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Alpine meadow plays vital roles in regional animal husbandry and the ecological environment. However, different grassland managements affect the structure and function of the alpine meadow. In this study, we selected three typical grassland managements including free grazing, enclosure, and artificial grass planting and conducted a field survey to study the effects of grassland managements on carbon fluxes in an alpine meadow. The carbon fluxes were observed by static chamber and environmental factors including vegetation and soil characteristics were measured simultaneously. Our results show that the alpine meadow was a CO 2 and CH 4 sink, and grassland managements had a significant effect on all CO 2 fluxes, including gross ecosystem production (GEP, P < 0.001), net ecosystem production (NEP, P < 0.001) and ecosystem respiration (ER, P < 0.001) but had no significant effect on CH 4 fluxes ( P > 0.05). The ranking of GEP under the different grassland managements was enclosure > free grazing > artificial grass planting. Furthermore, NEP and ER at enclosure plots were significantly higher than those of the free grazing and artificial grass planting plots. In addition, different grassland managements also affected the vegetation and soil characteristics of the alpine meadow. The aboveground biomass of artificial grass planting was significantly higher than that of the free grazing and enclosure plots. The vegetation coverage under three different grassland managements was ranked in the order of enclosure > artificial grass planting > free grazing and significant differences were observed among them. Moreover, significant differences in the number of species ( P < 0.01) and the Margalef richness index ( P < 0.05) were detected under three different grassland managements. Further analysis of the relationship between environmental factors and carbon fluxes revealed that GEP and NEP of the alpine meadow were positively correlated with vegetation coverage, the number of species, and the Margalef richness index. Therefore, grassland restoration should be configured with multiple species, which could improve carbon sink capacity while considering the functions of grassland restoration and production.

Soil microbial communities are crucial in ecosystem-level decomposition and nutrient cycling processes and are sensitive to climate change in peatlands. However, the response of the vertical distribution of microbial communities to warming remains unclear in the alpine peatland. In this study, we examined the effects of warming on the vertical pattern and assembly of soil bacterial and fungal communities across three soil layers (0–10, 10–20, and 20–30 cm) in the Zoige alpine peatland under a warming treatment. Our results showed that short-term warming had no significant effects on the alpha diversity of either the bacterial or the fungal community. Although the bacterial community in the lower layers became more similar as soil temperature increased, the difference in the vertical structure of the bacterial community among different treatments was not significant. In contrast, the vertical structure of the fungal community was significantly affected by warming. The main ecological process driving the vertical assembly of the bacterial community was the niche-based process in all treatments, while soil carbon and nutrients were the main driving factors. The vertical structure of the fungal community was driven by a dispersal-based process in control plots, while the niche and dispersal processes jointly regulated the fungal communities in the warming plots. Plant biomass was significantly related to the vertical structure of the fungal community under the warming treatments. The variation in pH was significantly correlated with the assembly of the bacterial community, while soil water content, microbial biomass carbon/microbial biomass phosphorous (MBC/MBP), and microbial biomass nitrogen/ microbial biomass phosphorous (MBN/MBP) were significantly correlated with the assembly of the fungal community. These results indicate that the vertical structure and assembly of the soil bacterial and fungal communities responded differently to warming and could provide a potential mechanism of microbial community assembly in the alpine peatland in response to warming.

Peatlands act as an important sink of carbon dioxide (CO2). Yet, they are highly sensitive to climate change, especially to extreme drought. The changes in the net ecosystem CO2 exchange (NEE) under extreme drought events, and the driving function of microbial enzymatic genes involved in soil organic matter (SOM) decomposition, are still unclear. Herein we investigated the effects of extreme drought events in different periods of plant growth season at Zoige peatland on NEE and microbial enzymatic genes of SOM decomposition after 5 years. The results showed that the NEE of peatland decreased significantly by 48% and 26% on average (n = 12, P < 0.05) under the early and midterm extreme drought, respectively. The microbial enzymatic genes abundance of SOM decomposition showed the same decreasing trend under early and midterm extreme drought, but an increasing trend under late extreme drought. The microbial community that contributes to these degradation genes mainly derives from Proteobacteria and Actinobacteria. NEE was mainly affected by soil hydrothermal factors and gross primary productivity but weakly correlated with SOM enzymatic decomposition genes. Soil microbial respiration showed a positive correlation with microbial enzymatic genes involved in the decomposition of labile carbon (n = 18, P < 0.05). This study provided new insights into the responses of the microbial decomposition potential of SOM and ecosystem CO2 sink function to extreme drought events in the alpine peatland.

