Search Results (8)

Located in the southwestern region of China, the Yunnan–Kweichow Plateau, is closely related to the origins of Pyrus L. Despite this important status, there has been relatively little population genetics research focused on the wild Pyrus species in this area. To address this gap in knowledge, the present study was conducted investigating wild Pyrus species distributions in the Yunnan–Kweichow Plateau region. These analyses entailed the collection of 80 accessions, whole-genome resequencing, and the detection of variants including SNPs, InDels, SVs, and CNVs. Genetic structure analyses revealed clear differences between P. pashia and P. calleryana, where the former was additionally subdivided into five groups. The genetic structure of these accessions was closely aligned with their geographic distribution, highlighting the fragmented nature of wild Pyrus populations on the Yunnan–Kweichow Plateau. Analyses of genetic diversity suggested that the central and easter portions of Yunnan Province are key centers of Pyrus diversity on the Yunnan–Kweichow Plateau, whereas the highest degree of differentiation was observed for wild Pyrus in the southwest and northwest regions. Demographic analyses indicated that wild Pyrus populations on the Yunnan–Kweichow Plateau are currently in a state of population contraction, with evidence of migration events between these populations. Full article

The Yunnan–Kweichow Plateau serves as a critical ecological security barrier in southwest China. The region has witnessed substantial transformations in land use patterns due to rapid urban expansion, economic development, and population growth. These changes have significantly impacted the structure and services of regional ecosystems. Conducting a quantitative analysis of the influence of land-use changes on ecosystem service value (ESV) proves to be invaluable for guiding regional land planning and environmental conservation efforts. Utilizing land use data, we calculated ESV variations linked to dynamic land-use changes spanning the period from 1980 to 2020. This comprehensive study delved into the spatiotemporal fluctuations and regional disparities in ESV. To enhance the reliability of our evaluation, we applied a regional coefficient to adjust the equivalent factor of ecosystem service value. Over the 40 years, the total ESV exhibited a decrease from USD 122,215.03 million to USD 121,838.82 million. Notably, water supply experienced the most significant decline, while hydrological regulation witnessed the largest increase. The continuous decline in water supply service capacity raises concerns about exacerbating water resource shortages in the region. Spatially, the ESVs in the study region primarily concentrated within the medium-low to medium-high value range. However, except for regions with medium values, the area of other level regions is expanding, and is particularly evident in the increase in low-value regions. The reduction of forestland, grassland, and cultivated land, coupled with the expansion of built-up land, emerged as the primary contributors to the overall ESV decrease. In particular, the negative ecological contribution rate of built-up land reached 37.97%, and the ESV decreased by USD 866.64 million, underscoring that the expansion of water bodies could not compensate for this loss. The study highlights the increasing sensitivity of ESV to land-use changes in the region. As a response, there is a pressing need for managers to reinforce the implementation of ecological engineering and engage in rational planning for production, living, and ecological spaces. This research serves as a crucial reference for establishing an ecological security pattern system and fostering the sustainable development and utilization of land resources in the region. Full article

The tropospheric delay caused by the temporal and spatial variation of meteorological parameters is the main error source in interferometric synthetic aperture radar (InSAR) applications for geodesy. To minimize the impact of tropospheric delay errors, it is necessary to select the appropriate tropospheric delay correction method for different regions. In this study, the interferogram results of the InSAR, corrected for tropospheric delay using the Linear, Generic Atmospheric Correction Online Service for InSAR (GACOS) and ERA-5 atmospheric reanalysis dataset (ERA5) methods, are presented for the study area of the junction of the Hengduan Mountains and the Yunnan–Kweichow Plateau, which is significantly influenced by the plateau monsoon climate. Four representative regions, Eryuan, Binchuan, Dali, and Yangbi, are selected for the study and analysis. The phase standard deviation (STD), phase–height correlation, and global navigation satellite system (GNSS) data were used to evaluate the effect of tropospheric delay correction by integrating topographic, seasonal, and meteorological factors. The results show that all three methods can attenuate the tropospheric delay, but the correction effect varies with spatial and temporal characteristics. Full article

Environmental factors are strong drivers of local adaptation in forest tree species. Toona ciliata var. pubescens, an endangered tree species endemic to China, is widely distributed across Eastern and Southwestern China. In this study, we used 8 genomic microsatellite markers and 17 EST-SSR markers across nine populations from the Yunnan–Kweichow Plateau and Eastern China, to explore the adaptive variation and genetic structure of T. ciliata var. pubescens. Patterns of population structure were apparent using a Bayesian clustering program, STRUCTURE, which identified four distinct clusters. We identified four outlier loci that were potentially under selection using the Dirichlet-multinomial and hierarchic simulation models. Through the Mantel test, it was found that geographic and climatic factors have jointly affected the genetic structure of T. ciliata var. pubescens in the study area. Based on redundancy analysis (RDA), it was shown that the correlation between climatic variables associated with variation is stronger than that of geographic variables. It is worth mentioning that the eight alleles from outlier loci have potentially adaptive and are associated with either precipitation or temperature variables. All analyses revealed high genetic diversity and significant genetic differentiation in the populations of T. ciliata var. pubescens. This indicated that the climatic variables including precipitation and temperature are drivers of local adaptation in the populations of T. ciliata var. pubescens. Full article

