2026 CSDMS meeting-083
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Earth-casting: Understanding the Role of Invasive Ecosystem Engineers in Landscape Evolution Through Organic Matter, Microtopography and Erosion
Nate Lund,
(he/him),University of Minnesota St. Paul Minnesota, United States. lund1736@umn.edu
Kyungsoo Yoo, University of Minnesota St. Paul Minnesota, United States. kyoo@umn.edu
Geomorphology and ecology are tightly coupled, so much so we cannot understand one subject without knowledge of the other. However, historically, the role of soil fauna has been relatively understudied in erosion and landscape evolution modeling. My research centers on the experimental basis of this intersection through the role of invasive earthworms, both European and Asian species, in soil morphology and erosion. Based on our current understanding, these ecosystem engineers likely impact the evolution of the landscapes they inhabit, but there exist no models, whether empirical or physical, that are well suited to evaluate this question. As a result, current research is restricted to experimental field studies with limited spatial scale. A holistic landscape evolution and erosion model, informed by field observations, that integrates ecological parameters is needed. We propose a new framework for understanding these processes in which the introduction of ecosystem engineers, here invasive earthworms, impacts landscapes directly (and rapidly) through bulk-density-driven surface dilation and collapse and indirectly over time through changes in soil erosivity. For instance, when European earthworms invade earthworm-free forests, the natural organic layer, the O-horizon, is rapidly mixed with lower mineral material, creating a thick A-horizon with organic and mineral components. Organo-mineral associations in this new A-horizon increase bulk density and therefore result in surface collapse. Further, this new A-horizon has a reduced hydraulic conductivity, which likely increases runoff, and the loss of the O-horizon eliminates surface shielding, impacting long-term erodibility. We seek to use published and experimental data on soil bulk density, organic carbon, hydraulic conductivity, and soil morphology for different earthworm invasion states to quantify these ecology-driven landscape-scale changes. This framework is demonstrated using earthworms, but it may be expanded to other species with variable soil morphology impacts and depth dependencies. This conceptual framework will serve as a basis for future numerical model construction.
