Thirty-five years of mangrove planting leads to measurable increases in blue carbon stocks in the Arabian Gulf

Context: Sustained mangrove planting over 35 years at Mubarraz Island (United Arab Emirates) allowed examination of blue carbon stock increases over decadal timescales. Aims: Investigate carbon storage in arid mangroves with implications for climate change mitigation and adaptation. Methods: Measured differences in carbon stocks among 2-, 6-, 10-, 17- and 35-year-old mangrove plantations. Key results: Total organic carbon content of upper 50-cm soil layers ranged from 51 to 159 Mg C ha⁻¹(mean: 99 ± 25 Mg C ha⁻¹) being lower than the global average but typical of arid mangroves. Soil organic carbon content was highest in surface soil layers (upper 4 cm) of 17 and 35-year-old plantations. Mangrove biomass increased from 20 ± 30 Mg ha⁻¹in 2-year-old stands to 479 ± 64 Mg ha⁻¹in 35-year-old stands. Total carbon stocks in mangrove biomass (excluding soil) increased from 9 ± 12 Mg C ha⁻¹in 2-year-old plantations to 209 ± 31 Mg C ha⁻¹in 35-year-old plantations. Conclusions: The 17.5 ha of planted mangroves represent a significant total blue carbon store of 1732 Mg C (39% in biomass, 61% in soil). Implications: Mangrove planting can measurably contribute to coastal carbon storage even in arid regions.