Plant sedimentary ancient DNA data from Far East Russia

Woody plants are expanding into the Arctic in response to the warming
climate. The impact on arctic plants is not well understood due to the
limited knowledge about plant assembly rules. Past plant diversity over
long time series is rare. Here, we applied sedimentary ancient DNA
metabarcoding targeting the P6 loop of the chloroplast trnL gene to a
sediment record from Lake Ilirney (central Chukotka, Far Eastern Russia)
covering the last 28 thousand years. Our results show that forb-rich
steppe-tundra and dwarf-shrub tundra dominated during the cold climate
before 14 ka, while deciduous erect-shrub tundra was abundant during the
warm period since 14 ka. Larix invasion during the late Holocene
substantially lagged behind the likely warmest period between 10 and 6 ka,
where the vegetation coverage was densest. We reveal highest richness
during 28–23 ka and a second richness peak during 13–10 ka, with both
periods being accompanied by low shrub abundance. During the cold period
before 14 ka, rich communities were phylogenetically clustered,
suggesting low genetic divergence in the communities despite the great
number of species. This probably originates from environmental filtering
along with niche differentiation due to limited resources under harsh
environmental conditions. In contrast, during the warmer period after 14
ka, rich communities were phylogenetically overdispersed. This results
from a high number of species which were found to harbor high genetic
divergence, likely originating from an erratic recruitment process in the
course of warming. Some of our evidence may be of relevance for inferring
future arctic plant assembly rules and diversity changes. By analogy to
the past, we expect a lagged response of tree invasion. Plant richness may
overshoot in the short term; in the long-term, however, the ongoing
expansion of deciduous shrubs will eventually result in a phylogenetically
more diverse community.