Ecosystem Aftermath
Carlos Hernandez-Morfin (he/him/his)
MPH Candidate at OHSU - PSU School of Public Health
What Happens After a Wildfire?
Wildfires are a natural occurrence in many ecosystems that aid in the clearing of dead and decaying matter on the forest floor (Pausas & Keeley, 2019). They allow for organic material to breakdown so that nutrients can be accesses by plants and animals. For some plant species, fire actually is part of their reproductive cycle (Supriya, 2017). However, fires are only beneficial when they serve their specific purpose. When fires burn too long or the grounds stays dry for extended periods of time, it puts ecosystems at risk (Supriya, 2017).
Climate change is a threat multiplier that can lead to longer droughts, more intense fires, and slower regrowth times. Making it harder for pioneer species to reclaim burnt territory and utilize nutrients. Therefore lessening our forest's ability to serve as carbon sinks and benefit the carbon cycle. Resulting in reduced atmospheric carbon uptake.
The Nutrient Cycle
Wildfires are a natural process in many environments. They allow the forest floor to be cleared of leaf litter, allow nutrients to return to the soil, make it easier for new plants to establish, and provide the foundation for pine trees to take root (Supriya, 2017).
Soil After a Fire
Wildfires reduce the total amount of nutrients present by burning excess organics (Northern Arizona University [NAU], n.d.).
Fire increases the nutrient availability by converting nutrients bound in decaying matter into more available forms (NAU, n.d.).
Fires can impact the soil minerality and increase surface area. Making it more accessible to microorganisms (NAU, n.d.).
Vegetation
After a fire, the forest floor is exposed and this allows seedlings released by the fire to sprout and grow (Cagle, 2018).
Reconstruction of forest scapes is a race. Often won by the fastest growers and most prolific reproducers (Cagle, 2018).
Many trees have evolved fire resistant bark and can survive low intensity fires (Cagle, 2018).
Pioneer Species
Post-fire revegetation is usually dominated by small flowering plants, followed by shrubs, and hardwood (Lukes, 2019) (Hibbs & Jacobs, 2011).
Research has shown that hardwood trees, specifically big-leaf maple is an excellent pioneer species and extremely beneficial for the regrowth of pine trees (Turks, Schmidt, & Smith, 2008).
Big-leaf maple helps to improve soil fertility by allowing increased moisture to reach the forest floor (Turks, Schmidt, & Smith, 2008).
Nutrient Blocks
Wildfires are only beneficial to ecosystems if they serve their purpose. If they burn too long, are too severe, or the ground stays dry too long, ecosystems can't recover (Supriya, 2017) . Given that climate change can lead to more fires and longer droughts soil erosion, invasive species, and pollution are becoming more prominent problems.
Soil Erosion
During severe wildfires, nearly everything is consumed in the fire. The lack of canopy, which helps to dampen and absorb dense rainfall is obsolete allowing for erosion to take place (Oregon State University [OSU], n.d.).
The protective leaf litter that was once part of the understory is also gone and cannot slow rainfall. Therefore resulting in greater erosion due to rainfall (OSU, n.d.).
Intense heat can make the upper layer of soil repel water and reduces the amount of water that is absorbed. Encouraging the displacement of soil (OSU, n.d.).
Invasive Species
Often times invasive species have an advantage over native species due to their adaptability and ability to establish themselves quickly after a fire (Lambert, D' Antonio, & Dudley, 2010).
Invasive shrubs and grasses increase the likelihood of severe fires because they serve as fuel to exacerbate the intense of a wildfire (Swartz & Smith, 2022).
Fire fighters may unintentionally the range of invasive species by dispersing their seeds throughout various parts of the forest (Swartz & Smith, 2022).
Pollution
Wildfires emit a variety of particulates matter (PM) in the form of smoke. Particularly concerning is the impact of PM2.5 which can cause respiratory problems and has been linked to chronic disease (State of Oregon Department of Environmental Quality [DEQ], 2022).
The production of nitrogen dioxide and volatile organic compounds can increase smog production as they are precursors for ozone formation (DEQ, 2022).
Mercury stored in vegetation and soil can be at risk of eroding into watersheds after a wildfire (DEQ, 2022).
Why Should We Care About Wildfires?
In Oregon, the highest level of carbon storage is found in our old growth forests in Western Oregon (Woods Hole Research Center, 2011). Carbon is stored in vast quantities both above ground and below ground (biomass). The burning of these lands impacts our ability to sequester carbon and releases vast amount of carbon as it burns (Woods Hole Research Center, 2011).
After repeated wildfires, many of the forests are struggling to regrow to levels comparable to what they once where (Supriya, 2017).
Since 2000, about 19 - 32% of sites that previously burned have not shown any significant signs of regrowth (Supriya, 2017).
