四川省森林植被碳储量的空间分异特征

Spatial differentiation characteristics of forest vegetation carbon stock in Sichuan Province

森林植被碳储量的空间分异特征研究可为以减排增汇为目标的森林生态系统碳库管理提供重要的基础数据。根据实测的林分含碳量和区域生物量-蓄积量回归模型计算了四川省森林植被碳储量,使用ArcGIS软件绘制和分析了四川森林植被碳储量的空间分异特征。结果表明,四川省森林植被的平均碳密度为38.04MgC·hm-2(12.15～59.51MgC·hm-2)。受青藏高原隆升和人类活动干扰及其叠加效应的影响,四川森林植被碳密度空间分异明显,总体上表现出随纬度、海拔高度和坡度的增加而增加,随经度的增加而减小,高海拔地区和陡坡地带具有较高的碳密度。减少人类活动对森林的破坏及采取森林分区经营管理是稳定和增强四川森林碳汇功能的有效途径。

The spatial differentiation characteristics of regional forest carbon stock can provide important scientific basis for forest ecosystem carbon pool management. Although numerous reports on national and regional carbon stock in forest vegetation have been published in the past three decades, more attentions have been given to the effects of climate, stand characteristics, land use/cover change and forest management on forest carbon stock, and little information has been available on spatial differentiation characteristics of forest carbon stock driven by distinct geographic differentiation and complex topography. Sichuan Province, located at the upper reaches of Yangtze River and in eastern Qinghai-Tibet Plateau, is the principal part of the second largest forest region in China as well as the key region of projects on natural forest resource protection, conversion of cropland to forest and grassland and protection forest in the upper and middle reaches of Yangtze River. As yet far less information is available on the spatial differentiation characteristics of forest carbon stock in the region. The forest carbon stock and its spatial differentiation characteristics were studied in order to provide scientific information for regionalized forest carbon pool management, employing the methods of carbon content measurement in the forest stand in combination with regional biomass-volume model, forest resource inventory and GIS technology. Average vegetation carbon density in Sichuan forest was 38.04 MgC·hm^-2 ranged from 12. 15MgC·hm^-2to 59.51 MgC·hm^-2, which was lower than average carbon density in China. Moreover, vegetation carbon density had clear spatial differentiation with the zonalities of longitude, latitude and altitude in Sichuan, and also showed obvious speciality and complexity resulting from the uplift of Qinghai-Tibetan Plateau, the disturbance of human beings in densely populated area such as the plain and low- mountain and hilly area and their interactions. However, the carbon density in Sichuan forest increased with the increases of latitude, altitude and slope, but decreased with the increase of longitude, i. e. , the forests in the areas with higher latitude, altitude and slope had higher carbon density, which was not in agreement with the result of ＂ carbon density in trees decreased with the increases of longitude, latitude and altitude＂ at home and abroad. The reason that carbon density in tree layer increased with the latitude, altitude and slope was the decline of human disturbance intensity, implying that the speciality and complexity of spatial differentiation on carbon density in Sichuan forest ecosystem caused mainly by human disturbances, which also meant that the measures of forest conservation, degraded forest ecosystem restoration and regionalized forest carbon management in combination with the projects of natural forest resource protection and conversion from farmland to forest or grass projects could significantly increase the potential of forest carbon sequestration in Sichuan province