The interactions between CO₂ flux, an important component of ecosystem carbon flux, and climate change vary significantly among different ecosystems. In this research, the inter-annual variation characteristics of ecosystem respiration (RE), gross ecosystem exchange (GEE), and net ecosystem exchange (NEE) were explored in the temperate grassland (TG) of Xilinhot (2004–2010), the subtropical artificial coniferous forest (SACF) of Qianyanzhou (2003–2010), and the tropical rain forest (TRF) of Xishuangbanna (2003–2010). The main factors of climate change affecting ecosystem CO₂ flux were identified by redundancy analysis, and exponential models and temperature indicators were constructed to consider the relationship between climate change and CO₂ flux. Every year from 2003 to 2010, RE and GEE first increased and then decreased, and NEE showed no significant change pattern. TG was a carbon source, whereas SACF and TRF were carbon sinks. The influence of air temperature on RE and GEE was greater than that of soil temperature, but the influence of soil moisture on RE and GEE was greater than that of air moisture. Compared with moisture and photosynthetically active radiation, temperature had the greatest impact on CO₂ flux and the exponential model had the best fitting effect. In TG and SACF, the average temperature was the most influential factor, and in TRF, the accumulated temperature was the most influential factor. These results provide theoretical support for mitigating and managing climate change and provide references for achieving carbon neutrality.

The freezing and thawing process is a unique feature of the alpine permafrost ecosystem, which controls the growth of microorganisms and alpine meadows, and plays a vital role in animal husbandry development, ecosystem functions and services. Meanwhile, the freezing and thawing process is also affected by external environmental factors, and its spatial differences are very significant, especially in the regions over 5000 m a.s.l. In this study, the freezing and thawing process periods of the Cuoma Township (CM), Xiangmao Township (XM) and Xiaotanggula Mountain (XTGL) sites in the Nagqu River Basin are divided, the effects of altitude, vegetation coverage, air temperature, and organic matter content on the freezing and thawing process are analyzed, the main influencing factors are discussed. The results show that in the regions over 5000 m a.s.l, the thaw initiation period (TIP) starts in early April, the entirely thawed period (ETP) starts in end of May, the freeze initiation period (FIP) starts in end of October, and the entirely frozen period (EFP) starts in early November. Compared with the regions below 5000 m a.s.l, FIP and EFP in the regions over 5000 m a.s.l start earlier, the TIP starts later and the freezing rate is faster. Organic matter content is the main influencing factor during FIP and EFP, and air temperature is the main influencing factor during TIP and ETP. This study is helpful to clarify the changes of freezing and thawing process in the regions over 5000 m a.s.l, and also provides theoretical support for ecological protection and restoration.

The Naqu River Basin (NRB) is a crucial water conservation and ecological barrier area in the Nujiang River. Climate change has significantly altered its hydrological cycle, affecting water source composition. To investigate recharge dynamics in alpine regions, precipitation, surface water, and groundwater samples were collected from the NRB in Tibet, China, and analyzed for hydrogen and oxygen isotopes. Precipitation isotopes showed strong seasonal fluctuations, with the lowest values in winter and the highest in summer. The local meteoric water line (LMWL) had a lower slope and intercept than the global counterpart, indicating notable sub-cloud evaporation. Along the Naqu River, isotopic values varied spatially, becoming more enriched downstream. Lacustrine water had a higher isotopic composition than river water, reflecting intense evaporation in Cuona Lake. The river's main recharge sources include precipitation, glacial meltwater, groundwater, and lake water, with variations between freeze-thaw periods and along different sections. Meltwater and groundwater dominated recharge in upstream tributaries, particularly during the freeze ignition period, while lake water became a key source downstream.

River–riparian interface (RRI) plays a crucial role in nitrogen removal and N₂O emissions, but different revetment constructions can significantly alter the associated outcomes. Identifying which type of revetment can reduce N₂O emissions while still removing nitrogen is a key issue in urban development. This study constructed three types of revetments along the same river section, and measured soil, vegetation, microbial, denitrification, and N₂O emission characteristics to explore the synergistic effects of revetment types on nitrogen removal and N₂O emissions. The study showed that revetments affected nitrogen removal and N₂O emissions in RRI by influencing denitrification. nirK mainly affected nitrogen removal, while nosZII mainly influenced N₂O emissions. Environmental factors in the permeable revetment led to significantly higher gene abundances of nirK and nosZII compared to those in the natural and impermeable revetments. As a result, the denitrification potential of the permeable revetment (34.32 ± 1.17 mg/(kg·d)) was 22.43% and 8.84% higher than those of the natural and impermeable revetments, respectively. The N₂O emission rate (0.35 ± 0.01 mg/(m²·h)) was 29.22% and 22.19% lower than those of the natural and impermeable revetments, respectively. Permeable revetment could have been the best for the nitrogen removal and N₂O emission reduction. These results provide a theoretical basis and guidance for urban ecological construction.