Forest Speaks

The greenhouse effect

On Barro Colorado, several research programs explore the effects of changes in the levels of greenhouse gasses. It is important to do these studies in the tropics, where most of the world's plant biomass is located.
Every year we pollute the earth's atmosphere with huge quantities of carbon dioxide (CO2)

The amount of CO2 in the atmosphere increased by 27% in the last 150 years and is expected to DOUBLE by the middle of the 21st century.

Carbon dioxide forms a "roof" over the earth's surface. Sunlight can still come in, but heat can't get out.

This is called the GREENHOUSE EFFECT. As it gets worse, we may expect:

  • higher than normal temperatures
  • severe weather patterns
  • melting polar ice that results in rising sea levels

When we cut down tropical forests more CO2 remains in the atmosphere, making the greenhouse effect worse.

Plants "eat" carbon dioxide. They use energy from the sun to change it into carbohydrates. This process is called photosynthesis.

Tropical forests "eat" a lot of carbon dioxide.

If we double the amount of CO2 in the atmosphere, will plants eat twice as much and grow twice as fast as they do now?


This high CO2 garden simulates a "natural" plant community. Plants in a community may react differently than isolated plants grown in pots.
Graduate student Juan Posada and Catherine Lovelock (post doctoral fellow, Above) measure the rate of photosynthesis of plants in these chambers, which are supplied with different levels of CO2.
Plants grown in high CO2 environments often have thicker leaves that may decompose more slowly than leaves grown in normal CO2.
Insects and other animals may have to eat more high carbohydrate leaves to get the same levels of protein and other nutrients that they need.
Catherine Lovelock and Damond Kyllo (graduate student) with assistant, Virginia Velez, showed that the roots of plants grown in high carbon dioxide environments have more mycorrhizae, a type of fungus that lives on the roots of plants and help the plant to absorb more nutrients.