Intertidal wetland sediment carbon budgets along eroding and prograding coasts

Stolpmann, Lea Marlene Merle (2024) Intertidal wetland sediment carbon budgets along eroding and prograding coasts. PhD thesis, University of Glasgow.

Abstract

Coastal ecosystems are vital in providing ecosystem services such as coastal protection, habitat provision and increasing biodiversity. With increasing global atmospheric CO2 concentrations and a warming climate, their ability to sequester large amounts of carbon within their biomass and soil, relative to their occupied area, has been of increased interest. The soil carbon salt marshes and mangroves sequestered is however under threat due to anthropogenic impacts and processes changing the formation and development condition of these ecosystems. Insufficient sediment supply and rising sea levels are threatening to drown these systems and turn a healthy ecosystem into an erosional stage. In particular the effect of erosion on soil characteristics and processes has to be understood to determine the emission of carbon to the atmosphere and thus their carbon storage capacity. This thesis aims to determine 1) the effect of geomorphic condition on the soil to atmosphere emission of CO2 within salt marshes and mangroves, 2) the hydrodynamic influences on soil processes such as soil temperature within salt marshes, 3) the difference between carbon fluxes at salt marsh sites of differing geomorphic conditions. Geomorphic condition was found to significantly influence CO2 emissions at salt marsh sites, with eroding sites having a greater emission rate. The emission rate of CO2 was further influenced by the tidal cycle as well as the interaction of groundwater level and soil temperature. The effect of geomorphic condition on CO2 emissions was also studied within mangrove forests, showing however no significant relationship. Soil processes driving the remineralization of carbon to CO2, such as soil temperature was found to be influenced by tidal driven hydrodynamics (i.e., current velocity and groundwater levels) and to be seasonal dependent. Geomorphic different coastal ecosystems were further expected to receive carbon sources of different origins. Within the mangrove ecosystems these differences were observed within the soil cores at depth, indicating a change in carbon origin, although with site specific variations. Sediment deposited on a salt marsh flat was however only significantly different between geomorphic conditions in the percentage of inorganic carbon. The results emphasise the connectivity of coastal hydrology and wetland soil processes, not only driving the carbon delivery to the wetlands but also the processes influencing its storage and emission. The conservation and restoration of vegetated coastal habitats does therefore need to address this connectivity in order to maintain and preserve the immense carbon storage capacity of these ecosystems.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences; Q Science > Q Science (General)
• Colleges/Schools: College of Science and Engineering > School of Geographical and Earth Sciences
• Funder's Name: Natural Environment Research Council (NERC)
• Supervisor's Name: Bass, Dr. Adrian and Vovides, Dr. Alejandra
• Date of Award: 2024
• Depositing User: Theses Team
• Unique ID: glathesis:2024-84674
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 08 Nov 2024 12:47
• Last Modified: 08 Nov 2024 12:47
• Thesis DOI: 10.5525/gla.thesis.84674
• URI: https://theses.gla.ac.uk/id/eprint/84674

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