利用不同时相遥感影像估算大兴安岭北部火干扰后NPP

Estimation of Net Primary Productivity of Northern Great Xing'an Mountain After Fire Disturbance Using Multi-temporal Remote Sensing Images

森林火灾是森林生态系统中重要的干扰,对碳循环和碳平衡具有影响。林火作为大兴安岭森林生态系统中主要的干扰因子,直接影响区域的净初级生产力NPP(net primary productivity)。林火的发生使NPP迅速下降,改变了区域碳平衡。以多时相遥感数据为基础,利用CASA(Carngie-Ames-stanford-Approach)模型估算大兴安岭北部地区未过火区和过火区植被NPP变化。结果表明:1987年6月,未过火区植被NPP为145 g C m-2,轻度过火区为74 g C m-2,中度过火区为58 g C m-2,重度过火区植被NPP为38 g C m-2,火干扰后NPP分别降低了49%、60%、73%;1999年8月,火干扰12 a后,过火区NPP是未过火区NPP的96%以上,NPP恢复迅速,基本达到未过火区水平。2009年8月,火干扰22 a后,过火区NPP是未过火区93%以上,与火干扰12 a时相比,下降3%。虽然NPP增速下降,但是NPP总量增加,生产力也与未过火区基本处于同水平。

Forest fire is an important disturbance in forest ecosystem, and it has a significant influence on the carbon cycle and carbon balance. Fire, as the main disturbance factor in the great Xing＇an Mountain, burned a lot of vegetation, which caused the rapid decrease of net primary productivity （NPP） of vegetation and changed the carbon balance in the great Xing＇an Mountains. The CASA （Carnegie-Ames-Stanford-Approach） model and muhi-temporal remote sensing data were used to estimate vegetation post-fire productivity in the northern great Xing＇an Mountain. The study showed that in June 1987, the vegetation NPP of unburned area was 145 g C m -2, low burned area was 74 g C m -2, medium burned area was 58 g C m-2 , and the NPP of high burned area was 38 g C -2 m Post-fire NPP were reduced by 49% , 60% , and 73% ,. respectiely. After 12 years （in August 1999）, the NPP of burned area accounted for more than 96% of the unburned area vegetation NPP, which implied that NPP restored rapidly and almost reached the level of unburned area. In August 2009, the vegetation NPP of burned area accounted for more than 93% of the NPP of unburned area. The proportion decreased by 3%. The growth rate of NPP dropped, however the total NPP increased, and it was basically at the same level of unburned area.