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首页> 外文期刊>Journal of Forestry Research >Evaluation of deriving fire cycle of forested landscape based on time-since-fire distribution
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Evaluation of deriving fire cycle of forested landscape based on time-since-fire distribution

机译：基于时间-自-火分布的森林景观衍生火周期评估

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Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed to be homogeneous with respect to fire spread processes. The authors imposed predefined fire cycles on a virtual landscape of 100 cell x100 cell, and obtained a mosaic composing of patches with different stand ages (i.e. time since fire). Graphical and statistical methods (Van Wagner 1978; Reed et al. 1998) were employed to derive fire cycle from the virtual landscape. By comparing the predefined and the derived fire cycles, the two methods and tested the effects of sample size and hazard of burning (i.e., stand's susceptibility to fire in relation to its stand age) were evaluated on fire cycle deviation. The simulation results indicated a minimum sample size of 10 times of the annual burnt area would be required for partitioning time-since-fire distribution into homogeneous epochs indicating temporal change in fire cycle. Statistically, there was significant difference among the imposed and the derived fire cycle, regardless of sample sizes with or without consideration of hazard of burning. Both methods underestimated the more recent fire cycle without significant difference between them. The results imply that deviation of fire cycle based on time-since-fire distribution warrants cautious interpretation, especially when a landscape is spatially partitioned into small units and temporal changes in fire cycle are involved.
机译：通过使用负指数函数作为假定相对于火势蔓延过程是均匀的景观的自发火灾分布以来的时间，对火灾周期进行了估算。作者在100个单元x 100个单元的虚拟景观上施加了预定义的火灾周期，并获得了由具有不同林龄（即火灾发生时间）的补丁组成的镶嵌图。使用图形和统计方法（Van Wagner 1978； Reed等人1998）从虚拟景观中得出火周期。通过比较预定义的火灾周期和派生的火灾周期，对两种方法进行了测试，并测试了样本量和燃烧危险（即林分相对于林分年龄的林分易燃性）的影响。模拟结果表明，将时间自火灾分配到均匀的时期（表示火灾周期随时间变化）需要最小的样本量是年燃烧面积的10倍。从统计学上讲，无论样本大小如何，无论是否考虑了燃烧的危险，施加的火焰周期和派生的火焰周期都存在显着差异。两种方法都低估了最近的火灾周期，两者之间没有显着差异。结果表明，基于时间-火灾分布的火灾周期偏差值得谨慎地解释，尤其是当景观在空间上划分为小单元并且涉及火灾周期的时间变化时。

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