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Scientia Silvae Sinicae ›› 2021, Vol. 57 ›› Issue (7): 121-130.doi: 10.11707/j.1001-7488.20210713

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Experiment on Spotting Ignition of Larix gmelinii Forest Based on Logistic Regression

Jibin Ning,Daotong Geng,Hongzhou Yu,Xueying Di,Guang Yang*   

  1. School of Forestry, Northeast Forestry University Key Laboratory of Sustainable Forest Ecosystem Management of Ministry of Education Harbin 150040
  • Received:2019-11-07 Online:2021-07-25 Published:2021-09-02
  • Contact: Guang Yang

Abstract:

Objective: Based on the laboratory simulated experimental data of spotting ignition,Logistic model was used to establish a model of factors influencing the spotting fire ignition,and the applicability of Logistic model in predicting spotting ignition was explored,in order to understand the formation mechanism of spotting fire and provide reference to fire behavior forecast. Method: In this study,Larix gmelinii of Daxing'an mountains,Heilongjiang province was targeted. The cones,1 hour and 10 hours time-lag twigs were used as firebrands. Fuel beds with different wind speed,packing ratios and moisture content of combustible substance were constructed for the ignited experiment. Three Logistic models were established for predicting ignited probability of 3 spotting firebrands. Result: A total of 1 800 ignited experiments were conducted for each firebrand,cone 414 times,1 hour time-lag twig 161 times,and 10 hours time-lag twig 337 times,respectively. In the range of experiment designed,wind speed was positively correlated with ignited probability; fuel moisture content was negatively correlated with ignited probability,but the oven-dry weight of fire firebrand had a great influence on ignited probability. When fuel moisture content was 40%,the larger oven-dry weight of 3 firebrands caused the increase of ignition rate. There was no significant correlation between packing ratio and ignited probability. In cone firebrand model,predicting ignition accuracy rate was 87.2%,total predicted accuracy rate was 71.1%. In 1 hour time-lag twig firebrand model,predicting ignition accuracy rate was 79.6%,total predicted accuracy rate was 78.6%. In 10 hour time-lag twig firebrand mode model,predicting ignition accuracy rate was 81.5%,total predicted accuracy rate was 79.5%. Conclusion: The ignition capability of 3 firebrands is in the order of cone,10-hour time lag twig and 1-hour time lag twig. Wind speed and fuel moisture content and firebrand oven-dry weight have significant effect on ignition. All 3 ignited probability Logistic models have high accuracy rate,and they can be used as a reference for the prediction of spotting fire,in order to improve the efficiency of forest fire fighting and reduce casualties.

Key words: Larix gmelinii, spotting fire, firebrand, wind speed, moisture content, Logistic

CLC Number: