岷江上游亚高山暗针叶林的生物量碳密度

Biomass Carbon Density of Sub-Alpine Dark Coniferous Forest in the Upper Reaches of Minjiang River

利用森林资源连续清查的样地数据，基于生物量与蓄积量之间的关系模型，估测岷江上游亚高山暗针叶林地上部分生物量碳密度、碳密度年增长率及其随林龄、海拔和坡向变化的分布规律。结果表明：岷江上游暗针叶林的成熟林、过熟林生物量碳密度较高，中龄林、幼龄林生物量碳密度较低，成熟林、过熟林生物量碳密度高于全国平均水平，而中龄林和近熟林低于全国平均水平，幼龄林与全国平均水平相近；中龄林生物量碳密度年增长率最大，为1.3％，其次为过熟林，生物量碳密度年增长率为0.8％，幼龄林生物量碳密度年增长率最小，为0.7％；海拔3600～3800m处生物量碳密度最大，明显高于其他海拔区段；海拔3000～3400m处生物量碳密度年增长率最高，为1.03％；半阴坡和半阳坡的生物量碳密度高且年增长率最大，其次是阴坡，阳坡生物量碳密度低，年增长率最小；过去20多年，岷江上游暗针叶林生物量碳密度呈现逐年增加的趋势，1997-2002年，生物量碳密度年平均增长率为1.15％，高于其他调查期间碳密度年增长率。

The forest biomass provides an important information for forest carbon storage estimation and carbon source/sink assessment. Based on the consecutive forest resource inventory data,the biomass carbon density （BCD） of dark coniferous forests （DCF） in the upper reaches of Minjiang River was calculated by using biomass expansion factors （BEF） method and its variation with age class,elevation and aspects were also examined. The results showed： The higher BCD was found in mature and overmature DCF and the lower BCD in young and middle aged DCF; For the same age class,the BCD values of the mature and overmature DCF were higher than those of the national average, while the BCD values of the middle age and pre-mature DCF were lower than those of the national average, the BCD value of the young forest was similar to the national average ; The annual increment rates of BCD in middle-age,young and over-mature DCF were 1.3 % ,0.8% and 0.7%, respectively; The higher BCD values occurred at the site with the elevation ranging from 3 600 to 3 800 m; The annual increment rate of BCD was found to be highest （1.03%） at the site with the elevation between 3 200 and 3 600 m; The higher BCD and its annual increment rate of BCD occurred on both north facing aspects and south-west and south-east aspects, while the lower values occurred on south facing aspects; The BCD of DCF in the upper reaches of the Minjiang River have been increasing over the past 20 years,the annual increment rate of BCD was 1.15% from 1997 to 2002, which was the highest among the five inventory periods.