…In the evolutionary blink of an eye, many of California’s intact habitats have become effectively isolated, biological islands locked into place by the altered, inhospitable land surrounding them. Because of the perils of isolation and small size, ecologists are unsure how long these islands can sustain the plants and animals living within their boundaries. Add to that already troubling situation the impacts of rapid climate change and you have a recipe for ecological disaster. Like prisoners locked in a burning jail, many plant and animals species will perish as they have no place to go when their ranges become unsuitably hot, or wet, or dry.

Below I focus on three very different places that clearly illustrate the problems climate change will pose—and in at least one case is already posing—to California’s fragmented habitats. The first is Ballona Wetlands, a battered but beautiful remnant of coastal wetland near Los Angeles. Second is Jasper Ridge, a chunk of serpentine grassland that’s been as well studied in relation to climate change as any piece of land on Earth. And finally, a new preserve linking Humboldt Redwoods State Park, which includes the world’s largest remaining patch of old-growth redwoods, to King Range National Conservation Area and the Lost Coast.

Overgeneralization is the bane of ecology, perhaps of any science, but there are some common themes that emerge from these three distinct places. Most importantly, to cope with relatively quick and severe changes in climate, California’s plants and animals will need room to move. As University of Florida biologist Reed Noss says, “When the climate changes, organisms must move, adapt, or die.” That goes for whole communities and ecosystems as well. In the unnaturally short time frame of current warming trends, genetic adaptation is out of the question for most species. So, in addition to doing what we can to slow the pace of climate change, the best we have to offer plants and animals is room to move. In many cases that will be impossible or impractical and extinctions will probably be high. But the opportunity to create a network of core reserves interlinked by protected corridors of habitat will never be as great as it is today. The California Wilderness Coalition is pursuing such a big-picture approach with their California Wildlands Project. If granted space, many of California’s extraordinary native organisms and habitats may be able to ride the wave of global warming, perhaps the biggest ecological challenge we’ve given them to date.

Ballona Wetlands Restoration Challenges

California’s coastal wetlands are like pearls,” says wetland ecologist Joy Zedler, now at the University of Wisconsin but long a student of coastal California. If they are evenly distributed and close enough to one another, you’ve got a beautiful necklace, a functioning network of integrated coastal ecosystems. Sell off some of the pearls and the necklace suffers, but it’s still a pearl necklace. Remove too many, cut the string, and scratch the luster off the remaining pearls and you have nothing. Except, perhaps, nostalgia and regret.

Californians have lost or sold off quite a few pearls in the past 150 years. Ninety-five percent of the state’s coastal wetlands have been filled and converted to some other purpose. Many of the pearls remaining are cracked and unevenly placed. Ballona Wetlands, for instance, is the only remaining large coastal wetland ecosystem in Los Angeles County. Once covering 2,100 acres, it has been diminished, battered, and abused almost beyond recognition. Today, only about 540 acres of wetland remain. Ballona, like many coastal wetlands today, is circumscribed by immovable perimeters: it is bounded to the north by Marina del Rey, Highway 1 cuts off its eastern end, and housing developments crowd the other edges.

The changes that will come with global warming pose several problems for Ballona and virtually every other coastal wetland. The most salient, says Zedler, will be sea level rise. In the past, the undulating patterns of ice age and thaw brought relatively slow climate change; wetlands would move upland as, over the centuries and millennia, the seas grew and swallowed up their lower marshes. No such retreat will be available to Ballona, the wetlands of south San Francisco Bay, or most of the other coastal wetlands along the Pacific. “If the upland margin is immovable,” says wildlife biologist Robert van de Hoek, “the wetland creatures dependent on areas above the tide will have no place to go.”

