Bowman David M J S, French Ben J, Prior Lynda D
School of Biological Sciences, University of Tasmania Hobart, TAS, Australia.
Front Plant Sci. 2014 Nov 4;5:590. doi: 10.3389/fpls.2014.00590. eCollection 2014.
By definition fire prone ecosystems have highly combustible plants, leading to the hypothesis, first formally stated by Mutch in 1970, that community flammability is the product of natural selection of flammable traits. However, proving the "Mutch hypothesis" has presented an enormous challenge for fire ecologists given the difficulty in establishing cause and effect between landscape fire and flammable plant traits. Individual plant traits (such as leaf moisture content, retention of dead branches and foliage, oil rich foliage) are known to affect the flammability of plants but there is no evidence these characters evolved specifically to self-immolate, although some of these traits may have been secondarily modified to increase the propensity to burn. Demonstrating individual benefits from self-immolation is extraordinarily difficult, given the intersection of the physical environmental factors that control landscape fire (fuel production, dryness and ignitions) with community flammability properties that emerge from numerous traits of multiple species (canopy cover and litter bed bulk density). It is more parsimonious to conclude plants have evolved mechanisms to tolerate, but not promote, landscape fire.
根据定义，易发生火灾的生态系统拥有易燃植物，这引发了一种假说，该假说由穆奇于1970年首次正式提出，即群落可燃性是易燃性状自然选择的产物。然而，鉴于难以确定景观火灾与易燃植物性状之间的因果关系，证明“穆奇假说”对火灾生态学家来说是一项巨大的挑战。已知个体植物性状（如叶片含水量、枯枝落叶留存情况、富油叶片）会影响植物的可燃性，但没有证据表明这些特征是专门为自燃而进化的，尽管其中一些性状可能已被次生修饰以增加燃烧倾向。鉴于控制景观火灾的物理环境因素（燃料生产、干燥度和火源）与由多个物种的众多性状（树冠覆盖度和枯枝落叶层堆积密度）产生的群落可燃性属性相互交织，证明自燃的个体益处极其困难。更简约的结论是，植物已经进化出耐受但不促进景观火灾的机制。
