## 1 Introduction
Specifically, the relative abundance of woody plants (i.e., trees and deciduous shrubs) has increased, and the cover of _Sphagnum_ mosses and herbaceous plants has decreased and even disappeared [31; 32]. The potential for ecosystems to store C on an annual basis depends on the equilibrium between gross primary production (GPP) and the C released from ecosystem respiration (ER), including plant and microbial respiration. Warmer temperatures can increase ER [33; 34; 35], which is driven by increases in both plant and microbial respiration [33; 36; 37]. Warming promotes woody-shrub expansion, which will increase plant productivity and litter input to soil [38; 39; 40]. The enhancement of plant productivity increases C storage by plants, and thus could compensate for some of the C loss from increased ER due to warmer temperatures [41; 42]. However, long-term field observations of experimental permafrost warming have shown that ecosystem C losses exceed C gain after less than a decade [43; 44]. Global climate is now warming rapidly because of vegetation changes in response to climatic change, and some terrestrial surfaces are expected to experience less water availability during the growing season in the future [45]. With the drying of the climate, the least drought-tolerant species are expected to disappear first. In the coming decades, long-term and continuous changes may have a significant impact on the distribution and function of vegetation [46]. The key issue is that seasonal changes in precipitation are more important to plant growth than annual changes. To control the rise in global mean temperatures, the reduction of CO\({}_{2}\) emissions and storage of CO\({}_{2}\) in land C sinks are indispensable. While the Great Hing'an Mountains ecosystem currently acts as a weak net carbon sink [47; 48], with an average carbon accumulation rate of 42.65 g C m\({}^{-2}\)yr\({}^{-1}\) over the past 2 ka [48], climate change could increase the ER of peatland and weaken or reverse the sink function of this region in the future [48; 49]. The consequences of climate change and vegetation change on the net ecosystem carbon balance remain uncertain [50; 51; 52]. As a result, the role of the permafrost region of the Great Hing'an Mountains as a carbon sink or source in the future is being actively debated [53; 54; 55; 56; 57]. To understand the regional consequences of climate and vegetation change and estimate the climate feedback of permafrost, future carbon emissions from peatlands can be quantified and predicted using CoupModel (a coupled heat and mass transfer model for soil-plant-atmosphere systems) [58]. CoupModel is a process-based biogeochemical model that focuses on heat and water transfer, and trace emissions from peatland ecosystems. This model combines biogeochemical processes with hydrological dynamics and has been constantly upgraded and improved. A large number of studies have shown that CoupModel is useful for simulating various types of emissions, such as heat transfer, water transfer, and GHGs [59; 60; 61]. With the continuous progress of global warming, a typical peat swamp located in the permafrost of the Great Hing'an Mountains in Northern China is being severely affected. In this study, carbon exchange in the peatland in the next 80 years was simulated and predicted. To this end, future scenario data of Coupled Model Intercomparison Project 5 (CMIP5) were analyzed using CoupModel and various preset vegetation succession schemes. The change trend and significant difference under different vegetation succession schemes were analyzed reasonably, and the influencing factors of carbon exchange in the future were clarified. This study could provide a reference in evaluating the changing trend and magnitude of the carbon exchange for the peatlands in the Great Hing'an Mountains.