Spatial variability of coastal wetland carbon

Owers, CJ; Rogers, K; Mazumder, D; Woodroffe, CD

Spatial variability of coastal wetland carbon

Date

2017-12-09

Authors

Publisher

Coastal & Estuarine Research Federation

Abstract

Blue carbon ecosystems, particularly mangrove and saltmarsh, sequester more atmospheric carbon per unit area than any other natural system in the world. Variation in above and below-ground carbon storage, that relate to the expression of environmental processes across wetland landscapes, are yet to be adequately quantified. We proposed that vegetation structure was a significant control on some of the spatial variation in carbon storage, and that this was a function of the dynamic nature of vegetation change at a site. Initially vegetation structural complexity was delineated using innovative remote sensing techniques. Above-ground biomass of mangrove and saltmarsh were quantified by developing region-specific allometric relationships. Cores were extracted from wetlands on the basis of delineated vegetation complexity to characterise the variation in carbon storage within sediments to 2m depth. We found that above-ground biomass varied with vegetation structural complexity, such that tall mangrove contribute more than 65% of above-ground biomass at some sites. The influence of vegetation structure on below-ground carbon storage was only detected to a depth of 50 cm, however >50% of below-ground carbon exists below this depth. Spatial variation in below-ground carbon storage is primarily due to sedimentary factors associated with estuary evolution and geomorphic setting and the influence these factors have on vegetation distribution over the mid-late Holocene. Current approaches to carbon stock assessment, based on extrapolating mean values of carbon storage to national and global scales, oversimplify carbon stock variation and may significantly under or overestimate carbon storage. Systematic approaches to carbon stock assessments characterising carbon storage variation at various scales will provide required confidence necessary for carbon markets.

Keywords

Carbon, Ecosystems, Mangroves, Marshes, Wetlands, Plants, Biomass, Environment, Quaternary period

Citation

Owers, C. J., Rogers, K., Mazumder, D., & Woodroffe, C. D. (2017). Spatial variability of coastal wetland carbon. Paper presented to CERF 2017, "Coastal Science at the Inflection Point: Celebrating Successes & Learning from Challenges", November 5-9, 2017, Rhode Island Convention Center, USA. Retrieved from: https://cerf.confex.com/cerf/2017/meetingapp.cgi/Paper/2639"