Natural and Political Determinants of Ecological Vulnerability in the Qinghai–Tibet Plateau: A Case Study of Shannan, China

Impacts of climate change and human activity on the potential distribution of Aconitum leucostomum in China

Aconitum leucostomum is a poisonous grass that disturbs grassland populations and livestock development, and its spread is influenced by climate change and human activities. Therefore, exploring its potential distribution area under such conditions is crucial to maintain grassland ecological security and livestock development. The present study initially selected 39 variables that may influence the spatial distribution of A. leucostomum, including bioclimate, soil, topography, solar radiation, and human footprint data; the variables were screened by Spearman's correlation coefficient and the jackknife method. Twenty variables were finally identified, and three types of models based on the maximum entropy (MaxEnt) model were constructed to predict the distribution of A. leucostomum within China under three shared economy pathways (SSP126, SSP245, and SSP585): A: prediction of environmental variables under the current climate model; B: prediction of environmental variables + human footprint under the current climate model; and C: prediction of environmental variables under the future climate model (including the 2030s, 2050s, and 2070s). The effects of human activities and climate change on the potential geographic distribution of A. leucostomum were explored separately. The results show that precipitation seasonality, human footprint, solar radiation and mean diurnal range are the main factors affecting the distribution of A. leucostomum. Human activities inhibit the spread of A. leucostomum, and climate change promotes its growth, with areas of high suitability and area variation mainly in northern Xinjiang and northern Yunnan. With climate change, in the future, the distribution center of A. leucostomum shows a tendency to migrate to the southeast on the horizontal gradient and to move to higher altitudes on the vertical gradient. This study provides a positive reference value for the control of A. leucostomum and the maintenance of grassland ecological security.

Spatial Response of Ecosystem Service Value to Urbanization in Fragile Vegetation Areas Based on Terrain Gradient

The contradiction between urban expansion and ecological protection in fragile vegetation areas has become increasingly prominent with regional development. Revealing the relationship between urbanization and ecosystem services will help to provide solutions to this problem. In order to clarify the impact of urbanization on typical mountain areas with fragile vegetation on the Qinghai Tibet Plateau, we built an ecosystem service value (ESV) evaluation index system. We also evaluated the ESV and its spatial response to the urbanization of Shannan Prefecture in Tibet from 1990 to 2015 based on different terrain gradients (TGs) using vegetation biophysical data obtained from remote sensing platforms. The results show that ESV in Shannan increased first and then declined as the TG increased, reaching a maximum value at the third TG. ESV showed a decreased trend during the study period, with a significant decline at the second and third TGs, which were the main distribution areas of vegetation in Shannan. Through spatial correlation analysis, we observed that urbanization and ESV showed a significant spatial aggregation effect. Among them, the high-low type accounted for the largest proportion in the grid with the agglomeration effect, mainly concentrated at the lower TG in the southern of Shannan, where ESV decreases with the increasing urbanization. We highlight the need for targeted, sustainable development policies to rationally organize the urbanization process in the different-gradient plateau regions with fragile vegetation. These results can provide a reference for applying ESV to vegetation restoration and ecological protection in ecologically fragile mountain areas.

A Long-Term Ecological Vulnerability Analysis of the Tibetan Region of Natural Conditions and Ecological Protection Programs

The combined impacts of drastic natural environment change and increasing human interference are making the uncertainty of the Tibetan Plateau’s ecological vulnerability the world’s largest. In this study, an ecological vulnerability index (EVI) of Tibet in the core area of the Tibetan Plateau was assessed using a selected set of ecological, social, and economic indicators and using a spatial principal component analysis (SPCA) to calculate their weights. The data included Landsat images and socio-economic data from 1990 to 2015 in five-year intervals. The results showed that the total EVI remained at a high vulnerability level, with drastic fluctuation from 1990 to 2000 (a peak in 1995, when there was a sudden increase in light vulnerability, which moved to extreme vulnerability in the next period), and minor fluctuations after 2000, gradually increasing from southeast to northwest. In addition, the spatial analysis showed a distinct positive correlation between the EVI and grassland area (0.33), land use degree (0.15), NDVI (0.14), livestock husbandry output, and a negative correlation in terms of desertification area. The artificial afforestation program (AAP) had a positive significant correlation with NDVI (R2 = 0.88), preventing the environment from becoming more vulnerable. The results provide practical information and suggestions for planners to improve the land use degree in urban areas and the vegetation coverage in pastoral regions of the Tibetan Plateau based on the spatial–temporal heterogeneity patterns of the EVI of Tibet.