| The effects of forest fire were studied on the characteristic and succession of flora, and were studied on the species diversity and biomass and soil physical and chemical properties, to analyze the correlation between them, according to the sample surveys, in typical forest types burned area of Huzhong and Nanwenghe Nature Reserve, Great Xing’an Mountain, using the grey sequence analysis, the results are sa follows:The flora component had changed by forest fire disturbance, and was adjusted during the plants development and succession. In Huzhong Nature Reserve, the flora changed to the North Temp.-Arctic, Sino-Japan, East Siberia from Temp. Aisa and N. E. China in Betula platyphylla forest; the flora changed to the North Temp.-Arctic, East Siberia, Temp. Asia, Sino-Japan from North Temp. in Larix gmelinii forest. In Nanwenghe Nature Reserve, the flora changed to the East Siberia, North Temp.-Arctic from Sino-Japan and Temp. Aisa in B. platyphylla forest; the flora changed to East Siberia, Sino-Japan, Temp. Aisa from North Temp.-Arctic in L. gmelinii forest.The coverage of herb layer and shrub layer in B. platyphylla and L. gmelinii burned area was lower than unburned area. The coverage annual variation of herb layer and shrub layer in burned and unburned area was increased and the increasing percentage in burned area were more than in unburned area.The total coverage, species richness and total biomass of understory vegetation in B. platyphylla and L. gmelinii burned area was lower than unburned area, and was descend with increasing of fire intensities:unburned> moderate> serious. The annual variation of total coverage, species richness and total biomass in burned and unburned area was increased. The total coverage in B. platyphylla in Nanwenghe:serious (20.26%)> moderate (14.75%)> unburned (10.64%). The species richness in L. gmelinii in Nanwenghe:moderate (8)> serious (6)> unburned (3). The total biomass of understory vegetation in L. gmelinii in Nanwenghe: serious (14.4t·hm-2)> moderate (8.45t·hm-2)> unburned (6.22t·hm-2).The understory vegetation diversity index in B. platyphylla and L. gmelinii burned areas has been descended with increasing of fire intensities. The annual variation of total coverage and species richness in burned and unburned area was increased during the vegetation development, and the increasing amount in burned area was more than the unburned area, and the diversity index in moderate burned area was higher than the diversity index in serious burned area.The soil nutrient content was changed by the interference of the different intensity of forest fires in both Huzhong and Nanwenghe Nature Reserve. The pH value (5.4-5.8)and organic matter contents of soil was increased with increasing of fire intensities, such as the organic matter contents in B. platyphylla in Nanwenghe:serious (6.88g·kg-1)> moderate (6.71g·kg-1)> unburned (5.41g·kg-1), but Nitrogen and Potassium contents was opposite, such as Nitrogen contents in B. platyphylla in Nanwenghe:unburned (1.33g·kg-1)> moderate (1.30g·kg-1)> serious (1.01g·kg-1). The Potassium contents:unburned (0.44g·kg-1)> moderate (0.38g·kg-1)> serious (0.35g·kg-1).The unit weight and Phosphorus of soil reached the maximum in moderate burned area. Such as the unit weightin in B. platyphylla in Nanwenghe: moderate (1.84g·cm-3)> unburned (1.60g·cm-3) and serious (1.41g·cm-3), and the Phosphorus of soil:moderat (0.68g·kg-1)> unburned (0.46g·kg-1) and serious (0.49g·kg-1).In the grey sequence analysis, the unit weight of soil, organic matter and Phosphorus and Nitrogen contents played leading roles on diversity index, the grey sequence value among0.6to0.8. And the unit weight of soil, organic matter contents and pH value played leading roles on biomass, the grey sequence value was above0.7.The fire created a living space and development conditions for understory vegetation, and changed the soil physical and chemical properties, to provide beneficial nutrients for understory vegetation. To some extent, the forest fire promoted the regeneration and succession of understory vegetation. The regeneration rate of understory vegetation in burned area was higher than unburned area. A certain intensity of forest fires interference can increase the species diversity and biomass of understory vegetation. |
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