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火烧对重庆缙云山土壤化学性质的影响

Effects of fire on the soil chemical properties in the Jinyun Mountain of Chongqing

  • 摘要: 探究不同强度火烧对不同林分林下土壤化学性质的影响,以期为火灾发生后森林生态系统功能的恢复及利用火烧促进林分更新提供参考。在2022年8月重庆市缙云山山火发生1周内,在火烧区针阔混交林和竹林的不同强度火烧及不同深度的土壤取样,测定土壤pH、有机质含量等化学指标。通过描述性统计分析、单因素方差分析和Fisher LSD检验研究土壤化学性质在同一林分不同强度火烧间,以及同一强度火烧下不同林分间的显著性差异和变化趋势。结果表明:1)2种林分内土壤pH、速效钾含量都随火烧强度增大表现出上升趋势,而土壤有机质、全磷含量随火烧强度增大表现出下降趋势,全氮、碱解氮、有效磷含量、阳离子交换量(CEC)随火烧强度增大没有明显变化;2)在相同火烧强度下,2种林分之间的土壤有机质、全氮、碱解氮、有效磷、速效钾和CEC存在显著差异(P<0.05),而pH、全磷无显著差异;3)总体来说,火烧后表层土化学性质变化强烈,短期内土壤养分含量降低,不利于植物生长。因此灾后植被恢复工作要以土壤肥力的改善为主,同时不同林分受灾后土壤化学性质变化具有较大差异,要针对其具体变化实行因地制宜的恢复措施。

     

    Abstract:
    Background Forest fires can cause severe disturbances to forest ecosystems and are not easily recovered in the short term. To investigate the short-term effects of fires of different intensities on soil chemistry at different depths in different forest stands, and to provide a reference for the restoration of forest ecosystem functions after fires and the use of fire to promote stand regeneration, it is important to study the changes in soil chemistry in the burned area in the short term (within 1 week) of recovery.
    Methods Three 20 m×20 m sample plots were set up in coniferous broad-leaved mixed and bamboo forests in Jinyun Mountain, which were lightly, moderately and severely burned areas and one unburned sample plot respectively. Soil sampling was carried out at different depths (0-10 and 10-20 cm) in the set plots, and chemical indicators such as soil pH, cation exchange capacity (CEC), organic matter content and soil available nutrient content were determined. Significant differences and trends in soil chemical properties between different stands and different intensities of fire were investigated by descriptive statistical analysis, one-way ANOVA and Fisher LSD test.
    Results 1) Soil pH and available potassium content showed an increasing trend with increasing fire intensity in both stands, while soil organic matter and total phosphorus content showed a decreasing trend with increasing fire intensity, while total nitrogen, available nitrogen, available phosphorus content and cation exchange capacity (CEC) did not change significantly with increasing fire intensity. 2) At the same fire intensity, there were significant differences (P < 0.05) in soil organic matter, total N, available nitrogen, available phosphorus, available potassium and CEC between the two stands, while pH and total phosphorus were not significantly different. 3) Fire had a significant effect on the chemical properties of the surface soil, and the changes in soil pH, CEC and organic matter, total N, total phosphorus, available phosphorus, available potassium and available nitrogen contents reached significant levels under the interaction of different stand types and different fire intensities.
    Conclusions Fire has a significant impact on the soil chemistry of different forest stands, especially high-intensity fire, which significantly reduces the soil nutrient content at different soil depths, thus post-disaster revegetation work should focus on soil nutrient restoration and fertility improvement, with site-specific restoration measures tailored to the specific changes of different forest stands.

     

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