Tropical MorphologyHow Plants Adapt To Rain Forest

The University of GeorgiaCollege of Agricultural and Environmental Sciences

Root & Stem Structures

Adaptation To Soft, Wet Soils

About The Author

• Dr. Paul A. Thomas– Professor of Floriculture– Department of Horticulture– The University of Georgia– Extension Specialist – Really into Photography!

Hope you enjoy my images

Learning Objectives

• 1. Describe the ways plant roots compensate for the often, wet, soft, loose soils that are common in the rainforest.

• 2. Understand the relationship between soil, water and how leaf litter and plant roots prevent erosion.

Most rainforests form in association with loose, porous, easily eroded soils. To survive, plants must deal with

the rainfall and somehow maintain stability.

A thin layer of organic debris protects the fragile, volcanic soils of Costa Rica from the force of rain.

The volcanic rainforest is often characterized by steep slopes.

Small ravines can wash out quickly if soil cover is disturbed or removed by bad farming practices

Disturbed SoilsUndisturbed soils

Stilt roots are one adaptation that allows support in wet/loose soils

An Example of a Buttress Root

Inland plain trees must also adapt to moist, soft but now more dense

volcanic soils.

Pandanus, or Screw Pine Prop Roots

Ficus trees have “Aerial Roots” that form in the canopy and then fuse or merge and

form a larger, spreading trunk!

Red Ginger forms colonies that share a root system to form a huge matt.

Palm tree trunks form masses of very long roots that originate near the base of the stem and force their

way down into the ground and then fan out.

Banana roots extending out along the surface of the leaf litter to increase the base support in wet soils.

Summary

We have seen that the plants have developed a common root system adaptation, or theme. The use of stilt , prop, aerial or spreading roots to increase stability, rather than employing tap or deep roots, is a direct response to the rainfall and loose soils in Costa Rica, rather than to the just soil type.

Assessment Opportunity

• Explain why an Oak tree in the United States might have a deep root system, and a Banana might have a shallow, wider root system in Costa Rica. What do they share in common? What is different?

• Explain why slash and burn deforestation is so devastating to tropical soils? What would be a better way to harvest wood and plant crops?

For Future Exploration

• http://www.k12connections.iptv.org/pdfs/WelcometotheRainforest.pdf

• http://www.fao.org/docrep/005/Y4632E/y4632e0a.htm

• https://www.cia.gov/library/publications/the-world-factbook/geos/cs.html