Small steps, giant leaps - Building coastal landscapes with spatially organizing plants

Vegetated coastal ecosystems provide vital ecosystem services, including flood protection, water and carbon storage, and biodiversity enhancement. Over the last century, however, these ecosystems and their services rapidly declined, often due to anthropogenic disturbance. Although there is wide consensus that these losses should be halted and reversed, declines continue while restoration has proven very difficult. An important cause is that self-sustaining feedbacks generated by habitat modification (engineering) by the vegetation itself only work beyond a certain minimum vegetation patch size and density. Below these thresholds, unpredictable losses can occur, while (re-)establishment is hampered. Although patchiness is known to control engineering strength, it remains unknown how clonal plants spatially organize their shoots to form patches and optimize self-sustaining feedbacks, and how this affects coastal landscape dynamics. In this project, I will investigate how plants optimize patch formation, and develop novel patch- to landscape-scale ecosystem management indicators and restoration techniques utilizing this organization capacity. Specifically, I will test the novel hypothesis that clonally expanding coastal plants follow a specific shoot placement strategy, a so-called “random walk”, in which the underlying step size distribution between shoots controls a trade-off between engineering strength and expansion rate. Moreover, I will develop novel planting designs, and 3D-printed biodegradable establishment structures that manipulate shoot placement and environmental conditions to allow colonizing plants to bridge thresholds in otherwise unsuitable environments, while minimizing the required transplant material. I will focus on five species, two dune-building, two salt marsh and a seagrass species, that represent the entire temperate vegetated coastal gradient and exhibit contrasting expansion strategies. I will conduct surveys, collaborative field experiments with stakeholders, and spatially-explicit individual-based models to test ideas and solutions from shoot to landscape scale. The results will provide indicators for feedback-dependence of ecosystems, and allow harnessing of species-specific engineering and expansion capacities for their restoration.