Vegetation Restoration and Carbon Sink Function Evaluation of the Grain for Green Project

Evaluation of the ecological process and carbon sink function of vegetation restoration is subject to afforestation activities, particularly after conversion of farmland to forests at different de-farming times. Based on the survey of sample plots ranging from 7 to 46 years in Larix olgensis plantation after returning farmland to forest, dynamic changing of vegetation restoration and carbon storage in representative region of Lesser Khingan Mountains were analyzed in the plantation. Firstly, community diversity situation was evaluated by Sorensen similarity index, Shannon-Wiener index, Peilou evenness index, Margalef richness index. Secondly, biomass of community was estimated by sampling harvest and allometric dimension analysis, and translated it to carbon storage via carbon rate. Thirdly, carbon storage quantity was conversed to the amount of CO2 fixation and O2 release according to the plant photosynthesis principle. At last, the economic benefit of CO2 and O2 were calculated through the current market price. The results showed that: (1) the ecological efficiency of the man-made communities raised as the reforested time increased, such as the number, richness and diversity index of species reached to 46, 6.443 and 1.733 respectively. Composition and biodiversity characteristics of plantation community changed significantly after reforested the cultivated land. (2) Carbon density of community, including arbor, shrub, herb and down woody material, increased over stand ages. Mean carbon density was 74.711 t·hm-2, and the carbon storage in regions of study was 106.624t, equaled to 13000.252t CO2 and 2585.938t O2. After conversion, economic benefit of 436.887 thousand RMB indicated remarkable benefits of the plantations. In conclusion, our study showed that the Grain for Green Project improved the land-use pattern, as farmland transformed to forests, aims of degenerated ecosystem restoration or reconstruction and plantations carbon sink potential development were achieved.