Marshland will in many cases be able to keep pace with sea level rise, says Zedler, as long as there is a good source of sediment that can be trapped and acquired by the salt-tolerant plants in a marsh. In some cases, where the movement of sediment through feeder streams and creeks has been impeded by damming and channelizing, sediment may have to be supplied from elsewhere. Dredge spoils, for instance, have been used to raise marshes at a quicker than natural pace around San Francisco Bay. In Ballona, some of the restorable land, now leveed off from the tides, has had much sediment dumped on it. Ironically, this may someday prove useful in helping the restored marsh stay above the tides.

Among the wetland critters van de Hoek studies are fiddler crabs, crustaceans whose earliest stage of life is spent eating plankton in the open water. Once they reach maturity, however, fiddler crabs spend their lives in the moist but rarely submerged area above the tides—an area, van de Hoek says, that may well be squeezed out of existence as higher water floods more upland areas of the salt marsh. “We will likely lose fiddler crabs at Ballona with sea level rise,” he says.

Another creature that relies on higher portions of Ballona is the wandering skipper, a butterfly whose caterpillars live in the salt grass in the lower marsh. Adult wandering skippers need access to drier upland marsh plants such as seaside heliotrope, a saltwater-intolerant plant likely to be squeezed out by rising tides and increasingly frequent and rough storms, says van de Hoek.

By far the most celebrated of wetland residents are the birds. Two hundred and fifteen different species live in or visit Ballona. Migratory birds in particular need the string of pearls to remain intact along the coast. Plying the Pacific Flyway, they rely on fecund wetland ecosystems for food and rest. Because Ballona lies halfway between the 2,000-acre Mugu Lagoon, 25 miles up the coast, and Los Cerritos Wetlands, 25 miles down, it was once and could again be a key pearl in the necklace.

Some birds, including the endangered light-footed clapper rail, are “island hoppers,” Zedler says. They can’t fly much farther than 25 miles at a stretch. Others, including Belding’s savannah sparrow, may be unable to make a 50-mile jump. Even strong-flying, long-distance migrants need rest stops, says van de Hoek, and a restored Ballona would be of great value to them as well.

The last clapper rail seen at Ballona was photographed there a decade ago. It was only visiting and must have come either from the north at Mugu Lagoon, where there is now a tiny nesting population of six pairs, or from Seal Beach National Wildlife Refuge to the south, where there are about 50 pairs. If those two populations could be linked by a restored Ballona, it would help them regain genetic vitality and help protect them against site-specific calamities. The light-footed clapper rails will need Ballona, says van de Hoek, whether its upland portions are lost to rising sea level or not.

Ballona is also isolated from large terrestrial animals on the mainland—some of which, coyotes, for instance, are helpful to clapper rails. “Coyotes hate to get their feet wet,” says Marcia Hanscom, executive director of the Wetlands Action Network, a group dedicated to the preservation of wetlands along the Pacific Flyway. “And the rails stay in the cordgrass. So coyotes [stay out of the marsh and] don’t prey on the clapper rails, but they do hunt other predators that eat juvenile rails and eggs, such as foxes and possums.” Although there are coyotes in the area, they often can’t get across the six-lane Highway 1 to access the upland portions of the wetland.

If a wetland island is too small, it can function as a population sink for birds, says Zedler, attracting them to a place that has no long-term future for them—a “wetland museum” as some ecologists call it, where they are likely to perish. Similarly, if a wetland is too far away from associated habitats to allow migration, it may have the same deleterious effect, stranding—and dooming—individuals and populations. If wetland islands are big enough, close enough, and connected to the larger ecosystems surrounding them, migrating birds will have a much better chance of surviving the changes to come.

In September, the State of California announced that it would pay $140 million for 540 acres at Ballona, rescuing them from a controversial housing development long in the works. The removal of roads that slice the wetlands into still smaller fragments, and the reconnection of several marsh areas to each other and to tidal flow, will give the plants and animals of Ballona a great advantage. The restoration plan also includes making a connection, along Ballona Creek, from the upland areas all the way to the beach. Within a decade or two this key piece in the coastal wetland necklace may have regained much of its former splendor and its value as critical wildlife habitat.

