Environmental and anthropogenic factors associated with coastal wetland differentiation in La Mancha, Veracruz, Mexico

Abstract

At least 10% of the wetlands in Mexico are situated in the State of Veracruz on the central Gulf coast. The region has been intensively used for agriculture by humans for the last thousand years and today pastureland for cattle ranching is the dominant element of the landscape. We present a study of the wetland vegetation in a series of representative and internationally significant freshwater wetlands near the coastal lagoon La Mancha in Veracruz State. We obtained eleven wetland types formed by three wetland communities dominated by trees (mangrove or swamps), eight dominated by herbaceous species which we classified as marsh, five of which were native emergent marsh, one was a non-native emergent marsh and two were floating-leaved marsh. The highest diversity values were found in the Annona swamp, followed by the Sagittaria marsh and the Rhizophora-Laguncularia-Avicennia mangrove. CCA ordination showed that water level, disturbance and species number were the major factors explaining variation along axis 1, and on axis 2 conductivity, salinity, and bulk density. Wetland size was a major factor in both axes. We examined the interplay of intrinsic and extrinsic factors that give rise to the nature and diversity of wetland types that characterize the important wetland landscapes in this part of Mexico, being disturbance by human activities an important factor that favors the appearance of diverse species combinations.

Biogeochemical processes along a nutrient gradient in a tropical ombrotrophic peatland

“…Low diversity tree communities are typical of Central American wetlands (Keogh et al 1999;Ellison 2004;Ramberg et al 2006;Lopez and Kursar 2007). For example, the low diversity in San San Pond Sak is similar to that in forested wetlands in Mexico (Shannon index 1.95; Moreno-Casasola et al 2009) and lowland forest swamp in Costa Rica (Shannon index 1.99-2.56; Webb and Peralta 1998). The basal area in the R. taedigera swamp (site 1) was high (103 m 2 ha -1 , but note that this was a slight overestimation due to the multi-stemmed growth form) compared to previous reports of tropical forest swamps, including 80 m 2 ha -1 in French Guiana (Koponen et al 2004) and 63-58 m 2 ha -1 in Kalimantan, Indonesia (Page et al 1999).…”

Soil water retention and carbon pools in tropical forested wetlands and marshes of the Gulf of Mexico

“…Thus the ecological service of soil water storage provided by marshes and swamps was similar. Forested wetlands have been cut down and, because they remain flooded for a shorter period of time, they are usually the first wetlands transformed into inundated pastures (sensu Moreno-Casasola et al 2009). The soil water storage values obtained in this study are comparable with published values in previous work.…”

“…For example, the coastal wetlands in the Mexican state of Veracruz are threatened mainly by cattle ranching, petrochemical activities and urbanization. Natural freshwater wetlands are becoming rare as a result of the impact of human activities (Moreno-Casasola 2008); most freshwater wetlands show significant changes in their ecology, mainly in relation to species composition, invasion of exotic species, siltation, pollution and hydrological regime (Travieso-Bello et al 2005, López Rosas et al 2006, Escutia-Lara et al 2009, Moreno-Casasola et al 2009). This has resulted in high costs-in both lives and economic welfare-for local communities, mainly through increased flooding, decreased soil productivity and increased pollution by agrochemicals.…”

Un caso de éxito en la restauración de un humedal tropical mediante la evaluación del ensamble de larvas de Odonata (Insecta)

“…Vegetation structure depends, in turn, on the variations in water depth, temperature, water movement, physical and chemical properties of the substrate, salinity, water transparency and competition (Mitsch & Gosselink, 2007;Moreno-Casasola et al, 2009), which make wetlands highly heterogeneous systems.…”