Dirt and Detritivores

This post is about heroes. Not your Pulitzer prize heroes or your comic book action heroes, but the unsung heroes of that seldom talked about part of the natural world: dirt. The heroes in this world are mostly invisible. They are silent partners, master recyclers, often ignored kingpins of making dirt viable and getting carbon back into our air - no small task. The underdogs of the understory deserve a post! Don't worry though, we are not getting down to the molecular level - after all many of you gardeners out there already know most of this, if you have a compost heap.

Now that all those colorful fall leaves are on the ground, the action really begins. I'm not talking about spending hours raking up your yard, although that can be good exercise - if you don't rely on one of those blowers!

After a few weeks of rain and several layers of leaf buildup, those underdogs start their work. Bacteria, fungi, insects, slugs, and worms all do their part. They arrive at different times and finish their work in parallel or independently. These detritivores, as they are called, are an important part of the ecosystem. For example, fungi will release enzymes and acids that break down the structure of the leaf.


As the older leaves on the bottom of the heap turn to mush with the help of bacteria and detritivores, nutrients are deposited into the soil and the leaves slowly disintegrate. In addition, the carbon within the leaves will also be left in the soil. Luckily for us living earth inhabitants, this carbon slowly returns to the atmosphere as carbon dioxide via carbon respiration (remember that carbon cycle you learned about in high school?!).

As the decomposition process of plant matter continues, a typical deciduous leaf will be completely gone within a year. Conifer needles take much longer, up to seven years. The nutrients in the leaf are passed on to the soil, either directly or via the detritivores.

One of the more visible aspects of this process are the mushrooms that pop up during this time. Generally speaking, the main visible parts of fungi (mushroom stem and cap) are agents of reproduction. They produce spores and/or create bud-like growths that become new fungi. The visible mushroom portion is of course what the culinary world is most interested in; as are we nature photographers. The subtle colors and fine texture of these organisms make for good subjects. You just need to be prepared to get down low with your gear.

Our climate, soil, and geography in western Oregon make for prime mushroom habitat. With that in mind, it's not uncommon to find fungi any time of the year. However, fall is the prime time for a good mushroom show, before snow and freezing weather arrive. As a side note, the term "mushroom" has been in use since at least 1400 A.D. Its actual origin is unclear but some scholars believe it may have come from the French word "mousse" (moss), because some mushrooms grow in or near moss.

Next time you are out for a walk on the dirt, just be mindful of all that heroic activity going on underfoot! It's always a "work in progress!"

Champoeg State Park in Early November

Shute Park in Mid November

Rood Bridge Park in Late November