Spatiotemporal Dynamics Of Carbon Storage Of Pinus Massoniana Forest In A Substropical Eroded Red Soil Region And Its Relationship With The Impact Of Human Activity

Measures such as closing hillsides for forest recovering and artificial afforestation can improve the ecological environment of soil erosion area,yet its accompanied carbon sink benefits has not been given due attention for a long time.This study focuses on spatial and temporal patterns in carbon storage and the carbon sink enhancement dynamics of the main afforestated Pinus massoniana forest and its relationship with the impact of human activity in the soil and water conservation area in Changting County,Fujian province.Based on the Landsat satellite image sets since beginning of harness in1981,as well as on forest subcompartment survey,on-site measurement and the statistical yearbooks of history,we extracted six periods' of distribution maps for carbon storage of Pinus massoniana forest from 1981 to 2013,and analyzed the variation of carbon storage and its landscape pattern during three major periods:1981-1989,1989-2000,and 2000-2013.The different terrain characteristics(including height and slope)and distances from residential areas were also extracted.We have endeavoured to make some quantitative analysis of the unique contribution worked by human activity.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.The main results and conclusions are as follows.(1)The inversion models(y=1.243 ×e8.3997x)of carbon storage of Pinus massoniana forest,established by vegetation index(MNDVI),has been proved to be effective by the practice test(R2=0.8692,RE=4%),and simultaneously has been proved to be accurate across over different time period(R2=0.965,RE=8.74%).(2)The carbon storage of Pinus massoniana forest grew up from 37.68×104t in 1981 to 189.63×104 t in 2013 dramaticlly since the governances carried out,and accompanied by an increase in carbon density from 20.14 t/hm2 to 41.72 t/hm2 during the period.The average annual growth rate of carbon storage is 3.35%.The increasing of the carbon storage mainly appeared in the area with an altitude below 600 m and in the area with the slope between 5° to 35°,and the increase of carbon density varies greatly due to different slope.(3)The grades of carbon storage of Pinus massoniana plantation are changing obviously,with the area proportion of C4,C5 and C6 level rising year by year,from 4.63%up to 34.24%on the whole.And the center of gravity in grades of carbon storage has extended from mountainous area to the interior of Hetian basin constantly.Meanwhile,the differences in grades of carbon storage landscape of Pinus massoniana forest in study area are inclined to wane,as a consequence,which may improve the carbon sequestration capacity of Pinus massoniana forest ecosystems.(4)The results of the principle components analysis showed that the driving factors of carbon storage dynamics of Pinus massoniana forest were policy implementation,economic structure adjustment and increasing income of peasant households,particularly in which policy governance implementation and subsistence allowance played a pivotal role in the carbon sink enhancement of the Pinus massoniana forest in study area,and natural elements,such as temperature and precipitation are insignificant by contrast.(5)The carbon storage dynamics of Pinus massoniana forest at the scope closer than 1 km to residences edges are vulnerable to human disturbance,and where the closer to residences,the lower carbon density and the slower speed of recovery there are in study area.And human activities also led to increasing landscape shape index and aggregation index,and decreasing patch density of carbon storage landscape in such area.Nevertheless,this phenomenon becomes gradually weaker with ecological management under the guidance of the government as time goes on.(6)With the gradually procedures of government predominant,human activities affecting on carbon storage of Pinus massoniana forest recover markedly,and the number of the proportion was 41.79%and 39.18%in two main governance periods,respectively.However,with the daily procedures of interference of local farmers predominant,human activities also lend a negative impact on local carbon storage recovery simultaneously,with the proportion of-24.32%,-23.28%and 12.09%during three major study periods,respectively.