Carbon storage by ecological service forests in Zhejiang Province, subtropical China

Ecological service forest (ESF) is established to maintain ecological processes and protect the environment. The main objective of this study was to evaluate the contribution of these forests to regional carbon storage and explore their carbon sequestration potential after ecosystem restoration. We sampled 149 stands from 6 to 41 years old, covering 101,800 km2, in Zhejiang Province, in China's eastern subtropical zone. The samples included four types of ESF: evergreen broad-leaved forest, coniferous and broad-leaved mixed forest, pine (Pinus massoniana) forest, and Chinese fir (Cunninghamia lanceolata) forest. The mean values of biomass in evergreen broad-leaved forest, coniferous and broad-leaved mixed forest, pine forest, and Chinese fir forest were 89.19, 70.06, 51.25, and 54.15 t ha−1, respectively. The NPP for the four types of ESF ranged from 4.41 to 8.35 t ha−1 year−1. Carbon densities for the four types of ESF were lower than the mean values (36–57.07 t C ha−1) for China because the ESFs are relatively young in Zhejiang Province. Overall, biomass, litter production, NPP, and carbon density were all significantly lower in pine forest and Chinese fir forest than in evergreen broad-leaved forest, whereas the values for the coniferous and broad-leaved mixed forest were intermediate. These results suggest that the evergreen broad-leaved forest has great potential for offsetting CO2 emissions, and that promoting succession from coniferous forests to evergreen broad-leaved forest can enhance carbon sinks in the forests of subtropical China. The next 50 years (as these forests mature) will represent an important period to enhance the carbon sink in Zhejiang Province.