What Happens To Plants After A Wildfire?

News regarding large wildfires typically covers the location of the fire, the size of the fire, and the fire’s impact on people and property. With the possibility of hundreds of homes destroyed, thousands of people displaced, and millions in damaged property, it’s no wonder much of the media’s attention of large wildfire events is focused on what happens DURING a fire.  But what happens after a wildfire is out?  Or specifically, what happens to plants and vegetation after a wildfire burn? Does the ground remained scorched, forever void of life like some scene out of Mad Max?

The truth is wildfire has helped to shape California’s vegetative landscape for thousands of years. It affects the kinds of plants growing in a particular area, their abundance, size, health, and lifespan. The fire kills some plants, rejuvenates others, and some plants may even need fire in order to thrive.

Some areas in Southern California have plants with leaves naturally coated in flammable oils that encourage a fire to spread. The heat from the fire causes their fire-activated seeds to germinate and the young plants can then take advantage of the fact that the other surrounding plant life was destroyed in the fire. The cones of the Lodgepole Pine are sealed with a resin that is melted away by fire, which then causes the seeds to be released. Other plants have smoke-activated seeds which function in a similar manner. Some trees, like the giant sequoia tree, rely on wildfires to make gaps in the vegetation canopy so that sunlight can reach the forest floor allowing their seedlings to grow.  

This map (courtesy of the Department of Agriculture, Forest Service) shows the effects of wildfires on plant life in various regions of the US. The color coding shows the different ecosystem types and the frequency of fire (and types of fire) that allow those plants to thrive.

Some key definitions (courtesy of the Department of Agriculture):

Understory Fire

A fire in forests or woodlands that is not lethal to the dominant, overstory vegetation and thus does not change stand structure substantially. Most (75%) of the dominant vegetation survives.

Mixed Severity Fire

A fire that causes partial (26-75%) replacement of the upper canopy layer.

Stand Replacement Fire

A fire that kills all or most of the living upper canopy layer and initiates succession or regrowth.

Sundowner Winds and Their Impact on Fire Behavior

A sundowner wind is an offshore northerly Foehn wind that occurs near Santa Barbara, California. The winds surface when a ridge of high pressure is directly north of the area, and they blow with greatest force when the pressure gradient is perpendicular to the axis of the Santa Ynez Mountains which rise directly behind Santa Barbara. These winds often precede Santa Ana events by a day or two, as it is normal for high-pressure areas to migrate east, causing the pressure gradients to shift to the northeast.

 

Sundowner winds are dried and heated by the warm inland valleys and deserts. As narrow canyons and valleys compress the winds, they become stronger and overpower the diurnal winds. Firefighting efforts during a sundowner wind event can become extremely difficult. The Jesusita fire in May 2009 burned 8,733 acres and destroyed 80 homes while damaging 15 more. Most of the destruction occurred while sundowner winds pushed the main fire through populated areas. The Painted Cave Fire during June 1990 rapidly grew to 5,000 acres, destroying 427 buildings and killing 1 civilian.

 

September a Historic Month for Wildfire in California

Containment of three major fires nears after a tumultuous and historic month for wildfires in California.

Incident management teams on all three fires have made great progress of late on containing the Butte, Rough, and Valley Fires. This month the Valley Fire near Clear Lake has destroyed 1,958 structures while the Butte Fire near Jackson has taken out another 818. In terms of structures lost, that makes them number 2 and number 5 respectively since 2003 in California. Only the 2003 Cedar fire in San Diego County has destroyed more. As the Rough fire continues to gain acreage burned, it has moved up to number 13 all-time in California in terms of acreage burned at 151,493. 

Three large fires nearing containment

According to the National Interagency Fire Center, California’s fires have burned 818,946 acres so far this year. These three are over one-third of that total.

 

California Wildfires By the Numbers

It’s been a busy year for California wildfires. To date, The Northern and Southern California Geographic Area Coordination Centers have reported a total of 7,541 fires for 783,968 total acres burned. To put it in perspective, that’s larger than the entire state of Rhode Island… burned.

 Let’s have a look at the previous five years as reported by the National Interagency Fire Center (NIFC):

Year

Total Fires

Total Acreage

2014

7,865

555,044

2013

9,909

577,675

2012

7,958

869,599

2011

7,989

126,854

2010

6,554

109,529

 

The previous five year average was 8,055 fires for 447,740 acres burned. And while California is a bit under the average this year, it’s only mid-September, and US Forest Service officials are expecting to see fire activity until at least November.

 

Fewer fires but more acreage can only mean one thing, larger fires. This year California has seen six fires over 50,000 acres in size, with four of those still actively burning. Again, let’s have a look at the previous five years as reported by NIFC:

 

Year

Fires > 50k acres

2014

3

2013

1

2012

2

2011

0

2010

0

 

The previous five year average was approximately one large fire per year in California. With so many large fires this season, firefighting resources have been stretched thin. Not to mention that California has sent equipment and manpower to other states that have also been impacted by wildfires this year.

Rain Not Always Welcomed Forecast for Wildfire Scorched Areas

As the Valley Fire in Northern California continues to burn, the forecasted rain can help and hurt.

The Valley Fire north of San Francisco, CA has burned 70,000 acres and is 30% contained. Active fire and visible flames still cover a lot of the area, and the rain expected today will likely help firefighting efforts to cool and douse these parts of the fire. However, for the areas already scorched by this blaze, like Middletown, with burned, unprotected soil, the rain brings further concerns of landslides and flash flooding.

20150915_ValleyFire

 

Many variables lead to increases in risk for an area for landslides and flash floods. One such consideration is recently burned areas that have little to no vegetation to hold the soil in place and minimize erosion. Another notable fire in Northern California is the Butte Fire (71,780 acres, 45% contained) near San Andreas which is also in areas of mountainous terrain. This increased slope is another concern after a wildfire when rain approaches.

Images like the one seen above (taken by a RedZone Liaison on the ground near the Valley Fire today) are becoming common as large wildfires continue to burn across the Western US and Alaska this fire season. Many show no signs of being contained until snowfall.

 

USA Wildfire update – 206 and counting

Alaska remains the unfortunate leader in wildfire, with more than 1.2 million acres involved in 17 major fires. RedZone is currently tracking 30 wildfires in Alaska.

As a comparison, the twenty largest fires in the Continental US combine to measure 382,000 acres – barely a quarter of the size of the Alaskan fires.

Within the CONUS, California has two of the five biggest fires: the Happy Camp Complex fire in Klamath National Forest at 134,000 acres, and the Lake Fire in San Bernardino National Forest at 31,000 acres. RedZone is currently tracking 18 wildfires in California, with varying levels of intensity and threat.

There are other significant fires in Oregon, Washington, and even New Mexico and Nevada. If you want reliable, timely intelligence on wildfire, turn to RedZone. For more information, visit our website at www.redzone.co.

RZAlert_Dashboard_by_RedZone_-_Google_Chrome_7292015_23406_PM

This screen shot from RedZone’s RZAlert dashboard shows the CONUS and wildfires currently tracked by RedZone.