中条山森林碳密度时空变化及其驱动因素分析

森林碳库在全球碳循环中发挥着重要的作用。为深入了解山西省中条山区森林植被碳密度的时空动态变化及其影响因素,以2005—2015年3期国家森林资源连续清查数据为基础,通过随机森林和结构方程模型,定量研究了森林植被的碳密度以及各驱动因子对碳密度空间分布的贡献度。结果表明:(1)2005年、2010年、2015年中条山森林植被碳密度和碳储量分别为24.87,26.56,31.42 Mg C/hm²和15.89,16.00,20.15 Tg C,二者均呈持续增加趋势,年均增长率分别为2.63%和2.68%。(2)植被碳密度空间分布特征为高(＞100 Mg C/hm²)和中高(60~100 Mg C/hm²)碳密度样地主要分布在中条山中部和西南部,低碳密度区(＜60 Mg C/hm²)主要在东北部。(3)林龄和年均降雨量是影响研究区植被碳密度空间格局的重要驱动因子,林龄对碳密度的直接正向影响最为显著,年均降雨量通过对林分因子的间接影响进而影响碳密度的空间分布格局。

Spatio-temporal Variation and Driving Factors of Forest Carbon Density in Zhongtiao Mountains

Forest carbon pool plays an important role in the global carbon cycle. In order to understand the temporal and spatial dynamics of carbon density of forest vegetation and its influencing factors in Zhongtiao Mountains region of Shanxi Province, we quantitatively studied the carbon density of forest vegetation and the contribution of each driving factor to the spatial distribution of carbon density by using stochastic forest and structural equation model based on the data of national forest resources continuous inventory from 2005 to 2015. The results showed that: (1) The carbon density and carbon storage of forest vegetation in Zhongtiao Mountains in 2005, 2010 and 2015 were 24.87, 26.56, 31.42 Mg C/hm² and 15.89, 16.00, 20.15 Tg C, respectively, which showed a continuous increasing trend with an average annual growth rate of 2.63% and 2.68%, respectively. (2) The spatial distribution characteristics of vegetation carbon density were as follows: high (> 100 Mg C/hm²) and medium-high (60~100 Mg C/hm²) carbon density plots were mainly distributed in the central and southwest of Zhongtiao Mountains, while low carbon density plots (< 60 Mg C/hm²) were mainly distributed in the northeast. (3) Stand age and average annual rainfall were two important driving factors affecting the spatial pattern of vegetation carbon density in the study area. The direct positive effect of stand age on carbon density was the most significant, and average annual rainfall affected the spatial distribution pattern of carbon density through an indirect effect on stand factors.