Site selection is a key link in the early stage of constructing a photovoltaic power station and providing accurate guidance for the development of such stations. Taking Longyang District, Baoshan City, Yunnan Province, as an example, this article utilizes land-use status data from the third national land survey. The study focuses on five land-use types: idle land, bare land, shrub land, forest land, and another grassland, while excluding interfering land types such as construction land, ecological conservation areas, and cultivated land. Thirteen factors including terrain, weather, environment, and neighboring resources are considered. By employing the fuzzy analytic hierarchy process, a site selection model is constructed to analyze the suitability of photovoltaic power station locations. This study emphasizes the influence of geological disaster factors when selecting environmental factors. Given the high frequency of geological disasters in mountainous areas, these factors significantly affect the safety of later-stage photovoltaic power station operations. Previous research has paid less attention to this factor. The results indicate a high level of suitability for photovoltaic site selection in Longyang District, Baoshan City, with suitable, moderately suitable, and unsuitable areas accounting for 20.09%, 34.14%, and 45.77%, respectively. Previous studies have lacked sufficient validation of site selection outcomes. In this research, validation is conducted using areas where photovoltaic power stations have already been established and are under construction within the region. The accuracy of this site selection method is found to be 92.78%. The aim is to provide a scientific reference for site selection in mountainous areas with photovoltaic power station construction needs.

Regional ecosystem service value (ESV) is significantly influenced by factors such as land use/cover change (LUCC). In this study, from the perspective of spatio-temporal heterogeneity, we constructed a dynamic and zonal equivalence table of ecosystem service values using the equivalence factor method and analyzed the spatio-temporal changes in ecosystem service values of different agricultural plantation regions of the karst mountainous areas of southwestern China (Yunnan Province, YP) in the years from 1990 to 2020. Also, the ESV of YP in 2030 was simulated using the Patch-generating Land Use Simulation (PLUS) model. The results showed the following: (1) land use/land cover (LULC) in YP from 1990 to 2020 was dominated by needle-leaved forestland, broadleaved forestland, grassland, and rainfed cropland. (2) The total ESV in YP fluctuated between CNY 876.74 and 1323.68 B from 1990 to 2020, expanding at a rate of 50.98%. The largest portion of the total ESV comes from climate regulation. The ESV increased from east to west, and the positive spatial correlation of the ESV gradually weakened. (3) The ESV in YP was projected to reach CNY 1320.70 B by 2030, representing a decrease of ~CNY 2.98 B since 2020. The results showed a decline in the ecological environment’s quality in YP.

The Five Lakes Basin of Central Yunnan Plateau (FLBOCYP) is located in the core area of Yunnan Province and has a developed economy, but the ecological and environmental problems in the basin are serious and the sustainable economic development is threatened. The analysis of ecological carrying capacity change and the study of influencing factors in the basin is conducive to protecting the ecology of the basin and maintaining the sustainable development of the social economy. Ecological carrying capacity is an important indicator for the quantitative assessment of regional sustainable development, and the assessment of regional ecological carrying capacity based on grid scale can more accurately and vividly reflect the regional sustainable status and provide reference for regional coordinated development. With the support of GIS technology, based on the unique ecosystem characteristics of the river basin itself, the research method of quantifying the ecological carrying capacity from the three perspectives of ecological function elasticity, resource and environmental capacity and socio-economic coordination was carried out, and a relatively complete comprehensive evaluation index system of ecological carrying capacity was constructed. The ecological carrying capacity of the five major lake basins of Qilu Lake and Yangzonghai from 2000 to 2018 was evaluated, and the temporal and spatial changes and driving mechanisms of ecological carrying capacity were analyzed. The results show that: (1) The FLBOCYP has an overall moderate ecological carrying capacity (average of ~0.5). The temporal trend in ecological carrying capacity was an initial rise followed by a fall, but there was an overall increasing trend at a rate of 0.019. (2) Areas with a strong ecological carrying capacity were mainly distributed in the mountainous and semi-mountainous regions outside of the lake area, whereas areas of weaker ecological carrying capacity were mainly distributed in the plain area around the lake. The ecological carrying capacity gradually increased from the area around the lake to the periphery. (3) At a basin scale, the ecological carrying capacities of the Dian, Fuxian, and Yangzong lake basins were relatively high, whereas those of the Xingyun and Qilu lake basins were relatively low. The greatest increase in ecological carrying capacity of Fuxian Lake has occurred since 2000. (4) The spatial pattern of ecological carrying capacity showed clear agglomeration. This agglomeration has been continuously enhanced but remained relatively stable over the past 19 years. The main agglomeration modes were identified as “high-high” (HH), “low-low” (LL), and “not obvious agglomeration”. (5) Among the many driving factors, ecological elasticity, biological abundance index, proportion of forest land, and degree of human disturbance showed the greatest explanatory power for spatial differentiation of ecological carrying capacity, and the interaction of any two factors affected the spatial analysis of ecological carrying capacity even more. In summary, the overall ecological environment of the FLBOCYP has experienced significant improvement since 2000, whereas that of the plain area has deteriorated more seriously in recent years.

Coronavirus disease 2019 (COVID-19) swept the world at the beginning of 2020, and strict activity control measures were adopted in China’s concentrated and local outbreak areas, which led to social shutdown. This study was conducted in southwest China from 2019 to 2021, and was divided into the year before COVID-19 (2019), the year of COVID-19 outbreak (2020), and the year of normalization of COVID-19 prevention and control (2021). A geographically and temporally weighted regression (GTWR) model was used to invert the spatial distribution of PM_2.5 by combining PM_2.5 on-site monitoring data and related driving factors. At the same time, a multiple linear regression (MLR) model was constructed for comparison with the GTWR model. The results showed that: (1) The inversion accuracy of the GTWR model was higher than that of the MLR model. In comparison with the commonly used PM_2.5 datasets “CHAP” and “ACAG”, PM_2.5 inverted by the GTWR model had higher data accuracy in southwest China. (2) The average PM_2.5 concentrations in the entire southwest region were 32.1, 26.5, and 28.6 μg/m³ over the three years, indicating that the society stopped production and work and the atmospheric PM_2.5 concentration reduced when the pandemic control was highest in 2020. (3) The winter and spring of 2020 were the relatively strict periods for pandemic control when the PM_2.5 concentration showed the most significant drop. In the same period of 2021, the degree of control was weakened, and the PM_2.5 concentration showed an upward trend.