Ask A Scientist

How do plants in the rainforest get enough carbon dioxide to live without people in that environment? 

Asked by: Angelina Zakrajsek
School: Glenwood Elementary School, Vestal
Grade: 5
Teacher: Mrs. Brunner
Hobbies/Interests: Enjoying nature, geocaching and hiking with family
Career Interest: Hoping to study life science


Answer from Valerie Imbruce

Grant Writer for Strategic Research Initiatives

Research area: Food systems, agroecology, food deserts, interdisciplinary learning Interests/hobbies: Cooking, knitting, nature walks, playing with my two little boys

Plants use carbon dioxide for photosynthesis and people exhale it as a byproduct of respiration, so it is no wonder you question how plants get the carbon dioxide they need in a depopulated area. But there is more to this story. Carbon dioxide moves between forests, soils, oceans, and the atmosphere in an interconnected global carbon cycle. And people do live in the rainforest!

The movement of carbon dioxide between terrestrial ecosystems like forests and the atmosphere occurs through the biological processes of photosynthesis and respiration in a roughly equal exchange on a yearly basis. While photosynthesis happens only in plants, algae and cyanobacteria, respiration occurs in all living organisms (plants included!). Carbon moves around in other ways, too. All living organisms contain carbon, so when they die and decompose, or if there is a fire, carbon moves from once-living organisms into the air. Clearing forests to make way for people to build roads, houses or farms releases carbon into the atmosphere. And burning fossil fuels like coal, natural gas and oil also adds carbon to the atmosphere because these fuels come from decayed plant and animal material that have been transformed over hundreds of millions of years. In fact, people are adding more carbon dioxide to the atmosphere by burning fossil fuels than can be taken up by photosynthesizing plants.

Once carbon dioxide is released into the atmosphere, it can move around far and wide. The average life-span of one molecule of carbon dioxide in the atmosphere is 5 to 120 years, but it could take tens of thousands of years for plants to uptake carbon dioxide emitted today. Carbon dioxide travels on a very large scale with weather patterns. Last year, NASA released a visualization of the global movement of carbon dioxide based on measurements of carbon dioxide concentrations in the atmosphere from May 2005 to June 2007 ( The video shows that the wind swirls carbon dioxide away from its sources around the globe, and that the explosive plant growth of the spring season in temperate areas like ours here in Binghamton greatly affects the movement of carbon dioxide as well.

The actions of people on one side of the world can affect the availability of carbon on the other side. At Glenwood Elementary School, you could be ingesting carbon from a banana grown near an Ecuadorian rainforest, and that rainforest could be getting carbon emitted from the bus that took you to school!

You can see more than 6,000 exotic plants, representing over 1,200 distinct species, at Binghamton University’s E.W. Heier Teaching & Research Greenhouses!

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Last Updated: 9/25/14