Driving factors and spatiotemporal dynamics of carbon storage of a Pinus massoniana plantation in reddish soil erosion region with ecological restoration
1. College of Geographical Sciences, Fujian Normal University, 350007, Fuzhou, China;
2. Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology, 350007, Fuzhou, China
[Background] Measures such as closing hillsides for forest recovering and artificial afforestation can improve the ecological environment of soil erosion area, yet its accompanied benefits from carbon sink have not been given due attention for a long time. [Methods] Taking the ecological restoration area with a project of soil and water conservation in Changting County, Fujian Province as the study area, we quantitatively analysed the spatial and temporal patterns in carbon storage and the carbon sink enhancement dynamics of afforested Pinus massoniana forest since ecological restoration in 2000. Based on the Landsat satellite image sets from 2000 to 2013, forest subcompartment survey, on-sitemeasurement, and the statistical yearbook of history, we extracted three periods of distribution maps for carbon storage of the P. massoniana forest from 2000 to 2013 and the different terrain characteristics (including height and slope), and then discussed the effects of main factors on the carbon sink enhancement with the method of the principle component analysis. [Results] 1) The inversion model (y =1.243 2e8.399 7x ) of carbon storage of the P. massoniana forest, established by the vegetation index (MNDVI), has been proved to be effective by the practice test (R2 = 0.869 2, RE =4%) in this study. 2) The carbon storage of the P. massoniana forest grew up from 127.01 *104 t in 2000 to 189.63*104t in 2013, accompanied by an increase of carbon density from 27.95 t/ hm2 to 41.72 t/ hm2 during theperiod. The average annual growth rate of carbon storage was 3.52%, much higher than that in the non-ecologica-restoration areas with only an average annual growth rate of 1.76%. 3) The increasing of carbon storage of the P. massoniana forest mainly occurred in the area with an altitude of below 600 m and a slope of lower than 25 particularly in the last seven years from 2000 to 2013, with respective annual growth rate of 41.6% and 50.9%. 4) The results of the principle components analysis showed that the driving factors of carbon storage dynamics of the P. massoniana forest were the implementation of ecological restoration policy, the adjustment of economic structure and increased income of peasant households, especially that the ecological restoration by government policy and subsistence allowance played a pivotal role in the carbon sink enhancement of the P. massoniana forest in the study area. By contrast, the physical environment factors, such as temperature and precipitation, were insignificant. [Conclusions] There was a significant increase of the carbon sink of the P. massoniana forest in the soil and water conservation area after ecological restoration, and the carbon density of P. massoniana forest grew with the increasing of elevation and slope, showing that in the flat areas where always densely populated, there still has a great potential for forest carbon sequestration to be improved. This paper might provide some essential scientific basis for revealing the potential of carbon sequestration in reddish soil erosion region, quantifying the carbon storage that accumulated in the historical period of ecological management in China, as well as undertaking effective measures to enhance the accumulation of carbon storage in deteriorated lands.