Tropical Lowland Evergreen Forest Habitat

The Tropical Lowland Evergreen Forest is often known as the Neotropical Rainforest. This forest type is characterized by little or no seasonal water shortage and rather uniform warm and humid conditions. In the Neotropics, the Lowland Tropical Evergreen Forest occurs up to 900 m.

Structure of the Tropical Lowland  Evergreen Forest

The Tropical Lowland Evergreen Forest is structurally complex showing multiple layers along its vertical length. Scientists recognize 3 to 4 vegetative or structural layers each of which constitutes habitat for a tightly packed community of vertebrate and invertebrates.

  • The Understory: The understory includes a height between 5-20 feet (1.5-6 meters) above the floor. It is structurally variable and contains shrubs, dwarf palms, and saplings of various ages. The plant community in the understory is adapted to life under low light conditions.
  • The Midstory and Sub-Canopy: it is composed of trees of various heights. Trees in the sub-canopy are thought to be subdued by the taller trees of the canopy. Trees in the sub-canopy spend most of their lives waiting for the opportunity of an opening to grow through and be part of the canopy.
  • The canopy: Includes the top layer composed of tree crows and emerging trees. Trees reach heights of 25-30 meters with emerging trees of up to 60 meters.

The Tropical Lowland Evergreen Forest has been found to support an extremely high amount of plant species per hectare (>400 species in SE Peru). This forest supports many species of vines and epiphytes, which include orchids, bromeliads, and mosses.

Many species of vertebrates such as mammals and birds inhabit the various layers of the forest. However, the highest animal diversity is found in the megadiverse insect life that reaches thousands of species, many of which are still undescribed by science.

Forest Floor

In spite of a high plant and animal diversity supported by the Tropical Lowland Evergreen Forest, the forest soil is rather poor in nutrients. The leaf litter on the forest floor breaks down rapidly and the resulting nutrients are observed by the shallow plant roots close to the surface. Nutrients that are not absorbed by the roots are washed off downstream by the frequent rains. The Amazonian region is rather old and soils have been weathered by thousands of years.

Plant Characteristics

There are many species of trees in the Amazonian Forest some of which are huge and emerge above the canopy layer. Many trees, particularly the larger ones, have buttressed trunks for support and shallow roots to take advantage of nutrients found on the topsoil.

Bark on tropical trees is usually smooth and thin, instead of the thick textured bark of dry or temperate forests. Smooth bark prevents epiphytes and lianas from growing on the tree surface, as well as reducing the risk of fungal infection. Leaves are often waxy with drip tips to shed excess water and prevent nutrient loss.

Plant Adaptations

Many other Amazon plants have mutualistic relationships with insects and other organisms for self-defense, such as providing habitat or food for biting ants, which in turn protect the plant against attack from herbivorous insects.

Many tropical plants have developed chemical defenses. For example the famous rubber trees (Hevea spp.) and many other plants produce latex as defense. Other plants produce alkaloids, tannins, and other active compounds that protect the plant against insects, pathogens, and other animal predators.

Seed Dispersal Mechanisms

The Tropical Lowland Evergreen Forest supports an array of seed dispersal mechanisms that respond to the lack of wind in the region. Many plants have developed elaborate mutualistic relationships with insects and other animals whereby the two species benefit from the services of one another. For example, plants provide edible fruits so that birds, monkeys, and other large vertebrates consume and disperse the seed as they move through the forest.

Tambopata_Tropical Lowland Evergreen Forest
View of the canopy layer of a typical Tropical Lowland Evergreen Forest. Emergent trees above the canopy are a typical feature of this forest ecosystem.

 

Tropical Lowland Evergreen Forest
Side view of the vertical length of the Tropical Lowland Evergreen Forest in the southeastern Peru region. Notice the prevalence of palm trees in the understory and the midstory.

 

understory_Tropical Lowland Evergreen Forest
View of the forest floor and the understory.

 

buttressed_tree_Tropical Lowland Evergreen Forest
Buttressed trees are a characteristic feature of the Tropical Lowland Evergreen Forest.

 

References:


  • The Tropical Rain Forest. Marietta College. Marietta, Ohio. Retrieved 14 August 2013,
  • Newman, Arnold. The Tropical Rainforest : A World Survey of Our Most Valuable Endangered Habitat : With a Blueprint for Its Survival. New York: Checkmark, 2002.
  • Impact of Deforestation – Extinction. Rainforests.mongabay.com.

 

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