Invasive plant overruning hillsides, capable of taking down oak trees
By Logan Hall
The hills surrounding Highway 150 near Lake Casitas are being overrun by cape ivy, an invasive plant that can destroy its surrounding ecosystem. Oaks and other native trees and plants are being smothered and, in many cases, officials say, the weight of the vine alone can pull down and devour entire trees. Spreading rapidly, it blankets the ground and hinders the new growth of almost all other vegetation. Soil erosion can then become rampant, which could lead to mud slides. If left unchecked, entire hillsides can be stripped of most other species including many animals that need native vegetation for their habitat. It’s happening now, and right here in Ojai.
Experts have discovered that cape ivy, originally found in the mountain forests of South Africa, was brought to the eastern United States in the 1850s as an ornamental vine. By the mid-1960s, it had staked its claim in Golden Gate Park in northern California. From there it spread over the West Coast and has been mapped from southern Oregon to San Diego being carried by water runoff, migrating birds and human traffic, among other things.
“It’s a phenomenon,” said Ventura County Agricultural Commissioner Henry Gonzales. “It’s like a forest fire in slow motion. It rises to the top of the trees and kills off native species. It’s an opportunistic weed, and it will continue to spread.”
One of its more serious implications is the vine’s ability to turn live trees and brush into veritable piles of dead lumber, making the hillsides much more susceptible to forest fire. Paul Rogers, one of Ojai’s leading experts in native vegetation, believes fire could be a legitimate concern. “The big thing is the potential for fires,” he said, studying a photo of an oak being taken down by a thicket of cape ivy taken just a few miles from his home. “This is very serious.”
Not only is it a potential fire hazard, the vine also destroys the habitat of many animal species. Animals such as squirrels and woodpeckers that depend on the oaks for acorns and shelter could be losing viable food sources. Oaks and other native trees are also habitat for many endangered or protected species, including bald eagles, that use the trees for nesting.
“It really disrupts the ecology of the area,” said David Magney about cape ivy. Magney, who is an Ojai resident and runs his own environmental consulting firm, has tracked the vine’s invasion of Ojai and the surrounding hillsides. “It just takes over. It kills everything and will eliminate the habitat for a wide variety of species. It needs to be dealt with.”
Therein lies the tricky part. Because cape ivy is so extensive, and spreads so rapidly and indiscriminately, it is nearly impossible to eradicate. The sheer manpower, funding and other resources required for such an undertaking is almost immeasurable. County and state officials all over California are being faced with similar challenges.
“Our first step is to map its locations,” said Gonzales. “Then we need to conduct a survey of property owners to see who is affected. After that we need to educate them.” It’s at this point that the plan seems to run into the economic wall that has a tendency to stop government projects in their tracks.
“Effective control strategies are not cheap,” said Gonzales. “You need a regional effort to control a weed like this. I just don’t have the resources.”
Doug Johnson, executive director of the California Invasive Plant Council, has similar concerns. “Cape ivy is not really possible to eradicate,” he said. “It’s so hard to contain that the federal government is working on a bio-control for it.” Different from pesticides, a bio-control uses insects, animals or even other plants that naturally hinder the growth and progression of a particular invasive species. “The research has been done. Now they need to do extensive testing on the bio-control agents,” he added.
The impact of the vine has gotten the attention of ranchers and farmers throughout the hills beyond Casitas, for whom its implications could be the most serious. Some are engaged in a year-round fight with it, which increasingly seems to be a losing battle.
“That stuff is crazy, man,” said local rancher Richard Palato about the cape ivy that has overrun his property. “I had this big oak tree … that stuff took it down and killed it.” Palato owns and operates Rancho Encino just past Casitas Pass up Highway 150 where he grows various cut flowers and avocados. Having spent more than 20 years in the agriculture business, Palato seems to be an expert in the local vegetation. “This plant is bad news,” he added as he pointed to a patch of the weed a few yards from his front door.
Most experts and officials say that awareness and education are the first steps in the eventual control of cape ivy. The more people know about it, the more it can be dealt with on individual properties. Until an effective control strategy is developed, this problem will continue to spread with no signs of stopping.