湖南省森林植被碳储量、碳密度动态特征

利用湖南省4次(1983—1987年、1990—1995年、2003—2004年和2009年)森林资源清查数据,采用材积源-生物量法,结合湖南省现有森林植被主要树种碳含量实测数据,研究近20多年来湖南省森林植被碳储量、碳密度的动态特征。结果表明:从1987年到2009年,湖南省乔木林植被碳汇为66.40×106tC,碳密度提高了5.65 tC/hm~2,阔叶林碳汇最大(48.43×10~6tC),其次是杉木林(9.54×10~6tC)和松木林(6.68×10~6tC),各乔木林植被碳密度波动较大;除过熟林外,各龄组乔木林均为碳汇,中龄林碳汇最大,幼龄林、中龄林、近熟林植被碳密度依次提高了4.75、4.09、0.83 tC/hm~2,成熟林、过熟林分别下降了6.87、13.88 tC/hm~2;天然林、人工林植被碳汇分别为41.01×10~6tC、25.39×10~6tC,碳密度分别提高了7.19、4.91 tC/hm~2。湖南省森林植被(包括疏林)碳汇为84.87×10~6tC,乔木林碳汇最大,其次是竹林,分别占湖南省森林植被碳汇的78.24%和33.31%,碳密度提高了6.24 tC/hm~2,各森林类型植被碳储量随其面积变化而变化。表明近20多年来,湖南省乔木林植被单位面积储碳能力明显提高,天然林在湖南省乔木林植被碳储量占有重要地位。

Dynamic characteristics of forest carbon storage and carbon density in the Hunan Province

Distribution and dynamics of carbon storage and carbon density were examined in forest vegetation in Hunan Province of China, based on four forest inventories during 1983-2009 (1983-1987, 1990-1995, 2003-2004, and 2009). Inventory data consisted of biomass expansion factors and carbon concentration of existing forest types in this region. The results showed that the arboreal forests were carbon sinks with a value of 66.40 × 10⁶ t C from 1987 to 2009. The highest carbon sink was in broad-leaved forests (48.43×10⁶ t C), followed by Chinese fir plantations (9.54 × 10⁶ t C) and pine forests (6.68 × 10⁶ t C). All age-group forests exhibited carbon sinks, except mature forests. The middle-aged forests had the highest value for carbon sinks. Carbon density increased 5.65 t C/hm² in arboreal forests during the four forest inventory periods. Carbon density increased by 4.75, 4.09, and 0.83 t C/hm² in young, middle-aged, and near mature arboreal forests, respectively, whereas it declined by 6.87 and 13.88 t C/hm² in mature and over-mature arboreal forests, respectively. Carbon sinks were 41.01 × 10⁶ and 25.39 × 10⁶ t C in natural forests and man-made plantations, respectively. Carbon density increased 7.19 and 4.91 t C/hm² in natural and plantation forests. The total carbon sink was 84.87 × 10⁶ t C in forest vegetation (including open forests). The arboreal and bamboo forests accounted for 78.24% and 33.31% of total carbon sinks, respectively. Carbon density increased 6.24 t C/hm² in forest vegetation. Carbon storage changed in various types of forest vegetation due to change in forested areas. Our results suggested that carbon sequestration ability is considerably high in the arboreal forest vegetation in the Hunan Province. In particular, the natural forests contribute substantially to carbon storage and sequestration in Hunan forests.