三北防护林体系森林碳密度及碳贮量动态

Dynamic forest carbon density and storage in the "Three North" protective forest system

基于1989-1993、1994-1998、1999-2003三期全国森林资源清查资料,结合区域尺度的材积源生物量模型估算了三北防护林工程区3个时期天然林和人工林的生物量碳密度和碳贮量,分析了不同林种的碳贮量动态。结果表明:三北防护林工程区三个时期碳密度分别为35.21、36.01和41.56 t.hm-2,暗示我国的森林质量在逐步提高;碳贮量分别为458.10、519.96和1268.84 Tg(1 Tg=1012g),分别占全国森林碳贮量的9.89%、10.95%和24.23%。相对于人工林,天然林碳贮量仍是森林总碳贮量的主体,占71-84%,并且所占比例有增加趋势。随林龄的增加,天然林碳密度呈现显著增加趋势,但人工林仅在初始阶段呈现增加趋势,到近熟林就逐渐趋于稳定;人工林碳贮量随林龄增加而降低,但天然林以中龄林碳贮量最高,之后随林龄增加而降低。就林种而言,用材林和防护林占据主导地位,但随时间推移,防护林碳贮量所占比例越来越接近用材林。

Based on inventory data of three periods from 1989 to 2003,forest biomass carbon density and storage were estimated by method that converts timber volume to total forest biomass at regional scales.During the three period,average carbon density in this region increased from 35.21 to 36.01,and to 41.56 t.hm-2,indicating an improvement in forest quality as time went by;carbon storage increased from 458.10 to 519.96 and to 1268.84 Tg（1 Tg = 1012g）.Carbon storage of natural forest accounted for 71-84 % of the total carbon storage,and the proportion seemed to increase as time went by.As stand aged,carbon density of natural forest increased markedly,while that of plantations increased at first,reached the peak in near mature forest,and then kept steady in mature stage.Carbon storage in plantations declined with stand age,and that of natural forest showed the highest value in middle-age forest,and then declined as stand aged.As far as forest category was con-cerned,carbon storage was predominated by timber forest and protection forest,and the proportion of protection forest would gradually get closer to that of timber forest as time went by.