Liang Huang

Habitat degradation has become a critical bottleneck that restricts watershed ecological security and sustainable development. This study aims to reveal the spatiotemporal evolution of habitats in the Chishui River Basin, in order to provide scientific guidance for regional ecological conservation and restoration. Based on land use datasets from 1990 to 2023 in the basin, the InVEST-PLUS model is adopted to quantify habitat quality and conduct exploratory multiscenario simulations of future habitat conditions across the study area. The main results are as follows: (1) The average habitat quality index of the Chishui River Basin tends to decrease, with the area of high-grade habitat decreasing by 50.30%. The basin has undergone four distinct phases: high-intensity degradation, continuous but low-intensity structural change, large-scale ecological restoration, and active bidirectional adjustment. (2) Spatial pattern of habitat quality is strongly heterogeneous. Specifically, high-quality habitats are primarily distributed in the northern region of Chishui River Basin, while degraded habitats are concentrated in the central and southeastern parts of the basin, with an expanding trend. Habitat changes are characterized by leapfrog transfer and path dependence. Notably, low-grade habitats show an extremely high persistence rate of 97.16%. (3) Simulation outputs under diverse scenarios show that ecological protection serves as an effective strategy for improving habitat quality within the basin. Habitat quality of the Chishui River Basin has displayed a phased evolutionary pattern of initial degradation followed by recovery. Strengthening ecological protection will be the core approach to ameliorate watershed habitat quality and safeguard ecological security in the future. The study provides a scientific reference for watershed ecological conservation and restoration, territorial spatial optimization, and the construction of ecological barriers in the upper reaches of the Yangtze River.

Alternanthera philoxeroides is a highly invasive alien species in China that causes waterway blockages, agricultural yield loss, biodiversity decline, and ecosystem degradation. This study assessed the invasion risk and environmental drivers of A. philoxeroides in Guizhou Province, a karst mountainous region in Southwest China. Occurrence records were obtained from field surveys and the Chinese Virtual Herbarium. The genetic algorithm for rule-set production (GARP) model and the jackknife method were employed to identify 13 key environmental indicators for predicting invasion risk. The global invasion risk index (GIRI) was applied to quantify the overall invasion risk. Additionally, the Geodetector model was utilized to analyze the spatially differentiated effects of six environmental factors. The results showed that A. philoxeroides poses a high invasion risk in Guizhou Province, and the invasion risk in the Yangtze River Basin within Guizhou is higher than that in the Pearl River Basin. The environmental factors influencing invasion risk, in order of impact, were slope, elevation, land use, river density, rocky desertification, and soil pH. Moreover, interactions among these factors further amplify the invasion risk. These findings provide valuable insights for developing targeted management strategies for A. philoxeroides in karst mountainous regions and support biodiversity preservation and regional ecological sustainability.

This study analyzed the changes in landscape patterns and the ecological health status of karst plateau wetlands, providing valuable insights into their conservation. Using land cover data from 1996 to 2021, DEM, and Landsat series satellite imagery, this study employed landscape ecology methods and the pressure–state–response (PSR) model framework. A regional landscape grid was constructed, and 13 indicators were selected to establish an ecological health evaluation system for karst plateau wetlands. This allowed us to explore the spatiotemporal change characteristics of the landscape pattern and the ecological health of karst plateau wetlands. The results showed that over a 25-year period, farmland, grassland, and construction land areas have increased, whereas forested land areas have decreased. Water bodies remained relatively stable but showed a trend of transitioning into grassland. Unused land showed no significant change. Landscape analysis indicated that grasslands experience the highest rate of fragmentation, complex shapes, and greater heterogeneity, whereas water bodies have the lowest fragmentation, more regular shapes, and lower heterogeneity. Other landscape types exhibited moderate characteristics. Overall, the landscape of the study area exhibited high fragmentation, specific patch aggregation, moderate patch density, and low diversity. A comprehensive ecological health evaluation revealed that the wetland health value remained at an “unhealthy” level from 1996 to 2021. Although there was a brief improvement in 2010, effective long-term recovery was not achieved. Spatially, the proportion of “diseased” areas peaked in 2006, and most grid zones remained in an “unhealthy” state over the years, with none reaching the “healthy” standard. These findings highlight the severe challenges faced by the wetland ecosystem.