La vegetación ribereña ha sido fuertemente fragmentado por acciones antrópicas modificando su estructura y sus funciones ecosistémicos. Se analizaron las variables de vegetación ribereña y su relación con las propiedades del suelo en un afluente del río Tacotalpa, Tabasco. A lo largo del cauce se seleccionaron tres zonas: baja, media y alta; en cada zona se establecieron ocho unidades de muestreo de 5x50 m y se censaron todos los árboles y arbustos con DAP≥1cm. Se identificaron las especies y se generó información sobre el índice de valor de importancia (IVI), diversidad de especies (Hʼ) e índice de similitud (IS). En cada unidad de muestreo se colectó una muestra de suelo a una profundidad de 0-30 cm, y se analizaron las propiedades textura, pH, materia orgánica (MO), nitrógeno total (Nt) y fósforo asimilable (P) y potasio (K). Las variables se analizaron con los paquetes estadísticos SPSS y PAST. En las tres zonas de vegetación ribereña se registraron 1681 individuos, 38 familias y 131 especies; las familias Fabaceae, Euphorbiaceae y Moraceae fueron las más representativas. La diversidad fue similar en las tres zonas y la similaridad osciló entre 31.3 y 53.3%. Los contenidos de Nt, MO y P fueron mayores en suelos de la zona alta con vegetación más conservada, y menores en las zonas baja y media con vegetación secundaria; estas variables edáficas se correlacionaron positivamente con la altura de los árboles (p<0.01), siendo evidencia del efecto benéfico de la interacción planta-suelo.

The cultivation of cocoa is a commodity of great importance worldwide. In Mexico, cocoa is grown in Tabasco and Chiapas states in agroforestry systems since pre-Hispanic times, where cocoa is grown under the canopy of shade trees. Crops such as sugar cane and extensive livestock production have gradually reduced the area devoted to cocoa cultivation in the region. Yet, farmers keep small portions of the cocoa agroforestry systems to maintain the local floristic diversity. This practice seems to be a successful contribution to plant conservation. To determine the management practices used by farmers in the agroforestry cocoa systems and the diversity of products they harvest, a non-probabilistic sampling was carried out in 38 shade cocoa plots of 20 × 50 m each (19 in Tabasco and 19 in Chiapas). We counted and identified all trees with DBH ≥ 5 cm, recording their height. We estimated canopy cover at 20 points within each plot. Our results show no tree species richness differences between states, but there were differences at the municipality level; Pichucalco (Chiapas) had the highest tree species richness. Considering all tree species, there was a higher tree density in Tabasco than in Chiapas. Regarding only cocoa trees, there was also a higher abundance in Tabasco than in Chiapas. In both cases, farmers obtain a wide variety of products for self-consumption and local market sale from their cocoa agroforestry systems (e.g., timber, fruit, grains). The wide floristic diversity in these agroecosystems aids native plant species conservation and could favor the increase of agroforestry plantations associated with cocoa cultivation.

The provision of valuable ecosystem services by tropical swamp forests (mainly carbon sequestration and storage in biomass and soil) explains their ecological importance. Current efforts toward the conservation of these ecosystems, however, face strong limitations as their spatial variation is largely unknown, particularly in regions where they occur over large areas. Here, we analyze the α-diversity (i.e., effective number of species or true diversity) and community structure variability of three tropical swamp forest communities distributed along an approximately 300 km long portion of the Usumacinta River Basin, southern Mexico. We sampled eighty-three 625-m2 plots to characterize the diversity and structural attributes of the woody plant communities. We recorded 2302 individuals belonging to 60 species and 25 families. Both α-diversity and structural attributes differed significantly among the three communities. The most inland community stood out for having the highest α-diversity for three true diversity values. Interestingly, the mangrove Rhizophora mangle L. was one of the dominant species, both in the swamp forest located closest to the coast and in the community farthest away from the sea. Basal area and density of individuals also had their maxima in the most inland swamp forest. The diversity and structural differences observed among the examined swamp forests seem to be related to contrasting environmental conditions, such as water salinity, distance to the coastline, and the hydrological dynamics of the Usumacinta River. We emphasize the urgency to conserve R. mangle populations in the swamp forest located farthest away from the coast due to its unusual habitat association, which appears to be a relictual condition.

Introduction: The spread of agricultural use leads to changes in vegetation cover, loss of biodiversity and ecosystem services. Objective: To analyze land use change and its effect on natural vegetation in the region of Los Ríos, Tabasco, Mexico, during the period 1947-2019. Materials and methods: A total of 14 land use and vegetation classes were identified using aerial photographs from 1947 and supervised classification of satellite images, verifying those from 1947 to 2000 with published cartography and those from 2019 (Landsat 8) in the field. Land use and vegetation cover change was analyzed by overlaying and comparing the maps with the Land Change Modeler module integrated in the TerrSet program. Results and discussion: In 72 years, natural vegetation was mostly replaced by crops, grassland and forest plantations, followed by human settlements. These uses, together, represented 14.2 % of the region’s surface and increased to 61.8 %; that is, an increase of 435 %. These uses replaced areas of rainforest, secondary vegetation and hydrophytes, which went from 82.3 % to 29.7 %, representing a loss of 64 % of these coverages. Between 1947 and 1984, natural vegetation suffered the greatest loss of area (53.7 %). Conclusions: The loss of natural vegetation in the region occurred because of the increase in agricultural land and human settlements. The increase in agricultural land was driven by government programs without considering the environmental factor.