Water use efficiency (WUE) plays a pivotal role in connecting the carbon and water cycles and represents the amount of water used by plants or ecosystems to achieve carbon sequestration. The response of WUE to climate warming and its underlying mechanisms remain unclear. Here, we examined the effects of varying levels of warming on carbon fluxes, water fluxes, and WUE in an alpine peatland, with Blysmus sinocompressus and Carex secbrirostris as dominant species. Open-top chambers were utilized to simulate two levels of warming: low-level warming (TL) and high-level warming (TH). The carbon dioxide and water fluxes were monitored over a growing season (June to September). Gradient warming significantly decreased both gross primary productivity (GPP) and net ecosystem carbon exchange (NEE); GPP was 10.05% and 13.31% lower and NEE was 21.00% and 30.00% lower in the TL and TH treatments, respectively, than in the control. Warming had no significant effect on soil evaporation, and plant transpiration and evapotranspiration were 36.98% and 23.71% higher in the TL treatment than in the control, respectively; this led to decreases of 31.38% and 28.17% in canopy water use efficiency (WUEc) and ecosystem water use efficiency (WUEe), respectively. Plant transpiration was the main factor affecting both WUEe and WUEc in response to warming. The findings underscore the essential function of water fluxes in regulating WUE and enhance our understanding of carbon–water coupling mechanisms under climate change.

Background Nitrogen plays a critical role in sustaining ecosystem functions in peatlands; however, the degradation of approximately 12% of global peatlands substantially alters nitrogen cycling. Although the abundance of stable nitrogen isotopes (δ 15 N) has been widely used to trace nitrogen processes, their patterns and implications across degradation gradients are not well understood. This study examined changes in δ 15 N and their relationships with nitrogen content and environmental factors along a degradation gradient in alpine peatlands, including flooded wetlands, wet meadows, moderately degraded meadows, and severely degraded meadows. Results Soil δ 15 N increased from flooded wetlands to wet meadows and moderately degraded meadows, likely due to increased nitrogen release as the peatlands dried. However, soil δ 15 N declined from moderately to severely degraded meadows, possibly reflecting reduced microbial activity and limited nitrogen transformation under extreme degradation. Across all sites, roots were depleted in 15 N relative to soil, with increasingly negative Δδ 15 N root–soil values in more degraded sites, likely driven by shifts in plant community composition and changes in nitrogen uptake strategies. Random forest analysis revealed that the soil water content, phosphorus, and nitrogen availability were the primary factors influencing the soil and plant δ 15 N values, as did 15 N fractionation during plant nitrogen uptake along the degradation gradient. Conclusions Peatland degradation leads to greater soil δ 15 N and increased 15 N depletion from soil to plants, indicating a shift toward more open ecosystem nitrogen dynamics and altered plant nitrogen uptake strategies associated with greater nitrogen losses. These findings provide new insights into the impact of peatland degradation on nitrogen dynamics and demonstrate the effectiveness of δ 15 N as a tool for monitoring changes in nitrogen cycling and availability across degradation levels. Graphical Abstract

An in-depth understanding of the associations between variations in the wetland area and socio-economic driving forces is essential owing to rapid urbanization. However, to date, no study has performed a quantitative study on the relationships between spatio-temporal patterns for wetland area variations and socio-economic driving factors in Yunnan Province. Based on Statistical Yearbook data, we found that during 10 years, different types of wetlands exhibited different change rates, with obvious spatial heterogeneity. The overall increase in wetland area in Yunnan Province was 13.35%, of which the increases in river, lake, and swamp wetland areas were 46.39%, −3.12%, and 295.56%, respectively. At the city level, the maximum decrease and increase in total wetland area were noted in Xishuangbanna (−84.30%) and Diqing (+185.22%), respectively. A total of 9 of 24 factors which were further selected according to collinearity diagnostics might help interpret changes in the wetland area of Yunnan Province according to the regression analysis results (R2 = 0.749, p < 0.01). Moreover, in different city development periods, the key socio-economic factors were different, which should be considered separately when formulating policies. Our results may clarify the socio-economic influencing factors for wetland spatio-temporal changes and help to guide policymakers.

PurposeAlpine peatlands are vital carbon pools and highly sensitive region. Water table level (WTL) changes caused by climate change and human activities may influence carbon fluxes. However, the impacts of WTL changes and the duration (DR) on carbon fluxes are still unclear.MethodsIn this study, we conducted a six water table level mesocosm controlled experiment and observed carbon fluxes, including net ecosystem productivity (NEP), ecosystem respiration (ER), gross ecosystem productivity (GEP), and CH4 fluxes for two consecutive years. Mixed effect model was performed to analyze the impacts of WTL changes and DR on carbon fluxes in alpine peatlands. Correlation analysis was used to analyze the relationship between carbon fluxes and environmental factors.ResultsBoth WTL and DR significantly affected CO2 fluxes. WTL had significant negative effects on ER (P < 0.01), NEP (P < 0.001), and GEP (P < 0.01). On the other hand, DR had significant positive effects on ER (P < 0.001), NEP (P < 0.05), and GEP (P < 0.001). In addition, WTL had a greater effect on CO2 fluxes than DR. CH4 fluxes significantly increased with increasing WTL (P < 0.001). Furthermore, the relationship between environmental factors and carbon fluxes varied with WTL.ConclusionWTL and DR jointly influenced carbon fluxes of alpine peatlands in Zoige Plateau. Therefore, both factors should be taken into account when carrying out peatlands protection and restoration efforts.