sedaDNA and pollen disclose treeline advancing and plant diversity trajectory under recent climate warming in southwestern Hengduan Mountains, China

• Published in: Quaternary science reviews Vol. 357; p. 109348
• Main Authors: Li, Kai, Yang, Yang, Shi, Shaolin, Liao, Mengna, Ni, Jian, Kong, Lingyang, Zhang, Enlou
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2025
• Subjects: Alpine vegetation; Climate warming; Hengduan Mountain; Plant diversity; Pollen; sedaDNA; Alpine vegetation; Pollen; Climate warming; Hengduan Mountain; Plant diversity; sedaDNA
• ISSN: 0277-3791
• DOI: 10.1016/j.quascirev.2025.109348

The ongoing climate warming has been casting unprecedented impacts on alpine ecosystems within the Hengduan Mountain (HDM), a globally renowned biodiversity hotspot. However, current knowledge of how alpine vegetation and plant diversity are responding to recent climate warming remains inadequate. Here, we conducted pollen and sedimentary ancient DNA (sedaDNA) analyses on a short sediment core from Tiancai Lake, located in the southwestern HDM, to explore the vegetation and plant diversity changes over the past four centuries. The results manifested that the regional vegetation composition has undergone obvious changes during this period. Specifically, the ratio of broad-leaved to coniferous taxa (B/C), as well as palynological richness and diversity, exhibited significant correlations with the increasing mean annual temperature, implying that alpine species in the southwestern HDM have been subjecting to recent climate warming trends. The sedaDNA results further illustrated watershed-scale vegetation turnover, characterized mainly by the replacement of Rhododendron scrub by Abies forest and the upward migration of the alpine ecotone. The establishment of alpine coniferous forest around Tiancai Lake occurred about 1880 C.E. Additionally, the trajectories of plant diversity on watershed scale were highly resembled the mean annual temperature variations during post-industrial warming, indicating that the plant diversity around Tiancai Lake should be highly sensitive to and controlled by climate changes. Concurrently, warming-induced alpine habitat degradation may be imperiling plant diversity in the Tiancai Lake region, despite the upward trend in palynological diversity observed in the southwestern HDM. [Display omitted] •Pollen and sedaDNA revealed alpine vegetation change since 1600.•The Abies forest established at ca.1880 around Tiancai Lake.•Alpine vegetation is subject to climate warming.•Climate warming and community succession regulated plant diversity.•Warming-induced alpine habitat loss have threatened specific alpine taxa. In the Hengduan Mountain region (HDM), a crucial hotspot for biodiversity, climate warming is impacting alpine ecosystems, yet current comprehension of plant responses to this warming remains inadequate. We analyzed pollen and sedimentary ancient DNA (sedaDNA) from sediments in Tiancai Lake to uncover the changes in vegetation and plant diversity over the last 400 years. Our findings indicate that the vegetation changes are linked to long-term warming trends. Specifically, the sedaDNA results reveal a transition from Rhododendron shrubs to Abies forests, along with an upward shift in plant communities. The diversity of plants surrounding Tiancai Lake appears to be closely correlated with temperature fluctuations. Although alpine plant diversity is increasing, the loss of alpine habitats due to warming poses a potential threat to certain alpine species in the southern HDM. These findings underscore the urgency for international cooperation to alleviate the impacts of climate change on alpine ecosystems.