Abstract A 24,000-year record of plant community dynamics, based on pollen and ancient DNA from the sediments (sedaDNA) of Lake Bolshoye Shchuchye in the Polar Ural Mountains, provides detailed information on the flora of the Last Glacial Maximum (LGM) and also changes in plant community composition and dominance. It greatly improves on incomplete records from short and fragmented stratigraphic sequences found in exposed sedimentary sections in the western Russian Arctic. In total, 162 plant taxa were detected by sedaDNA and 115 by pollen analysis. Several shifts in dominance between and within plant functional groups occurred over the studied period, but most taxa appear to have survived in situ. A diverse arctic-alpine herb flora characterised the interval ca. 24,000–17,000 cal years BP and persisted into the Holocene. Around 17,000 cal years BP, sedges (e.g. Carex) and bryophytes (e.g. Bryum, Aulacomnium) increased. The establishment of shrub-tundra communities of Dryas and Vaccinium sp., with potentially some Betula pubescens trees (influx ∼290 grains cm2 year−1), followed at ca. 15,000 cal years BP. Forest taxa such as Picea and ferns (e.g. Dryopteris fragrans, Gymnocarpium dryopteris) established near the lake from ca. 10,000 cal years BP, followed by the establishment of Larix trees from ca. 9000 cal years BP. Picea began to decline from ca. 7000 cal years BP. A complete withdrawal of forest tree taxa occurred by ca. 4000 cal years BP, presumably due to decreasing growing-season temperatures, allowing the expansion of dwarf-shrub tundra and a diverse herb community similar to the present-day vegetation mosaic. Contrary to some earlier comparative studies, sedaDNA and pollen from Lake Bolshoye Shchuchye showed high similarity in the timing of compositional changes and the occurrence of key plant taxa. The sedaDNA record revealed several features that the pollen stratigraphy and earlier palaeorecords in the region failed to detect; a sustained, long-term increase in floristic richness since the LGM until the early Holocene, turnover in grass and forb genera over the Pleistocene-Holocene transition, persistence of a diverse arctic-alpine flora over the late Quaternary, and a variable bryophyte flora through time. As pollen records are often limited by taxonomic resolution, differential productivity and dispersal, sedaDNA can provide improved estimates of floristic richness and is better able to distinguish between different plant assemblages. However, pollen remains superior at providing quantitative estimates of plant abundance changes and detecting several diverse groups (e.g. Poaceae, Cyperaceae, Asteraceae) which may be underreported in the sedaDNA. Joint use of the two proxies provided unprecedented floristic detail of past plant communities and helped to distinguish between long-distance transport of pollen and local presence, particularly for woody plant taxa.

中文翻译：

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来自极地乌拉尔 24,000 年的古老 DNA 和花粉记录揭示了北极和北方植物群落的时间动态

摘要 一项 24,000 年的植物群落动态记录，基于来自极地乌拉尔山脉 Bolshoye Shchuchye 湖沉积物 (sedaDNA) 的花粉和古代 DNA，提供了关于末次盛冰期 (LGM) 植物群的详细信息，并提供在植物群落组成和优势方面。它极大地改善了俄罗斯西部北极暴露沉积剖面中发现的短而破碎的地层序列的不完整记录。总共有 162 种植物分类群被 sedaDNA 检测到，115 种被花粉分析检测到。在研究期间，植物功能组之间和内部的优势发生了几次变化，但大多数分类群似乎在原位存活。一个多样化的北极-高山草本植物群以大约间隔为特征。24,000-17,000 卡年 BP 并持续到全新世。大约 17,000 卡年 BP，莎草（例如苔藓植物）和苔藓植物（例如 Bryum、Aulacomnium）增加。Dryas 和 Vaccinium sp. 的灌木 - 苔原群落的建立，可能有一些 Betula pubescens 树（流入 ∼290 粒 cm2 年-1），随后在大约 15,000 卡年 BP。森林类群，如云杉和蕨类植物（例如 Dryopteris fragrans、Gymnocarpium dryopteris）从大约 10 年开始在湖边建立。10,000 卡年 BP，随后从大约 10,000 年建立了落叶松树。9000 卡年 BP。云杉从大约开始下降。7000 卡年 BP。森林树木分类群的完全退出发生在大约。4000 cal years BP，大概是由于生长季节温度降低，允许矮灌木苔原和类似于当今植被镶嵌的多样化草本群落扩张。与早期的一些比较研究相反，来自 Bolshoye Shchuchye 湖的 sedaDNA 和花粉在组成变化的时间和关键植物分类群的发生方面表现出高度相似性。sedaDNA 记录揭示了该地区花粉地层学和早期古记录未能检测到的几个特征；自 LGM 到全新世早期植物区系丰富度持续、长期增加，更新世 - 全新世过渡期间草和杂草属的更替，第四纪晚期北极 - 高山植物多样性的持续存在，以及可变的苔藓植物区系时间。由于花粉记录通常受到分类分辨率、差异生产力和传播的限制，因此 sedaDNA 可以提供对植物区系丰富度的改进估计，并且能够更好地区分不同的植物组合。然而，花粉在提供植物丰度变化的定量估计和检测可能在 sedaDNA 中被低估的几个不同的群体（例如禾本科、莎草科、菊科）方面仍然具有优势。两种代理的联合使用提供了过去植物群落的前所未有的植物区系详细信息，并有助于区分花粉的长途运输和本地存在，尤其是木本植物分类群。