火烧烈度对滇中云南松林灌木层植物多样性的影响

Effects of fire intensities on plant diversity ofshrub layers in Pinus yunnanensis forest

调查火后1 a滇中云南松林灌木层植物群落组成及其物种多样性的变化,采用多重比较LSD检验分析了火烧烈度对云南松林灌木层植物群落特征影响的差异性,采用RDA探讨了物种多样性指数与火烧烈度(综合火烧)指数、土壤pH值、碳氮化学计量特征的相关关系,量化了不同火烧烈度下滇中云南松林灌木层植物群落结构和物种多样性指数的变化。结果表明:(1)随火烧烈度增加,调查区灌木层植物种类呈线性减少趋势,由未过火样地的11种降低至重度火烧样地的6种;虽然未过火、轻度、中度和重度火烧样地中优势物种均是车桑子,但阴性树种的重要值和多度降低,而阳性树种重要值和多度增加,火烧样地多数灌木植物的高度有降低;(2)随火烧烈度增加,滇油杉幼苗的重要值和密度大幅降低,云南松幼苗重要值和密度呈非线性增加,中度火烧样地云南松幼苗的重要值和密度最大,各火烧样地2种乔木幼苗的高度均减小;(3)随火烧烈度增加,Shanon-Wiener多样性指数、Simpson优势度指数、Pielou均匀度指数和Margalef丰富度指数均有降低,但仅重度火烧样地各物种多样性指数显著降低,各指数均与综合火烧指数、土壤pH值、土壤总碳(TC)和碳氮比有较大的相关性。

Changes of ligneous-plants in Pinus yunnanensis forests of post-fire after one year in Dianzhong region were surveyed,and multiple comparisons were used to analyze changes in ligneous-plant diversity of shrub layers in Yunnan pines forests with different fire intensities.The results showed that:(1)Responses of plants growth in shrub layers were depended on fire intensities and species characteristics,the amounts of ligneous-plant species in shrub layers after one year of post-fire were linearly reduced with increasing of fire intensity,heavy fires could stimulate the growth of several shrubs,only low fires stimulated the growth for most shrubs.(2)Impacts of fire intensities on tree seedling varied with species,Keteleeria evelyniana was dramatically decreased as fire intensities increased wheras Pinus yunnanensis was non-linearly increased,and the medium and heary fire significantly stimulated germination of Pinus yunnanensis.(3)Effects of fire intensities on plant diversity index were non-linear,Margalef index of plants in shrub layers were negatively correlated with fire intensities(Composite Burn Index,CBI),whereas Shannon-Wiener index and Simpson index had positively correlations with CBI.