Printed in the Mendocino County Observer and aired on KZYX&Z Community News, by Clare Nunamaker
"Large woody debris" (LWD) is a fancy term for pieces of wood from large stumps to logs that you find in the forest. Besides offering part of the visual complexity that makes the forest feel and look like a forest, LWD provides structure and habitat in the woods and in our streams.
Different species decay at different rates. And as they decay, they serve different purposes. That's why forest managers like to see a diversity of species and also "decay classes" throughout the forest. How many years it takes a log to decay depends on factors like the species, the size of the log, and the weather. A large redwood log may be around for hundreds of years, whereas smaller logs or less rot-resistant species will completely decay in a few decades.
There's habitat to be found in any and all of the decay classes. A newly downed tree may provide hiding places for small forest critters like salamanders that can crawl between the loosening bark and the still-sound wood of the log. On a moderately decayed log, you may find plants taking root or thick mosses growing. On a severely decayed log you may find interesting fungi, though, you're as likely as not to step over it without even seeing it as the log literally becomes part of the forest floor.
In and around creeks, LWD is critically important. Its functions are many, from playing a role in creating pools to contributing to the food web that helps keeps fish populations healthy. LWD is so important that a lot of grant dollars are spent hauling LWD into stream zones and carefully placing it. There's even a company that sells artificial LWD, just in case you're lacking for good logs.
How large is large woody debris? It depends on whom you ask. Some say it's a piece over 10 inches in diameter. Others say 20 inches. Still others say 24 inches. But what's more important than the exact size is the recognition of its role in our ecosystems.
Clare Nunamaker is a Registered Professional Forester and member of NorCal SAF and the Forest Guild.
