火干扰对大兴安岭北部原始林下层植物多样性的影响

The effects of fire disturbance on the biodiversity of understory plant in virginal forest,northern region of Daxinganling Mountains,China

在景观尺度自然火干扰历史研究的基础上,采用1个物种丰富度指数(物种数S)、2个均匀度指数(Pielou均匀度指数Eh’和Alatalo均匀度指数E)、3个物种多样性指数(Shannon-Wiener指数H’,Hill多样性指数N1和N2)共6个α多样性指数,研究了长期火干扰与最近一次火干扰对大兴安岭北部原始林下木层、草本层及下层总体的植物多样性的影响。研究结果表明,本区下层植物的物种数、均匀度指数和多样性指数都以下木层显著大于草本层,因而下木层对下层植物总体生物多样性的贡献最大,也是主要影响因子。火干扰对下木层、草本层和下层总体的物种丰富度和物种多样性有显著影响,而对均匀度的影响不显著。长期的火干扰影响下,下木层、草本层和下层总体的物种数、各类均匀度指数和物种多样性指数都呈现如下格局:高频类>中频类>低频类,低强类>中强类>高强类。最近一次火干扰影响下,各个生物多样性指数都表现为一致的趋势:低强类>中强类>高强类;短期类>长期类>中期类。下层植物多样性与火干扰的关系是长期适应的结果。

Based on the study of the natural fire disturbance history at scale of landscape, this paper discusses the influences of long fire disturbance and last fire disturbance regime upon the biodiversity of shrub, herbivore and whole underlayer vegetation in virginal forest, northern Daxinganling Mountains, China. Six biodiversity indices are used in this paper, including one species richness index （i.e. number of species, S）, two evenness index （i.e. Pielou evenness index Eh＇ and Alatalo evenness index E） and three species diversity indices （i.e. Shannon-Wiener index H＇, Hill indices N1 ＆ N2）. In general, the shrub layer shows higher values in species diversity indices than the herbivore layer does, which mrans that the shrub layer plays a more significant role in the plant diversity of the underlayer vegetation. Based on the ANOVA, the influences of fire disturbance upon the species richness and species diversity of the shrub, herbivore and whole underlayer are very significant, however, the effects on the evenness indices are not obvious. Influenced by the long fire disturbance, almost all the biodiversity indices show the following sequence： high frequency 〉 middle frequency 〉 low frequency, low severity 〉 middle severity 〉 high severity. However, under the effect of last fire disturbance, much of the biodiversity indices are that： low severity 〉 middle severity 〉 high severity, short duration 〉 long duration 〉 middle duration. The relation between the underlayer biodiversity of plant community and the fire disturbance is resulted from the long adaptation. Under the influence of fire disturbance with low-frequency ＆ high-intensity, a lot of the on-site plants are destroyed while it is difficult for other plants to colonize. This results in a poor status in species diversity. However, a lot of on-site plants can recover and even survive from the fire disturbance with highfrequency ＆ low-intensity, and much more other plants can invade into the site too, which leads to the higher values in plant diversity.