摘要
为明确计划烧除火强度对云南松林的影响,合理评价计划烧除的防火效应与生态效益。运用野外调查采样与实验室测定法,探究云南省新平县照壁山云南松纯林样地内,计划烧除前后云南松树皮、地表凋落物松针燃烧性能参数,基于实地数据建立Pyrosim模型,并结合计划烧除火场实际情况筛选200和500 kW/m两种工况,模拟不同火强度下温度和速度场分布。结果表明:计划烧除前,当火强度从200 kW/m增至500 kW/m时,由无焰燃烧发展为明火燃烧所需时间从80 s降为30 s,冠层表面温度由309℃增至894℃;水平蔓延速度从2.2 cm/s增至4.8 cm/s,垂直方向速度由2.00 cm/s增至5.06 cm/s。计划烧除实施后,200 kW/m火强度下火焰无法蔓延,火强度为500 kW/m时火焰最高温度为557℃,火蔓延速度为1.2 cm/s,蔓延速度较烧除前下降76.3%。计划烧除前,可燃物质量燃烧速率随火强度增加而增加,当火强度从200 kW/m增加至500 kW/m时,质量燃烧速率从1.1 g/s升高至2.6 g/s;计划烧除实施后两种火强度下质量燃烧速率均出现显著下降,降幅均达95%以上,说明计划烧除能够极大减少地表可燃物数量,降低区域火灾风险。根据数值模拟结果,火强度控制在200~500 kW/m能实现防火目标,同时也能兼顾生态效益。
In order to clarify the impact of prescribed fire intensity on Yunnan pine(Pinus yunnanensis) forest and evaluate the fire prevention effect and ecological benefit reasonably, field survey sampling and laboratory determination were used in the Zhaobi Mountain pure forest of Yunnan pine sample plot to analyze the combustion characteristics of Yunnan pine needles and tree bark before and after the prescribed burning. Based on the field data, the Pyrosim model was established. Two working conditions of 200 and 500 kW/m were selected according to the actual situation of prescribed fire. Temperature and velocity field distributions under different fire intensities were simulated. The results showed that, before the prescribed fire, when the fire intensity increased from 200 to 500 kW/m, the time required for the development from flameless combustion to open combustion was reduced from 80 to 30 s. The canopy surface temperature increased from 309 to 894 ℃. The horizontal spread rate increased from 2.2 to 4.8 cm/s. The vertical velocity increased from 2.00 to 5.06 cm/s. After the prescribed fire was implemented, the flame could not spread under the 200 kW/m fire intensity. When the fire intensity was 500 kW/m, the highest flame temperature was 557 ℃ and the fire spread rate was 1.2 cm/s, which was 76.3% lower than that before the prescribed fire. Before the prescribed fire, the mass burning rate of combustibles increased with the fire intensity. When the fire intensity increased from 200 to 500 kW/m, the mass burning rate increased from 1.1 to 2.6 g/s. After the prescribed fire was carried out, the mass burning rate were both decreased significantly under the two fire intensities, and the decline rate was more than 95%, indicating that the prescribed fire can greatly reduce the amount of surface combustibles and the risk of regional fires. According to the numerical simulation results, controlling the fire intensity between 200 to 500 kW/m can attain the fire prevention target, which also achieve ecological benefits at the same time.
作者
龙腾腾
李佳琳
王劲
张文文
王秋华
LONG Tengteng;LI Jialin;WANG Jin;ZHANG Wenwen;WANG Qiuhua(School of Civil Engineering,Southwest Forestry University,Kunming 650224,China)
出处
《林业工程学报》
CSCD
北大核心
2022年第6期164-170,共7页
Journal of Forestry Engineering
基金
国家自然科学基金(31960318,32160376)
云南省农业联合面上项目(2018FG001-055)。
关键词
计划烧除
火强度
云南松纯林
场分布
滇中地区
prescribed fire
fire intensity
pure forest of Pinus yunnanensis
field distribution
central Yunnan
