Shifts in Ecological Legacies Support Hysteresis of Stand Type Conversions in Boreal Forests
Shifts in Ecological Legacies Support Hysteresis of Stand Type Conversions in Boreal Forests
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生态遗产的变化支持北方森林林分类型转换的滞后性
DOI：
10.1007/s10021-023-00866-w
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发表时间：
2023
期刊：
影响因子：
3.7
通讯作者：
Mack, M. C.
中科院分区：
文献类型：
--
作者：
Walker, X. J.;Okano, K.;Berner, L. T.;Massey, R.;Goetz, S. J.;Johnstone, J. F.;Mack, M. C.
由于气候和人类活动的变化，许多干扰在严重程度、频率和程度上都在发生变化。干扰制度的改变会引发生态系统状态的变化，其中恢复到干扰前的生态系统是不确定的。在北美西部的北方针叶林中，野火的加剧可能会导致树冠优势从黑云杉(Picea Mariana)转向落叶乔木，如阿拉斯加纸桦(Betula Nealaskana)和颤杨(Pillius Tremuloides)。为了预测未来的森林动态，需要了解决定这些替代群落类型的复原力和稳定性的关键机制。在这里，我们评估了阿拉斯加内陆云杉到落叶为主的森林在火灾前梯度上的树木恢复模式，并量化了支持替代树冠类型弹性的成分和环境阈值。结果表明，林分在火后恢复到落叶优势林分的土壤深度(7.3 ± 5.5m)与火前组成相似，显著低于云杉(14.9 ± 9.0m)和混交林(10.4 ± 5.9m)。落叶为主的林分对火有很强的弹性，因为100%的林分在火灾后仍以落叶为主。即使落叶乔木只占火前林分的很小比例(12%)，但在野火过后，落叶乔木往往成为主导。我们的结论是，落叶芽库和种子源的建立造成了林分恢复的强烈滞后，从而增强了以落叶为主的北方针叶林对野火的韧性。考虑到这种替代稳定状态对野火的弹性，表明野火转移导致的从云杉到落叶优势地位的转变将对北方森林的未来结构和功能以及植被对气候变化的反馈产生长期影响。
Many disturbances are shifting in severity, frequency, and extent due to changing climate and human activities. Altered disturbance regimes can trigger shifts in ecosystem state where recovery to the pre-disturbance ecosystem is uncertain. In the western North American boreal forest, the intensification of wildfire can cause canopy dominance to switch from black spruce (Picea mariana) to deciduous trees such as Alaska paper birch (Betula neoalaskana) and trembling aspen (Populus tremuloides). Understanding the key mechanisms that determine the resilience and stability of these alternative community types is required for the prediction of future forest dynamics. Here, we assess patterns of post-fire tree recovery across a pre-fire gradient of spruce- to deciduous-dominated forests in Interior Alaska and quantify compositional and environmental thresholds that support the resilience of alternative canopy types. We found post-fire organic soil depth of stands on a recovery trajectory to deciduous dominance (7.3 ± 5.5 cm) were similar regardless of pre-fire composition and significantly shallower than spruce (14.9 ± 9.0 cm) or mixed trajectories (10.4 ± 5.9 cm). Deciduous-dominated stands were highly resilient to fire, as 100% remained deciduous-dominated post-fire. Even when deciduous trees only accounted for a small proportion (12%) of the pre-fire stand, deciduous trees often became dominant after wildfire. We conclude that the establishment of deciduous bud banks and seed sources creates a strong hysteresis in stand recovery that reinforces the resilience of deciduous-dominated boreal forests to wildfire. Accounting for the resilience of this alternative stable state to wildfire suggests that shifts from spruce to deciduous dominance caused by shifting wildfire will have long-term effects on future structure and function of boreal forests and vegetation feedbacks to climate change.
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3.1
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2.2
作者：
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通讯作者：
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作者：
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影响因子：
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