春季降雨对鲁东低山丘陵区主要森林类型地表可燃物含水率的影响

The Influence of Rainfall on the Moisture Content of Surface Fuel of Main Forest Types in Mountainous Area of Shandong Province

以山东省莱芜市香山地区2种主要森林类型地表死可燃物为研究对象,从2015年3月中旬开始分别观测不同地表死可燃物的含水率,分析3次降雨对不同地表死可燃物含水率的影响;根据野外观测的气象数据,分析可燃物含水率与部分气象因子的相关性;并且测定不同林分枯落叶的熄灭含水率,结合熄灭含水率分析雨后不同林分的火险情况。结果表明:1)不同可燃物类型含水率受降雨影响程度具有差异性,麻栎林内,降雨前后可燃物含水率变异率表现为枯落叶>10h枯枝>1h枯枝;油松林内表现为10h枯枝>1h枯枝>枯落叶。并且3次不同的降雨对可燃物含水率影响具有差异性,第1次降雨对可燃物含水率影响较小,第2次降雨较大,第3次降雨中等。不同可燃物类型含水率雨后衰减率具有差异性,麻栎林内,可燃物含水率3次降雨后衰减率绝对值均表现为枯落叶>10h枯枝>1h枯枝;油松林内表现为10h枯枝>1h枯枝>枯落叶。2)所调查6种可燃物类型含水率与空气相对湿度均呈极显著正相关,与林内空气温度呈负相关,但未达到显著水平,与林内平均风速呈极显著负相关。3)麻栎、油松枯落叶熄灭含水率分别为16.62%、23.23%,降雨导致栎林、油松林地表枯落叶含水率增大,枯落叶含水率在雨后一定时间内,高于熄灭含水率,此时,林内无火灾危险;但随着降雨结束,雨后天数的增加,林内枯落叶含水率降低,当低于熄灭含水率时,林内开始有火灾危险。

To study the effects of rainfall on the moisture content of the dead fuel,we took 2 main forest types of surface dead fuel in Mount Tai as the research objects. We measured the moisture content of sur- face dead fuel from the beginning of March 2015 ,and analyzed the influence of rainfall on the moisture con- tent of dead fuel in different surfaces. According to the meteorological data observed in the field, we ana- lyzed the relationship between moisture content of the fuel and some meteorological factors. We measured the extinction moisture content of different litters of stands, and analyzed the probability of forest fire according to the extinction moisture content. The results showed that.l） The moisture content of different fuel types was different from the impact of rainfall,and 3 different rainfalls had different influences on the moisture content of the fuel. After-rainfall attenuation rate of the moisture content of different fuel types has the difference. 2） The moisture content of the 6 types of fuel showed extremely significant positive cor- relation with the relative humidity of the air, and extremely significant negative correlation with the average wind speed. 3） The leaf litters extinction moisture content of Quercus acutissima forest and Pinus tabuli- forrnis forest were 16.62% and 23.23%. The rainfall caused the increase of moisture content of litters. In a certain period of time after rainfall, the moisture content of litters is higher than its extinction moisture content. But with the end of rainfall, the moisture content of litters decreased, and gradually became lower than its extinction moisture content.