Misconceptions of Roots

Today we talked about roots in my soil ecology class. During the lab we saw a digital 3D model of a root system (viewing it involved wearing 3 glasses). It was pretty cool.

All this talk about roots made me think of the misconception of root systems that exists. When most people look at a tree they fail to imagine the scope of the root system. You might hear someone say that the root system is approximately the same size as the tree’s canopy. This is not true.

I made a simple sketch to illustrate this:

roots

Tree A is rocking the root system the average person imagines. You’re not going to find many any trees with roots like that. Tree B is much more realistic. Now for a few points.

  • Many false statements have a bit of truth to them. The root system size being approximately equal to canopy size is no exception. You see, there are two major classifications of roots. Coarse roots and fine roots. If you looked exclusively at the coarse roots you would might see something like Tree A in the sketch above. The coarse roots provide anchorage, manipulate pore space, and move water. But the story doesn’t end there. Fine roots are extremely important. They are the primary source of nutrient and water uptake and are also involved in carbon and nutrient cycling. They typically extend well past the canopy of the tree and are quite thick in the top twelve inches of soil. When you add fine roots to the picture, the canopy and root system no longer look alike.
  • You’ll notice little clusters of roots deep in the soil on Tree B. These represent roots that develop near pockets of available water or nutrients.
  • Different plants produce very different root systems. Broad all-inclusive statements about plant roots are difficult to make because so many differences exist.
  • It is very easy to cause severe damage to trees by compacting the soil, raising the soil level, or excavating soil around their root systems. It might take weeks, months, or even years for symptoms to show up.

OK, I’m finished thinking about roots for the day.

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