Southern California’s Urban Forest Hazard

Tinderbox forests jeopardize cities, air quality and environment

By Richard Minnich, Ph.D.

 

Southern California’s once-beautiful forests have been shaped by Santa Ana winds, real-estate values, self-proclaimed environmentalists, Baja-like weather and more. When they go, they’re going to go big.

 

Lake Arrowhead is one ill-timed fire and wind event from losing 30,000 homes, millions of trees and exposing more than 100,000 people to horribly unhealthy air. Idyllwild and Big Bear are in similar danger, embedded in overgrown forests that stand shockingly dead and dry.

 

Our forests have tripled in density and sprouted cities. They’ve endured drought, insect infestation and fire-suppression practices that prevented natural clearing of the forest floor. Picture 200-foot flames fanned by fullon Santa Ana winds ripping through an urban forest where you can drive a mile and not see a living tree to grasp the scale of loss should fire meet severe weather here any time soon.

 

Clearly we must reduce forest fuel loads to lessen the threat to life, property and environmental resources. Many forests stand choked with hundreds of trees per acre where 40-50 trees per acre once stood. There are not enough nutrients or water to go around. Trees become prone to insect infestation and die. They become big, dry match sticks.

 

Of course, these tinderbox forests face uniquely Southern California challenges. The infrastructure to thin forests, for instance, is virtually nonexistent in the area. The land-ownership dynamic – lots of individually owned parcels surrounded by national forestland – complicates matters.  Even the mix of chaparral and conifer forests is quintessentially Southern California.

 

The region needs a solution that prioritizes community protection and returns historic, open forests to Southern California’s landscape.  Today’s forests look nothing like forests here did 200 years ago, when large, widely spaced pines and fir dominated the landscape.

 

Addressing economic realities

Following the drought and beetle-kill of 2001-2003, liens were placed on Lake Arrowhead landowners to pay to cut trees and ship logs hundreds of miles. Liens and abatements may be necessary to address fuel loads again.  Dead logs aren’t worth enough to cover the transportation costs. It’s time to come up with a sustainable local solution.

 

To sustain forests that are safe to live in, you need the infrastructure to reduce fuels, restore watersheds, mill logs, generate energy, study fish and do all the things that go along with managing forest resources responsibly. There must be environmental and business opportunities if both forest and community are to thrive.

 

Urban forests in particular would benefit from a mill to anchor infrastructure investment.  The focus can’t be solely on small vegetation – if some larger trees are not removed the forest will still be a fire trap.  Sawmills and power plants can and make productive use of excess fuels.

 

Certainly an urban-forest solution will require innovation. Trees must be cut, the cutting must be paid for and something has to be done with the cuttings. The solution may include new conservation incentives, but infrastructure in some form is critical to long-term success.

 

Outside the urban interface, the landscape dynamic could allow low-intensity fire to be used as a tool against high-intensity fire.  Prescribed burns, low-level fires set under certain conditions, can clear the forest floor before fuels accumulate to dangerous levels.  Once these forests are thinned, they can be

managed more economically through a mix of harvesting and prescribed burns.

 

One step at a time

The first phase of returning sustainable forests to the landscape will be the most difficult; unprecedented fuel loads have accumulated across massive land areas. But looking to the south and skies can help set a clear direction for restoring forests.

 

Southern California’s climate is very much like that of Baja. Our forests used to be similar too.  Baja forests still are predominantly open, and haven’t been influenced by fire suppression or development.  Baja forests suffered during the 2001-2003 drought and beetle attacks, but not nearly to the extent Southern California forests did. Baja forests experienced far lower mortality and less severe wildfire.

 

Baja fires tend to burn in the summer, when Baja, like Southern California, experiences its most predictable weather. Smoke columns go straight up 10,000 feet then disperse. In Southern California, when fires burn Santa Ana winds blow smoke low where everyone gets to breathe it. In Baja, fire burns about 2,000 acres a day. The 2003 Old and Cedar fires burned 300,000 acres in a week.

 

We can re-establish safe forests with Southern California biodiversity and grandeur, but we must invest in making them a reality. Fuels must be reduced and urban forests sustained with sufficient infrastructure to manage annual growth, minimize catastrophic wildfire threats and protect air quality.

 

Baja forests can provide the model. We have the technology to turn fuels safely into wood and clean energy to help get there. But the Santa Anas are persistent and the problem is extreme.  Time isn’t all that’s wasting away in our forests.

 

 

Richard Minnich, Ph.D. is a professor in the department of earth sciences at the University of California-Riverside. He focuses on the fire ecology of Mediterranean brushland and coniferous forest ecosystems of California.