Oak
disease attacks redwoods, Douglas fir
Discoveries in Sonoma, Santa Cruz counties confirm scientists'
fears, will trigger new restrictions on logging
By
MICHAEL COIT/THE PRESS DEMOCRAT/September 5, 2002
The
disease killing California's oaks also threatens the state's
majestic redwood groves, scientists said Wednesday, citing findings
from Sonoma and Santa Cruz counties.
Researchers
said the disease also was found on Douglas fir.
UC scientists aren't yet certain if the disease will prove fatal
to either tree, but they said the findings confirm their worst
fears about the disease, which has killed tens of thousands
of oaks trees.
"This
is kind of a worst case scenario," UC Berkeley scientist
Matteo Garbelotto said. "Those two hosts are not only ecologically
important but also economically important."
Garbelotto
and UC Davis scientist Dave Rizzo discovered the microbe that
causes sudden oak death and have led the effort to find a cure.
They said redwoods and Douglas firs are essential to the health
of coastal forests.
Gov.
Gray Davis said Wednesday's announcement "significantly
raises the stakes." He called on President Bush to provide
$10 million to bolster $2 million in new state funding to fight
the disease.
The
spread into redwoods and Douglas fir means logging companies
will face new restrictions under state and federal quarantines
aimed at preventing the disease from spreading beyond 12 coastal
counties where it has been found.
Scientists
were surprised that the disease moved into the two trees because
they are conifers and far different from oaks and the other
host plants.
Sudden
oak death appears to spread more easily than most plant diseases.
The
two types of conifers bring the number of affected plant families
to 10 with a total of 17 specific hosts.
"Not
all diseases kill everything. But now that we have these two
hosts, almost every woody plant species in all these forests
in the coastal areas can be infected," Rizzo said.
"Now,
each one of those hosts is going to be impacted in a different
way. But the cumulative affect may change a lot of ecosystems.
It's just going to look different," he said.
The
disease might wipe out some host plants and shrubs and reduce
forest diversity. In other instances, tree stands could be diminished.
Above
Glen Ellen in Jack London State Park, where some of the infected
redwoods were found, the disease already has wiped out many
tanoak stands and killed some coast live oaks.
"If
redwoods are affected, that would certainly be alarming. You're
covering most of the trees that occur in the plant communities
of the parks," said Greg Hayes, a supervising ranger for
the state park's Silverado District, which covers areas of Sonoma,
Napa and Lake counties.
At
Jack London Park, he said, "the groves that we have are
significant because they're often along creek areas and trails
that pass through mixed vegetation. They provide the shade in
the park that make it possible for people to hike through on
hot summer days."
The
infected Douglas fir trees were found in Fairfield Osborn Preserve,
the research site Sonoma State University operates east of Rohnert
Park on the other side of Sonoma Mountain from Jack London.
The disease has killed a black oak and some coast live oaks
there.
"We're
losing individual trees on a case-by-case basis over time,"
said Julia Clothier, preserve manager.
While
Clothier said there's plenty of fear about how the disease might
progress, she also said findings made at the preserve and other
sites have helped scientists learn more about how the disease
spreads and harms plants and trees.
"It's
nice to be at the center and to have those discoveries being
made here," she said. "We're just learning about this.
Something's going on and it's interesting."
On
both redwoods and Douglas fir, needles and very small branches
turned brown, with the fir branches wilting or dying.
Only
saplings appeared infected and the disease was not observed
on trunks. But scientists cautioned that not enough is known
to assess whether trees might die or other potential ecological
impacts.
The
other known hosts are: Coast live oak, black oak, tanoak and
Shreve oak, rhododendron, manzanita, California huckleberry,
madrone, California bay laurel, California buckeye, big leaf
maple, California coffeeberry, Toyon and California honeysuckle,
as well as arrowwood in Europe.
Sudden
oak death has been found in 12 counties, including Sonoma, Napa
and Mendocino.
State
and federal quarantines aimed at keeping the disease in check
regulate the movement of host trees, plants and materials out
of those areas and California.
Redwoods
and Douglas fir are two of the state's most heavily logged trees.
While
timber companies remove branches before hauling logs out of
forests, a quarantine requirement to also remove bark could
hamper operations and limit the use and sale of some products.
"We
need to make sure it doesn't become a huge bottleneck,"
said David Bischel, president of the California Forestry Association.
Timber
companies operating in the four logging counties covered by
the quarantine -- Humboldt and Mendocino, and to a lesser degree
Sonoma and Santa Cruz -- now haul some of their trees to mills
outside those counties. Bark is removed at the mills for a variety
of uses.
Bischel
said the restrictions don't seem reasonable given that their
foresters have not found sudden oak death on lands where trees
are cut. "We've been managing those forests and we don't
find it in those forests," he said.
Scientists
noted the quarantine is needed given the range of the two trees.
Redwoods
are found in coniferous forests and range along the coast from
the Oregon border to Monterey.
Douglas
fir are found in hardwood and coniferous forests and range from
British Columbia to Santa Barbara County and east into the Rocky
Mountains.
Coastal
woods also are a major draw for hikers, campers and other visitors
to state and national parks. Signs have been posted in some
parks urging users to wash boots and bike tires before leaving
and not to collect wood or plants.
Sudden
oak death was first observed in Marin County in 1995. Five years
later, Garbelotto and Rizzo identified the cause: a fungus-like
microbe called Phytophthora ramorum, which is related to the
fungus thought to have caused the Irish potato famine and the
death of Port Orford cedar trees in the Pacific Northwest.
Experiments
have revealed that the microbe survives in rainwater, soil and
leaf litter.
Scientists
suspect it spreads through the air and infects host plants other
than oaks and then is spread to oaks in rain splash. The microbe
apparently builds up in bay foliage and then spreads to oaks.
You
can reach Staff Writer Michael Coit at 521-5470 or mcoit@pressdemocrat.com.
Return
to previous page