Evolution of river systems as plants colonized the land

植物在土地上殖民时河流系统的演变

• 批准号: 8437-2009
• 负责人: Gibling, Martin
• 金额: $ 5.61万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=450293
• 关键词: Evolution; river; systems; plants; colonized

The Paleozoic "greening" of the terrestrial surface as vascular plants colonized the landscape was among the most profound evolutionary changes in all of Earth history. Oceanic and atmospheric events during the early to mid Paleozoic have been widely linked to the spread of land vegetation, which decreased atmospheric CO2 , promoted global cooling, increased the runoff of nutrients to the oceans, and caused marine organisms to become extinct. Surprisingly, however, Paleozoic rivers barely feature in these discussions, even though early terrestrial plants colonized many river plains. Limited previous research suggests that, when river plains were unvegetated, channels inundated coastal areas with sand, but meandering rivers with muddy floodplains appeared in the Silurian as vegetation stabilized river banks. The present research programme aims to document river deposits through the crucial Cambrian to Devonian interval (540 to 360 million years ago), comparing the timing of events with what is known about the first appearances and abundance of early plants. Following a literature compilation, studies of river deposits and some of the world's earliest plant assemblages will be carried out at selected sites in North America and Europe. In younger Carboniferous rocks, we are studying the plants of river basins within mountain belts, in order to assess when plants spread into challenging inland areas: it seems, however, that they were there from the earliest days. We will also explore early evidence for wildfires, microbial contributions to river plains, and log jams that promoted channel switching once plants were sufficiently large and abundant.

古生代维管束植物在地表的“绿化”是整个地球历史上最深刻的进化变化之一。早古生代到中期的海洋和大气事件与陆地植被的扩张有着广泛的联系，陆地植被减少了大气中的二氧化碳，促进了全球变冷，增加了海洋营养物质的流失，并导致海洋生物灭绝。然而，令人惊讶的是，古生代河流几乎没有出现在这些讨论中，尽管早期陆地植物已经在许多河流平原上繁衍生息。先前有限的研究表明，当河流平原没有植被时，河道会用沙子淹没沿海地区，但随着植被稳定河岸，志留纪出现了带有泥泞漫滩的蜿蜒河流。目前的研究计划旨在记录关键的寒武纪到泥盆纪时期（540至3.6亿年前）的河流沉积物，将事件发生的时间与已知的早期植物的首次出现和丰度进行比较。在文献汇编之后，将在北美和欧洲的选定地点对河流沉积物和一些世界上最早的植物群落进行研究。在较年轻的石炭纪岩石中，我们正在研究山地带内河流盆地的植物，以评估植物何时扩散到具有挑战性的内陆地区：然而，它们似乎从最早的时候就在那里。我们还将探索野火的早期证据、微生物对河流平原的贡献，以及一旦植物足够大和丰富就会促进河道转换的原木堵塞。