Estimating the Effects of a Hurricane on Carbon Storage in Mangrove Wetlands in Southwest Florida

Lauren N Griffiths,William J Mitsch

doi:10.3390/plants10081749

Lauren N Griffiths, William J Mitsch

Open Access

https://doi.org/10.3390/plants10081749

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Abstract

Tropical and subtropical mangrove swamps, under normal conditions, can sequester large amounts of carbon in their soils but as coastal wetlands, they are prone to hurricane disturbances. This study adds to the understanding of carbon storage capabilities of mangrove wetlands and explores how these capacities might change within the scope of a changing storm climate. In September 2017, Naples Bay, FL, USA (28°5′ N, 81°47′ W) encountered a direct hit from hurricane Irma, a Saffir–Simpson category 3 storm. By comparing carbon storage, forest community structure, and aboveground productivity collected in 2013 and in 2019, we estimated the effects of hurricane Irma on mangrove functions. Aboveground biomass increased during the study period at a rate of approximately 0.72 kg m−2 yr−1, significantly less than the average found in undisturbed mangrove forests. Soil carbon storage decreased at all study sites. On average, 2.7 kg-C m−2 was lost in the top 20 cm between sample collections. Carbon loss in belowground pools could point to a feedback of mangrove swamps on climate change as they lose their ability to store carbon and increase net atmospheric carbon. Nevertheless, mangrove swamps remain resilient to tropical storms in the long term and can recover their carbon storage capacity in the years following a storm.

Highlights

Excess carbon dioxide in the atmosphere is a major global concern, causing increased atmospheric temperatures, rising sea levels, and theoretically more frequent intense storms, among other widespread issues [1,2,3,4]
The goal of this study is to gain a better understanding of soil carbon dynamics in mangroves and how this is affected by hurricane and tropical storm activity
This study analyzed carbon dynamics in mangrove soils and aboveground biomass in southwest Florida to help determine the effect of a singular Saffir–Simpson category

Summary

Introduction

Excess carbon dioxide in the atmosphere is a major global concern, causing increased atmospheric temperatures, rising sea levels, and theoretically more frequent intense storms, among other widespread issues [1,2,3,4]. The world’s wetlands have been estimated to sequester as much as 1 Pg-C yr−1 , which was, at the time, approximately 10% of the total carbon emitted from burning fossil fuels [5,6]. Mangroves are unique because, in normal conditions, they rarely emit the greenhouse gas methane unlike freshwater wetlands [7,11], making them important atmospheric carbon sinks. With climate change effects such as sea level rise and potential increased storm intensity coupled with human development, mangroves and their large carbon pools are at risk [6,10]

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