Wetlands account for up to 70% of the natural source of methane (CH ₄ ) in terrestrial ecosystems on a global scale. Soil microbes are the ultimate producers and biological consumers of CH ₄ in wetlands. Therefore, simulating microbial mechanisms of CH ₄ production and consumptionwould improve the predictability of CH ₄ flux in wetland ecosystems. In this study, we applied a microbial-explicit model, the CLM-Microbe, to simulate CH ₄ flux in three major natural wetlands in northeastern China. The CLM-Microbe model was able to capture the seasonal variation of gross primary productivity (GPP), dissolved organic carbon (DOC), and CH ₄ flux. The CLM-Microbe model explained more than 40% of the variation in GPP and CH ₄ flux across sites. Marsh wetlands had higher CH ₄ flux than mountain peatlands. Ebullition dominated the CH ₄ transport pathway in all three wetlands. The methanogenesis dominates while methanotroph makes a minor contribution to the CH ₄ flux, making all wetlands a CH ₄ source. Sensitivity analysis indicated that microbial growth and death rates are the key factors governing CH ₄ emission and vegetation physiological properties ( flnr ) and maintenance respiration predominate GPP variation. Explicitly simulating microbial processes allows genomic information to be incorporated, laying a foundation for better predicting CH ₄ dynamics under the changing environment.

Permafrost peatland is a unique ecosystem that represents a huge carbon terrestrial pool. Soil quality has a relatively high level of variation at small scale in this ecosystem and is closely related to the carbon cycle. To quantify this variability, we analyzed total organic carbon, total nitrogen, total phosphorus, nutrient, and element (sodium, magnesium, potassium, and calcium), and microbial respiration activities (microbial biomass carbon, soil basal respiration, metabolic, and microbial quotients) in the humus layer to deeper soil layer of 6 plots at small scale (meters). For all samples, the coefficients of variation (CV) values of total carbon concentrations were lowest and these values of sodium, magnesium, potassium, and calcium concentrations were higher than those of total carbon, nitrogen, and phosphorus concentrations. The largest variations of total phosphorus, ash, and Na were in the 10–20 cm layer with soil depths. The litter decomposition and water table may cause this variation at small-scale. The CV values of microbial respiration activities were largest compared with soil properties. There were different correlations between basal respiration and soil properties among the plots. Our results showed that soil properties and microbial respiration activities in permafrost peatland exhibits considerable variability at small scale. This variability indicates that sampling location and number are very important in peatland studies if we want to accurately estimate the biogeochemistry in a peatland.

Climate change is accelerating its impact on northern ecosystems. Northern peatlands store a considerable amount of C, but their response to climate change remains highly uncertain. In order to explore the feedback of a peatland in the Great Hing’an Mountains to future climate change, we simulated the response of the overall net ecosystem exchange (NEE), ecosystem respiration (ER), and gross primary production (GPP) during 2020–2100 under three representative concentration pathways (RCP2.6, RCP6.0, and RCP8.5). Under the RCP2.6 and RCP6.0 scenarios, the carbon sink will increase slightly until 2100. Under the RCP8.5 scenario, the carbon sink will follow a trend of gradual decrease after 2053. These results show that when meteorological factors, especially temperature, reach a certain degree, the carbon source/sink of the peatland ecosystem will be converted. In general, although the peatland will remain a carbon sink until the end of the 21st century, carbon sinks will decrease under the influence of climate change. Our results indicate that in the case of future climate warming, with the growing seasons experiencing overall dryer and warmer environments and changes in vegetation communities, peatland NEE, ER, and GPP will increase and lead to the increase in ecosystem carbon accumulation.

Zonation along a water level is the main spatial distribution characteristic of wetland plants. This is mainly because of the influences of hydrological conditions and interspecific competition, which finally narrow the fundamental niche of a species to its realized niche. In the present study, a controlled experiment was conducted in order to analyze the relationship between Carex lasiocarpa/Carex pseudocuraica and Glyceria spiculosa, in conditions of three competitive treatments at four water levels. The results showed that in no competition, C. lasiocarpa preferred low water levels, but this preference receded when competing with G. spiculosa. In contrast, C. pseudocuraica had greater preference for low water level when competing with G. spiculosa. The root/shoot ratios of the two Carex species decreased with increasing water levels, but they were almost unaffected by different competition treatments. With the increase in water level during full competition with G. spiculosa, the competitive ability of C. lasiocarpa showed an increasing trend, whereas a contrary trend was observed in C. pseudocuraica. Our results suggested the effects of water levels and their interactions with interspecific competition varied between the two Carex species and played an important role in determining spatial distribution patterns and potential community succession of wetland plants.