NEOTROPICAL (NEOTROPIC) BIOREGION: CLIMATE, VEGETATION, FAUNA - ENVIRONMENT - 2024

The neotropical or neotropic bioregion is the name given to an extension of territory, ecosystems, fauna and flora that extends from Mexico to southern Brazil, covering all of Central America, the Caribbean and almost all of South America, although some studies include the entire Southern Cone.

The name of bioregion is attributed to it from the branch of biogeography and serves to differentiate it from other large bioregions of the world. The Neotropics is characterized by the high presence of tropical forests, great animal and plant wealth; well-marked seasons of rainfall and droughts throughout the year.

Neotropical bioregion

Due to the extension of what is considered the tropical bioregion, the territory that corresponds to each nation and its different ecosystems may present specific features that may not manifest in the same way in other places in the same ecozone.

The Amazon, which once accounted for a third of South America; The Cerrado and the Atlantic Forest are the largest plant bodies in the Neotropics.

Geologically, the Neotropics is distributed along three tectonic plates: the North American, South American and Caribbean plates.

Some mountainous or wooded territories with temperate characteristics, such as the Patagonian or Valdivian forests, are included within the tropical bioregion.

Origin of the neotropical or neotropic bioregion

The origin of the qualities that characterize the neotropical zone date back to the Paleozoic-Mesozoic period (between 200 to 135 million years), when the separation of the mega continent Pangea resulted in two large bodies: Laurasia and Gondwana.

What today corresponds to South America was attached to the African continent, separating during the Cretaceous; for this reason the Neotropics to date share similarities in vegetation with some African regions.

The consolidation of the American continent materialized during the Upper Cretaceous, 90 million years ago. The gradual rise of the Andes Mountains began to generate climate changes, drier and colder, in the hitherto unaltered Neotropical relief.

For millions of years, the South of the American continent had many periods of ice age, before settling a temperate climate with periodic rainfall.

Studies estimate that the neotropical region at some point presented characteristics different from today:

1- A sea level lower than the current one (up to 120 meters less), and the possibility that some current islands were connected to the continent.

2- The boundary of the moor fell to 1500 meters in the Andean region.

3- The average temperature of the sea was lower.

4- The end of the glacial period generated a drier climate.

Physical and climatic features of the Neotropics

The Andes mountain range is the main natural component, or macroenvironment, that divides the South American continent in the east-west direction, presenting an Amazonian and an Andean block, with greater diversity in altitudes and valleys.

The other macroenvironments represented in the Neotropical region are Brazil and Guyana; the sedimentary depressions of the Amazon, the Orinoco, and the Chaco-Pampeana plain; the extra-Andean Patagonia; el Monte and Sierra Pampeana.

The division into both blocks mentioned above, and their proximity to the equator, directly influenced the fauna and flora of each subregion within the American continent.

Tropical climates dominate most of the continent and the Caribbean, while maritime climates dominate to the south.

Research has even divided the neotropics into 47 different provinces, throughout the continent, in order to highlight the natural differences that the different portions of the territory present, despite being under a kind of common climatic mantle.

The importance of these differentiations shows situations within the Neotropics related to the rate of rainfall and droughts in different areas.

The western region of Colombia can present a rainfall index of up to 9000mm per year, while the Amazon basin has an average of 2000mm per year.

Wind directions are also a factor, and this is where the Andes Mountains play a fundamental role. Winds from the Atlantic maintain humid climates in the Amazon block, for example.

Neotropic vegetation

The natural conditions of the Neotropical bioregion do not allow it to present an equitable plant distribution in all its territories; reflecting the climatic zoning of the region.

However, the neotropical plant variety is one of the richest on the planet. The vegetation is characterized as follows:

1- Tropical forests (Brazil, Ecuador, Central America and southern Mexico), represent 44% of the region, with a predominance of tropical moist forests, followed by moist deciduous forests and mountain forests. This is the most common habitat of the neotropical fauna.

2- Savannas (Brazil, Colombia, Venezuela, Bolivia), cover 12% of the neotropical region and present more defined periods of drought. It is one of the most productive ecosystems (agriculture, livestock) and its quality as a habitat depends on the type of soil and relief that they present.

3- Andean herbaceous formations (Costa Rica, Peru), cover the Andean valleys and highlands above 3500 meters of altitude, distributed throughout the region in a north-south direction.

4- The Argentine Pampas and temperate prairies, present a gradient of desert, steppes and dry scrub. Vegetation not only present in the Southern Cone, but also in some regions of Mexico. They are not very productive habitats, although they present a particular fauna.

5- Wetlands, are the formations between terrestrial and aquatic ecosystems, such as riparian forests, mangroves and flooded savannas. They represent 4% of the entire Neotropical region.

Fauna

Like vegetation, animal diversity in the Neotropics is very rich, but it is marked by immediate environmental conditions, resulting in the presence of certain species in specific territories and their absence in others, as well as differences between species of the same family.

Most of the species of the Neotropics belong to mammals; variety of marsupials (opossums, raccoons), rodents, primates (monkeys), bears (frontin bear), felines (jaguar, jaguar, cunaguaro), bats, artiodactyls (deer, gazelle, wild boar), perissodactyls (horse, donkey, tapir), lagomorphs (rabbit), xenarthros (anteater, sloth, armadillo), sirenians (sea dog, manatee).

Among the birds you can find species of the condor and eagle family, and small and wild birds such as cocuyo or cardinal.

References

1. Antonelli, A., & Sanmartín, I. (2011). Why are there so many plant species in the Neotropics? Taxon, 403-414.
2. Eisenberg, JF (1989). Mammals of the Neotropics. Chicago: University of Chicago Press.
3. Ojasti, J. (2000). Neotropical Wild Fauna Management. Washington, DC: Smithsonian Institution.
4. Rull, V. (2011). Neotropical biodiversity: timing and. Trends in Ecology and Evolution, 1-6.
5. Udvardy, MD (1975). A Classification of the Biogeographical Provinces of the World. Morges: International Union for Conservation of Nature and Natural Resources.