School of Arts, Sciences and Humanities, University of São Paulo, São Paulo, SP, Brazil.
Institute of Geosciences, University of São Paulo, São Paulo, SP, Brazil.
Sci Rep. 2024 Oct 1;14(1):22833. doi: 10.1038/s41598-024-72725-0.
Understanding the role of open vegetation, particularly in white-sand ecosystems (WSE) and savannas, is crucial for elucidating their role in Amazonian biotic diversification. These ecosystems predominantly develop on sandy terrains, suggesting that the geological substrate significantly influences the vegetation upon it. Therefore, the interaction between landscape changes and biotic diversification is closely tied to the dynamics and resilience of these sandy substrates. Current WSE and savannas in lowland Amazonia colonized fluvial sediments deposited during the past 120 ka, with marked synchronicity over the last 23 ka, as shown by optically stimulated luminescence (OSL) and radiocarbon ages of such sandy substrates. In contrast, sandy substrates supporting open vegetation in highland areas, unsuitable for Quaternary sand accumulation, would have persisted beyond the Quaternary, as ancient sedimentary rocks in these areas are prone to developing sandy soils. The current distribution of open vegetation ecosystems in lowland Amazonia is coupled with the deposition and erosion of sandy sediments by Quaternary fluvial systems, while weathering sandy substrates in highland areas serve as long-term and resilient refugia beyond the Quaternary. The contrasting spatiotemporal dynamics of landscape changes in lowland and highland areas has implications for biodiversification or extinction events leading to current biogeography patterns in Amazonia.
理解开阔植被的作用至关重要，特别是在白沙生态系统（WSE）和热带稀树草原，这对于阐明其在亚马逊生物多样性中的作用至关重要。这些生态系统主要在沙质地形上发育，这表明地质基底对其上的植被有重大影响。因此，景观变化和生物多样性之间的相互作用与这些沙质基质的动态和恢复力密切相关。当前低地亚马逊的开阔植被和热带稀树草原是由过去 12 万年来的河流沉积物所形成的，这些沉积物在过去 2.3 万年里具有明显的同步性，这可以通过这些沙质基质的光释光（OSL）和放射性碳年龄来证明。相比之下，在高海拔地区支持开阔植被的沙质基质不适合第四纪的沙质堆积，因为这些地区的古老沉积岩容易形成沙质土壤，因此它们可能会在第四纪之外继续存在。目前低地亚马逊开阔植被生态系统的分布与第四纪河流系统的沉积物的沉积和侵蚀有关，而在高海拔地区风化的沙质基质则作为第四纪之外的长期和有弹性的避难所。低地和高地地区景观变化的时空动态对比，对导致亚马逊当前生物地理格局的生物多样性或灭绝事件具有重要意义。
