Biogenic volatile organic compound emissions in relation to plant carbon fixation in a subtropical urban

Biogenic volatile organic compound emissions in relation to plant carbon fixation in a subtropical urban–rural complex

Guo, Peipei / Guo, Kejian / Ren, Yuan / Shi, Yan / Chang, Jie / Tani, Akira / Ge, Ying

Graphical abstract

Highlights • Bamboo forest is the major contributor to the BVOC emissions also an important loss of carbon in low-latitude subtropical Ningbo. • Contribution of carbon emitted as BVOC to NPP (BVOC/NPP ratio) for built-up areas is higher than rural forests (excluding bamboo forest). • BVOC/NPP ratios between native and exotic tree species exhibit no significant difference. • G. biloba, L. chinensis and S. mukorossi are the top three tree species with beneficial BVOC/NPP ratios in subtropical urban area. • BVOC/NPP ratios increase with a drop in latitude.

Abstract Changes in vegetation coverage and species composition have contributed to the alteration in biogenic volatile organic compounds (BVOC) emissions, which are regarded as losses of photosynthetically fixed carbon. This study estimates the amount of BVOCs carbon emitted in relation to carbon fixation for the built-up areas and rural forests in a subtropical urban–rural complex. Urban greenspace was subdivided into block greenspace and linear greenspace, while rural areas were characterized by four forest types. A field survey was conducted to assess the vegetation composition, biomass and foliar mass for each tree species. Results showed (1) the emissions intensity of BVOC in the greater Ningbo area is 4.48×10⁶ gCkm⁻² yr^-1, the average emission intensity of the greenspace in the built-up areas (2.86×10⁶ gCkm⁻² yr⁻¹) is higher than rural forests excluding bamboo forest (2.66×10⁶ gCkm⁻² yr⁻¹); (2) the contribution of carbon emitted as BVOCs to net primary production (NPP) (BVOCs/NPP ratio) is about 4.3%, with 1.8% for the built-up areas which is lower than that for rural forests including bamboo forest (4.4%), but higher than rural forests excluding bamboo forest (0.96%); (3) the BVOCs/NPP ratio between native and exotic tree species exhibits no significant difference. The results suggest that BVOC emissions can be reduced while carbon sequestration can be increased by planting trees with low-emitting but high carbon fixation capacity in built-up areas, and by reducing bamboo forest while restoring broad-leaved forest in rural forests.