Effects of land consolidation intensity on landscape pattern and biodiversity in paddy ecosystem

Abstract

Land consolidation (LC) are introduced in agricultural landscapes to streamline mechanical field operations, and increase crop production. However, it may cause adverse effects on landscape patterns, biodiversity and potentially ecosystem services. To investigate the effects of varying intensity of LC (high-, medium-, and low-) on landscape patterns and biodiversity, we selected 30 paddy landscapes in the Chengdu Plain, China. The landscape change before and after LC were compared, and the diversity of vascular plants, rice planthoppers, carabids, spiders, and birds in landscapes with different LC intensities were assessed. The findings revealed that the proportion of semi-natural habitats significantly decreased following LC, while the mean field size significantly increased. As the increase of LC intensify, there was a significant decline in the abundance of spiders and the species richness of ground hunting spiders in 2021, while an increase in abundance of rice planthopper and species richness of omnivorous birds and carnivorous bird. However, the diversity of vascular plants, carabids and also their functional groups, remained largely unaffected. Except the species composition of spider in low- and medium-intensity of LC was significantly different than that in high-intensity in 2021, there were no significant differences were observed in the species composition of birds, carabid beetles, their respective functional groups, and vascular plants. Notably, the abundance ratio of spiders to rice planthoppers in landscape with medium-intensity of LC was significantly higher than in Low- and high-intensity, yet the NDVI of paddy fields showed no significant variation. Overall, a higher intensity of LC corresponded to decline diversity of spiders and increase of rice planthopper, thereby diminishing biological control within the paddy ecosystem. Nevertheless, with the preservation of the original semi-natural habitats and the overall landscape pattern, coupled with an appropriate increase in field size, landscapes with medium-intensity of LC emerged as the optimal strategy to harmonize the benefits of biodiversity and mechanized production.