Ecology and geomorphology - the search for a signature of life on Earth

As my lecture on  'Ecology and Geomorphology' demonstrated, there are many direct and indirect ways in which vegetation, animals and microorganisms influence geomorphology.  Beavers create dams which affect whole water courses, badgers burrow and cause huge amounts of sediment to be moved around hillslopes, whilst vegetation can protect many soil surfaces from wind and water-based erosion.  But does all this biogeomorphic effort actually add up to anything recognisable?  Is there a signature of life on Earth? These questions have received much attention from geomorphologists over recent years, as evidenced by this paper by Dietrich and Perron which is well worth looking at.  Read it and see what you think...

The search for a topographic signature of life.

Dietrich WE, Perron JT.  Nature 2006, 439: 411-418

Abstract

Landscapes are shaped by the uplift, deformation and breakdown of bedrock and the erosion, transport and deposition of sediment. Life is important in all of these processes. Over short timescales, the impact of life is quite apparent: rock weathering, soil formation and erosion, slope stability and river dynamics are directly influenced by biotic processes that mediate chemical reactions, dilate soil, disrupt the ground surface and add strength with a weave of roots. Over geologic time, biotic effects are less obvious but equally important: biota affect climate, and climatic conditions dictate the mechanisms and rates of erosion that control topographic evolution. Apart from the obvious influence of humans, does the resulting landscape bear an unmistakable stamp of life? The influence of life on topography is a topic that has remained largely unexplored. Erosion laws that explicitly include biotic effects are needed to explore how intrinsically small-scale biotic processes can influence the form of entire landscapes, and to determine whether these processes create a distinctive topography.