Riverine Biogeomorphology

Summary

Biota has long been shown to influence surface processes, described already by e.g. Darwin (1899), and Rudemann and Schoonmaker (1938), but it has not been since recently that geoscience has taken a serious interest in understanding abiotic-biotic feedbacks. This is especially true for the influence of animals, also because humans have modified and limited animal distribution and density since thousands of years. Recent decades have seen an effort to re-introduce animals long-lost to ecosystems, with sometimes unforeseen consequences, an approach that is gaining fast traction within the context of ‘rewilding’. In this presentation, I take a closer look at animal ecosystem engineering, and make a case how we can use their ecosystem engineering capabilities to improve the apparent negative effects of our own (human) engineering legacy. I zoom into research on Beavers, which are one of the most influential mammalian ecosystem engineer, heavily modifying river corridor hydrology, geomorphology, nutrient cycling, and ecosystems, mainly through the construction of dams, which impounds flow and increases the extent of open water, from which most other ecosystem feedbacks follow. Other examples of river ecosystem engineering presented in this talk are net spinning Caddisflies, spawning Salmons, Crayfishes, and the Hippopotamus. I also introduce the influence apex predators can have on river-floodplain dynamics, with examples from the US (Wolf) and new research from Nepal (Tiger).