What Happens to the Stump of a Cut-Off Cedar Tree?

Fungi to the Rescue

• Wood becomes susceptible to decomposition when it is no longer part of a living tree. Bacteria are the primary decomposers of vegetable matter in a compost pile, but isolated chunks of wood are consumed primarily by fungi. Mature wood contains a high portion of lignin, which is a fibrous compound that is extremely resistant to decay. Fungi, however, excel at digesting lignin. Wood decomposition is a slow process, but stump decomposition can be even slower when a healthy, living tree leaves behind a healthy, living stump. If your stump is still sending up new shoots and suckers, it is still alive and thus less susceptible to decay.

The Downside of Durability

• Cedar wood is naturally resistant to decay. This characteristic is usually regarded with enthusiasm, as seen in cedar's reputation as a superior material for such applications as fence posts, exterior siding, decks and seed flats. Stump removal is one of the few instances when cedar's durability is a nuisance. A typical stump might take 10 years to decay into soft chunks of rotten wood that can be raked up and composted. Cedar, however, could take much longer. An untreated cedar fence post can remain in decent condition for more than 20 years, and it is possible that a cedar stump will be around for a similar length of time.

Fungi and Their Preferences

• Like all organisms, fungi operate most effectively when environmental conditions are in their favor. The most basic requirement is moisture. Decay-producing fungi need water to grow and reproduce, and they cannot digest wood that is below about 20 percent moisture. If your tree was long dead when you cut it down, the resulting stump might be dry enough to inhibit fungal activity. Temperature is also an important factor. Most of the fungal species responsible for wood decay prefer ambient temperatures of 75 to 90 degrees Fahrenheit.

Accelerated Decay

• You can facilitate the decomposition process by creating an environment that fungi appreciate. The first step is to remove consistently and promptly all new shoots and suckers to gradually deplete the stump's food reserves; this hastens the death of the stump so that fungi experience less resistance. You can then use whatever means available to keep the stump moist and warm. During the summer, hose down the stump occasionally to keep it moist. In the cooler seasons, cover the stump with row cover fabric or a piece of transparent plastic sheeting. These retain moisture and trap sunlight to increase temperature.