Burns result in a lack of biodiversity as species outcompete each other for space instead of retaining a multilayered ecosystem.
Biodiversity increases soil organic compounds (NAU, n.d.).
Carbon rich forest have been found to support biodiversity across various animal, plants, and fungal species.
Who Suffers the Most?
Wildfires disproportionately impact communities of color. In fact, communities that are mostly black, Latino/Hispanic, or Native American are 50% more vulnerable to wildfires (The Nature Conservancy, n.d.).
Native Americans in particular are 6x more likely to live in fire prone areas (The Nature Conservancy, n.d.).
Infants, young children, women who are pregnant, and older adults are most affected by the health impacts from smoke and ash (World Health Organization [WHO], n.d.).
The ash and smoke can exacerbate pre-existing respiratory diseases or heart disease (WHO, n.d.).
Safety personal and Firefighters are at greater risk of injuries, burns and smoke inhalation (WHO, n.d.).
Connection to Other Pages
References
Cagle, A. (2018, September 5). What happens after a wildfire sweeps through a forest? Sierra Club. Retrieved November 23, 2022, from https://www.sierraclub.org/sierra/what-happens-after-wildfire-sweeps-through-forest#:~:text=During%20wildfires%2C%20the%20nutrients%20from,fire%20to%20sprout%20and%20grow
Fire Effect on Soil. Northern Arizona University. (n.d.). Retrieved November 23, 2022, from https://www2.nau.edu/~gaud/bio300w/frsl.htm
Hibbs, D., & Jacobs, R. (2011, November 22). Vegetation Recovery after Fire in the Klamath-Siskiyou Region, Southern Oregon. Southern Oregon: U.S. Geological Survey Fact Sheet 2011-3140. Retrieved November 23, 2022, from https://pubs.usgs.gov/fs/2011/3140/
Lambert, A. M., D' Antonio, C. M., & Dudley, T. L. (2010, June 3). Invasive Species and Fire in California Ecosystems. Fremontia. Retrieved November 23, 2022, from https://www.tehamacountyrcd.org/files/4d3a4a81a/CNPS+Report+-+Native+Plants+and+Fire+.pdf
Lukes, L. (2019, February 8). There's green in the burn. Agriculture and Natural Resources, University of California. Retrieved November 23, 2022, from https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=29311#:~:text=Plant%20recolonization%20after%20a%20fire,with%20the%20summer%20dry%20period
Mitigating soil erosion after a fire. Oregon State University. (n.d.). Retrieved November 23, 2022, from https://extension.oregonstate.edu/sites/default/files/documents/8341/soil-erosion-mitigation-summary.pdf
Pausas, J. G., & Keeley, J. E. (2019, May 6). Wildfires as an ecosystem service. Ecological Society of America. Retrieved November 23, 2022, from https://doi.org/10.1002/fee.2044
Supriya, L. (2017, December 19). Ecosystems could once bounce back from wildfires. Now, they're being wiped out for good. Science. Retrieved November 23, 2022, from https://www.science.org/content/article/ecosystems-could-once-bounce-back-wildfires-now-they-re-being-wiped-out-good
Swartz, K., & Smith, H. (2022, March 1). Share Teaming Up to Take On the Double Threat of Invasives and Wildfires. U.S. Department of the Interior. Retrieved November 23, 2022, from https://www.doi.gov/wildlandfire/teaming-take-double-threat-invasives-and-wildfires#:~:text=Invasive%20plants%20such%20as%20cheatgrass,invade%20or%20even%20re%2Dinvade
The Nature Conservancy. (n.d.). Wildfires Impact Minorities. Retrieved November 23, 2022, from https://www.nature.org/en-us/about-us/where-we-work/united-states/washington/stories-in-washington/wildfires-impact-minorities/#:~:text=Communities%20that%20are%20mostly%20black,wildfires%20compared%20with%20other%20communities
Turks, T. D., Schmidt, M. G., & Roberts, N. J. (2008, April). The influence of bigleaf maple on forest floor and mineral soil properties in a coniferous forest in coastal British Columbia. ScienceDirect. Retrieved November 23, 2022, from https://www.sciencedirect.com/science/article/abs/pii/S0378112707009358
Wildfire Smoke Trends and the Air Quality Index. State of Oregon Department of Environmental Quality. (2022, June). Retrieved November 23, 2022, from https://www.oregon.gov/deq/wildfires/Pages/default.aspx
Woods Hole Research Center. (2011, June). Oregon’s Carbon Sinks. Oregon Wild. Retrieved November 23, 2022, from https://oregonwild.org/sites/default/files/pdf-files/Woods_Hole_Carbon_Report_Oregon_Analysis.pdf
World Health Organization. (n.d.). Wildfires. World Health Organization. Retrieved November 23, 2022, from https://www.who.int/health-topics/wildfires#tab=tab_2