The recent record-breaking rains raised expectations for glorious wildflowers come spring in our local canyons and deserts. A century ago this most certainly would have been a logical consequence. But in recent decades the natural landscape has changed. Many native plants have disappeared as exotic (non-native species) have been introduced and taken an aggressive foothold. As result, the native wildflowers that we are anticipating may be trumped by the exotic vegetation. ”Only about one percent of California’s native grasslands still exist, including the perennial bunch grasses, pushed out by the more than 300 invasive species that have colonized the Santa Monica Mountains, according to restoration ecologist Christy Brigham of the Santa Mountains National Recreation Area. ”Suzanne Goode, senior resource ecologist with California State Parks, the Topanga district of Topanga State Park, says that Southern California is one of the most vulnerable to invasive exotic vegetation because of its benign climate. ”All over California, natural wildlands are under attack by invasives. As exotic plants replace our native habitat, we are also losing many species of birds, insects, fish and other wildlife. ”The chief offenders, according to Goode are: ”Arundo donax, a giant reed that grows in all our canyons, consumes more water than natives, eliminates native plants and wildlife habitat and fuels wildfires; ”Cape ivy, a transplant from South Africa that has infested all coastal-facing canyons, smothers riparian vegetation, and has no natural check; ”Pampas grass, an ornamental grass used in domestic landscaping that invades and degrades habitats along the entire California coast; ”Harding grass, a nonnative that has the potential to establish in dense stands, at least in localized areas and is a constant threat to native grasses; ”Euphorbia terracina, a large shrub-like herb that forms dense thickets, which out-compete native species for space, light and nutrients. Its rapid growth and prolific seeding gives it the potential to invade areas of healthy bushland; and ”Yellow star thistle, a gray-green annual whose extensive root system allows it to survive well into summer, long after other annual species have dried up. ”These and a host of other exotics are taking over in our local canyons, such as Los Liones and Temescal. This is because neither the National Park Service nor California State Parks began focusing on the problem until about 20 years ago, and there are still too few resource people to tackle the crisis, and minimal funding. ”’We take a triage approach to start with,’ says Goode, who until September was the only permanent resource ecologist in the Topanga district, which includes parks from Pt. Mugu on the western border to Baldwin Scenic Overlook in Baldwin Hills. ”’We had no natural resource maintenance money until just three or four years ago. The legislature was going to allocate $11 million two years ago, then we had the energy crises, and we were left with $2 million among all the state’s parks, with our share under $100,000 a year. I could use $500,000 to $1 million a year for state parks in Los Angeles and five to six people for each park before we can make inroads on this problem. ”’The climate in Los Angeles is very welcoming to weeds,’ Goode explains. ‘These weeds, mostly annuals, were preadapted from other Mediterranean areas, but when they came to our canyons, they changed the look and ecological function. Our native perennial grasses are bunch grasses, which would have allowed wildflowers to grow in between. But the annual grasses have taken over the understory. Their strategy is to come up quick, suck up the surface water, produce a seed head and multiply. Our natives are not in so much of a hurry so they lose out on water, and by the time they start thinking about sprouting around February, they will already be crowded out by the aggressive proliferation of non-native grasses.’ ”One of Goode’s most vicious outlaws is Arundo, which was originally introduced in Los Angeles in the 1820s as an erosion-control agent in drainage canals, and was also used as thatching for roofs of sheds, barns and other buildings. Today it poses the greatest threat to riparian areas. It takes away the shade provided by willows, traps mud in creeks, which raises the elevation, flattens out the channel and interrupts fish migration. And it is highly flammable, whereas riparian forests once presented a natural firebreak. And, like so many successful invasive plants, Arundo grows at an incredible rate, a foot a week in its growing season, Goode says. ‘ There are a number of eradication methods that can be used, including localized use of a state-approved herbicide such as Rodeo, controlled burning, and most often, hand removal. ”Local volunteers, including the Temescal Canyon Association, Heal The Bay, the California Native Plant Society, the Mountains Restoration Trust and the Lower Topanga Canyon group, work with State Parks on weed-whacking forays. ”’There is also money available through Propositions 12 and 40 and there is funding from the Santa Monica Conservancy for the lower Topanga Arundo project,’ Goode says. Last year the state suspended using herbicides on Arundo after residents felt that it was poisoning the environment, she says. ‘We are in disagreement on the science.’ Goode believes that often a combination of herbicides plus controlled burning or mowing can control the problem significantly. ”Stephanie Landregan, chief landscape architect with the Mountains Recreation and Conservation Authority (MRCA), takes a look at the bigger picture in suggesting ways to keep the native grasses thriving.” ”’Landscape architects have to come up with a balance between our desire to have an ever- verdant, tropical environment, and reintroducing an appreciation for the natives. People say the native plants look too weedy. I say, ‘So do your tomato plants.” ”Jo Kitts, program director with the Mountains Restoration Trust and inveterate weed whacker, has been battling horticultural grasses for some time. She condemns the use of fountain grass and pampas grass in gardens that are adjacent to wild lands. ‘Horticulturalists can find a number of alternatives to these weeds,’ she says. ‘For example, deer grass (Muhlenbergia rigens), looks like a small pampas grass but without the bad leaf cuts and the aggressive seeding.’ ”’We have to start respecting and teaching the seasonal and climatic cycle instead of living in denial, a favorite way to live in California,’ says MRCA’s Landregan. ‘We have to figure out the best way to deal with parks and development: What is the responsibility of all of us in making sure we buffer the invasion of nonnatives in our wild areas while allowing us to have individual gardens?’
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