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Vegetation Carbon Accumulation Driven by Stand Characteristics and Climatic Factors in Subtropical Forests of Southeastern China

ABSTRACT Subtropical forests act as a carbon sink and play an important role in mitigating global warming. However, the understanding of the effects of stand characteristics and climatic factors on forest carbon sequestration capacity remains limited. Based on multiple regression analyses using structural equation modeling and plot-level data of coniferous and broadleaf forests from the national forest resource inventories, our study quantified vegetation carbon accumulation rate (VCAR) and the underlying influence pattern in Zhejiang Province, Southeastern China. The mean VCAR of coniferous and broadleaf forests was 2.30 Mg C ha−1 yr−1 and 4.53 Mg C ha−1 yr−1 during 2004–2009, and 1.56 Mg C ha−1 yr−1 and 1.98 Mg C ha−1 yr−1 during 2009–2014, respectively. Stand characteristics (i.e., change in tree density and mean diameter at breast height) and climatic factors (i.e., mean annual precipitation (MAP), temperature, sunshine hours, and monthly precipitation fluctuation) were the major driving factors on the change patterns of VCAR. All factors, except precipitation fluctuation, had positive effects on VCAR. The positive effects of MAP decreased with the increase in MAP, but the negative effects of precipitation fluctuation increased with the increase in precipitation fluctuation. Precipitation increased with increasing elevation, while the VCAR was lower at lower elevations. Additionally, we found that broadleaf forests could be able to cope better with the negative effects of precipitation fluctuation. Overall, this study provides new insights into the sensitivity and potential of vegetation carbon accumulation for structural development and climate change response in Zhejiang Province to better promote sustainable forestry development.