Leaf litter and soil protect acorns from prescribed fire

Jul 18, 2012

U.S. Forest Service scientists have found that prescribed fires with the heat insulation of leaf litter and soil can help restore oak ecosystems.

Forest Service researchers are helping land managers find the best time to use prescribed fire when oak regeneration from acorns is a concern.

"Acorns inside the or in the soil are for the most part protected from fire," says Cathryn Greenberg, Forest Service Southern Research Station (SRS) researcher and lead author of the study published in July in the journal . "However, when acorns lie on top of the leaf litter, even low intensity surface fires will kill most of them."

Prescribed fire is increasingly used as a tool in oak ecosystem restoration, with the goal of reducing competition and creating light and seedbed conditions that help germinate and flourish. Forest Service researchers are helping land managers find the best time to use prescribed fires when oak regeneration from acorns is a concern.

To see how fire affected acorns, researchers placed nuts on the leaf litter surface, inside the duff (leaf litter plus smaller fragments of plant material), and underneath the duff, about 2 inches into the soil. The temperature of the , measured just above the surface of the leaf litter, ranged from less than 174o F to almost 700 o F.

After the burn, researchers retrieved the acorns and placed them in ideal conditions for germination. "Almost all the acorns that were on the leaf litter surface and exposed to fire died," says Greenberg. "However, acorns in the duff or in the soil were better protected from , and generally unaffected by low intensity fires."

When acorns fall to the forest floor they don't stay on top of the leaf litter too long. Squirrels, jays, chipmunks and mice bury acorns, or they settle into the litter because of weather, falling leaves and gravity. Once acorns are blanketed by leaf litter or soil, low-intensity burns are usually safe. However, should consider the timing and size of acorn crops, as well as the forest floor condition when determining the timing and frequency of prescribed burning.

"Frequent burning that reduces litter and duff depth could compromise the availability of 'safe sites' where acorns are insulated from high fire temperatures," says Greenberg.

Explore further: Does it help conservation to put a price on nature?

More information: Access the full text of the article: www.srs.fs.usda.gov/pubs/40794

add to favorites email to friend print save as pdf

Related Stories

Presence of snails points to forest recovery

Feb 16, 2010

A team of Catalan researchers has studied the changes in the make-up of animal populations following forest fires, and have concluded that malacological fauna are a good indicator of forest recovery. The conclusions ...

Recommended for you

Does it help conservation to put a price on nature?

just added

Putting a price on the services which a particular ecosystem provides may encourage the adoption of greener policies, but it may come at the price of biodiversity conservation. Writing today in the journal ...

Reef-builders with a sense of harmony

1 hour ago

Cold-water corals of the species Lophelia pertusa are able to fuse skeletons of genetically distinct individuals. On dives with JAGO, a research submersible stationed at GEOMAR Helmholtz Centre for Ocean Research Kiel, scientists ...

Selling and buying water rights

6 hours ago

Trying to sell or buy water rights can be a complicated exercise. First, it takes time and effort for buyers and sellers to find each other, a process that often relies on word-of-mouth, local bulletin boards, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.