Carbon Stocks and Organic Matter Composition in Coastal and Lake Wetlands in Peru


Mangrove ecosystems are vital for storing large amounts of organic carbon (Corg) in their sediment, making them crucial natural carbon sinks. Although mangroves growing in arid regions can survive extreme conditions of low precipitation, high solar radiation, wide temperature fluctuations, and mangroves have distinct geomorphology, hydrology, forest structure, tree physiology and soil biogeochemistry of mangroves. Most estimates of carbon sequestration and stocks in mangrove forests have been derived from mangrove forests in the southern sites wet tropics. Whether those growing in the arid tropics contribute significantly to carbon sequestration remains an open question. Past assessments of mangrove carbon stocks  were mainly limited to a certain carbon stock component (biomass carbon). There has been more attention paid to monitoring mangrove vegetation representing the aboveground biomass stock, but estimation of the soil carbon stock remains insufficient. To better understand the blue carbon sink of mangrove ecosystems, the organic carbon stock of three  mangroves: San Pedro de Vice (Piura), Chulliyache (Piura), and San Felipe de Vichayal Mangrove (Paita, Piura), and a lake soil, Laguna Napique (Piura, Peru) was analyzed. The mean total Corg stock in San Pedro de Vice (78. 8 ± 17. 9 Mg C ha-1) is twice as high as the lake soil Napique (36. 7 ± 21. 7 Mg C ha-1). However, Chulliyache displayed a little difference (25. 1 ±  13. 1 Mg C ha-1) more than San Felipe de Vichayal (24. 6 ± 23. 7 Mg C ha-1 ). The predominant accumulation of aquatic and high plant material likely contributed to higher carbon stock in San Pedro de Vice and Laguna Napique. Globally, the carbon stock in Piura mangroves is below average. The relatively low carbon stock could be due to extreme environmental  conditions such as low rainfall, nutrient limitation, and high temperature, reducing and increasing soil respiration rates. These mangroves have more negative high d15N and d13C values compared to subhumid and humid mangroves. Further studies in arid mangroves are needed as the current global carbon stock estimates do not take into account the effect of mangrove migration and carbonate offset of these systems.