Chunbo Su

Under the dual pressures of climate change and anthropogenic activities, the sustainability of the fragile ecosystem on the Qingzang Plateau has garnered considerable attention. This study, taking the Yarlung Tsangpo River, Lhasa River, and Nianchu River Basin (YNL) of Xizang as a case study, systematically assesses the spatiotemporal evolution of its ecosystem services from 2000 to 2020. It reveals a critical dynamic: while regional ecosystem services have shown an overall improving trend over the past two decades, driven jointly by a warmer and wetter climate and ecological engineering projects, the adverse impacts of human activities have intensified significantly, posing an emerging and growing threat to regional ecological security. Based on the InVEST model, this research quantifies four key services and constructs a Comprehensive Ecosystem Service (CES) index to evaluate the overall ecosystem function. Subsequently, an integrated Principal Component Analysis and Partial Least Squares Structural Equation Modeling (PCA-PLS-SEM) analytical framework is employed to decouple the complex pathways driving CES successfully. The results confirm that climate and topography are the fundamental natural drivers determining the spatial pattern of ecosystem services, which is characterized as being high in the east and low in the west. The core contribution of this study lies in its quantitative identification of the coexisting reality of “ecological improvement” and “development pressure” in the region. It emphasizes that future management strategies must urgently shift from a static conservation approach to an integrated paradigm capable of proactively addressing human–land contradictions. This provides a critical scientific basis for safeguarding China’s national ecological security barrier.

Terrestrial ecosystem vegetation are vulnerable to the joint impacts of human activities and climate change, particularly in ecologically fragile areas such as the Tibetan Plateau. Identifying vegetation cover changes and distinguishing their driving factors are crucial for ecological conservation in this region. This study utilized MODIS normalized difference vegetation index (NDVI) data from 2000 to 2019, combined with trend analysis (univariate linear regression and the Mann–Kendall test), partial correlation analysis, and residual analysis methods, to investigate the spatial and temporal dynamics of vegetation cover and its responses to climate change and human activities in the Yarlung Tsangpo River, Lhasa River, and Nianchu River Basin (YLN Basin) on the Tibetan Plateau. The results revealed significant differences in vegetation dynamics both in summer and the growing season: the average summer NDVI showed a significant decreasing trend during the study period, whereas the growing season NDVI exhibited no significant overall temporal trend, which highlighted the necessity of assessing vegetation dynamics seasonally to accurately capture their interannual complexity. Partial correlation analysis indicated that precipitation was the key limiting climatic factor for vegetation growth in this region, with its positive influence covering over 90% of the land area during summer and over 60% during the growing season. The residual analysis further indicated the dual and spatially heterogeneous roles of human activities: on the one hand, positive impacts, primarily from vegetation restoration projects, promoted NDVI increases in some areas; on the other hand, negative impacts, such as continuous grazing pressure, population growth, and associated land use changes, inhibited vegetation development in other areas. This study quantitatively assessed the combined effects of climate variability and complex human activities on the vegetation NDVI in the YLN Basin, emphasizing that the development of adaptive management and effective vegetation restoration strategies must fully consider seasonal differences, the key climatic limiting factor (water availability), and the spatial heterogeneity of human impacts to promote sustainable development in this ecologically fragile region.

Because the cytotoxic DNA methylated bases are chemically inert and small in size, limited biosensing strategies especially with high sensitivity were established to detect DNA methylation damage. In this work, a label-free electrochemical assay was proposed for the sensitive detection of DNA methylation damage in dsDNA film on indium tin oxide electrode. The human alkyladenine DNA glycosylase was employed to recognize and selectively remove DNA methylated bases, generating apurinic site. Subsequently, exonuclease III not only further converted the methylation sites into strand breaks, but also progressively removed nucleotides from the 3′ to 5′ end starting from the apurinic sites. These processes could maximum amplify DNA methylation damage, also confirmed by gel electrophoresis and fluorescence measurements. The damaged DNA film bound much less electrochemical indicator, Ru(bpy)₂(dppz)²⁺, and accompanied by an anodic current drop. As a result, DNA methylation damage produced with as low as 10 μM of methyl methanesulfonate can be detected, which was 100-fold lower than the previously reported photoelectrochemical sensing strategy. Other DNA base modification products showed much less decrease of oxidation current, demonstrating its good selectivity. This strategy can be utilized to sensitively and rapidly assess the genotoxicity of environmental pollutants.