火干扰强度对兴安落叶松林物种组成及多样性的影响

Effect of Fire Disturbance Intensity on Species Composition and Species Diversity of Larix Gmelinii Forest in Daxing'anling Mountain

以大兴安岭地区兴安落叶松林为研究对象,采用群落调查方法,分析不同火强度对大兴安岭地区落叶松林物种组成及物种多样性的影响。结果表明,重度火干扰对兴安落叶松林物种组成影响较大,火烧迹地的演替从喜光、耐旱的草本及灌木开始,形成以草本层占主要优势的白桦灌草林群落;中度火干扰保留了少量的兴安落叶松,白桦萌条形成更新层和演替层,促进森林群落由针叶林向针阔混交林演替的过程;轻度火干扰不能改变原有的树种组成,林分群落结构变化只是在灌木层和草本层中一些物种的更替。随着火干扰强度的增加,落叶松林物种多样性指数和均匀度而呈现线性下降趋势,优势度呈现乘幂性上升趋势。

Taking the Larix gmelinii forest in Daxing＇anling Mountain area as research object,the effect of different fire intensities on species composition and species diversity of Larix gmelinii forest was analysed with community survey methodology.The results showed that severe fire disturbance had more impact on species composition of Larix gmenilii forest,and the succession of burned areas began from herbs and shrubs that were photophil and drought-tolerant,then the Betula platyphlla shrub-grass forest community formed,in which the herbaceous layer occupied main position.Moderate fire disturbance retained a small amount of Larix gmelinii and the stump plant of Betula platyphlla formed the update layer and succession layer,which promoted the forest succession process from needleleaved forest to broad-leaved and needle-leaved mixed forest.Mild fire disturbance could not change the original species composition,whereas the change of forest community structure was just the replacement of some species in shrub layer and herb layer.With the increase of fire disturbance intensity,the species diversity index and evenness degree of Larix gmelinii forest showed a linear downward trend,and the dominance degree showed an upward trend.