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Sampling mangrove peat in the Southern Gulf of California

Mangrove forests, tropical coastal wetland ecosystems, are severely threatened by human activities,1 on local scales due to development and worldwide by sea level rise.2 They provide many important ecosystem services, including nursery habitat for fishery species,3 protection of coastal communities from storm surge damage,4 timber, and ecotourism.5 Mangroves are highly productive6 and contain more carbon per area than other tropical forests.7 This long-term carbon sequestration is the most important ecosystem service that mangroves provide on the global scale. Mangrove carbon is stored in deep layers of organic-rich sediment, or peat. In some forests, mangrove peat deposits have been found to extend more than 10 m below ground and back in time more than 10,000 years.8 However, little effort has been made to use careful sampling and mapping of mangrove peat to quantify carbon stocks. My research with the Gulf of California Marine Program aims to do so for the mangrove forests of Mexico.Watch Full Movie Online Streaming Online and Download

Belowground carbon storage may be spatially variable. Quantifying the amount of carbon in mangrove forests therefore requires some understanding of the geological and ecological processes that control fluxes of carbon into and out of the sediment. Of the many factors that may control carbon storage, I set out to examine two in this study: forest size and location in the forest. I hypothesize that large forests contain more carbon per unit area as they likely have a longer and more stable history of sediment deposition in any given location. I also hypothesize that the waterfront fringe zone will store less carbon per unit area than the landward hinterland zone because hinterland areas usually represent the older parts of the forest where a relatively large amount of sediment build-up has occurred over time. Earlier field work at one of our mangrove study sites supports this idea.9

In the summer of 2014, my colleagues and I sampled mangrove sediments in forests near the city of La Paz, BCS, in the southern Gulf of California. We sampled in a range of forests that varied in total area, and, in each forest, we sampled in both fringe and hinterland locations. Though our coring device could reach down to 3 m, the actual depth sampled varies from site to site, because hard material (such as limestone or sand) resisted the corer and thus marked the bottom of each of our core samples.