PROPER TREE AND VEGETATION MANAGEMENT
By JENN HOPPEL
This article first appeared in CAI CA North Chapter’s, The Voice Magazine’s Spring 2025 Issue.
While there are many benefits to living in California, as with anywhere, there are risks associated with living here as well. Wildfires are one of California’s most dangerous issues, with over 7 million acres burned in the last 10 years. The duration and severity of these fires is increasing each year due to a variety of factors. A primary way to reduce risk to people and their communities is through proper tree and vegetation management and planning. But before we dive into how to implement this, let us first consider some general information about wildfires and how they affect our communities.
CALIFORNIA FIRE SAFETY: INVESTMENT, RESOURCES, AND RESPONSE California is one of the most proactive states in the nation when it comes to wild- fire prevention. In the past five years, there has been substantial investment in our wildfire prevention programs. Since 2020, the state has invested over $3.5 billion in proactive projects, including 61 large-scale fuel reduction projects throughout the state. Just this year, specific areas to note are near the Palisades and Eaton fire perimeters, totaling over 14,500 acres. As of February 2025, under the Newsom administration, the state of California has prioritized the support of CAL FIRE operations, investing over $2 billion to increase personnel from 5,829 positions to 10,741 positions since 2018 and a goal of adding 2,400 additional state firefighters over the next five years.
The fires that ripped through Southern California in January of 2025 were devas- tating due to their proximity to the public. During this time, the state of California mobilized more than 16,000 personnel, including firefighters, National Guard service members, California Highway Patrol , and transportation teams. Additionally, there were over 2,000 firefighting apparatuses used to fight the fires, which included en- gines, aircraft, dozers , and water tanks.
Even with some resources in place within our communities, it is essential that we plan ahead and create goals for wildfire prevention and response. This requires investment in a comprehensive tree management plan to reduce wildfire risk through a proactive approach. It is best to avoid deferred maintenance and have your community under the supervision of a Certified Arborist. This partnership can be instrumental in prioritizing the work to be completed through the assessment process.
IT’S THE LAW AND A LIABILITY!
The state of California, as well as local municipalities, have laws in place regarding managing the vegetation around structures. According to the California Public Resources
Code (PRC) 4291, minimization of potential fuels is required within 100 feet of structures or to the property line. Check with your local fire department or fire protection district for defensible space or weed abatement requirements in your area. Some counties offer rebate programs to property owners to offset the cost of hiring a contractor to improve defensible space. It is also important to check the governing documents within your com- munity for additional requirements that may be in place to minimize the risk of fires.
Improper management of trees can substantially impact the liability of not only the individual homeowner but the community as a whole. With the ever-increasing risk of wildfires, many insurance carriers will not approve policies because there is too much risk from excess and dead vegetation. Carriers regularly review communities with the highest potential for wildfires and may cancel policies immediately if they deem the site to be beyond their risk threshold. The good news is that most insurers will give notice of cancellation so that action can be taken before policy cancellation. The most common issues regarding trees are when limbs are overhanging the home, and there are unmanaged common areas of wildlands adjacent to the community. Through the implementation of a tree management plan, li- ability is decreased, and the homeowner and community can maintain their insurance.
CLIMATE CHANGE IN CALIFORNIA
One of the most significant factors contributing to the severity of wildfires in California is ongoing climate change. With the increase in temperatures, severe droughts in California have increased and spread into previously less susceptible areas. Decreased rainfall has also contributed to these drought conditions , resulting in fires that are ignited more easily and spread more rap- idly. Wildfires themselves can significantly contribute to an increase in greenhouse gas emissions, having a cyclical impact on our climate. 2024 was the third hottest summer and fall on record since 1895, with global temperatures continuing to rise each year.
Although it seems counterintuitive, rainfall can increase the likelihood of and speed of wildfire spread. During rainy seasons, weeds grow substantially within wildland areas, which then dry and serve as readily available and highly flammable fuel. Due to this, it is important to keep your grass maintained in addition to your tree management.
HUMAN IMPACTS
A significant contributing factor to wildfires is an increase in population adjacent to wildlands, referred to as the Wildland-Urban Interface. According to the Census Bureau, in the state of California, the population increased by approximately 5.8% between 2010 and 2020. The National Interagency Fire Center approximates that between 85% and 90% of all wildfires are started by humans, and of these, approximately 97% directly impact homes. Recognizing the responsibility we must all take to protect ourselves and our communities is key. Let us now consider how we can reduce the impact wildfires have on our communities.
