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This work describes the floristic composition, ecology and diversity of marshes along the central coastal plain of Veracruz, from Tecolutla to the lowlands of the Papaloapan River, where more diverse sites were found (highest value in Conejo Lagoon). Eleven localities were sampled and 95 species were recorded (41 families and 74 genus). The classification (hierarchic Beta Flexible) grouped species in nine types and annual hydroperiods were represented graphically for each type. PCA explained 47.81% of the variation and samples showed a gradient in species richness from northern and central sites towards the Papaloapan as well as a soil gradient from Gleysols to Histosols (predominating in Papaloapan). The great variability in species composition and dominance suggests that they form a landscape complex with different combinations of monocotyledons and dicotyledons which should be named popal-tular.

Se describe la composición florística, diversidad y ecología de humedales herbáceos de la planicie costera de Veracruz, entre Tecolutla y la cuenca baja del río Papaloapan, teniendo éstos últimos mayor diversidad, principalmente laguna Conejo. Once localidades fueron muestreadas, encontrándose 95 especies (41 familias y 74 géneros). La clasificación jerárquica Beta Flexible conformó nueve grupos; para cada uno se graficó el régimen de inundación anual. La ordenación por componentes principales explicó el 47.81% de la variación mostrando un gradiente de riqueza de especies de los sitios de la zona norte y centro hacia los del Papaloapan, así como un gradiente de suelos Gleysol e Histosol (predominando histosoles en el Papaloapan). Existe gran variabilidad en la composición florística y dominancia de los humedales herbáceos emergentes y se considera que forman un complejo de riqueza de especies y combinaciones de monocotiledóneas y dicotiledóneas por lo que se sugiere usar el término popal-tular para denominarlos.

The expansion of alien invasive species is a worldwide threat that affects most ecosystems. Islands and freshwater ecosystems are among the most vulnerable to species invasion, resulting in reduced biodiversity. In this study, we aimed to explore the floristic composition of the aquatic vegetation in four lagoons in southeastern Cozumel and assess the occurrence and abundance of alien and potentially invasive plants. We found a total of 43 aquatic or underwater herbaceous species that are subject to periodic flooding. Cluster analyses grouped the lagoons into two groups according to their floristic composition. The results demonstrate that alien and potentially invasive plants were dominant in 3 of the 4 lagoons, representing from 7 to 43% of the species. Six of these species were notably abundant, especially in three lagoons. Further, 2 species are considered among the 100 worst invasive species worldwide, although their abundance in Mexico remains relatively reduced. Five alien and potentially invasive species are terrestrial and grow on the shore of the lagoons, while one is aquatic. Urgent control and management actions are necessary. These should include (a) early detection and surveillance to determine if the alien species found behave as invasives; (b) understanding the relevance of invasive species; (c) preventing and intercepting; and (d) control and management. Habitat restoration, adequate legislation, collaboration between stakeholders, and raising awareness of the dangers of releasing or cultivating invasive species in the wild are also necessary.

The invasion of natural communities by exotic plants, which may turn into invasive or potentially invasive, is one of the most severe known threats to biodiversity, and coastal dunes are among the most affected habitats. Mexico’s coastal dunes are abundant and contain high plant biodiversity but attempts to determine the occurrence and impact of exotic plants are absent. First, we explored the number of invasive plant species found on Mexican coastal dunes. Second, we analyzed if the coastal dune flora native from Mexico acts as a source of invasive species worldwide. We found the relevant spread of exotic plants towards and from Mexico, reaching high percentages: 5% of the coastal dune flora are considered exotic plants; this increases to 8.7% when only plants typical of the coastal dune environment are considered. The Mexican coastal dunes flora is also a relevant source of invasive plants affecting all continents. Furthermore, almost half of the 35 worst worldwide invasive plants (according to the Global Invasive Species Database GISD) grow on Mexican coastal dunes, most native to Mexico and invasive elsewhere. Indeed, the worldwide exchange of coastal dune flora between Mexico and the world seems massive, relevant and highlights the need for worldwide and countrywide management and control strategies.

Debido a las condiciones físico-biológicas derivadas de su situación geográfica, México cuenta con una importante superficie cubierta por humedales, los cuales son considerados en la ley como reservas estratégicas de agua bajo la responsabilidad de la Comisión Nacional del Agua. En este estudio se desarrollaron dos niveles de caracterización: el primero en escala 1:250 000 aplicado a nivel de cuenca hidrográfica y el segundo en escalas de 1:25 000 a nivel de humedal. El primero comprendió la elaboración de dos mapas de uso de suelo y vegetación con base en imágenes de satélite. Uno con imágenes tomadas en 1979 y el otro con imágenes tomadas en 2003. De esta manera se obtuvieron los cambios en las coberturas de vegetación y uso de suelo en un intervalo de 25 años. El segundo nivel abarcó la elaboración del mapa detallado de uso de suelo y vegetación con imágenes de 2006 para el humedal Laguna de Alvarado. La comparación entre coberturas de 1979 y 2003 mostró cambios negativos en la clase hidrófila, cuerpos de agua y forestal, lo que constituye una seria amenaza a la sustentabilidad de los humedales.