Road to Recovery 204

Mount St. Helens and the sur-rounding forest land in south-west Washington State wereheavily used before 1980 formountain climbing, backpack-ing, hunting, and fishing, as wellas tree farming. That changed onMay 18, 1980, when the volcanicmountain erupted violently. Itsent a massive avalanche of mol-ten rock and other debris fromthe top and north side of MountSt. Helens into the North ToutleRiver valley.

Within 15 minutes, 151,000acres of forest and recreationland were devastated by the lat-eral blast. This blast blew downforests on 52,000 acres, and itsheat killed trees and otherplants but left them standing onanother 24,000 acres.

The large debris avalanche,pyroclastic flows, mudflows, newlakes, the volcano, and areasclearcut before the eruptioncomprised the rest of the devas-tated area. Most of the land wasowned by the Weyerhaeuser Co.or Burlington Northern Timber-lands, or was managed by theForest Service or the WashingtonState Department of NaturalResources.

Mudflows scoured the NorthToutle, South Toutle, and MuddyRiver valleys. Streams, chokedwith sediment, gurgled aroundthe many trees blown into them.Cooked forest canopies wereblown into lake waters warmedby the blast, killing the fish andother organisms.

The 9-hour eruption coveredthe area with 1 to 20 inches of

After Eruption of

Mt. St. Helens

By Joseph E. Means and

Jack K. Winjum

Joseph E. Means isResearch Forester,Pacific NorthwestForest and Range Ex-periment Station. U.S.Forest Service, Cor-vallis, Oreg.

Jack K. Winjum isManager, Mount St.Helens Research andDevelopment, Weyer-haeuser Co., Cen-tralia, Wash.

Within 15 min-utes of the Mt.St. Helens erup-tion, 151,000

acres of forestand recreationland weredevastated.

In the firstgrowing seasonafter the erup-tion,fireweedand otherplants sproutedreadily through

the tephra (ash,pumice and pul-verized rock)where it wasless than 8inches thick.

Road to Recovery After Mt. St Helens 205 206 Managing Natural Resource Systems

tephra: ash, pumice, and rockpulverized by the blast.

Immediately after the eruption,the devastated area presented apicture painted in shades ofgray—there were no signs ofgreenery or animals. We won-dered, "How long will it be be-fore these hills are green again?Fifty years? One hundred?"

Life ReappearsLife began to reappear on that

landscape almost immediatelyafter the eruption, however, withthe springtime warming in themountains. Essentially all plantsthat appeared the first growingseason sprouted up through thetephra from the buried soil.

Trillium and huckleberryemerged amid the fallen trees,and even small silver fir andmountain hemlock trees sprangup in areas where they were pro-tected from the force and heatof the blast by a heavy wintersnowpack.

Fireweed and other plantscommon to old clearcutssprouted readily through the te-phra where it was less than 8inches thick the first growingseason.

Partial erosion of the tephraoff hillsides allowed many plantsto reach the surface. Indeed,plants emerging in rills were theonly ones seen soon after theeruption in clearcuts with deepdeposits of tephra.

Some streamside and lake-shore areas also recovered rap-idly as water removed the tephra

208 Managing Natural Resource Systems

Road to Recovery After Mt St Helens

so sprouts from buried plantscould reach the surface. In otherareas tephra eroded off hillsidesand, carried by streams, buriedwould-be survivors.

Oasis on Debris AvalanchePlants survived even in the de-

bris avalanche deposits in fist-size pieces of soil scraped fromthe valley floor and walls. Plantsrecovered most rapidly in west-ern portions of the devastatedarea because the blast depositswere cooler and the tephra wasgenerally thinner than in easternportions.

Seeds had been blowing intothe devastated area since theeruption. From these seeds, andseeds produced by survivingplants, natural seedlings becamemuch more common starting thesecond year as the rate of ero-sion slowed.

Plant establishment from seed,though very sparse, was mostimportant on the debris ava-lanche where residual plantswere extremely rare and on thepyroclastic (volcanic) flowswhere they were nonexistent

Plants with light, wind-dis-persed seeds—such as purple-flowered thistle, yellow-floweredgroundsel, and red-flowered fire-weed seedlings—were appearingin unexpected places. One siteon the debris avalanche hadsuch lush vegetation in 1981that researchers named it "theoasis," in contrast to the rela-tively barren miles of fragmentedrock, gravel, and sand.

207

Animal, Fish SurvivorsLike the plants, some of the

first animals observed in thedevastated area were those thatsurvived the eruption underground. Ants and gophers werethe most common of these.Many small animals, such asmites and springtails, survivedin rotten wood.

Fish, salamanders, aquatic in-sects, and micro-organisms sur-vived in many lakes in the devas-tated area, chiefly those with iceand snow in them when theeruption occurred. A few fishalso survived in streams, espe-cially where water movingaround logs or rocks createdcool pools that fish could hidein and where cobbles (roundedstones) occurred on which liveaquatic insects that fish use asfood.

