Blue carbon stocks, accumulation rates, and associated spatial variability in Brazilian mangroves

Abstract

We assessed the influence of the intertidal and salinity gradients and mangrove forest structure on C stocks and sequestration rates in mangrove soils of an estuarine system in Todos os Santos Bay, Eastern Brazil. The accumulation rates of organic C (Corg) during the last century varied between and within estuarine zones, ranging from 65 to 1073 g Corg m−2 yr−1. The mean stocks of Corg and N for the top 1 m soils were 263 ± 14 Mg Corg ha−1 and 11.8 ± 0.4 Mg N ha−1, respectively. We found a less variable distribution pattern on Corg and N stocks throughout the salinity gradient than along the intertidal gradient, being significantly higher at the fringe mangroves than at the interior forest. We estimated that Brazil, one of the major reservoirs of mangroves (~ 10%) on the planet, has 207 ± 34 Tg Corg in the upper meter of soils, which represents 3–8% of the C stored in mangrove soils globally. Given that Brazil is a Blue Carbon hotspot, it is emphasized the urgent need for the establishment of better mangrove conservation practices and a comprehensive evaluation of their value in climate change mitigation and adaptation strategies for reducing CO2 emissions.

Carbon Removal Using Coastal Blue Carbon Ecosystems Is Uncertain and Unreliable, With Questionable Climatic Cost-Effectiveness

“…Whilst national or regional data would seem inherently more acceptable (by limiting the influence of large-scale environmental and biogeographic factors), local variability in carbon burial rates can also be very high. For example, Hatje et al (2021) found that the variability in measured burial rates for six intertidal transects of mangrove forest in a single Brazilian estuary was as great as the global range.…”

Determination of Trace Elements in Sediments Samples by Using Neutron Activation Analysis

“…Instead of sand, the soft ground is mostly formed of clay and silt (Sasmito et al 2020). The inputs of mangrove-derived organic matter into intertidal and river estuaries are important for a variety of fish and shellfish, including many commercial species, because nutrients are often adsorbed onto muddy sediment particles (Hatje et al 2020). In recent years, the pressures due to increasing population in coastal areas, food production, economic activities, and urban development have caused the resources of the world's mangroves to be degraded (Friess et al 2019).…”

Impacts of Climate Change on Blue Carbon Stocks and Fluxes in Mangrove Forests

“…Mangrove forests have the largest organic carbon (C ORG ) stocks of any of earth's ecosystems, with a global mean total forest stock of 692.8 ± 23.1 (±1 SE) Mg C ORG ha −1 (updated from [8] with [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]). Soil standing stocks average 516.4 ± 19.8 Mg C ORG ha −1 over the upper 1 m depth, accounting for 74% of total ecosystem standing stocks.…”

“…These large amounts of C ORG reflect rapid rates of soil accumulation on the forest floor, sustained accumulation over long time periods, and high rates of primary productivity. In contrast, global mean aboveground and belowground mangrove biomass average 105.8 ± 4.2 Mg C ORG ha −1 (±1 SE) and 68 Mg C ORG ha −1 , respectively, as updated from Alongi [8] with new data [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], which underscores the dominance of the soil component.…”