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重庆缙云山2种林分土壤呼吸对火干扰的响应

Response of soil respiration to fire interference in two forest types in Jinyun Mountain, Chongqing

  • 摘要: 探讨火干扰对缙云山2种林地土壤呼吸速率的影响,明晰不同等级火干扰下不同林分土壤呼吸速率短期变化规律及其影响因子,从而为该地区火干扰后的植被恢复和土壤治理工作提供科学依据。利用无人机勘测结合实地踏查,根据熏黑高度和植被受损情况,划分并布设火干扰Ⅰ(轻度)、Ⅱ(中度、)Ⅲ(重度)级和对照样地,采用密闭式动态气室法测定不同样地的土壤呼吸速率,同时测定土壤环境及理化性质。结果表明:2种林地在不同等级火干扰下的土壤温度变化趋势相同,顺序为Ⅲ级样地>Ⅱ级样地>Ⅰ级样地>对照样地,土壤湿度与土壤温度变化趋势相反;针阔叶混交林地Ⅰ、Ⅱ、Ⅲ级火干扰下的土壤呼吸速率分别为1.81、1.5和1.38 μmol/(m2·s),与对照相比分别降低24.9%、37.8%和43.8%。毛竹纯林Ⅰ、Ⅱ、Ⅲ级火干扰下的土壤呼吸速率分别为2.78、2.34和1.65 μmol/(m2·s),与对照相比分别降低29.1%、51.4%和57.9%。针阔叶混交林和毛竹纯林细根生物量均随火烧等级的增加而减少;土壤pH和碳氮比随火烧等级的增加而增加。综上,火干扰使林地土壤温度升高,湿度降低;土壤呼吸速率随火干扰等级的增加受到显著抑制,同一林分不同等级火干扰下的土壤呼吸速率存在显著差异,相同等级火干扰下,针阔混交林土壤呼吸速率显著低于毛竹纯林;土壤呼吸速率与细根生物量呈显著正相关,与土壤pH呈显著负相关,二者是火干扰下土壤呼吸速率差异的主要影响因素,发展针阔叶混交林可有效降低火干扰的影响。

     

    Abstract:
    Background The effects of fire interfernce on the soil respiration rates of two kinds of woodland in Jinyun Mountain were discussed, and the short-term changes of soil respiration rate and its influencing factors under different fire disturbance levels of different forest stands were clarified, so as to provide a scientific basis for vegetation restoration and soil treatment after fire disturbance in this area.
    Methods The UAV survey combined with field inspection was used to divide and deploy fire interference Ⅰ (lightl), Ⅱ (moderate), Ⅲ (severe) and control sample plots according to the blackening height and vegetation damage. The closed dynamic air chamber method was used to measure the soil respiration rate in different areas, and the soil environment and physical and chemical properties were measured at the same time.
    Results 1) The change trend of soil temperature in the two forest lands under different levels of fire interference was the same, and the order was: Ⅲ sample plot > Ⅱ sample plot > Ⅰ sample plot > control sample plot. The change trend of soil moisture was opposite to that of soil temperature. 2) The soil respiration rate of mixed coniferous and broad-leaved forest land under Ⅰ, Ⅱ and Ⅲ fire interference was 1.81, 1.5 and 1.38 μmol/(m2·s), respectively, which was 24.9%, 37.8% and 43.8% lower than that of the control. The soil respiration rate of the pure Phyllostachys pubescens forest under grade Ⅰ, Ⅱ and Ⅲ fire disturbance was 2.78, 2.34 and 1.65 μmol/(m2·s), respectively, which decreased by 29.1%, 51.4% and 57.9% compared with the control. 3) Fine root biomass of mixed coniferous and broad-leaved forest and pure P. pubescens forest decreased with the increase of fire grade. Soil pH and C/N ratio increased with the increase of fire interference level.
    Conclusions Fire interference increases soil temperature and decreases soil moisture. The soil respiration rate is significantly inhibited with the increase of fire interference level, and there was a significant difference in soil respiration rate under different fire interference levels in the same stand. Under the same fire interference level, the soil respiration rate of mixed coniferous and broad-leaved forests was significantly lower than that of pure P.pubescens forests. There was a significant positive correlation between soil respiration rate and fine root biomass, and a significant negative correlation between soil respiration rate and soil pH, which were the main factors influencing the difference of soil respiration rate under fire interference, development of mixed coniferous and broad-leaved forests may effectively reduce the impact of fire interference.

     

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