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Abstract：
The impact of disturbances on boreal forest plant communities is not fully understood, particularly when different disturbances are combined, and regime shifts to alternate stable states are possible after disturbance. A long-term monitored semi-natural forest site subject to intense combined storm and bark beetle damage beginning in 2005 provided an opportunity to investigate the postdisturbance development of the vegetation community. Previous studies suggest that a shift from Picea abies to Fagus sylvatica domination was possible.We analyzed pre- and postdisturbance vegetation data to investigate to what extent vascular plant species abundances, diversity, traits, and community composition have changed. We were particularly interested in differences between remaining apparently unaffected areas (potential refugia) and disturbed areas, and in signs of consistent change over time in community composition in response to disturbance that could indicate an impending regime shift.We found that the vegetation community present in the refuge areas has remained substantially intact through the period of disturbance. Nonrefuge areas diverged from the refuges in community composition and showed increased taxonomic and functional diversity. Despite this, and an increase in deciduous tree species (particularly F. sylvatica), P. abies has shown strong postdisturbance regeneration. The refuges may be important in the apparent ongoing recovery of the disturbed areas to a P. abies-dominated state similar to that found predisturbance. This fast recovery is interpreted as evidence of a system resilient to a potential shift to a deciduous-dominated state. Synthesis: Our results show that even powerful combined disturbances in a system with multiple stable states can be insufficient to initiate a regime shift. Resilience of the P. abies-dominated forest community is increased by the survival of refuge areas functioning as a form of ecological memory of the previous ecosystem state. The results also demonstrate the value of data generated by long-term monitoring programs.
摘要：
干扰对北方森林植物群落的影响尚未完全了解，特别是当不同的干扰组合在一起时，扰动后，政权可能会转移到交替的稳定状态。从2005年开始，长期监测的半自然森林遗址遭受了强烈的风暴和树皮甲虫的联合破坏，这为研究植被群落的扰动后发展提供了机会。先前的研究表明，从云杉云杉到Fagussylvatica的统治是可能的。我们分析了扰动前和扰动后的植被数据，以调查维管植物物种丰度的程度，多样性,性状,社区组成发生了变化。我们对剩余的明显未受影响的区域（潜在避难所）和受干扰的区域之间的差异特别感兴趣，并且有迹象表明，随着时间的推移，社区组成不断变化，以应对可能表明即将发生的政权转移的干扰。我们发现，在整个扰动期间，避难所地区的植被群落基本保持完整。非避难所地区在群落组成上与避难所不同，并显示出增加的分类和功能多样性。尽管如此,落叶树种（特别是F.sylvatica）的增加，冷杉显示出强烈的扰动后再生。避难所对于将受干扰的地区明显持续恢复到与发现的扰动前类似的以冷杉为主的状态可能很重要。这种快速的恢复被解释为系统能够适应向落叶主导状态的潜在转变的证据。综合：我们的结果表明，在具有多个稳定状态的系统中，即使是强大的组合干扰也不足以引发政权转移。保护区的生存作为先前生态系统状态的一种生态记忆形式，增加了以冷杉为主的森林群落的恢复力。结果还证明了长期监测程序产生的数据的价值。
