Key message

Above 40° N/S, increasing latitude is linked to greater post-fire tree regeneration. However, species dominance shifts from conifers to short-lived deciduous trees, which may negatively impact flora, fauna, and ecosystem services dependent on coniferous forests. These results were primarily driven by studies from North America, highlighting the need for more research that directly measures post-fire forest recovery in other high-latitude regions.

Context

As the size and frequency of wildfires increase across many regions, high-latitude forests may be at particular risk for decreases in regeneration and state shifts post-fire.

Aims

Through this systematic review, we sought to determine the general relationship between post-fire tree regeneration densities and latitude in forests above 40° N/S. We expected regeneration densities post-fire would decrease with increasing latitude, and that forest regeneration would be negatively impacted by high burn severities, forest management, harsh site conditions, and unprotected microsites. We also anticipated that light-demanding species with adaptations to fire would replace shade-tolerant species that lack such adaptations post-fire.

Methods

We conducted a literature search that returned over 4500 articles. We selected those that directly measured post-fire regeneration at or above 40° N/S and retained 93 articles for analysis. Fire characteristics, pre- and post-fire tree species compositions and regeneration densities, and regeneration predictors were then extracted from the retained articles. We fit linear mixed models to post-fire regeneration density with latitude and species traits as explanatory variables and also explored the significance and magnitude of predictors that informed post-fire tree species response.

Results

Contrary to our expectations, post-fire regeneration increased significantly with latitude. High burn severities and unprotected microsites had negative impacts on post-fire regeneration; higher elevations and more prolific pre- or post-fire reproduction were positively correlated with post-fire regeneration, while management of any type did not have an impact.

Conclusion

Although forests are regenerating after wildfires at the most extreme latitudes included in this study (above 55° N), regeneration is often limited to only a handful of genera: aspen (Populus) and birch (Betula), for example. Regeneration was less abundant at the lower range of our study area. Certain lower latitude forests that occupy marginal habitats are under increasing stress from drier, warmer conditions that are exacerbated by wildfires. Results were largely driven by studies from Canada and the USA and may not be applicable to all high-latitude forests.

中文翻译：

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高纬度地区火灾后森林恢复：树木再生以适应火灾的早期系列物种为主，随纬度的增加而增加

关键信息

北纬 40° 以上，纬度增加与火灾后树木再生能力增强有关。然而，物种优势从针叶树转移到寿命较短的落叶树，这可能会对依赖针叶林的动植物群和生态系统服务产生负面影响。这些结果主要是由北美的研究推动的，强调需要进行更多的研究来直接衡量其他高纬度地区火灾后的森林恢复情况。

语境

随着许多地区野火规模和频率的增加，高纬度森林可能面临着火灾后再生减少和状态转变的特别风险。

目标

通过这次系统回顾，我们试图确定北纬 40° 以上森林火灾后树木再生密度与纬度之间的一般关系。我们预计火灾后的再生密度将随着纬度的增加而降低，并且森林再生将受到高燃烧严重程度、森林管理、恶劣的场地条件和未受保护的微场地的负面影响。我们还预计，适应火灾的耐光物种将取代缺乏火灾后适应能力的耐荫物种。

方法

我们进行了文献检索，返回了 4500 多篇文章。我们选择了那些在 40° N/S 或以上直接测量火灾后再生的文章，并保留了 93 篇文章进行分析。然后从保留的物品中提取火灾特征、火灾前和火灾后树种组成和再生密度以及再生预测因子。我们将线性混合模型拟合到火灾后再生密度，以纬度和物种特征作为解释变量，并探讨了影响火灾后树种反应的预测因子的重要性和大小。

结果

与我们的预期相反，火灾后的再生随着纬度的增加而显着增加。高燃烧严重度和未受保护的微型场地对火后再生产生负面影响；更高的海拔和火灾前或火灾后更多产的繁殖与火灾后的再生呈正相关，而任何类型的管理都没有影响。

结论

尽管本研究中包括的最极端纬度地区（北纬 55° 以上）的森林在野火后正在再生，但再生通常仅限于少数属：例如白杨（杨）和桦树（桦）。在我们研究区域的较低范围内，再生不太丰富。某些占据边缘栖息地的低纬度森林正面临着越来越大的压力，这些压力来自干燥、温暖的环境，而野火又加剧了这种压力。结果主要是由加拿大和美国的研究得出的，可能不适用于所有高纬度森林。