Norwegian Institute for Nature Research (NINA), FRAM - High North Research Centre for Climate and the Environment, Tromsø, Norway.
Department of Ecological Science, VU University Amsterdam, Amsterdam, The Netherlands.
Physiol Plant. 2023 Mar;175(2):e13882. doi: 10.1111/ppl.13882.
Arctic ecosystems are increasingly exposed to extreme climatic events throughout the year, which can affect species performance. Cryptogams (bryophytes and lichens) provide important ecosystem services in polar ecosystems but may be physiologically affected or killed by extreme events. Through field and laboratory manipulations, we compared physiological responses of seven dominant sub-Arctic cryptogams (three bryophytes, four lichens) to single events and factorial combinations of mid-winter heatwave (6°C for 7 days), re-freezing, snow removal and summer nitrogen addition. We aimed to identify which mosses and lichens are vulnerable to these abiotic extremes and if combinations would exacerbate physiological responses. Combinations of extremes resulted in stronger species responses but included idiosyncratic species-specific responses. Species that remained dormant during winter (March), irrespective of extremes, showed little physiological response during summer (August). However, winter physiological activity, and response to winter extremes, was not consistently associated with summer physiological impacts. Winter extremes affect cryptogam physiology, but summer responses appear mild, and lichens affect the photobiont more than the mycobiont. Accounting for Arctic cryptogam response to multiple climatic extremes in ecosystem functioning and modelling will require a better understanding of their winter eco-physiology and repair capabilities.
北极生态系统全年越来越多地受到极端气候事件的影响，这可能会影响物种的表现。隐花植物（苔藓和地衣）在极地生态系统中提供重要的生态系统服务，但可能会受到极端事件的生理影响或死亡。通过野外和实验室的操作，我们比较了七种主要亚北极隐花植物（三种苔藓，四种地衣）对单一事件和冬季中期热浪（6°C 持续 7 天）、再冻结、除雪和夏季氮添加的组合的生理反应。我们的目的是确定哪些苔藓和地衣容易受到这些非生物极端条件的影响，以及组合是否会加剧生理反应。极端条件的组合导致更强的物种反应，但包括特有的物种特异性反应。无论极端条件如何，冬季（3 月）休眠的物种在夏季（8 月）几乎没有表现出生理反应。然而，冬季的生理活动和对冬季极端条件的反应与夏季的生理影响并不一致。冬季极端条件会影响隐花植物的生理学，但夏季的反应似乎较温和，地衣对地衣的影响大于对真菌的影响。要在生态系统功能和建模中考虑到北极隐花植物对多种气候极端条件的反应，需要更好地了解它们的冬季生态生理学和修复能力。
