General Biotic Components
Species Composition
Tropical dry forests are mostly less complex than wet forests. When considering relatively small plots of land (several Ha), as well as larger plots, dry forests possess around 50% or less tree species than wet forests, on average. Drier areas tend to show lower amounts of tree species. Tropical wet and dry forests do not tend to have many species in common. [3]. Studies in an area in Guanacaste Province, Costa Rica showed that adult tree species were not distributed in a uniform fashion in any species (as claimed by previous scientists), with 72% of species showing significant clumping. Juveniles also showed no such uniform dispersal pattern. The clumping patterns shown explain the past descriptions of widespread dispersal. In actuality, species that may have appeared to be rare (according to relatively smaller land samples) were actually not rare at all when a larger area of study was recorded. This clumping may be due to a variety of reasons, including the fact that areas where adults are located are already the most suitable microhabitats for the species’ survival. Species that were deemed rare may be stragglers from an earlier successional stage, and some may have established populations by random luck, but they definitely had less reproductive success than in areas where considered common. It was pointed out that just because a species has exhibited itself as most abundant in a community, does not mean that its high “importance” is due to dominant adaptations or success in competition between other species. [2]. Tropical dry forests are unique in the sense that they tend to have high rates of species endemism. In the Neotropical regions where Tropical dry forests are located, up to 20% of the occurrent species have been found to be endemic species. [4]. |
Life forms in tropical dry forests are exposed to a much wider spectrum of climatic conditions than those found in southern tropical wet forests. Species that occur in tropical dry forests encounter long periods of drought and often still experience low amounts of water even during wet seasons. Temperatures also tend to fluctuate much more in dry forests than compared with those of more stable wet forests. These conditions mean the species that live in tropical dry forests must be more resilient to changes in climate; many species have developed adaptations in order to survive more diverse conditions.
[4].
Successional Development and Soil Seed Banks
Vegetation structure and the make-up of seed banks in the soil were studied in different areas of Yucatán, Mexico. Various successional study sites include areas that were slashed, slashed-and-burned, or regenerating for either 1, 6, 10, 15, 30, 40, or 100 years. Approximately 33% of individuals grew from coppiced shoots, and 10/20 species identified account for over 50% of shrub density. This dominance is likely due to the fact that certain species are more able to withstand fires that are common in TDF. While only one species of tree seeds were found in the soil, herbs made up a large proportion of seeds in seed banks. In addition to this, the number of seeds that were germinating in slash-and-burn areas appeared to be double that of seeds in areas that were just slashed. The occurrence of fire most likely has an effect on dominance in early successional stages, allowing certain species’ seeds to germinate more successfully.
[7].
[4].
Successional Development and Soil Seed Banks
Vegetation structure and the make-up of seed banks in the soil were studied in different areas of Yucatán, Mexico. Various successional study sites include areas that were slashed, slashed-and-burned, or regenerating for either 1, 6, 10, 15, 30, 40, or 100 years. Approximately 33% of individuals grew from coppiced shoots, and 10/20 species identified account for over 50% of shrub density. This dominance is likely due to the fact that certain species are more able to withstand fires that are common in TDF. While only one species of tree seeds were found in the soil, herbs made up a large proportion of seeds in seed banks. In addition to this, the number of seeds that were germinating in slash-and-burn areas appeared to be double that of seeds in areas that were just slashed. The occurrence of fire most likely has an effect on dominance in early successional stages, allowing certain species’ seeds to germinate more successfully.
[7].