Welcome to the Rhizotron!

Our facility is located at the US Forest Service’s Houghton, Michigan field office.It was built to give scientists a better look into the intricate processes that control our forests from below the ground surface. Lets take a look inside…

There are 24 windows in the Rhizotron. The East (left) side windows look out into native, “undisturbed” soils. The West (right) side windows look into a sandier forest soil that was brought in from a nearby Red Pine forest.

Lets take a closer look at a couple of the windows…

East, “undisturbed” side window West, “disturbed” side window

A color difference is evident between the two soil types. This is due to different carbon contents in the two soils. Further, distinct layers are visible (darker on top) due to more biological activity near the surface.

There is more biological activity near the surface of the soil because there is more carbon (food for microorganisms), more roots (food for grazers), and there is a more abundant supply of water and oxygen.

Woody roots Herbaceous roots

Fun Fact: In just 1 square yard of soil, 4 inches deep, you will find 1 mile of roots.

1 Yard X 4 inches = 1 mile of roots !

Fun Fact: Earthworms are not native to the northern United States (at least not since the last ice age, 10,000 years ago). All of the earthworms in Northern Michigan are European species who migrated along with their human counterparts.

In addition to the worms physically bringing carbon (in the form of dead leaves, their food) into the soil, their tunnels act as pathways for rain water which brings in other nutrients from the surface and creates a favorable habitat for a host of soil fungi, plant roots, centipedes, pill bugs, slugs and many other soil organisms. Worm tunnels also make great entry points and “dens” for some of the larger “bugs”.

Carbon comes into the soil from dead surface organic material (mostly leaves), through tree roots, and also through soil organisms.

Soil fungi and other microorganisms use some of the carbon and nutrients stored in the soil and release it as CO2.

Understanding this carbon balance (Carbon In vs. CO2 Out) helps determine how much is being stored in the forests, which is critical to climate change studies.

CO2CO2

Fun Fact: 2/3 of forest carbon in the soil.

This means that the portion of the forest we can see everyday (tree trunks, branches, leaves) contains only half as much carbon as the soil. So, it is just as important (if not more important) to study and manage the belowground portion of our forests as it is to study and manage the aboveground portion. Our Rhizotron will help us accomplish this.