Even so, there may be other losses with climate change, ones more difficult to predict than the narrowing of upland boundaries. The extent and severity of these losses will depend on how much warming occurs. Zedler fears, for instance, that as temperatures rise at Ballona and other coastal wetlands, so will evaporation and the photosynthesis rate of plants, causing more salt to be drawn up into the soil. “If evaporation and plant activities increase soil salt concentrations to 4.5 percent, that will be toxic to many native wetland plants,” she says. “Pickleweed may be the only plant around here that can tolerate such high concentrations.” She’s not predicting that, only saying it is possible. “There are so many variables,” Zedler says, “and therefore many, many plausible scenarios.”

Too Late for Jasper Ridge Checkerspots

For the past decade and a half, ecologists have warned that warming would shift temperature zones northward and up slopes to higher, cooler elevations, leaving overheated “island” populations behind. But scientists have also warned that changing precipitation patterns—specifically, increases in the extremes of wet and dry—will make it even more difficult for plants and animals to survive. Those worries proved justified for two of the last peninsular populations of Bay checkerspot butterflies at Jasper Ridge Biological Preserve, a Stanford University research center in the eastern foothills of the Santa Cruz Mountains.

The serpentine grassland found at Jasper Ridge was once part of a continuous ocean of grassland flowing down the San Francisco Peninsula and east through the coastal ranges, out into the Central Valley, and on into the Sierra foothills. Today, the Jasper Ridge grassland is no longer connected to that sea. In fact, most of that original grassland has been replaced by development or by invasive plants that outcompete the natives. Because some of California’s native grasses are well adapted to serpentine soils, however, which are inhospitable to many invasive aliens, native grasslands have found refuge in serpentine habitats at a few places, such as Jasper Ridge.

Jasper Ridge’s 37 acres of grassland form an isolated island, too distant from any others for them to replenish ailing populations or contribute genes. The nearest sizeable chunk of serpentine is 25 miles southeast on Coyote Ridge. To the north, up the San Francisco Peninsula, the once-abundant serpentine is “mostly paved over,” says biologist Stuart Weiss, who has studied serpentine species at Jasper Ridge and elsewhere since 1979.

Last April, Huxley College biologist John McLaughlin, Stanford biologist Paul Ehrlich, and others published a study in the Proceedings of the National Academy of Sciences drawing a direct link between increasingly extreme weather conditions at Jasper Ridge and the extinction of the checkerspots there. Ehrlich had been watching the butterfly’s population dynamics at Jasper Ridge since 1960 and had seen their numbers rise and fall in response to weather conditions. He had long noted a close relationship between the number of butterflies, rainfall patterns, and the timing of the butterfly’s primary host plants. If it rained enough and at the right time, the butterfly larvae had adequate host plants to survive to their reproductive stage. Too much or too little rain, or rain coming too early or too late, and butterfly numbers dropped.

As predicted by several global warming models, extremes in precipitation did increase at Jasper Ridge through the 1970s, ‘80s, and ‘90s. Finally, in 1998 the last Jasper Ridge Bay checkerspots flickered out.

In the past, periodic weather fluctuations probably led to the disappearance of local checkerspot populations, including Jasper Ridge’s, says Weiss, but proximity and access to other populations would have allowed for recolonization. Although there are still checkerspot populations in the Coyote Ridge area, they are too distant to repopulate peninsula habitats. And though it is possible that precipitation patterns amenable to long-term checkerspot survival occur elsewhere, island-bound populations, hemmed in by urban development and alien-dominated habitats, have no way to find them.

The extinction of Jasper Ridge’s checkerspots is a significant loss in itself. But far more important are the indications of broader threats to California’s biological diversity from changing precipitation regimes.

Redwoods to the Sea

One of the most dramatic examples of island making in California’s history is the cutting of the once vast redwood forests. Today’s old-growth redwood stands, only about four percent of the original, are isolated remnants, exposed on all sides to a number of threats, the most immediate being continued logging for their high-priced timber.

