The Simulation Study On Effects Of Climate Warming On Plant Litter Decomposition In Peatlands Basing On Three Experimental Modes

The cover of peatlands is 3%on the land's surface,but store approximately one-third of all soil carbon.It is clear that peatlands play a major role in the global carbon cycle.Carbon in peat lands mainly exists in unstable forms such as plant litters and peat,and is sensitive to environmental changes.Although the impact of climate warming on the decomposition of litters in peatlands has received widespread attention,there has been relatively little research on that through changes in the species composition of plant communities and the chemical traits of the original species.The paper tried to answer the question"whether climate warming will accelerate the decomposition of peat plant litters"through the following three aspects:?1?the effects of climate warming on the decomposition of plant litters in peatlands,regardless of the changes in the species composition of plant communities and the chemical traits of the original species,?2?the effects of climate warming on the decomposition of plant litters in peatlands,considering the changes in the chemical traits of the original species,?3?the effects of climate warming on the decomposition of plant litters in peatlands,considering the changes in the species composition of plant communities.Litter bag technique was used in this experiment and the climate warming was simulated by decreasing altitude and latitude and open top chambers.The experimental site spaned cold temperate zone,middle temperature zone and subtropical temperature zones along the latitudinal direction,and spaned Betula ermanii forest climate zone?cold zone?,coniferous forests climate zone?cold temperate zone?and mixed broadleaf-conifer forest?middle temperate zone?.The dominant Sphagnum hummock were used as the decomposition environment,and decomposition materials involved bryophytes,herbs,and shrubs.The main conclusions are as follows:?1?Climate warming has different effects on Sphagnum and vascular plants?herbs and woody plants?.In peatlands climate warming does not promote decomposition rate of Sphagnum litters.Under certain temperature conditions,climate warming promotes the decomposition rate of vascular plant litters.?2?Climate warming can change the decomposability of plant litters by changing the initial chemical traits of plant litters.The initial chemical traits of different plant litters showed different trends following climate warming,thus the impact of climate warming on the decomposability of different plant litters showed different trends.Climate warming reduced the decomposability of Betula genera plant litters and increased Carex genera plant litters,respectively,and has no effect on litters of Sphagnum genera plant.?3?The decomposition rate of litters between different growth types in peatlands showed obvious grade.The decomposition rate of different plant litters was ranked as follows:herbs?Carex?>shrubs?Betula?>bryophytes?Sphagnum?.Because the litters decomposition rate of vascular plants was greater than that of Sphagnum,if climate warming changes the species composition in peatlands,leading to the replacement of vital carbon-forming plants Sphagnum by vascular plants such as shrubs and herbaceous plants,it will accelerate the decomposition of litters and the carbon loss in peatlands.?4?The constant?S?in Long-term Intersite Decomposition Experiment Team(LIDET,M_t=M₀e^-kt+S)was long-term average annual accumulation rate in the process of generation and decomposition of litters.The short-term and long-term effects of litters decomposition were differents.Peatlands may continue to accumulate carbon if they are exposed to moderate climate warming without regard for other environmental changes.In conclusion,the chemical traits of plant litters dominated its decomposition,while the impact of temperature was in a secondary position.Species can regulate the effects of climate warming on litters decomposition.Considering the species composition of plant communities and the chemical traits of the original species was vital to predict the effect of climate warming on litters decomposition in peatlands.Such as,considering that climate warming will cause increased dominance of vascular plants coupled with decreased cover by Sphagnum,climate warming and the associated changes to vegetation community composition can synergistically accelerate plant litters decomposition in peatlands.