| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Letters to the Editor Oak Death and Wildlife The recently identified fungus that is killing coast live oaks, black oaks, and tanoaks could mean disaster for California’s wildlife. This consequence of the infestation is perhaps less apparent to many than its effects on fire danger, landscape esthetics, and property values, but it is no less important and, indeed, is related to them. That the catastrophic loss of oaks is not simply alarmist is supported by the history of the American chestnut. For millennia it was the dominant tree of forests from Maine to Florida; its abundant mast crops were important both to Native Americans and wildlife. The fungus that caused chestnut blight first appeared in 1904; by the1950s, the American chestnut was ecologically extinct. It now exists in the wild only as scattered sprouts from old trees. There is little information on the effects of the loss of the American chestnut on wildlife. After the disappearance of the American chestnut, oak and hickory trees became common in the eastern forests. In California, no similar ecological replacement exists. What would be the effect of the loss of oaks on California’s wildlife? Using the California Wildlife Habitat Relationships system, a collection of models of ecological relationships between wildlife species and their habitats developed by the California Department of Fish and Game and other biologists, we can begin to predict which species might be affected. More than 200 of California’s 675 species of birds, mammals, reptiles, and amphibians are associated with oaks in California’s coastal counties. The models indicate that more than 95 percent of these would be negatively affected by an oak die-off; only a few would benefit. Songbirds feed nestlings insects gleaned from oaks in the spring; band-tailed pigeons are closely tied to acorns. Mule deer feed upon oak leaves, twigs, and acorns, are preyed upon by mountain lions and coyotes, and serve as carrion for a variety of scavengers, including California condors. The complex social organization of acorn woodpeckers depends on oaks, and the oak titmouse is unique to oak woodlands. The dusky-footed woodrat depends on good acorn crops for increased reproduction and is important prey for the spotted owl and other predators. Interestingly, both the dusky-footed woodrat and the band-tailed pigeon had analogs in the eastern forests that disappeared with the American chestnut: the Allegheny woodrat and the better-known passenger pigeon. Many wildlife species also depend on oaks for reproduction and cover. Cavity-nesting birds such as the northern pygmy-owl, several species of woodpecker, and tree swallows nest in oak trees. Downed logs are used as cover by amphibians and reptiles such as the California newt, Pacific treefrog, western fence lizard, and western skink. In the southern Sierra Nevada, the Pacific fisher, a rare carnivore recently proposed for listing as endangered, uses large oaks for maternal dens, and preys on many species that depend on oaks for food. Without oaks, these and many other species, both common and rare, would disappear from vast areas of California. Ecological changes after fires burned the dead oaks, such as the spread of exotic weeds and reduction of riparian areas, would further disadvantage wildlife. Aquatic systems would be damaged; increased water temperatures and erosion following fires would harm anadromous fish and those species depending on them, such as bald eagles and river otters. In sum, the cascade of ecological effects and their impacts to wildlife from loss of oaks may be the most profound since the arrival of humans 10,000 years ago, when much of the large fauna went extinct. Let us hope that those in Sacramento and Washington, D.C., appreciate the enormity of the situation. Thomas E. Kucera Support for China Research As participants in the Academy’s ambitious field research program in China, we were delighted to see the expedition to the Gaoligong Mountains of western Yunnan featured in your Winter 2001 issue. Dong Lin’s photographs and your firsthand written account capture well the sensory experiences that remain so vivid for us and, we hope, excite your readers. We would like to take this opportunity to acknowledge with thanks the generous support of the Yunnan Commission for Science and Technology, the National Geographic Society, and devoted contributors to the China Natural History Project, without which this and the initial expedition in 1998 would not have been possible. Nina Jablonski and David
Kavanaugh Cultural Timeframes Is it not possible that both Diamond and Landes are correct (“Counterpoints in Science,” Summer 2000)? I feel that they are talking about two different time frames of history: Diamond’s theory discusses the situation some hundreds to thousands of years ago, wheareas Landes is talking about situations much more recently. Geoff Potter |
Spring 2001
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