Fuel bed variation in coastal tropical freshwater forested wetlands in three disturbance regimes at La Encrucijada Biosphere Reserve, Mexico

Abstract

Tropical freshwater forested in coastal regions are rapidly disappearing as a result of wildfires caused by high accumulations of forest fuels, which can vary in quantity and availability. Therefore, the objective of this study was to characterize fuel beds in tropical freshwater forested wetlands with three levels of disturbance at El Castaño, La Encrucijada Biosphere Reserve. Seventeen sampling units were used to describe the structure of the forest’s fuel beds (canopy, sub-canopy, understory). Fallen woody material, surface litter, and fermented litter were characterized using the planar intersection technique. Diversity was composed of eight species of trees, two shrubs, five lianas, and two herbaceous species. The vertical strata were dominated by trees between 2 to 22 m high. The horizontal structure had a higher percentage of trees with a diameter at breast height between 2.5 and 7.5 cm (61.4%) of the total. The non-disturbed sites presented the highest arboreal density (2686 ind. ha −1 ). The richness and diversity of species showed that the Fisher, Margalef, Shannon, and Simpson α indices were higher in the undisturbed sites. The Berger-Parker index exhibited greater dominance in the site’s with high disturbance. Pachira aquatica showed the highest importance value index and was the largest contributor to fuel beds. The sites with the greatest disturbance had a greater accumulation of dead fuel beds, with the greatest accumulations of woody fuels in classes 1, 10, and 1000 h (rotten). This study contributes to defining the areas prone to fire in these ecosystems and designing prevention strategies.