Dry forests fuel wild­fire risk

Die-off slows, but toll of 147 mil­lion trees since 2010 alarms state

San Francisco Chronicle - - FRONT PAGE - By Kur­tis Alexan­der

Two years af­ter Cal­i­for­nia’s his­toric drought came to an end, the sweep­ing die-off of the state’s forests has slowed, yet vast tracts of dry, brown­ing trees con­tinue to am­plify the threat of wild­fire, fed­eral of­fi­cials re­ported Mon­day.

About 18.6 mil­lion trees died in 2018, mainly the re­sult of de­hy­dra­tion and bee­tle in­fes­ta­tion, ac­cord­ing to new es­ti­mates from the U.S. For­est Ser­vice. That pushes the to­tal num­ber of dead since 2010, shortly be­fore the five-year drought be­gan, to 147 mil­lion, a toll not seen in mod­ern times.

With once-green moun­tain­sides still bask­ing in star­tling hues of rust and apri­cot, par­tic­u­larly in the South­ern and Cen­tral Sierra, fed­eral of­fi­cials warned that weak­ened trees are apt to fall atop roads, power lines and homes while wood­lands re­main in such poor shape that they’re ripe for burn­ing.

Even Pres­i­dent Trump has taken shots at the grim con­di­tion of Cal­i­for­nia’s wild­lands, call­ing for more ac­tive for­est man­age­ment. Fed­eral of­fi­cials are work­ing with state and lo­cal gov­ern­ments to try to re­store the health of the forests, but they’re up against a die-off that’s be­come in­creas­ingly en­trenched

and only has­tened by a warm­ing cli­mate.

“If this con­tin­ues, we’re go­ing to have mas­sive prob­lems, par­tic­u­larly re­lated to wild­fire,” said Randy Moore, re­gional forester for the Pa­cific South­west Re­gion of the For­est Ser­vice. “It makes it com­pli­cated to do all the sup­pres­sion we need to do to pro­tect com­mu­ni­ties.”

Over the past two years, Cal­i­for­nia has al­ready ex­pe­ri­enced some of its most de­struc­tive wild­fires. The Novem­ber Camp Fire in Butte County killed 86 peo­ple and de­stroyed nearly 14,000 homes.

In ad­di­tion to the fire risks, fed­eral of­fi­cials cau­tioned Mon­day that the sprawl­ing stands of dead trees threaten to un­der­mine such crit­i­cal for­est func­tions as pro­vid­ing clean wa­ter and ab­sorb­ing heat-trap­ping car­bon diox­ide. For­tu­nately, Moore said, the rate of tree mor­tal­ity fell last year. The num­ber of dead trees was a third less than in 2017 and about two-thirds less than in 2016. That year, at the peak of the drought, 62 mil­lion trees per­ished.

De­ci­pher­ing the ex­act cause of death is dif­fi­cult, of­fi­cials say, as trees can die from de­hy­dra­tion or pest in­fes­ta­tion, or a com­bi­na­tion of both. Na­tive bark bee­tles take ad­van­tage of the tree’s drought-de­pleted de­fenses, of­ten de­liv­er­ing the fa­tal blow.

While it’s un­clear if mor­tal­ity rates will con­tinue to de­cline, most for­est ex­perts say a third year of im­prove­ment could sig­nal that a re­cov­ery is un­der way.

“It is en­cour­ag­ing that the rate of mor­tal­ity slowed,” Thom Porter, di­rec­tor of the Cal­i­for­nia Depart­ment of Forestry and Fire Pro­tec­tion, or Cal Fire, said in a state­ment Mon­day. “How­ever, 18 mil­lion trees are an in­di­ca­tion that the forests of Cal­i­for­nia are still un­der sig­nif­i­cant stress.”

Cal­i­for­nia’s dead trees are mostly con­cen­trated in the Sierra, south of Lake Ta­hoe, at low- to mid-level el­e­va­tions. Pon­derosa Pine, as well as cedar and oak trees, have been hard­est hit. The epi­demic, though, has spread to higher el­e­va­tions, where su­gar pine and fir are preva­lent, as well as to the north­ern half of the state, in­clud­ing coastal ar­eas.

Four years ago, the state con­vened a Tree Mor­tal­ity Task Force, con­sist­ing of lo­cal, state and fed­eral land man­age­ment agen­cies, along with power com­pa­nies and tim­ber har­vesters. The group has since helped co­or­di­nate the re­moval of more than 1.5 mil­lion dead trees.

While the pro­gram has made only a dent in the prob­lem, its fo­cus has been clear­ing the most haz­ardous of the life­less trunks, like those im­per­il­ing com­mu­ni­ties in densely forested ar­eas and along high­ways. State and fed­eral of­fi­cials have also opted to close some Sierra roads and recre­ational sites out of con­cern of fall­ing trees.

Tree-re­moval ef­forts have re­cently been joined by broader ini­tia­tives by Cal Fire and the U.S. For­est Ser­vice to shore up the for­est health. In the wake of re­cent wild­fires, both agen­cies have pledged to re­store na­tive veg­e­ta­tion, thin over­grown wood­lands and re­ju­ve­nate the land­scape with con­trolled fire.

Gov. Gavin New­som last month pro­posed an ad­di­tional $305 mil­lion for such for­est man­age­ment ac­tiv­i­ties in the state bud­get.

“I’m re­ally op­ti­mistic that we’re go­ing to be­gin to make a dif­fer­ence,” Moore said.

While the re­cent push by state and fed­eral agen­cies has gen­er­ally been met with ap­plause, the past man­age­ment of Cal­i­for­nia’s wild­lands has ac­tu­ally ex­ac­er­bated the tree die-off, many forestry ex­perts say.

A long­time pol­icy of ag­gres­sively putting out fires that can be ben­e­fi­cial, be­cause they clean and strengthen wood­lands, has cre­ated a buildup of trees that’s left forests more crowded and vul­ner­a­ble.

Chad Han­son, a re­search ecol­o­gist with the John Muir Project, said the tree die-off is sim­ply na­ture restor­ing it­self.

“We don’t want too many ar­eas of live for­est and we don’t want too many ar­eas of dead for­est,” said Han­son, who has writ­ten ex­ten­sively about the need for new trees and plants born from the loss. “We want a bal­ance in the for­est.”

Han­son es­ti­mates that about 9 per­cent of the Sierra is in a re­cov­ery phase, which he main­tains is lower than the amount of for­est that would be in this state nat­u­rally.

Some sci­en­tific stud­ies also have shown that these re­cov­er­ing ar­eas, with lots of dead trees, are at no more fire risk than ar­eas with few dead trees. These stud­ies note that life­less trees have fewer nee­dles and less fo­liage to burn.

Moore said this wasn’t his ex­pe­ri­ence. But ei­ther way, he agreed that the forests are not in equi­lib­rium and would be much bet­ter off in their nat­u­ral state.

“We have to in­crease the pace and scale of restora­tion,” he said.

Max Whit­taker / Spe­cial to The Chron­i­cle 2016

Dead trees dot the land­scape of the Sier­ras just south of Yosemite. Weak­ened trees fall atop roads, power lines and homes.

Bill Miller / Cal­i­for­nia State Parks 2015

The brown and red tops of dead and dy­ing pine trees stand out in a for­est on the east side of Mount Di­ablo in the Bay Area.

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