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Fluctuations in monsoonal climate on orbital‐ to millennial‐timescales have had a major impact on vegetation change in East Asia since the last deglaciation. However, the influence of centennial‐scale oscillations on the spatio‐temporal characteristics of vegetation and climate during the last deglaciation remains controversial. We present a well‐dated, decadal‐resolution pollen record from the sediments of annually laminated Lake Xiaolongwan in Northeast Asia, which reveals major orbital‐/millennial‐scale and minor quasi‐periodic, that is, ∼500‐year (yr) cyclic, vegetation changes from ∼19.96 to ∼10.79 Kyr ago (covering the last deglaciation). The ∼500‐yr cycles are characterized by alternations in broadleaved forest/boreal coniferous forest with tundra steppe representing warm and humid/cold and dry phases of the monsoonal climate. This cyclicity may be related to El Niño‐like/La Niña‐like state and low‐latitude atmosphere‐ocean processes, against the background of the long‐term trend of the deglacial climatic evolution. Our findings demonstrate a close relationship between ecosystem succession and climate change on centennial scale. Plain Language Summary: The East Asian monsoon climate influences around 50% of East Asia's land surface and ecosystems. Past dynamics of vegetation and monsoon climate on orbital‐, millennial‐ and centennial‐ scale across East Asia is essential for better understanding the processes and mechanisms of vegetation and climate changes. We present a pollen record from the annually laminated sediments of Lake Xiaolongwan in Northeast China, which demonstrates a significant quasi‐500‐yr cyclic pattern of vegetational changes, stacking on the orbital‐scale trend and millennial events, triggered by shifts in the East Asian monsoon linked to the El Niño–Southern Oscillation. Regional vegetation is not only affected by the deglacial‐ and millennial‐ scale climate changes, but also influenced by ∼500‐yr climate oscillations. These findings show that the regional vegetation responded sensitively to centennial‐scale changes in the monsoon climate. Key Points: Orbital‐scale climate warming is evidenced by alterations in broadleaved forests and boreal coniferous forests with tundra steppeMillennial‐ to centennial‐scale vegetation changes in response to monsoonal climate change in East Asia∼500‐yr vegetation cycles are triggered by East Asian monsoon changes linked to the El Niño‐Southern Oscillation [ABSTRACT FROM AUTHOR]

[Display omitted] • Four sections of subgenus Chamaecerasus plus six outgroup taxa were used to recover the main clades of Lonicera L. • Extensive cytonuclear discordance across sections of subgenus Chamaecerasus. • Results suggest merging L. korolkowii into section Coeloxylosteum , L. caerulea into section Nintooa and L. albiflora into subgenus Lonicera. • The genus Lonicera is estimated to have originated in the Early Oligocene (26.45 Ma). • Subgenus Chamaecerasus may have originated in Eastern Asia and Central Asia during the Late Miocene, with subsequent dispersal or vicariance across other areas. The genus Lonicera L. is widely distributed in the north temperate zone and is well-known for its high species richness and morphological diversity. Previous studies have suggested that many sections of Lonicera are not monophyletic and phylogenetic relationships within the genus are still poorly resolved. In this study, we sampled 37 accessions of Lonicera , covering four sections of subgenus Chamaecerasus plus six outgroup taxa, to recover the main clades of Lonicera based on sequences of nuclear loci generated by target enrichment and cpDNA from genome skimming. We found extensive cytonuclear discordance across the subgenus. Both nuclear and plastid phylogenetic analyses supported subgenus Chamaecerasus sister to subgenus Lonicera. Within subgenus Chamaecerasus , sections Isika and Nintooa were each polyphyletic. Based on the nuclear and chloroplast phylogenies, we propose to merge Lonicera korolkowii into section Coeloxylosteum and Lonicera caerulea into section Nintooa. In addition, Lonicera is estimated to have originated in the mid Oligocene (26.45 Ma). The stem age of section Nintooa was estimated to be 17.09 Ma (95% HPD: 13.30–24.45). The stem age of subgenus Lonicera was estimated to be 16.35 Ma (95% HPD: 14.12–23.66). Ancestral area reconstruction analyses indicate that subgenus Chamaecerasus originated in East Asia and Central Asia. In addition, sections Coeloxylosteum and Nintooa originated in East Asia, with subsequent dispersals into other areas. The aridification of the Asian interior likely promoted the rapid radiation of sections Coeloxylosteum and Nintooa within this region. Moreover, our biogeographic analysis fully supports the Bering and the North Atlantic Land Bridge hypotheses for the intercontinental migrations in the Northern Hemisphere. Overall, this study provides new insights into the taxonomically complex lineages of subgenus Chamaecerasus and the process of speciation. [ABSTRACT FROM AUTHOR]