity in semi-natural small habitat and landscape heterogeneity were strongest at a spatial scale up to 250 m radius around the sampling point. But the relationship between ground arthropod species and diversity in semi-natural small habitat and landscape heterogeneity was strongest at a spatial scale up to 250 m radius around sampling points in artificial forest and cropland; (3) Results of GLM regression on plant species diversity and landscape variables at the scale up to 250 m radius around sampling points confirmed that vegetation richness (Sveg) was negatively correlated to interspersion and juxtaposition index (IJI) in artificial forest and hedgerows; In ditches, vegetation richness (Sveg) had a negative effect on edge density (ED) and aggregation index (AI) but a positive effect on Shannon's diversity (SHDI); (4) Results of GLM regression on ground arthropod species diversity and landscape variables confirmed that at the range of 250 m radius around sampling points, abundance was negatively related to Shannon's diversity (SHDI) and land use richness, and was only significantly negatively related to Shannon's diversity (SHDI) in cropland fields. Generally speaking, the semi-natural habitat elements in intensively farmed agricultural landscapes may function as refugia and sources of dispersal or stepping stone habitats. It will play an increasingly important role in regional biodiversity conservation and improvement by connecting these scattered semi-natural habitat elements in agricultural landscape into networks. However, attributes of semi-natural habitats, such as area, quantity, type, and spatial distribution, are among the important research topics in urgent need of study and consideration.

Key words: biodiversity, semi-natural habitat, multi-scale effect, agricultural landscape