The recent fires have touched everyone. The physical composition and appearance of our landscapes, and our relationship with them, is forever changed. From wildlands and rural hillsides to city streets, what seemed permanent and safe can in fact be vulnerable to periodic fire. Not just the built environment, but many of our trees, shrubs and gardens are gone, living elements that act to soften and aesthetically anchor houses and buildings to the earth.
Our homes and businesses are set within and adjacent to our wild landscapes. In our leisure time, we walk, bike or drive through their majestic scenes. People travel from all over the world to enjoy the atmospheric and rugged areas that are part of appeal of Wine Country. Our intense engagement with these environments has created a strong urban-wildland interface that is susceptible to fire, a natural aspect of our dry summer landscapes.
There are things homeowners can do to protect their properties by planting and maintaining a landscape, with less-flammable plants and trees and maintained in such a way that will reduce the chance of fire spreading.
It helps to understand the larger context of fire within our built environment. California is a fire-prone landscape because of the state’s long dry season, low relative humidity, occasional high heat and winds and frequently abundant vegetation that provides fuel to fire. Ecosystems and their communities have developed and evolved in this environment. Periodic fires are a natural aspect of most California ecosystems. Some are fire-dependent and require fire for seeds to germinate, renew overgrown vegetation, open forests to sunlight and provide nutrients for certain plants. The soft, new growth of native shrubs that grow after a fire provide food for deer and other wildlife. Bare soil and the lack of competition from shrubs and trees allow annual wildflowers to grow. Too frequent fires destroy seedbanks, and young trees and shrubs before they are old enough to set seed, which leads the landscape to convert to grasslands.
Dry conditions, low relative humidity and winds help create physical conditions conducive to fire. Dry vegetation and structures like houses feed fires. The golden hills that are an ubiquitous feature of California’s identity, are composed of more than 90 percent non-native grasses and forbs, generally found as broad-leafed flowering plants.
We have both purposely and inadvertently converted our natural understory landscape of perennial grasses and annual wildflowers to very flammable non-native grasses. These plants grow quickly with the advent of winter rains, set seed and die early in the spring. They are highly flammable (often called “flashy), and allow fires to spread rapidly. They are dangerous when they invade or are adjacent to shrub or chaparral plant communities, as the grasses act as ladders into the flammable shrub overstory. These grasses also dry much earlier in the season than other vegetation, extending the seasonal fire danger.
Chaparral, the most common plant community in the state, is composed of densely growing shrubs such as manzanita, chamise and Ceanothus that form a closed stand over time. It is a fire-dependent ecosystem, yet fires historically occur there only about once or twice a century. They are often severe, eliminating most standing vegetation. Many shrubs and trees of this ecosystem either sprout from the base, or their seeds are stimulated to grow by fire and the resulting bare soil. Fires rejuvenate these areas. In conifer forests, fires were more frequent, and usually patchy, and lighter in intensity, mostly consuming the understory and young trees with branches that reach the ground.