Newly Discovered Megafossil Flora Sheds Light on the Evolution of Northern Vietnam’s Vegetation
Vietnam is renowned for its rich plant species diversity and endemism, but the origins and evolutionary history of this exceptional biodiversity have long remained a mystery. A recent study conducted by researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences has provided valuable insights into the vegetation evolution of northern Vietnam. By analyzing a newly discovered megafossil flora from the late Miocene period in the Yen Bai Basin, the researchers have reconstructed the paleovegetation and climate, shedding light on the driving factors behind the region’s plant diversity.
A Glimpse into the Late Miocene Yen Bai Flora
The researchers meticulously collected and studied 302 well-preserved plant megafossil specimens, primarily leaves with intricate venation patterns. This comprehensive collection allowed them to identify 15 families, 20 genera, and 30 species that constituted the late Miocene Yen Bai flora. Among the dominant families were Fabaceae, Fagaceae, and Lauraceae, with a significant presence of Sapindaceae, Annonaceae, Euphorbiaceae, Anacardiaceae, Hernandiaceae, Malvaceae, and Betulaceae. These findings suggest that the vegetation during the late Miocene period in northern Vietnam comprised a mix of tropical evergreen and deciduous broadleaf forests, with a seasonal tropical forest composition.
Reconstructing the Paleoclimate of Yen Bai Basin
To gain a deeper understanding of the late Miocene environment in northern Vietnam, the researchers employed both the Coexistence Approach and the Climate-Leaf Analysis Multivariate Program. Through these quantitative methods, they reconstructed the paleoclimate of the Yen Bai Basin. The results indicated a warm and humid tropical monsoon climate, resembling the modern climate of the region. The study also revealed a relative stability of temperature seasonality and distinct seasonal variation in precipitation, with the only notable difference being lower dry season precipitation compared to the present. These findings suggest that a monsoon climate type has persisted in northern Vietnam since at least the Paleogene, with a notable development from the middle Eocene to the late Miocene and maximum intensification in the middle to late Miocene.
The Influence of the Asian Monsoon on Plant Diversity
The research findings highlight the significant influence of the Asian monsoon, characterized by seasonal precipitation patterns, on the evolution of plant diversity in northern Vietnam. The presence of a seasonal tropical forest in the late Miocene Yen Bai flora indicates the impact of monsoonal conditions on the composition of the regional vegetation. The study further suggests that this monsoon climate type has persisted in the region for millions of years, shaping the plant diversity and ecological dynamics of northern Vietnam.
Conclusion:
The newly discovered late Miocene megafossil flora from the Yen Bai Basin in northern Vietnam has provided valuable insights into the evolutionary history of the region’s plant biodiversity. The presence of mixed tropical evergreen and deciduous broadleaf forests during this period, along with the influence of the Asian monsoon, has played a crucial role in shaping the composition and diversity of vegetation in northern Vietnam. The study’s findings contribute to a deeper understanding of the factors driving plant evolution and provide a foundation for future research on the ecological dynamics of this biodiverse region.
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