Cave Trees

Introduction

When looking at trees, people usually only see the top half. This Science Update discusses how some scientists are using caves as windows into trees' subterranean life.

Podcast

Cave Trees

Transcript

Probing the secret life of trees. I’m Bob Hirshon and this is Science Update.

Most of what we know about trees comes from carefully observing and analyzing just the top half. This is according to ecologist Rob Jackson, at Duke University.

Jackson:
"But there's a whole other half of the plant below ground that we really don't have any way to do that with."

So he and his colleagues are using caves as windows into trees' subterranean life.

Jackson:
"The caves provide a way to have access to the trees, to the plants, and then to be able to do in-situ or real-time measurements down in their world rather than in ours."

Jackson and his colleagues explored nineteen caves in central Texas, ranging in depth from less than 20 feet to over 200. From the roots that poked their way into the caves, they took tissue samples. Using DNA analysis, they then matched the roots to the species growing on the surface.

Jackson:
"We can now go in and basically do physiological studies with the plants that we have there. We can also start to ask what resources plants are getting from what depth."

Dr. Jackson says these roots help shape how fresh water flows deep underground, and how it cycles back up into our environment at the surface. He says that understanding them is critical to managing freshwater aquifers, and modeling how the world may be affected by climate change.

For the American Association for the Advancement of Science, I’m Bob Hirshon.

Making Sense of the Research

Although trees are very common organisms, there is much that remains unknown about them. One reason is that half of every tree is buried underground. In this story, a researcher goes into caves to study trees from the bottom up, looking at their roots, how deeply they grow, and how they interact with water sources deep underground.

The tree is also part of an ecosystem, especially with regard to water resources. From the standpoint of scientific inquiry, you can think about other organisms that may be difficult to study, and what methods or instruments scientists might use to overcome these difficulties.

Now try to answer the following questions:

1. What parts of trees have scientists traditionally studied to learn about them?
2. What parts of trees do ecologist Rob Jackson and his colleagues study? Why?
3. How do Rob Jackson and his colleagues go about studying trees below ground?
4. How do they match the tissue samples with the species growing on the surface?
5. Why is it important for scientists to understand trees’ roots?

Going Further

To extend your understanding of natural systems, you can go to the Franklin Institute’s Living Things online exhibit. You may want them to pay particular attention to the section on Neighborhoods, which deals specifically with ecosystems, biomes, and habitats.