Weldon James, Grandin Ulf
SLU, Institutionen för vatten och miljö Uppsala Sweden.
Ecol Evol. 2019 Mar 15;9(7):4275-4288. doi: 10.1002/ece3.5061. eCollection 2019 Apr.
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 to 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 ), has shown strong postdisturbance regeneration. The refuges may be important in the apparent ongoing recovery of the disturbed areas to a 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. : 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 -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.
干扰对北方森林植物群落的影响尚未完全明了，尤其是当不同干扰因素叠加时，干扰后可能会出现状态转变，进入另一种稳定状态。一个长期监测的半自然森林站点自2005年起遭受了强烈的风暴和树皮甲虫联合破坏，这为研究干扰后植被群落的发展提供了契机。先前的研究表明，可能会从 主导转变为 主导。我们分析了干扰前后的植被数据，以研究维管植物物种丰富度、多样性、性状和群落组成在多大程度上发生了变化。我们特别关注剩余明显未受影响区域（潜在避难所）和受干扰区域之间的差异，以及群落组成随时间的持续变化迹象，这些迹象可能表明即将发生状态转变。我们发现，避难区域内的植被群落在干扰期间基本保持完整。非避难区域在群落组成上与避难区域出现了分化，分类和功能多样性增加。尽管如此，落叶树种（尤其是 ）数量增加，但 仍表现出很强的干扰后再生能力。这些避难所在受干扰区域明显正在恢复到类似于干扰前的 主导状态中可能起着重要作用。这种快速恢复被解释为系统具有恢复力的证据，能够抵御潜在的向落叶主导状态的转变……我们的研究结果表明，即使在具有多种稳定状态的系统中，强大的联合干扰也可能不足以引发状态转变。作为对先前生态系统状态的一种生态记忆形式，避难区域的留存增强了 主导森林群落的恢复力。研究结果还证明了长期监测项目所产生数据的价值。
