北京地区森林枯死可燃物含水率预测模型及变化规律

Prediction model and change regularity of moisture of forest surface dead fuel in Beijing

以不同树种的枯死可燃物含水率为对象，通过对可燃物含水率的逐日观测，对不同种类的可燃物含水率与天气条件之间的关系进行研究，运用非线性回归分析得出栓皮栎、槲栎、侧柏和油松不同树种不同种类可燃物含水率的预测模型，并运用模型对不同树种不同种类的枯死可燃物含水率在时间上的变化规律进行分析。结果表明：不同树种不同种类的可燃物含水率差异显著，栓皮栎树种含水率远高于其他树种；枯叶含水率普遍比不同时滞的枯枝高；不同树种不同种类可燃物含水率差异也很显著；可燃物含水率与温度和风速呈负相关，与相对湿度呈正相关；建立的非线性回归模型均大于30％的含水率变幅，且通过平均绝对误差（MAE）和平均相对误差（MRE）的检验，效果良好；可燃物含水率每天从1：00～24：00呈现先上升后下降再上升的趋势，7：00～8：00达到最高值，在14：00左右达到最低值；防火期中，可燃物含水率在12～2月比较高，3～5月和11月相对偏低。

Taking the dead fuel moisture content of different tree species as the research object, we researched the relationships between the fuel moisture of different types and weather conditions according to the daily observation of fuel moisture content. The prediction model of fuel moisture content for different fuel type of different species including Quercus variabilis, Q. aliena, Platycladus orientals and Pinus tabulaeformis was built by using non-linear regression. The results showed that there were obvious differences in fuel moisture content of different tree species and among different fuel types. Q. variabilis had higher dead fuel moisture content than other species. The moisture content of dead leaves was generally higher than that of dead branches. Fuel moisture content was negatively correlated with temperature and wind speed, and was positively correlated with relative humidity. The established non-linear regression model could explain more than 30% of variance for fuel moisture content of different species, and the prediction model performed well by the mean MRE and mean MRE test. Fuel moisture content showed a trend of firstly increasing and then declining and lastly increasing during a day. Fuel moisture content peaked at 7： 00-8：00 pm, and reached the lowest value at 14： 00. During the period of fire prevention, fuel moisture content was relatively high from December to February, while it was relatively low from March to May and in November.