ECO-EVOLUTIONARY DYNAMICS
We investigate how evolutionary and ecological processes interact and feedback on each other, scaling from genotypes to ecosystems, in the context of global environmental change
Rapid evolution of Schoenoplectus americanus in coastal salt marshes
Using ‘resurrected’ seeds of the coastal marsh plant Schoenoplectus americanus as an eco-evolutionary model system (Vahsen et al. 2021, Evolutionary Applications),we investigate how plant traits can rapidly evolve in response to global environmental change and alter ecosystem-level dynamics. Coastal marshes provide important global ecosystem services yet are highly vulnerable to climate change. Plant responses to global change are important because plant growth contributes to the building of the soil surface elevation and promotes carbon sequestration. These plant responses have traditionally been understood to be primarily plastic. However, we have shown that plant traits are also strongly governed by genetic variation and rapid evolution. For example, descendant genotypes (ca. 2000-2020) allocated less biomass belowground and had shallower root depth distributions compared to ancestral genotypes (ca. 1930-1970) (Vahsen et al. 2023, Science). Evolution of plasticity is also a common (yet complex) response of S. americanus traits to global change drivers such as elevated CO2 and sea-level rise (Vahsen et al. 2023, New Phytologist).
Data-model integration for coastal wetland forecasting
We use data-model integration approaches as a quantitative framework for scaling processes from genotype to ecosystem. For example, using a marsh accretion ecosystem model we scaled the differences in traits between ancestral and descendant genotypes found in Vahsen et al. (2023, Science) to quantify the impact of evolutionary change on ecosystem function. We collaborate as a part of the Coastal Carbon Research Coordination Network to increase the accessibility of data and analytical tools needed to support the forecasting of carbon sequestration in coastal soils, and have recently released an R-package of a commonly used marsh accretion model accompanied with a manuscript detailing the model mathematics and dynamics (Vahsen et al. 2024, JGR: Biogeosciences).
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