川西米亚罗自然保护区森林地上碳储量遥感估算

Estimation of forest aboveground carbon storage in Sichuan Miyaluo Nature Reserve based on remote sensing

研究米亚罗自然保护区的森林地上碳储量,有利于掌握高山峡谷区森林植被碳储量的分布特点,对区域森林资源的有效科学管理和维护森林生态环境具有重要意义。通过对保护区内的7个主要树种分别构建模型来初步估测森林地上碳储量,利用实地调查的样地数据与同期Landsat 8遥感卫星影像,得到波段信息、植被指数、主成分分析、纹理特征、地形因子、植被生长六大类共80个因子,用以构建乔木层不同树种地上碳储量的多元线性逐步回归模型,而灌木层的碳储量则由生物量密度法估算得出。研究结果表明:①模型预测值与实测值相关系数在0.675—0.775之间,精度较高,预测结果可靠;②米亚罗自然保护区森林地上碳储量为5.861 Tg,其中乔木层5.632 Tg,灌木层0.229 Tg。云冷杉林是研究区分布最广的林分类型,其碳储量为5.098 Tg,占森林地上碳储量总量的86.98%,在维持区域碳平衡方面发挥着重要作用。③研究区森林平均碳密度为53.138 t/hm^2,其中冷杉的碳密度最高,达到74.467 t/hm^2。④区域内森林地上碳储量以杂谷脑河流域及支流为中心,以一定缓冲距离呈树枝状发散分布,海拔3000—4000 m区域的森林植被碳储量最大,且阴坡的碳储量明显高于阳坡。

The Miyaluo Nature Reserve is an important carbon sequestration region in Western Sichuan.Study of aboveground forest carbon storage in Miyaluo Nature Reserve is necessary for elucidating the distribution characteristics of forest vegetation carbon storage in alpine gorge areas.Furthermore,it is of great significance to the scientific management of forest resources and the maintenance of forest ecological environments in the nature reserves.In this study,carbon storage models were established for seven main tree species to estimate the carbon storage on forest land.Firstly,897 samples were obtained from a field survey,and sample biomass and carbon storage were calculated based on the volume-derived biomass method.Secondly,Landsat 8 satellite remote sensing data were used to obtain image characteristics of forest vegetation.Thirdly,combined with forest survey data,80 factors were determined that were classified into six categories(band information,vegetation index,principal component analysis,texture features,topographic factors,and vegetation growth).Moreover,the correlation between these factors and the biomass of different tree species was analyzed,according to the order of Pearson′s correlation coefficient,the significant correlation factors were then introduced into the multiple linear stepwise regression equation as independent variables,and the estimation models of aboveground carbon storage of different tree species in the tree layer were established.Finally,the aboveground carbon storage of the arbor layer was calculated by the estimation model,and the carbon storage in the shrub layer was calculated using the average biomass density method.The results showed that①the accuracy of models for carbon storage estimation was within the margin of error,and the correlation coefficient between the measured value and the predicted value of the model was 0.675—0.775.②The total carbon storage in the forest in the Miyaluo Nature Reserve was 5.861 Tg,of which the aboveground carbon storage in the arbor layer was 5.632 Tg,and the carbon storage in the shrub layer was 0.229 Tg.The order of the aboveground carbon storage of the prominent species was Abies faberi>Picea asperata>Tsuga chinensis>Larix gmelimi>Quercus acutissima>Betula chinensis>Pinus tabulaeformis>Pinus armandi;The total carbon storage of fir trees was 5.098 Tg,accounting for 86.98%of the aboveground carbon storage in the study area.The spruce-fir forest was the most widely distributed forest type in the Miyaluo Nature Reserve,and it played an important role in maintaining the carbon balance.③The average carbon density in the forest in Miyaluo Nature Reserve was 53.138 t/hm^2,and the carbon density of Chinese fir species was higher than the average.The carbon density of fir was much higher than that of other tree species and was 74.467 t/hm^2.④The spatial distribution characteristics of aboveground forest carbon storage in the study area were obtained by overlapping the Digital Elevation Model(DEM)with carbon storage.Taking the Zagunao River and its tributaries as the center,the carbon storage spatial distribution data were extended to the surrounding area by a given buffer distance in the whole region,similar to arborization.The largest area of forest vegetation carbon storage was distributed in regions with elevation of 3000—4000 m.The aboveground carbon storage on shady slopes was higher than that on sunny slopes.