DEFENSIBLE SPACE AND VEGETATION MANAGEMENT
One of the best ways to protect your com- munity is through the implementation of defensible space. Defensible space works as a barrier between the fire and your home by clearing the area of dead and dying debris and pruning existing trees. The goal is not to irradicate all plants within the defensible space but to properly manage and selectively remove highly flammable vegetation. This includes removing dead and dying plant material, reducing the density of vegetation and ladder fuels, and replacing hazardous vegetation with less flammable, well-irrigated, fire-resistant plants.
Below is a diagram illustrating the amount of defensible space required in California per Public Resources Code (PRC) 4291:
To break down the necessary standards, we will refer to CalFIRE, which recognizes the three zones that need to be considered for fire mitigation.
ZONE 0 “EMBER RESISTANT ZONE” (WITHIN 5 FEET OF HOME):
– Regularly remove leaves and needle debris throughout the landscape, in gutters, and on roofs.
– Reduce limbs within 10 feet of chimneys, and prune trees to provide clearance of 5 feet from roofs and the sides of homes.
– Have your home inspected regularly for any wiring or structural issues that would cause or increase the likelihood of substantial fire damage, particularly from ember ignition.
ZONE 1 “LEAN, CLEAN, AND GREEN ZONE” (WITHIN 30 FEET OF HOME) – Remove all dead and dying material on the
ground and in the canopy of adjacent trees.
– Prune trees to separate them a mini- mum of 10 feet from one another to limit tree-to-tree transfer of fire.
– Prune trees away from surrounding structures, furniture, wood piles, trash/ recycling, etc., a minimum of 5 feet.
ZONE 2 “REDUCE FUEL ZONE” (WITHIN 100 FEET OF HOME):
Zone 2 is most often neglected because it is not directly adjacent to homes. However, this is one of the most important areas to manage your trees.
– Remove all fallen debris and dead or dying trees.
– To provide vertical clearance, raise the canopy of trees to a minimum of 6 feet above grade. Raise branches on trees to a minimum of 3 times the height of adjacent bushes.
– Prune to create space between trees a minimum of 10 feet from canopy to canopy to provide horizontal clearance.
The diagram (below) illustrates the recommended actions for tree management within Zone 2.
The risk of fire damage can be decreased substantially by managing trees and vegetation within the noted zones. Another benefit to creating defensible space through vegetation management is ensuring the safety of firefighters defending your home.
MINDFUL LANDSCAPE CHOICES
Just because you are trying to mitigate fires does not mean you can- not have any trees or shrubs near your home or within defensible spaces. However, being mindful of landscape choices and maintaining your landscape is key, including properly functioning irrigation. For example, deciduous broad-leaf trees are less flammable than coniferous trees. It is recommended that all juniper, cypress, arbor- vitae, and podocarpus, which are directly adjacent to structures, be removed. These species hold dead material within the inner canopy, making them more susceptible to ember ignition. There are many shrubs and ground covers that are more fire resistant, such as creeping thyme and sedum. An additional benefit to choosing these types of plants is that they are drought-tolerant, thus having a lower mortality rate, creating less available fuel for fires.
Another good strategy for managing ground vegetation is the installation and spreading of chip mulch; however, it is not recommended within 5 feet of structures. In this area, non- combustible materials such as rock, gravel, and pavers can be used and serve as fuel breaks. Outside of this area, organic mulch is an excellent fire mitigation tool. It improves the soil by increasing water retention, which controls heat, provides enriching nutrients to keep stressed trees healthier, reduces weeds, and prevents erosion. Particularly, when creating Zone 2 defensible space, it is recommended that chips be broadcast in the area to discourage the growth of fast-burning grasses and weeds.
TAKING ACTION TOGETHER
It is impossible to completely eradicate the risk of wildfires, but we can take measures to reduce their impacts. Immediate action is recommended for tree and vegetation management, but this is a multi-step process. The ultimate goal is to manage the fuel reduction process over time, and you can work with your Certified Arborist to prioritize each step of the tree management plan. What is paramount to remember is that fire is not concerned with liability, damage, or even loss of life; it is simply driven by fuel. Managing your trees to reduce the amount of fuel avail- able is one of the first steps to keeping our communities safe. Through increased knowledge and recognition of how we can improve our fire risk reduction measures, we will make progress to keep our families, homes, and communities safe.
