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Studying the peatlands accumulation and carbon (C) storage in monsoonal areas could provide useful insights into the response of C dynamics to climate variation in the geological past. Here, we integrated 40 well-dated peat/lake sediment cores to reveal the peatlands evolution history in the Sanjiang Plain and examine its links to East Asian monsoon variations during the Holocene. The results show that 80% peatlands in the Sanjiang Plain initiated after 4.7 ka (1 ka = 1000 cal yr BP), with the largest initiating frequency around 4.5 ka. The mean C accumulation rate of peatlands in the Sanjiang Plain exhibits a synchronous increase with the peatlands expansion during the Holocene. Such a peatlands expanding and C accumulating pattern corresponds well to the remarkable drying event subsequent to the Holocene monsoon maximum. We suggest that in addition to the locally topographic conditions, Holocene variations of East Asian summer monsoon (especially its associated precipitation) have played a critical role in driving the peatlands initiation and expansion in the Sanjiang Plain.

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Soil degradation, a growing problem in the arid and semi-arid area, significantly influences wetland dynamics and nutrient cycling. Using tussock wetlands as objectives, this study aims to explain the effects of long-term soil degradation on plant diversity and dominant species and identify the impacts of long-term soil degradation, growing month, species, and their interactions on plant nutrient stoichiometry in Momoge wetland. Field experiments were undertaken to explore the responses of plant diversity and nutrient to soil degradation in Momoge wetland. The relationships between plant nutrient and soil physicochemical properties were examined by canonical correspondence analysis (CCA). Soil nutrient significantly decreased in degraded tussock wetlands. Long-term soil degradation altered plant diversity and the important values of dominant species. Plant nutrient indicated that the effects of soil degradation on plant carbon, nitrogen, and phosphorus were not significant at the single species level. Furthermore, plant stoichiometric patterns were not sensitive to soil degradation. However, both the N/P ratio in soil and plants showed a nitrogen limitation for the plant growth in wetlands. The CCA indicated that the soil total nitrogen and electrical conductivity were the primary factors affecting the cycle of biogenic elements in tussock wetlands. Results highlight the differences in biogenic elements in wetland soil and vegetation and identify the significant effects of soil degradation on the wetland plants. These findings suggest that the variation of nutrient availability and electronic conductivity affects the growth of the wetland species.