Resumen

TRAVIESO-BELLO, Ana Cecilia; MORENO-CASASOLA, Patricia  y  CAMPOS, Adolfo. Efecto de diferentes manejos pecuarios sobre el suelo y la vegetación en humedales transformados a pastizales . INCI [online]. 2005, vol.30, n.1, pp.12-18. ISSN 0378-1844.

Cattle ranching has a negative impact on wetlands, as it generally gives way to modifications of the hydroperiod, introduction of non native species and large amounts of cattle. Ranching is the most important economic activity in the state of Veracruz, in the Gulf of Mexico. This paper presents the results of studying the impact on soil and vegetation (hidrology alteration, introduction of non-native grasses and cattle) caused by different management practices as well as by abandonment of fields which were transformed from herbaceous freshwater wetlands into inundated pasture lands, in Veracruz, Mexico. Soil variables such as pH, organic C, total N, extractable P, concentrations of ionic K, Na, Ca and Mg, and moisture soil retention capacity were analyzed during the dry season. Three times a year, during the dry season, the wet season, and the cold winter months, aerial and subterranean biomass was quantified. Species richness and wetland species turnover were also evaluated. Management practices change species composition and decrease species richness. Excluding cattle increases richness during the initial years but later on numbers of species decrease; wetland species are not retained. Hydrological alterations reduce the period of time the inundation lasts, increases pH, change nutrient availability and reduce the ability of wetlands soils to retain humidity. It also changes biomass subterranean assignation. Introduction of non-native species also modifies nutrient availability and species richness. On the other hand, high numbers of heads of cattle reduce retention of soil humidity and modify the chemical composition of the soil. Different management practices produce a loss of the wetland attributes. These aspects should be taken into account before implementing cattle management practices that can alter the functioning of freshwater wetlands.

Palabras clave : Biomasa; Especies no Nativas ; México; Riqueza de Especies ; Variables Edáficas .