Data from: Islands in the ice: detecting past vegetation on Greenlandic nunataks using historical records and sedimentary ancient DNA meta-barcoding

Nunataks are isolated bedrocks protruding through ice sheets. They vary in age, but represent island environments in “oceans” of ice through which organism dispersals and replacements can be studied over time. The J.A.D. Jensen’s Nunataks at the southern Greenland ice sheet are the most isolated nunataks on the northern hemisphere - some 30 km from the nearest biological source. They constitute around 2 km2 of ice-free land that was established in the early Holocene. We have investigated the changes in plant composition at these nunataks using both the results of surveys of the flora over the last 130 years, and through reconstruction of the vegetation from the end of the Holocene Thermal Maximum (5528±75 cal yr BP) using meta-barcoding of plant DNA recovered from the nunatak sediments (sedaDNA). Our results show that several of the plant species detected with sedaDNA are described from earlier vegetation surveys on the nunataks (in 1878, 1967 and 2009). In 1967, a much higher biodiversity was detected than from any other of the studied periods. While this may be related to differences in sampling efforts for the oldest period, it is not the case when comparing the 1967 and 2009 levels where the botanical survey was exhaustive. As no animals and humans are found on the nunataks, this change in diversity over a period of just 42 years must relate to environmental changes likely being climate-driven. This suggests that even the flora of fairly small and isolated ice-free areas reacts quickly to a changing climate.冰原岛峰（nunatak）是指穿透冰盖的孤立基岩露头。其形成年代各异，但代表了冰封“海洋”中的岛屿生境，借此可长期研究生物的扩散与更替过程。位于格陵兰南部冰盖的J.A.D. Jensen冰原岛峰，是北半球最孤立的冰原岛峰——距最近的生物源地约30公里。该区域拥有约2平方公里的无冰土地，形成于全新世早期。本研究针对该冰原岛峰的植物组成变化展开分析，一方面梳理了过去130年间的植物区系调查数据，另一方面通过对冰原岛峰沉积物中提取的植物沉积古DNA（sedimentary ancient DNA, sedaDNA）开展元条形码测序，重建了全新世热盛期（Holocene Thermal Maximum）结束时（距今5528±75校准年）的植被状况。研究结果显示，通过sedaDNA检测到的多种植物物种，曾在该冰原岛峰此前的三次植被调查中被记录，分别为1878年、1967年与2009年的普查。其中1967年的调查检测到的生物多样性远高于其他所有研究时段。尽管这一差异可能与最早的1878年调查采样力度不足有关，但对比1967年与2009年的调查结果时该差异依然存在——这两次调查均为详尽全面的植物学普查。由于该冰原岛峰上从未发现动物栖息与人类活动痕迹，仅42年间的多样性变化必然与环境变化相关，且极有可能由气候驱动。这表明，即便面积狭小且地理位置孤立的无冰区植被，也能对气候变化做出快速响应。