Department of Ecological Science, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
British Antarctic Survey, Natural Environment Research Council, Cambridge, UK.
Glob Chang Biol. 2022 Feb;28(3):816-828. doi: 10.1111/gcb.15979. Epub 2021 Nov 19.
Human activity and climate change are increasing the spread of species across the planet, threatening biodiversity and ecosystem functions. Invasion engineers, such as birds, facilitate plant growth through manuring of soil, while native vegetation influences plant germination by creating suitable microhabitats which are especially valuable in cold and dry polar regions. Here we tested how penguin-derived nitrogen, several common Antarctic moss species and warming affect seed germination and growth of the non-native grass Agrostis capillaris under laboratory conditions. Experimental settings included a simulation of contemporary season-specific Antarctic light and temperature (2°C) conditions and a +5°C warming scenario. Mosses (Andreaea depressinervis, A. regularis, Sanionia uncinata and Chorisodontium aciphyllum) incorporated a range of nitrogen content and isotopic nitrogen signatures (δ N) due to variation in sampling proximity to penguin colonies. Moss species greatly affected time to germination with consequences for further growth under the simulated Antarctic conditions. Grass seeds germinated 10 days earlier among A. regularis compared to S. uncinata and C. aciphyllum and 26 days earlier compared to A. depressinervis. Moss-specific effects are likely related to microclimatic differences within the moss canopy. Warming reduced this moss influence. Grass emerged on average 20 days earlier under warming, leading to increased leaf count (88%), plant height (112%) and biomass (145%). Positive correlations were identified between moss and grass nitrogen content (r = 0.377), grass biomass (r = 0.332) and height (r = 0.742) with stronger effects under the warming scenario. Transfer of nitrogen from moss to grass was confirmed by δ N (r = 0.803). Overall, the results suggest a shift from temperature-limited to N-limited growth of invasive plants under increased warming in the maritime Antarctic.
人类活动和气候变化正在促使物种在全球范围内扩散，从而威胁生物多样性和生态系统功能。鸟类等入侵工程师通过施肥来促进植物生长，而本地植被通过创造合适的小生境来影响植物的萌发，这些小生境在寒冷和干燥的极地地区尤为有价值。在这里，我们在实验室条件下测试了企鹅衍生的氮、几种常见的南极苔藓物种和升温如何影响非本地草 Agrostis capillaris 的种子萌发和生长。实验设置包括模拟当代特定南极光照和温度（2°C）条件以及+5°C的升温情景。苔藓（Andreaea depressinervis、A. regularis、Sanionia uncinata 和 Chorisodontium aciphyllum）由于靠近企鹅栖息地的采样位置不同，其氮含量和氮同位素特征（δ N）存在差异。苔藓物种对萌发时间有很大影响，对在模拟南极条件下的进一步生长有影响。与 S. uncinata 和 C. aciphyllum 相比，A. regularis 中的草种子提前 10 天萌发，与 A. depressinervis 相比提前 26 天萌发。苔藓特异性的影响可能与苔藓冠层内的微气候差异有关。升温减少了这种苔藓的影响。在升温条件下，草平均提前 20 天出现，导致叶片数量（88%）、植物高度（112%）和生物量（145%）增加。在升温情景下，苔藓和草的氮含量（r = 0.377）、草的生物量（r = 0.332）和高度（r = 0.742）之间存在正相关关系，且升温情景下的相关性更强。从氮同位素（r = 0.803）证实了从苔藓到草的氮转移。总的来说，研究结果表明，在海洋南极地区变暖加剧的情况下，入侵植物的生长将从温度限制转变为氮限制。
