I like the little path in Beaver Willows Nature Habitat Park. There’s always something to notice when I walk along with eyes focused … down. This routine for observing the path is one I’ve taken for granted … until today when I realized that many people have been robbed of the opportunity to see what I see when I look… down.
When I look… down... I can see all that falls on and along the path. Sometimes the changes are subtle, and other times they are grand. The blessing along this trail is that what drops on the path stays there until it is moved by natural forces. Those who visit the path in Beaver Willows are not robbed of this wondrous experience by leaf blowers, street sweepers, or landscape crews.
This phenomenon is called … litterfall. It’s the beginning of an incredible nature cycle that starts when dead plant material like leaves, bark, twigs, leaves, flower petals, nuts, and seeds fall on the ground. Other names for litterfall include: plant litter, leaf litter, tree litter, soil litter, and duff.
In the Willamette Valley ecoregion of Oregon, litterfall is most noticeable in Autumn when deciduous trees drop their leaves. The material that drops as litterfall is still recognizable and hasn’t started the process of decomposing. The holes seen in these leaves were caused by an alder flea-beetle outbreak that occurred earlier in the season.
Litterfall (when left where is falls) forms a covering of dead organic material on top of soil. It is known as the “O Horizon” or Organic Horizon and is formed by three layers(1) as shown on the diagram below.
Litterfall is amazing! It has some important jobs.
Litterfall- dead plant material, also known as detritus- jumpstarts the Nutrient Cycle process by providing organic matter for decomposers, called detritivores, something to consume. Forest environments are sustained when detritivores breakdown simple carbon compounds into carbon dioxide and water, and release nitrogen and phosphorous into the soil for surrounding plants to reabsorb.
When I look … down, I see this process in action as fungi go to work on the surface of the leaves.
And… on the ends and edges of twigs and sticks.
Litterfall facilitates in the capture and infiltration of ground water into the soil. The fallen leaves protect the soil from the impact of raindrops as they hit the surface. This helps to prevent erosion and clay formation. Leaves also have nutrients leached from them that are transported down into the soil.
In addition to providing habitat and nutrition for detritivores, litterfall is also helpful to larger animals who rely on fallen leaves, twigs, sticks, and lichen for shelter or forage.
When I look down… and find lichen on the Beaver Willows path, I find it interesting and beautiful. But, if I were an elk or deer and looked down… litterfall lichen would provide a major source of food in the winter months.
And, for many others: reptiles, amphibians, birds, and small mammals… litterfall provides a place for shelter. Like this Northwestern Garter Snake.
Seriously… Can you tell me what “litterfall” is?
And… now that you know, perhaps next time the leaf blower will stay in the garage, the street sweepers will have less to sweep, and the landscape crew will be guided to leave the litterfall for you to enjoy when you look…down. Besides, litterfall will most likely be “gone” in time for spring!
Webliography– resources used to help synthesize my thoughts for this post:
- Plant Litter; http://en.wikipedia.org/wiki/Plant_litter; accessed 01/18/14
- Ecology of the Forest- Decompostion and Decay; http://www.treesforlife.org.uk/forest/ecological/decomposition_decay.html; accessed 01/18/14
- USDA Soil nutrient Cycle Chart ; http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/technical/nra/rca/?&cid=nrcs143_014198; accessed 01/17/14; additions to chart by Jane Wilson as noted.