Unlike the plants, most verte-brate animals invaded the devas-tated area from the surroundinggreen forests in the first twoyears after the blast In fact, deerand elk entered the area immedi-ately after the eruption. Popula-tions increased as returning veg-etation provided food so thatresident herds numbered in thehundreds in 1981 and 1982.

Birds occurred throughout thearea the first summer. The sightof a hummingbird hovering infront of bright orange flaggingheld by a forester five miles fromgreen forest was a very encour-aging sign that life was begin-ning to return to the devastatedzone.

Spiders came many milesthrough the air by ballooning—letting out long filaments of weband being lofted long distanceswhen the web was caught by thewind.

Fire-Fungi Feed AntsMicro-organisms also played

important roles in the recoveryof these forest ecosystems. So-called "fire-fungi," common afterforest fires in the Pacific North-west, were seen within severalweeks of the eruption becausetheir spores were stimulated togerminate by the heat of theblast deposits.

Peggy Wi/z- streams in thebach, aquatic devastated areaecologist, and after theTom Lisle, hy- streams weredrologist, found washed cleanaquatic insects of pumice andon rocks in ash.

Ants from different coloniescompeted for the whitish mats offungus because they were one ofthe first food sources to appear.

Many kinds of fungi that occurin the buried soil form close as-sociations (called mycorrhizae)with plant roots, in which thefungi grow between and withincells of the plant roots. Thesefungi obtain food from the plantand in turn bring important nu-trients (such as phosphorus) tothe plant from the soil.

210 Managing Natural Resource Systems

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Road to Recovery After Mt St Helens

Bacteria in the buried soildecompose organic matter andin the process release nitrogen,another important nutrient, in aform available to plants. Whendeposited, the tephra was essen-tially devoid of life, and the nu-trients it contained were quicklyleached into the buried soil byrainwater because the tephracould not hold them.

Thus one can see the impor-tance of the buried soil, with itsability to hold nutrients and itsteeming community of micro-or-ganisms, to recovery of vegeta-tion and productivity of futureforests.

Ash Effect on Live ForestThe green forest outside the

devastated area received a cover-ing of ash that stuck to needles,killing some. No large trees died,however, and most grew just asmuch in 1980 as they had inprevious years.

Growth on young trees in adja-cent clearcuts increased dramat-ically in 1981 and 1982, possiblybecause the tephra acted as amulch, retaining soil water forplant use. Understory plants ofgreen forest fared poorly wheretephra up to 8 inches thickkilled huckleberries, othershrubs, many herbs, and smalltrees.

Bulb plants, such as avalanchelily, and some other herbs wereable to sprout through the te-phra, and at least a few survivedin many places. Also, some un-derstory trees grew roots fromtheir trunks into the tephra, ex-ploiting the water it held, a re-

209

source most other plants hadnot yet tapped.

Managers' ResponseDealing with large natural ca-

tastrophes is not an unfamiliarjob for forest land managers.Wildfire, windstorms, and insectepidemics are examples of natu-ral phenomena that periodicallydevastate large areas of forest Insize and suddenness, the vol.,canic devastation around MountSt. Helens was not that unusualwhen compared with othercatastrophes.

At the same time, forestsblasted with lethally hot gases,then blanketed with falling te-phra, and river valleys inundatedwith debris and mudflows wereall quite new to the region's for-est managers. Within a few days,however, the stunned reactiongave way to thoughts and plansfor restoring the managed forestas had been done historicallyfollowing other largecatastrophes.

Assessing LossesAssessment of losses came

first Within a few weeks, a tallyfrom aerial photos and groundchecks from helicopters showedthat in the blast zone, foreststands of merchantable size oc-cupied 82,600 acres and totaled4.7 billion board feet in volume.Nonmerchantable stands,planted or seeded during theprevious 20 years or so, coveredanother 48,000 acres.

These forests of dead trees—standing, broken off, blowndown, or blown away—consistedprimarily of Douglas-fir, westernhemlock, noble fir, and silver fir,all commercially valuable coniferspecies.

Other critical losses includedthe transportation system andworking equipment in the area,all important parts of a managedforest

Over 500 miles of truck roadsand 16 miles of railroads wereburied under tephra deposits ormudflows. Twelve key bridgeswere out Also destroyed orheavily damaged were three non-resident logging camps, dozensof woods vehicles, and heavy log-loading machinery from manylogging sites.

Technical Help Sought 'Restoration plans of land man-

agers addressed the timing, re-

Road to Recovery After Mt. St. Helens 211

sources, people, and safety con-siderations required to open andrebuild transportation systems,salvage and market dead butmerchantable trees, reforest po-tentially productive lands cov-ered with tephra deposits, andprovide protection against fur-ther losses by wildfire, insects,or wood-rotting organisms.

