Spatio-temporal trends in Holocene peat/carbon accumulation rates in China: climatic and human drivers

Abstract Peatlands play a crucial role in the global carbon cycle and in climate change feedbacks. Hence, understanding the dynamics of peat/carbon accumulation in response to climate change and human activities is essential for assessing the future fate of carbon reservoirs. We compiled records of Holocene peat accumulation rate (PAR) and carbon accumulation rate (CAR) from sites at different altitudes in China. At high altitudes (> 2400 m a.s.l.), we observed a long-term decreasing trend in PARs and CARs, indicating the adverse impact of climatic warming and drying on peat/carbon accumulation. In contrast, peatlands at mid-altitudes (~ 1000–2400 m a.s.l.) and low altitudes (< 1000 m a.s.l.) showed increased PARs after 6 kyr BP and 7.5 kyr BP, respectively, primarily due to human activities. However, CARs in the mid-altitude peatlands showed a decreasing trend after 6 kyr BP, while CARs in the low-altitude peatlands continued to increase after 7.5 kyr BP, influenced by variations in the total organic carbon content of input materials sourced from soil erosion. On the scale of the whole of China, the PARs and CARs show similar trends throughout the Holocene. During the early Holocene, there was a gradual decrease in PARs and CARs, possibly in response to climate change. During the middle Holocene, the PARs and CARs were relatively stable, suggesting a balance between natural climate changes and relatively moderate-level human activities. However, after 4 kyr BP, human activities intensified on a large spatial scale and became the dominant driver of PARs and CARs in China, which showed a consistent increasing trend, indicating that human activities had a positive impact on peat/carbon accumulation. Our findings highlight the vulnerability of high-altitude peatlands to climatic warming and the positive impact of human activities on carbon sequestration in peatlands. They contribute to our understanding of carbon cycle dynamics and have important implications for future projections of peatland carbon reservoirs and sustainable land management strategies in China and elsewhere.