Assemblage of vascular epiphytes associated to seasonally inundated forest in the Southeastern Mexico: challenges for its conservation

Acceso en línea sin restricciones

Wetlands are ecosystems characterized by a high level of biodiversity and among those most under threat from human activities. Tintal (seasonally inundated forest dominated by Haematoxylum campechianum L.) are a characteristic wetland of the Yucatan Peninsula, and have a long history of commercial exploitation. In both conserved and human-disturbed wetlands, differences in relation to species richness, diversity and degree of specialization are expected. The objectives of this study were to analyze the variations in the richness and abundance between preserved and human-disturbed tintales, and to identify relationships between the characteristics of the epiphyte assemblage and the tintal assemblage. The study was carried out at 21 tintal sites in the Yucatan Peninsula, 10 preserved and 11 human-disturbed. At each sampled tintal sites, two 100 x 8 m (800 m²) transects were randomly plotted, in which the vascular epiphytes were quantified and identified. All the phorophytes (any plant on which an epiphyte grows) within the transects were divided into three microsites (low and middle trunk section, and branches), and all vascular epiphytes were recorded in each one of these microsites. Species-accumulation curves, dominance-diversity graph, Hill series diversity indices and species richness were calculated. Similarity matrices were calculated taking into account the relative abundance and the presence absence of the species, and a similarity analysis was performed. To assess the effect of the three microsites and the conservation status of tintales a generalized linear model was applied. The similarity matrices between locations for vascular epiphytes and phorophytes were correlated. The richness and abundance of vascular epiphyte species were related to degree of conservation but not with the richness, evenness, density, average DBH and average height of forophytes. A total of 55 taxa of vascular epiphytes (51 angiosperms, 4 ferns), 12 families and 7051 individuals were registered. The Orchidaceae family was the best represented (26 species, 3225 individuals). In preserved tintales, 6396 individuals (90.71% of the total), belonging to 49 taxa and 9 families were recorded. There is a similarity of 45.07% between both types of tintales. The preferred microsite in preserved and human-disturbed tintales was the branches (47 species; 5262 individuals). The most abundant species of tree was H. campechianum (62.84% of the total). The tintales can be important reservoirs of vascular epiphytes (richness and abundance) and they can function as islands and sources of diversity in degraded land matrices. In addition to working on the restoration of disturbed tintales, it is also essential to protect preserved tintales, considering the ecological importance of the latter. The tree species H. campechianum must be considered as a key species in this ecosystem. eng