计划烧除对云南松林土壤理化性质及可蚀性的影响

Effects of Prescribed Burning on Soil Physicochemical Properties and Erodibility in Pinus yunnanensis Forests

计划烧除是预防森林火灾的重要措施,为了正确评价计划烧除后生态环境的响应,以滇中云南松天然次生林为研究对象,通过野外调查取样和室内测试分析相结合的方法,探讨了一年一度的周期性连续低强度计划烧除对云南松林土壤理化性质及土壤可蚀性的影响。结果表明:1)计划烧除对土壤化学性质的影响表现在土壤表层,随着土层的加深影响减弱。有机C、全N、全P在0~20 cm土层计划烧除样地显著低于未烧除样地;全K、速效P、速效K在0~10 cm土层,硝态N、pH值在0~60 cm土层显著高于未烧除样地。2)计划烧除对土壤物理性质影响也主要表现在土壤表层。土壤含水量在0~60 cm土层、容重在0~20 cm土层计划烧除样地高于未烧除样地,毛管持水量在0~10 cm土层低于未烧除样地。3)计划烧除改变了土壤表层团粒结构,减弱了土壤抗蚀能力。计划烧除使土壤粉粒、黏粒、有机碳含量在0~10 cm土层下降,沙粒在0~10 cm土层升高,土壤可蚀性因子K在0~40 cm土层增加,土壤可蚀性增强。计划烧除对云南松林土壤理化性质及可蚀性影响主要在于土壤表层,随着土层加深受到计划烧除影响越来越弱。

Prescribed burning(PB),which is the intentional,controlled application of fire with low-intensity to a forest annually prone to wildfires,is one of the main strategies in forest management for fire prevention.In order to correctly evaluate the ecological environment response to PB,the natural secondary forest of Pinus yunnanensis was taken as the research object.The methods of field investigation and indoor analysis were adopted to examine the effects of periodic yearly PB with low intensity on the soil physicochemical properties and erodibility of the forests.The results showed that 1)the soil chemical properties in the top soil were influenced significantly by PB,the influences decreased with soil depth.The soil organic carbon,total nitrogen,total phosphorus and ammonium nitrogen in 0-20 cm soil layer were significantly lower than those in the soil of unburned forests.However,the nitrate nitrogen and the pH value in 0-60 cm soil of PB were significantly higher than that in unburned forests.2)The soil physical properties were influenced significantly by PB,the 0-60 cm soil moisture content and 0-20 cm soil bulk density after PB were significantly higher than those of the soil in unburned forests,but the capillary moisture capacity of 0-10 cm soil after PB were significantly lower than that of unburned forests.3)PB had significant effects on aggregate structure and erosion resistance of the top soil.Compare to unburned forests,the 0-10 cm soil silt and clay content,organic carbon decreased and sand content of soil increased.The soil erodibility factors(K)in 0-40 cm soil decreased after PB,and the soil erodibility increased.Therefore,the PB had significant effects on top soil physicochemical properties and erodibility in P.yunnanensis forest and with slight influence on that of deep soil.