A tenfold slowdown in river meander migration driven by plant life

Meandering rivers are diagnostic landforms of hydrologically active planets, and their migration regulates the continental component of biogeochemical cycles that stabilize climate and allow for life on Earth. The rise of river meanders on Earth has been linked to riverbank stabilization driven by the Palaeozoic evolution of plant life about 440 million years ago. Here we provide a fundamental test for this hypothesis using a global analysis of active meander migrations that includes previously ignored unvegetated rivers from the arid interiors of modern continents. When normalized by channel size, unvegetated meanders universally migrate an order of magnitude faster than vegetated ones. While providing irrefutable evidence that vegetation is not required for meander formation, we demonstrate how profoundly vegetation transformed the pace of change for Earth's landscapes, and we at last offer a mechanistic explanation for the radically distinct stratigraphic records of barren and vegetated rivers. We posit that the migration slowdown driven by the rise of land plants dramatically impacted biogeochemical fluxes and rendered Earth's landscapes even more hospitable to life. Therefore, the tenfold faster migration of unvegetated rivers may be key to deciphering the environments of barren worlds such as early Earth and Mars.

曲流河是水文活跃行星的典型地貌，它们的迁移调节着生物地球化学循环的大陆部分，稳定了气候并使地球上能够存在生命。地球上河流曲流的兴起与大约4.4亿年前植物生命在古生代的演化所驱动的河岸稳定有关。在此，我们利用对活动曲流迁移的全球分析对这一假说进行了一项基础检验，该分析包含了此前被忽视的来自现代大陆干旱内陆的无植被河流。当根据河道大小进行归一化时，无植被的曲流普遍比有植被的曲流迁移快一个数量级。在提供了曲流形成不需要植被的无可辩驳的证据的同时，我们展示了植被如何深刻地改变了地球地貌的变化速度，并且我们最终为贫瘠河流和有植被河流截然不同的地层记录提供了一种机制性解释。我们认为，由陆地植物的兴起所导致的迁移减缓极大地影响了生物地球化学通量，并使地球的地貌对生命更加适宜。因此，无植被河流快十倍的迁移速度可能是解读像早期地球和火星这样贫瘠世界的环境的关键。