Effects of rural landscape spatial morphology on plant diversity in the Yangtze River Delta region

Analyzing rural plant diversity in relation to landscape spatial morphology is necessary to improve rural living environments and maintaining stable rural ecosystems and biodiversity. Fourteen villages in Jiangning District, Nanjing City, Jiangsu Province were selected as experimental areas, and models such as stepwise regression and NMDS-Envfit were used to explore the impact of rural landscape spatial indicators on the α diversity and β diversity of rural plants in the Yangtze River Delta region. Landscape indicators included two-dimensional plane forms, three-dimensional surface features, and four-dimensional historical dynamics. The research conclusions can be summarized as follows: 1) Landscape spatial morphological indicators, such as the percentage of the landscape area covered with semi-natural patches, landscape cohesion index, surface roughness, and patch Euclidean nearest neighbor distance, had relatively significant impact on plant diversity. The patch Euclidean nearest-neighbor distance and patch area significantly and negatively affected the diversity of the arborous layer. Patch fragmentation, higher road density, and higher comprehensive dynamic degree of land use had a negative impact on the α diversity of shrub layer, while the distance from the road obviously affected the α diversity of herbaceous layer. 2) Rural landscape spatial morphological indicators had an impact on plant β diversity. Specifically, in the arborous layer, surface roughness and percentage of landscape area covered with semi-natural patches were the most important influencing factors. In the shrub layer, surface roughness and Shannon diversity index were the most important influencing factors. In the herbaceous layer, patch area and rural road density were the most important influencing factors. 3) Considering the significance of landscape indicators, landscape ecological indicators and three-dimensional surface characteristics had the most significant impact on plant diversity. The main manifestations were the positive correlation between the proportion of semi-natural patch area, patch area, cohesion degree, surface roughness, and plant diversity. The historical dynamics of the four-dimensional landscape had a weak impact on plant diversity, mainly manifesting as a positive correlation with the dynamic degree of semi-natural patches. Two-dimensional landscape indicators based on urban spatial morphology had the weakest impact on plant diversity, mainly manifesting as the negative effects of rural spatial accessibility and road density on plant diversity. Based on the above results, landscape response strategies are proposed to provide guidance for the rural landscape construction process, such as effectively increasing the proportion of semi-natural habitat areas and landscape heterogeneity, comprehensively improving rural landscape cohesion, scientifically maintaining rural high-value woodland landscapes, and fully focusing on rural historical land use. This study provides a reference for the maintenance of biodiversity during rural landscape construction and useful quantitative guidance for rural spatial planning in the Yangtze River Delta region.