This is the fifth article in our Fire Ecology for Non-Scientists series. Read the the first on The Fire Triangle & Fire Behavior, the second on Renewal for Pepperwood’s Trees and Shrubs, the third on Fire Followers, and the fourth on Fire and Wildland Animal Habitat.
Fire Ecology for Non-Scientists: And Now the Upside – Ecological Benefits of Fire
By Sandi Funke, Education Director
Always look on the bright side of life? Ok, call me Sandi Sunshine, but as I am happily discovering, there are actually some crucial benefits that can result from fire coming to wildlands. Fire can be a housecleaner, a germinator, and even a forest doctor. Read on to learn more.
Fire sweeps away dead leaves and twigs, cleaning the forest floor. This clearing can help trees like our native oaks regenerate. After getting rid of the accumulated layer of dead leaves and sticks, freshly fallen seeds are better able reach the soil where they can root and grow. Can you imagine being a newly germinated seedling reaching down towards vital water and nutrients only to realize that there is a dense blanket of dead leaves between you and the essentials for life? How disappointing! As a research institution, Pepperwood is examining whether our oaks are better able to regenerate after fire, as they produce a fresh new generation of seedlings.
Our awakening geophytes—plants that grow from some type of thick underground storage organ like a bulb—also seem very happy this spring. Plants like soaproot (Chlorogalum pomeridianum), death camas (Toxicoscordion fremontii), and leopard lily (Lilium pardalinum ssp. pardalinum) send up leaves from their bulbs and can more easily reach sunlight. Look for these and similar plants in areas all around the North Bay that have burned.
Not only does fire clean up the forest floor, it also burns away larger dead tree trunks and branches. With this detritus gone, it is no longer a potential fuel for a future fire. An area that has recently burned is less likely to harbor a large, destructive fire again in the near future since the fuel load has been reduced.
As we have mentioned in previous blog articles, fire is actually required for some plants to germinate. The seeds of chaparral plants such as manzanita (Arctostaphylos spp.) and chamise (Adenostoma fasciculatum) require fire to emerge from their seed coats. As explained by Cal Fire, “without fire, these trees and plants would eventually succumb to old age with no new generations to carry on their legacy.”
Fire can also help control harmful diseases and pests. Sudden Oak Death is caused by a non-native fungus-like pathogen (Phytophthora ramorum). It has killed over 1,000,000 trees in California. Researchers have found prescribed fires and wildland fires can reduce the prevalence of this harmful forest disease. Pepperwood’s Ecologist Michelle Halbur explains that, “another benefit of getting rid of leaf litter is a reduction in fungal pathogens that can infect young oak seedlings, killing them off while they’re young and vulnerable.”
Though we will surely be watching out for wood boring beetles this spring that could be enjoying a smorgasbord from all of the dead and dying trees, wildland fire has also been known to reduce some insect pests. Filbert weevil (Curculio occidentis) and filbert worm (Cydia latiferreana) are moths whose larvae bore into acorns, destroying the vital kernels. These insects are very common in oak woodlands—including at Pepperwood—and can destroy up to 80% of an acorn crop. If you have ever seen an acorn with a tiny hole, it is probably because of this insect. As it turns out, the adult moths tend to lay their egg on the shadier side of oak trees. At Pepperwood, hundreds of our tall Douglas-fir (Pseudotsuga menziesii) trees that were adjacent to and shading out our oaks were destroyed in the fire. Now I’m not a scientist (that may be obvious by the title of the article!) BUT, with many of our oaks more exposed, I wonder if these little pests will have a harder time attacking the acorns? So many questions!!!
As we move forward at Pepperwood, we will be closely examining how the ecosystem recovers and potentially benefits from the events of last fall. We invite you to follow along and track our discoveries!
References and additional helpful resources:
• University of California – The Role of Fire in California’s Oak Woodlands
• Oak Savanna Foundation – Oak Savannas
• Cal Fire – The Benefits of Fire
• University of California – Sudden Oak Death and Fire in California
• UC Davis – Sudden Oak Death and Fire in Big Sur
• University of California – Filbert Pests in Live Oaks