Redwoods prefer cool, damp conditions. Because large forests can preserve their own microclimates by keeping sunshine out and moisture in, says University of Florida biology professor Reed Noss, even a few degrees average difference on the outside of the forest might not make that big a difference inside. But the more exposed edge a forest has, the less able it is to determine its own interior climate, says Noss. Today’s old-growth groves are all relatively small islands with a lot of edge exposure to weather change and other dangers.

The ice age, if it comes, would be centuries or millennia off, says Noss. Chances are good that we’ll have other, more drastic ecological breakthroughs and catastrophes before then. But in the long run, Noss’s point is valid: “Like everything else, when climates undergo major changes, redwood forests have to move or go extinct,” he says.

Individual redwood trees will respond slowly, perhaps imperceptibly, to warming, and whole forests more slowly still, but more transient plants and animals that live within their protective cover are much more vulnerable. Steve Sillett, a botany professor at Humboldt State University, studies the ecosystems in the upper canopy of redwood forests. Because of their proximity to the world outside the forest, these little-known communities are exposed to hotter, drier weather as the climate shifts. Hundreds of feet up, in the crotches of upper branches in redwood trees, as much as a meter of soil can accumulate. In and on that soil Sillett finds earthworms, salamanders, arthropods, ferns, and shrubs. If warming desiccates those upper soils and those organisms are lost, the ecology of the larger forest community will likely be affected.

At Humboldt Redwoods State Park (HRSP) that community includes some celebrated megafauna: spotted owls, mountain lions, red tree voles, golden eagles, pileated woodpeckers, Pacific fishers, and the extremely rare Humboldt marten. Of course there are also thousands of lesser-known plants and animals that have evolved in conjunction with the redwood forest. The park contains the largest protected stand of old-growth redwoods in California—which means it is the most impressive stand of the most impressive trees on Earth.

An effort is under way to link the 55,000-acre Humboldt Redwoods State Park to the 60,000-acre King Range National Conservation Area (KRNCA), five miles to the southwest. Below King Range is the 7,367-acre Sinkyone Wilderness State Park, which includes the wild mountains of the Lost Coast. Together the KRNCA and Sinkyone constitute the longest roadless coastline in the lower 48 states. The new linkage, known as the Gilham Butte/Redwoods to the Sea corridor, would unite three distinct forest habitat types: redwood, mixed fir and hardwood, and upland coastal. It would also protect key portions of the headlands of the Mattole River watershed and serve as a bridge to the Eel River watershed.

The creation of this new preserve, or network of preserves, is a step toward the de-islanding of HRSP, and it could be a model of conservation planning for the era of climate change.

“Heterogeneity of a preserve’s landscape is important,” says Stanford botanist David Ackerly. As climate changes, if there are a variety of elevational and latitudinal refugia for plants and animals, their chances of survival are heightened. If it gets too hot on the valley floor, they can move upslope. If a north-facing slope grows too dry, they can move around to a south-facing one. The absence of such alternatives may doom small island populations, says Ackerly.

It is easy to become hopeless about the likely impact of global warming on California’s coastal ecosystems. But if Save-the-Redwoods League can negotiate the purchase of private logging land, thereby creating a corridor connecting three major ecosystems, and if, even in the midst of budget woes, the State will buy a Pacific Flyway wetland already slated for development, then there is surely room for hope. Projects like Ballona and Redwoods to the Sea embody the best strategies for helping our wild lands cope with change: preserve as much intact habitat as possible, restore wherever possible, and make it a priority to link habitats that will help plants and animals adapt most naturally when the climate changes. It is also a great consolation that the scientists at Jasper Ridge have for decades been focusing their genius on observing the impacts of climate change as objectively as possible. In as charged a field as climate studies, where hyperbole is cheap and plentiful, scientific fact is a precious thing.

GORDY SLACK, guest editor for this issue of Coast & Ocean, is a freelance science writer and a columnist for California Wild.

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