Hydrology, Soil Carbon Sequestration and Water Retention along a Coastal Wetland Gradient in the Alvarado Lagoon System, Veracruz, Mexico

The Alvarado Lagoon System (ALS) is a wetland complex in the Gulf of Mexico, with different types of wetlands. We studied six wetland types that differ in species composition and dominant life forms: Rhizophora-Avicennia mangrove, Pachira aquatica freshwater forested wetland, Sabal mexicana flooded palm forest, two broad-leaved marshes (Pontederia sagittata marsh in Rio Blanco; Pithecellobium-Spartina marsh in Popoyeca) and a cattail (Typha domingensis) marsh. The hydroperiod data indicate that all wetland types are flooded for several months of the year, the palm forest having the longest period of time without inundation. Significantly higher (p <= 1).05) carbon stocks at a depth of 1 m and soil water storage were recorded for the forested wetlands (60 6 kg C m(-2), 889 L m(-3) respectively) and P. sagittata broad-leaved marshes (67 +/- 9 kg C m(-2), 882 L m(-3)). The lowest values were recorded for the flooded palm forest (16 +/- 5 kg C m(-2), 533 L m(-3)) and the mangrove (16 +/- 2 kg C m(-2), 463 L m(-3)). This makes the ALS an important provider of ecosystem services, most notably via its freshwater forested wetlands and marshes. Draining these wetlands for agricultural purposes could lead to differing degrees of change in the soil's hydraulic characteristics, such as a decrease in its capacity to retain water and the loss of organic matter, and therefore a reduced capacity for carbon storage.