Multisource meteorological precipitation products are an important way to make up for a lack of observation sites or a lack of precipitation data in areas with a complex topography. They have important value for local industrial, agricultural, and ecological water use calculations, as well as for water resource evaluation and management. The Yunnan-Kweichow Plateau is located in southwest China and has a relatively backward economy and few meteorological stations. At the same time, the terrain is dominated by mountain valleys, precipitation is greatly affected by the terrain, and meteorological data are lacking, making the calculation of local water resources difficult. In this study, the applicability of the 3-hourly merged high-quality/IR estimates (3B42) of the Tropical Rainfall Measuring Mission (TRMM), China Meteorological Forcing Dataset (CMFD), and China Meteorological Assimilation Driving Datasets (CMADS) in the Yunnan-Kweichow Plateau was analyzed using multiple evaluation indicators of different temporal scales and precipitation intensity levels as well as the spatial distribution of the indicators based on measured daily precipitation data from 59 national meteorological basic stations in the study area in 2008–2018. The results showed that (1) the three products had performed well and could be applied to the calculation of local water resources with CMFD performing the best; (2) the performance of precipitation products was slightly worse on the daily scale, and the overall performance of the yearly, quarterly, and monthly scales was better; (3) good results were achieved in most regions, but there were also some regions with prominent overestimation and underestimation; (4) the three precipitation products had the highest probabilities of detection and the lowest false alarm rates for no rain and light rain, and the probability of detection gradually decreased with an increase in the precipitation intensity; and (5) the mean absolute error of precipitation products in rainy months is large, so the accuracy of products in the calculation of heavy rain and flood will be limited. Full article

Currently, fires (e.g., biomass burning and/or straw burning) are still prevailing and serious globally. However, the issue of the characteristics, types, and drives of fire occurrence is always a challenge and varies distinctively worldwide. Using Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 (C6) active fire products during 2001–2020, here, we analyzed the occurrence frequencies and spatiotemporal characteristics of active fires at the provincial and regional to national scales and at the monthly and annual scales in China. The accumulated occurrence frequencies of MODIS C6 active fires in China were up to 184.91 × 10⁴ in the past two decades, and the average annual level was 9.25 × 10⁴, especially in 2014 (15.20 × 10⁴). The overall trend of active fires was rising and then falling, but with significant spatial and temporal differences in the last 20-years. Temporally, nearly 61% of active fires occurred in spring (36%) and autumn (25%), particularly in August (16%), April (14%), and October (13%). Spatially, about 90% of active fires occurred in the east of the Hu Huanyong Line, particularly in Northeast China (25%), South China (23%), and East China (20%). In China, the most active fires were concentrated in the Northeast Plain, the North China Plain, the southeast hills, and the Yunnan–Kweichow Plateau. In terms of temporal differences across regions, active fires in Northeast China, North China, and Northwest China were concentrated in spring and autumn, especially in March, April, and October; in East China, they were concentrated in summer, especially in June; and in South China and Southwest China, they were concentrated in winter and spring, especially from December to April of the following year. Our study provides a full analysis of spatio–temporal characteristics and changes of active fires in China, and it can also assist in supplying a beneficial reference for higher monitoring and controlling of fires such as straw burning. Full article

The quantitative retrieval of the chlorophyll-a concentration is an important remote sensing method that is used to monitor the nutritional status of water bodies. The high spatial resolution of the Sentinel-2 MSI and its subdivision in the red-edge band highlight the characteristics of water chlorophyll-a, which is an important detection tool for assessing water quality parameters in plateau lakes. In this study, the Nine Plateau Lakes in the Yunnan-Kweichow Plateau of China were selected as the study area. Using Sentinel-2 MSI transit images and in situ measured chlorophyll-a concentration as the data source, the chlorophyll-a concentrations of plateau lakes (CCAPLs) were investigated, and the surface temperatures of plateau lakes (STPLs) were retrieved to verify the hypothesis that the lake surface temperature could increase the chlorophyll-a concentration. By comparing feature importance using a random forest (RF), the Sentinel-2 MSI surface reflectance and in situ data were linearly fitted using four retrieval spectral indices with high feature importance, and the accuracy of the estimated concentration of chlorophyll-a was evaluated by monitoring station data in the same period. Then, Landsat-8 TIRS Band 10 data were used to retrieve the STPL with a single-channel temperature retrieval algorithm and to verify the correlation between the STPL and the CCAPL. The results showed that the retrievals of the CCAPL and the STPL were consistent with the actual situation. The root-mean-square error (RMSE) of the fifteenth normalized difference chlorophyll-a index (NDCI15) was 0.0249. When the CCAPL was greater than 0.05 mg/L and the STPL was within 28–34 °C, there was a positive linear correlation between the CCAPL and the STPL. These results will provide support for the remote sensing monitoring of eutrophication in plateau lakes and will contribute to the scientific and effective management of plateau lakes. Full article

Based on the Langley method and the EuroSkyRad (ESR) pack retrieval scheme, we carried out the retrieval of the aerosol properties for the CE–318 sunphotometer observation data from March 2012 to February 2014 in Kunming, China, and we explored the possible mechanisms of the seasonal variations. The seasonal variation of the aerosol optical depth (AOD) was unimodal and reached a maximum in summer. The retrieval analysis of the Angstrom exponent (α) showed the aerosol types were continental, biomass burning (BB), and urban/industrial (UI); the content of the desert dust (DD) was low, and it may have contained a sea–salt (SS) aerosol due to the influence of the summer monsoon. All the aerosol particle spectra in different seasons showed a bimodal structure. The maximum and submaximal values were located near 0.2 μm and 4 μm, respectively, and the concentration of the aerosol volume was the highest in summer. In summer, aerosol particles have a strong scattering power but a weak absorption power; this pattern is the opposite in winter. The synergistic effect of the East Asian monsoon and the South Asian monsoon seasonal oscillations can have an important impact on the variation of the aerosol properties. The oscillation variation characteristic of the total vertical columnar water vapor (CWV) and the monsoon index was completely consistent. The aerosol types and sources in the Yunnan–Kweichow Plateau and the optical radiation properties were closely related to the monsoon circulation activities during different seasons and were different from other regions in China. Full article