Fire disturbances are increasing under global climate change and ecological transformations of forests are occurring. Specifically, shifts from productive closed-canopy feather moss forests to low-productivity open-canopy lichen (Cladonia spp.) woodlands have been observed in boreal forests of eastern Canada. It has been hypothesized that high severity of fires would be the cause of this change, but this is difficult to validate a posteriori on mature forest stands. Because charcoal properties are affected by fire severity, we have put forward the hypothesis that the amount and physicochemical properties of charcoal (C, N, H, O, ash, surface area) would be different and indicative of a greater fire severity for open-canopy forests compared to closed canopy ones. Our hypothesis was partly validated in that the amount of charcoal found on the ground of closed-canopy forests was greater than that of open-canopy forests. However, the physicochemical properties were not different, albeit a greater variability of charcoal properties for open canopy stands. These results do not allow us to fully validate or reject our hypothesis on the role of fire severity in the shift between open and closed canopy stands. However, they suggest that the variability in fire conditions as well as the amounts of charcoal produced are different between the two ecosystem types. Furthermore, considering the role that biochar may play in improving soil conditions and promoting vegetation restoration, our results suggest that charcoal may play a role in maintaining these two stable alternative ecosystem states.

中文翻译：

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北方森林木炭特性与火后生产力之间的关系


在全球气候变化和森林生态变化的情况下，火灾干扰不断增加。具体来说，在加拿大东部的北方森林中观察到从多产的封闭树冠羽毛苔藓林向低生产力的开放树冠地衣 （Cladonia spp.） 林地的转变。据推测，高度严重的火灾将是造成这种变化的原因，但这很难在成熟林分上进行后验验证。由于木炭特性受火灾严重程度的影响，我们提出了木炭的数量和物理化学性质（C、N、H、O、灰分、表面积）会有所不同，表明与封闭树冠森林相比，开阔树冠森林的火灾严重程度更高。我们的假设部分得到了验证，因为在封闭的树冠森林地面上发现的木炭数量大于开放树冠森林。然而，物理化学性质没有差异，尽管开放式树冠林分的木炭性质变化更大。这些结果不允许我们完全验证或拒绝我们关于火灾严重程度在开放式和封闭式树冠林分之间转换中的作用的假设。然而，他们表明，两种生态系统类型之间的火灾条件变化以及产生的木炭数量是不同的。此外，考虑到生物炭在改善土壤条件和促进植被恢复方面可能发挥的作用，我们的结果表明木炭可能在维持这两种稳定的替代生态系统状态方面发挥作用。