IMPACT OF INUNDATION ON CARBON STORAGE IN SALT MARSH SOIL

Abstract

Considering nature’s own ability to sequester carbon, limited research is available on the influence of inundation as multidimensional factor on terrestrial carbon dynamics. This research is having a unique approach by investigating the correlation between relative seawater inundation duration (INDr) and carbon storage of salt marshes in the Eastern,- and Western Scheldt (The Netherlands) using the Tea Bag Index (TBI), which facilitates data comparison of biomes, ecosystems and soil types all over the world. Sampling sites, differing in INDr [0,4-20%], are compared in terms of decomposition measured by weighting litter bags. With these data, the decomposition rate constant k and the stabilization factor S are computed. The standardized litter is supplemented with location-specific, organic matter collected as floodmark from the selected salt marshes. In addition to this, decomposition data is further interpreted with a simple assessment of organic carbon concentrations, obtained by measuring soil organic carbon (SOC) fractions at a depth of 5-10 cm. Based on the negative correlation (R=-0,69) between the decomposition rate constant k and INDr, a positive effect of INDr on short-term dynamics of carbon input is seen in terms of carbon storage within the used INDr-scale [0,4-20%]. The effect size of the used INDr-scale [0,4-20%] on the decomposition rate constant k was ~0,010. In contrast to this, no correlation was established between the indicatives for long term carbon storage -the stabilization factor S and SOC fractions- and INDr [0,4-20%]. This finding is thereby suggesting the used INDr-scale [0,4-20%] not to have a significant effect on long term carbon storage in salt marshes. Although this outcome would ease the salt marshes’ management, further study is needed to understand the impact of INDr on carbon storage’s temporal and spatial variation. Follow-up research should especially unravel what factors are causing the relatively large variation as seen for the stabilization factor S [ranging between 0,127;0,477] and SOC [ranging between 0,7;12,4%] the most. Since the urgency to lower atmospheric CO2 concentrations is only increasing in time, the highest priority should be given to get better acquainted with the salt marshes’ discriminatory potential to store carbon and contribute to combat climate change.

Date of Award	27 Sept 2021
Original language	English
Supervisor	Dennis Uit de Weerd (Examiner), J van Belzen (External assessor) & Angelique Lansu (Co-assessor)