Planning the restoration ofmanaged forests in the blastzone called for technical infor-mation not previously available.Managers sought help from amyriad of engineers and scien-tists, including representativesfrom the physical, biological, andsocial sciences.

Geologists worked out aneruption forecasting system thatwas the basis for warning andevacuation plans. Industrial hy-gienists studied health hazardsto people working in heavy vol-canic dust and recommendedthat respirators be worn duringdry, windy periods.

Log Value Holds UpWood scientists were flown

into the blast zone early tocheck log quality. They foundthat charring or pitting by theblast was limited to bark layersof dead trees and that breakagecaused by the blast caused littleloss in usable volume; thus thewood had no significant loss invalue.

No one, it seemed, knew muchabout the tephra, and chemistswere quick to determine itschemical and physical proper-ties—most important, it wasnontoxic, largely inert, but phys-

ically quite abrasive. This infor-mation led engineers to developspecial equipment and mainte-nance schedules to overcomeabrasive effects of the tephra.

Knowing the tephra was nottoxic and seeing many earlysigns that the ecosystems werebeginning to recover, forestersand wildlife biologists realizedthat the normal complement offorest life would no doubt returnto the devastated area. Indeed,they theorized that natural re-covery might even be enhancedthrough managementtechniques.

Seeding by AirTephra erosion was severe the

first summer and fall. Each rain-storm washed tephra from bar-ren hillsides, and heavy sedi-ment loads in streams and riversraised beds and increased floodhazards.

To control surface erosion,20,000 acres of the devastatedarea were aerially seeded andfertilized in the fall of 1980 withmixtures of grasses and leg-umes. Most hillside surface ero-sion, however, occurred by theend of the first winter, beforesignificant vegetation—naturalor seeded—was established.

Surface erosion of the tephrawas greatly reduced naturallythe second and third winters be-cause the infiltration capacityincreased, and rock fragmentsand pumice—exposed by sheeterosion and frost heaving—ar-mored the surface against fur-ther erosion.

212

In rills and small gullieseroded in the tephra, seededgrasses, natural vegetation,roots, and buried brancheshelped control erosion of thevaluable buried soil and probablyreduced peak runoff rates duringstorms.

Logs RetrievedSalvage logging began May 19,

1980, with the first retrieval oflogs swept by mudflows downthe Toutle River west of the vol-cano into the Cowlitz River andultimately down the ColumbiaRiver. The logs had been storedat truck-to-rail transfer pointsalong the Toutle River. East ofthe volcano, logs that had comedown the Muddy River were sal-vaged from the Swift Reservoir.

Salvage operations in thesewaters took 4 months, and 15million board feet of timber wererecovered.

Meanwhile, reopening of roadsin the blast zone was begun.During the first 2 years, nearly700 miles of forest roads werereestablished or newly built, in-cluding bridge construction atkey points.

Logging of dead timber in theblast zone was started in latesummer 1980. Timing was veryimportant. Operations could notsafely and effectively begin untilgood information was availableon the important technical ques-tions discussed earlier in thischapter. Yet experience fromother forest catastrophes under-scored the need for rapidsalvage.

Managing Natural Resource Systems

Potential secondary problemscould be a threat in a large areaof newly killed forests. For in-stance, buildups of wood-boringinsects and decay fungi can re-duce the value of logs as timepasses. During periods of dryweather, wildfire is a hazard.Also, the time the land is notproducing trees is a substantialloss to the landowner.

1,000 Salvage WorkersOnce underway, however, sal-

vage operations were most inten-sive. At one point in 1981, over60 logging settings involvingmore than 1,000 workers wereoperating simultaneously in thewestern blast zone. About 600truckloads of logs a day weretransported. This work paceshifted to the eastern side of thezone in 1982 and 1983.

By the end of 1984, plans callfor completion of salvage loggingon about 47,000 acres, totaling2.7 billion board feet of timber.Remaining lands that containedmerchantable timber were buriedby debris or mud, were inun-dated by new lakes, or are inMount St. Helens National Vol-canic Monument and will not besalvaged.

Precautions PayPrecautions designed into sal-

vage plans paid off. Volcanic ac-tivity continued periodically andwas accurately forecast. Evacua-tions and closures during theseevents prevented life-threateningsituations for workers.

Managing Natural Resource Systems214Road to Recovery After Mt St Helens 213

No significant increases in lostworktime were encountered as aresult of heavy exphasis onhealth and safety. Extra mainte-nance kept excessive wear onequipment down except for rapiddulling of chains on powersaws.Use of carbide-toothed chainseventually solved this problem.

Overall logging costs wereslightly greater than normal, pri-marily because of higher fellingand bucking costs caused by thetephra.

