Plant biodiversity and spatial heterogeneity influences on vegetation restoration in coastal wetlands

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Coastal communities are challenged by climate change. Sea level rise and increased storm severity threaten coastal infrastructure, supply lines for essential goods and services, and the overall sustainability of human life and native biodiversity in our region. Nature-based approaches such as ecosystem restoration can increase resilience to the effects of climate change. Current approaches to restoring coastal wetlands in Atlantic Canada rely on restoring tidal flow, which usually allows natural process and vegetation to return, but we have recently shown that active planting can speed up the recovery of habitat for fish and wildlife, as well as coastal protection functions. Past studies also suggest that restored tidal wetlands may lack features like sediment mounds, ponds and creek networks found in natural tidal wetlands, leading to poor recovery of biodiversity and coastal protection. Restored coastal wetlands may also be lower in plant diversity than natural wetlands. Increasing plant diversity via planting may help a wetland recover functions including the stabilization of sediment faster. The coastal wetlands along Nova Scotia's coastlines show great variation in tidal height (the difference between high and low tide water lines) as well as the amount of sediment in the water that helps wetlands build elevation to keep pace with sea level rise. My students and I will survey coastal wetlands across mainland Nova Scotia coastlines to determine how sediment amount and tidal height affects the types of plants that occur and the resilience of wetland vegetation to sea level rise. We will also conduct planting experiments to determine whether increasing the diversity of plant species helps the wetland build elevation and resist erosion. We will create features including sediment mounds and shallow depressions on bare mudflats to see whether this increases the trapping of seeds and helps plant establishment. We will also examine the role of the shape and size of larger features such as creek networks and vegetation patches to determine whether these features are related to the overall resilience of coastal wetlands. This research will lead to the improvement of restoration techniques for Atlantic Canada tidal marshes, and contribute to our fundamental understanding of the role of ecological processes in the development of resilient coastal ecosystems. This work will provide a stimulating training platform for six MSc students and seven undergraduate honours students.