Data from: Fifty thousand years of arctic vegetation and megafaunal diet

Although it is generally agreed that the arctic flora is among the youngest and least diverse on Earth, the processes that shaped it are poorly understood. Here we present 50 thousand years (kyr) of arctic vegetation history, derived from the first large-scale ancient DNA metabarcoding study of circumpolar plant diversity. For this interval we additionally explore nematode diversity as a proxy for modelling vegetation cover and soil quality, and diets of herbivorous megafaunal mammals, many of which became extinct around 10 kyr BP (before present). For much of the period investigated, arctic vegetation consisted of dry steppe tundra dominated by forbs (non-graminoid herbaceous vascular plants). During the Last Glacial Maximum (25–15 kyr BP), diversity declined markedly, although forbs remained dominant. Much changed after 10 kyr BP, with the appearance of moist tundra dominated by woody plants and graminoids. Our analyses indicate that both graminoids and forbs would have featured in megafaunal diets. As such our findings question the predominance of a late Quaternary graminoid-dominated arctic “mammoth steppe”.尽管学界普遍认为北极植物区系（arctic flora）是地球上最年轻、多样性最低的植物类群之一，但其形成演化过程仍鲜有研究阐明。本研究基于首个针对环北极植物多样性（circumpolar plant diversity）的大规模古代DNA元条形码测序（ancient DNA metabarcoding）研究，重建了距今5万年（kyr）以来的北极植被演化历史。在此时间跨度内，我们还额外探究了线虫多样性（nematode diversity），将其作为模拟植被覆盖、土壤质量以及大型草食巨型哺乳动物（herbivorous megafaunal mammals）食性的代用指标（proxy）——这类巨型哺乳动物中有许多在距今约10千年（kyr BP）前后灭绝。在本研究覆盖的绝大多数时段内，北极植被以旱生草原苔原为主，优势类群为非禾本科草本维管植物（forbs，即non-graminoid herbaceous vascular plants）。末次冰盛期（Last Glacial Maximum，25–15 kyr BP）期间，植物多样性显著下降，但非禾本科草本仍为优势类群。距今10千年之后，北极植被面貌发生显著转变：出现了以木本植物与禾本科草本（graminoids）为优势的湿生苔原。我们的分析结果显示，禾本科草本与非禾本科草本均可能出现在巨型草食动物的食谱中。据此，本研究结果对晚第四纪北极“猛犸草原”（mammoth steppe）以禾本科草本为主导的主流认知提出了质疑。