大兴安岭北部多年冻土区植被对活动层厚度变化的响应

植被与多年冻土共同维系着大兴安岭地区的冷湿环境。随着全球气候变暖，大兴安岭多年冻土已发生严重退化，植被的生长也受到影响。在大兴安岭北部多年冻土区设置55个采样点，每个采样点采集多年冻土活动层厚度、林下灌木生物量和落叶松胸径树龄等指标，同时借助增强型植被指数（EVI）在区域尺度比较大片多年冻土区和岛状融区多年冻土区的植被生长状况。结果表明：黑龙江呼中国家级自然保护区（简称呼中保护区）活动层厚度的平均值为（0.47±0.14） m，保护区周边为（0.83±0.38） m，呼中保护区周边的活动层厚度大于保护区内。大片多年冻土区的活动层厚度平均值为（1.04±0.47） m，小于岛状融区多年冻土区的（1.40±0.41） m。呼中保护区和周边灌木生物量的平均值分别为（201.75±71.70） g·m^-2和（259.10±111.14） g·m^-2，胸径与树龄比值的平均值分别为（0.20±0.08）和（0.26±0.14）。大片多年冻土区和岛状融区多年冻土区林下灌木生物量的平均值分别为（128.31±63.33） g·m^-2和（199.04±66.13） g·m^-2，胸径树龄比的平均值分别为（0.30±0.13）和（0.59±0.21）。活动层厚度大的区域，灌木的生物量以及落叶松胸径树龄比都大于活动层厚度小的区域，表明活动层厚度增加对灌木和乔木的生长有一定的促进作用。EVI的结果显示岛状融区多年冻土区植被的生长状况以及植被覆盖情况好于大片多年冻土区，从区域尺度证明了多年冻土对植被生长存在限制作用。研究结果对于深入理解多年冻土变化及其环境效应具有重要意义。

The response of vegetation to the change of active layer thickness in permafrost region of the north Greater Khingan Mountains

Vegetation and permafrost jointly maintain the cold and humid environment in the Greater Khingan Mountains. With global warming， the permafrost in the Greater Khingan Mountains has been severely degraded， and the growth of vegetation has also been affected. In order to further explore the relationship between vegetation and permafrost in the Greater Khingan Mountains， this study set up 55 sampling points in the permafrost regions of the North Greater Khingan Mountains， and at each sampling point we collected indicators such as the active layer thickness （ALT）， the biomass of understory shrubs， and the diameter of larch trees at breast height. Then we used the enhanced vegetation index （EVI） to compare the vegetation growth status of predominantly continuous permafrost and permafrost with isolated taliks at a regional scale. The results show that： （1） The average of ALT in Heilongjiang Huzhong National Nature Reserve is （0.47±0.14） m， and the ALT around the reserve is （0.83±0.38） m. The ALT around Heilongjiang Huzhong National Nature Reserve is greater than that in the reserve. The ALT in predominantly continuous permafrost is （1.04±0.47） m， which is less than （1.40±0.41） m in permafrost with isolated taliks. （2） The average biomass of Heilongjiang Huzhong National Nature Reserve and surrounding shrubs are （201.75±71.70） g·m^-2 and （259.10±111.14） g·m^-2， respectively， and the average ratios of diameter at breast height to tree age are （0.20±0.08） and （0.26±0.14）， respectively. The average biomass of understory shrubs in predominantly continuous permafrost and permafrost with isolated taliks regions are （128.31±63.33） g·m^-2 and （199.04±66.13） g·m^-2， respectively， and the ratio of diameter at breast height to tree age was （0.30±0.13） and （0.59±0.21）， respectively. In areas where the ALT is large， the biomass of shrubs and larch diameter at breast height are greater than those in the areas where the ALT is smaller， indicating that the increase in the ALT can promote the growth of shrubs and trees to a certain extent. （3） The results of EVI show that vegetation growth and vegetation coverage in permafrost with isolated taliks are better than those in predominantly continuous permafrost region. The study proves that at the regional scale permafrost has a restrictive effect on vegetation growth. The results of this study are of great significance for in-depth understanding of the relationship between permafrost changes and its environmental effects.