Beneficial EffectsSalvage logging had several ef-

fects on recovery of these forestecosystems. Mixing of the buriedsoil with the tephra and break-ing up its continuous mantle in-creased infiltration of rainwaterwhich decreased the threat offurther surface erosion, allowedmore buried plants to reach thesurface, and made the buriedsoil—with its micro-organismsand nutrients—available to colo-nizing plants.

Logs blown into streams wereoften salvaged, although in sev-eral locations stable logs wereleft to maintain fish habitat atthe request of fisheriesbiologists.

In June 1980, only a monthafter the blast, the first test ofplanting tree seedlings was be-gun with several hundred bare-root, two-year-old Douglas-firand noble fir trees.

When roots were planted incontact with original buried soil,the seedlings survived and grewwell. When planted so roots wereonly in tephra, performance was

poor primarily because of a ni-trogen deficiency. Shovelsproved the most useful tool inclearing or scalping away thintephra.

Operational PlantingsBased on these research re-

sults, plans were made to beginoperational planting during thenext scheduled period whichstarted in February 1981. Openareas with less than 6 inches oftephra received the first plant-ings—about 6,000 acres intotal the first winter after theeruption.

During the 1982 reforestationperiod, another 14,000 acreswere planted, including many ofthe first acres that had been sal-vage logged. Douglas-fir wasplanted below 3,000 feet in ele-vation and noble fir above, bothat densities of 350 to 500 treesper acre.

Reforestation was more diffi-cult in 1983 because wholedense plantations of dead treesand sites with tephra up to 12inches deep were encountered.Treatment was needed beforeplanting could be done.

Dead trees were felled andburned, and crawler tractorswith front-mounted V-bladeswere used in areas with deep te-phra to clear rows along the con-tours down to buried soil. Onslopes too steep for tractors,power augers proved effective inbringing the buried soil close tothe surface in the planting holeso contact with tree roots waspossible.

Experience to date indicatesthat planting costs are averageto significantly greater than av-erage, depending on site prepa-ration and planting difficulty.

Elk Damage SeedlingsSurvival and growth of seed-

lings have generally been favora-ble, though animal damage hasbeen severe in some localities,particularly browsing by thegrowing herds of elk. By 1985, a

First test plant- just one monthing of tree seed- after the Mt. St.lings was done Helensin June 1980, eruption.

total of about 70,000 acres willbe reforested in the blast zone ofMount St. Helens.

Riparian zones along riversand streams where tephra ormud accumulated several feetdeep were reforested with cot-tonwood and willow cuttings be-cause such soil conditions arenot suitable for conifers. These

Road to Recovery After Mt St Helens 215

hardwoods grow quickly, stabi-lizing the new deposits and pro-viding shade that keeps watertemperatures favorable for fishduring sunny periods. Reforesta-tion was conducted along thesides of 55 miles of river andstream in this manner.

Natural seedlings of red alderand cottonwood were commonon mud deposits along manystreams outside the blast zone.

Volcanic MonumentSome 110,000 acres of the

area around the volcano is nowMount St Helens National Vol-canic Monument It includes thevolcano, Spirit Lake, the debrisavalanche, and many other inter-esting features created by theeruption.

The monument will be man-aged by the Forest Service to"protect the geologic, ecologicand cultural resources ... allow-ing geologic forces and ecologicsuccession to continue substan-tially unimpeded," according tothe establishing Act For years tocome, its unique features will beavailable for public enjoymentand scientific study consistentwith their protection.

Nature led the way to the re-covery of forest ecosystemsaround Mount St. Helens. Plants,animals, and micro-organismsinvaded the barren surface frombelow the ground, over the sur-face, and by air in the first threeyears. Perhaps this rapid recov-ery should have been expected.

Adapting to VolcanismMany forests in the Cascade

Range grow on soils of volcanicorigin that have literally fallenfrom the sky. Also, eruptionsoften occur within the 400- to800-year lifetimes of dominantforest trees such as Douglas-fir.

Eruptive periods of Mount StHelens, the most active volcanoin the Cascade Range, have beenseparated by only 100 to 500years in the last 35 centuries.Evidence indicates some treesnortheast of the volcano, an arearepeatedly covered by tephra, aregenetically adapted to repeatedvolcanism.

Families of Douglas-firs fromthis area survived temporaryburial by the 1980 eruption bet-ter than trees from areas not sofrequently covered by tephra atthree planted test sites.

Further ReadingMount St. Helens: One Year

Later. S. A. C. Keller, ed. Univer-sity Bookstore, 830 Elm Street,Cheney, Wash. 99004. $22 percopy.

Volcanic Eruptions of 1980 atMount St. Helens: The First 100

Days. Bruce L. Foxworthy andMary Hill. U.S. Geological Survey,Professional Paper 1249. StockNo. 004-001-03452-2. For sale bySuperintendent of Documents,Washington, D.C. 20402.