Tree biomass and soil carbon stocks of a mangrove ecosystem on the Egyptian-African Red Sea coast

Abstract

Mangroves are key ecosystems in strategies addressing the mitigation of climate change through carbon storage in several countries around the world. The main objective of this study is to quantify the carbon storage (above- and below-ground) in the biomass and sediment of mangrove forests (Avicennia marina and Rhizophora mucronata), as well as to estimate the carbon sequestration potential in the Gebel Elba Protected Area along the Egyptian–African Red Sea Coast. The mean recorded soil bulk density in both mangrove species was 1.16 g cm–3, while the recorded mean soil organic carbon (SOC) content was 34.95 g C kg–1. The total mean SOC content was statistically higher in A. marina stands (39.66 g C kg–1) than in R. mucronata stands (33.15 g C kg–1 ). The total mean SOC density for A. marina and R. mucronata amounts to 40.60 kg C m–3. We recorded the carbon sequestration rate of mangrove forests in Egypt as 11.36 g C m–2 year–1 and the total carbon sequestration potential as 5.97 Gg C year–1. The average single tree biomass was notably highly variable between different mangrove species and sites, with a total average tree biomass of 164.8 and 43.7 kg tree–1 for A. marina and R. mucronata, respectively. The results show that the average total tree carbon content is 74.3 and 18.0 kg tree–1 for A. marina and R. mucronata, respectively. While the recorded tree below-ground biomass was 54.1 and 32.6 kg tree–1, and above-ground biomass was 110.7 and 11.1 kg tree–1 for A. marina and R. mucronata, respectively. The recorded average biomass per hectare of mangrove was 74997.1 and 22536.8 kg for A. marina and R. mucronata, respectively. Moreover, the average total tree carbon content per hectare was 33782.3 and 9304.7 kg for A. marina and R. mucronata, respectively. However, for Egypt mangroves (525 ha), the total organic carbon content amounts to 17.73 Gg C for biomass and 5.97 Gg C year–1 for soil, with total of 23.7 Gg C of organic carbon content storage in the mangrove ecosystem in Egypt.