Bokhorst Stef, Huiskes Ad, Convey Peter, Aerts Rien
Netherlands Institute of Ecology, Centre for Estuarine and Marine Ecology, Korringaweg 7, 4401 NT Yerseke, The Netherlands.
BMC Ecol. 2007 Dec 19;7:15. doi: 10.1186/1472-6785-7-15.
Antarctic terrestrial vegetation is subject to one of the most extreme climates on Earth. Currently, parts of Antarctica are one of the fastest warming regions on the planet. During 3 growing seasons, we investigated the effect of experimental warming on the diversity and abundance of coastal plant communities in the Maritime Antarctic region (cryptogams only) and the Falkland Islands (vascular plants only). We compared communities from the Falkland Islands (51 degrees S, mean annual temperature 7.9 degrees C), with those of Signy Island (60 degrees S, -2.1 degrees C) and Anchorage Island (67 degrees S, -2.6 degrees C), and experimental temperature manipulations at each of the three islands using Open Top Chambers (OTCs).
Despite the strong difference in plant growth form dominance between the Falkland Islands and the Maritime Antarctic, communities across the gradient did not differ in total diversity and species number. During the summer months, the experimental temperature increase at 5 cm height in the vegetation was similar between the locations (0.7 degrees C across the study). In general, the response to this experimental warming was low. Total lichen cover showed a non-significant decreasing trend at Signy Island (p < 0.06). In the grass community at the Falkland Islands total vegetation cover decreased more in the OTCs than in adjacent control plots, and two species disappeared within the OTCs after only two years. This was most likely a combined consequence of a previous dry summer and the increase in temperature caused by the OTCs.
These results suggest that small temperature increases may rapidly lead to decreased soil moisture, resulting in more stressful conditions for plants. The more open plant communities (grass and lichen) appeared more negatively affected by such changes than dense communities (dwarf shrub and moss).
南极陆地植被面临着地球上最极端的气候之一。目前，南极洲部分地区是地球上变暖速度最快的地区之一。在三个生长季节里，我们研究了实验性升温对南极海洋区域（仅隐花植物）和福克兰群岛（仅维管植物）沿海植物群落多样性和丰度的影响。我们将福克兰群岛（南纬51度，年平均温度7.9摄氏度）的群落与西格尼岛（南纬60度，-2.1摄氏度）和安克雷奇岛（南纬67度，-2.6摄氏度）的群落进行了比较，并在这三个岛屿的每一个上使用开顶式气室（OTC）进行实验性温度操纵。
尽管福克兰群岛和南极海洋区域在植物生长形式优势方面存在显著差异，但整个梯度上的群落总多样性和物种数量并无差异。在夏季，各地点植被5厘米高度处的实验性温度升高相似（整个研究期间为0.7摄氏度）。总体而言，对这种实验性升温的响应较低。西格尼岛的地衣总覆盖度呈不显著的下降趋势（p < 0.06）。在福克兰群岛的草地群落中，OTC内的总植被覆盖度比相邻对照地块下降得更多，并且仅两年后OTC内就有两个物种消失。这很可能是先前夏季干旱和OTC导致温度升高共同作用的结果。
这些结果表明，小幅升温可能会迅速导致土壤湿度下降，从而给植物带来更具压力的条件。与密集群落（矮灌木和苔藓）相比，更为开阔的松植物群落（草和地衣）似乎受此类变化的负面影响更大。
