Biswell, Gibbens and Buchanan. 1968. Fuel Conditions and Fire Hazard Costs in a Giant Sequoia Forest. California Agriculture 22:2-4.

Fuel Conditions and Fire Hazard Reduction Costs in a Giant Sequoia Forest

H. H. Biswell. R. P. Gibbens and Hayle BuchananPhotographs by R. P. Gibbens; map by James K. Agee

IN RECENT PERIODS as long as 100years, California’s groves of giantsequoia have been protected fromdestructive forces – including the fireswhich were once an integral part of theirenvironment. There is today a growingconcern that such protection, while ofvital importance, is not of itself anadequate substitute for natural habitatconditions. Plant successions arechanging conditions within the grovesthe understory shade-tolerant trees,

chiefly white fir, are increasing innumber; and large amounts of debris areaccumulating.

With the steady increase in fuel buildup,irreplaceable giants are faced with anever-increasing threat to their existencebecause even modern fire-fightingequipment and technology are not totallyeffective in suppressing wild- fires insuch areas. The fire-scarred trunks ofgiant sequoias attest to their ability to

Biswell, Gibbens and Buchanan. 1968. Fuel Conditions and Fire Hazard Costs in a Giant Sequoia Forest. California Agriculture 22:2-4.

survive repeated ground fires. However,the sequoia trees may not withstandcrown fires which are sure to occur if afire burns uphill through the heavy fuelaccumulations and understory treesduring the dry season. Protection fromwildfire is vital, but it is apparent thatsteps must be taken to insure a fire ofrelatively 3ow intensity, if one shouldoccur.

Investigations of ways to reduce fuelsand improve esthetic values in giantsequoia groves are under way onWhitaker’s Forest, a 320-acre forestowned by the University of California.Whitaker’s Forest lies on the westernslope of Redwood Mountain in TulareCounty and adjoins the magnificentRedwood Mountain grove of giantsequoias in King’s Canyon NationalPark. Plant successions followinglogging of Whitaker’s Forest in the1870’s have resulted in the developmentof extreme fire hazards. Dense stands ofincense cedar, Scouler willow, second-growth sequoia, and white fir becameestablished following the logging, whichremoved most of the pines and abouthalf of the original stand of giantsequoias.

In the dense second-growth stands,many of the incense cedars whichbecame established following thelogging disturbance of the 1870’s havesuccumbed to competition and are nowdead, but still standing. For example, ona photo plot of 33 x 33 feet there were19 dead trees, the equivalent of 760 peracre. These dead trees help form a fuelbridge between the ground and theoverhead canopy. Another fuel typewhich is characteristic of the second-

growth stands is Scouler willow debris.This formerly abundant species grew indense clones which have now beenshaded out and killed. The slowlydecaying stems form dense tangles offuel. Much heavy debris from limbs andfallen trees of other species is found onthe ground also. Such accumulations areespecially prevalent where the relativelyshort-lived white fir stands areapproaching maturity, or havesuccumbed to disease or insects.

Understory trees are found in greatnumbers on Whitaker’s Forest as well asin many other giant sequoia groves.These trees, principally the shade-tolerant white fir, have increasedsteadily in numbers since the inceptionof protection from fires. Now theyfrequently form a continuous mass offuel from the ground to near the tops ofthe tallest trees. Where these trees havegrown high in the understory, withheavy debris accumulation below,serious fire hazards exist. Bear cloverand manzanita occur as understory topines on drier sites on Whitaker’sForest. When these shrubs are drapedwith pine needles they form a veryflammable fuel.

In 1964 a manipulation program wasstarted on Whitaker’s Forest with thecooperation of the California Division ofForestry and its MiramonteConservation Camp. A “minimum”treatment has been applied to about 60acres. This treatment consists of theremoval of understory white fir andincense cedar trees between one and 11feet tall, cutting of dead standing trees,and removal of heavy debris on theground.

Biswell, Gibbens and Buchanan. 1968. Fuel Conditions and Fire Hazard Costs in a Giant Sequoia Forest. California Agriculture 22:2-4.

Above: a tangle of debris from dead clones ofScouler willow creates high fire hazard. Denseunderstory of white fir shown in back-groundalso adds to likelihood of disastrous fire. Baseof large second-growth giant sequoia appearsat right, a white fir trunk at left.

At right: heavy fuels from white fir debris haveaccumulated near a mature giant sequoia.Decadent stands of white fir are found in manygroves of Sequoia gigantea Below: views of a one-tenth acre test plot be-fore (left) and after (right) clearing. Denseunderstory stand of white fir and incense cedarblocks view of mass of Scouler willow debrison ground in left-hand photo. Hazards weregreatly reduced and vistas opened up bytreatment, as seen in right-hand photo.

H. H. Biswell is Professor and R. P. Gibbenswas Assistant Specialist (now in the PlantSciences Division, University of Wyoming),University of California, Berkeley. HayleBuchanan of Weber State College, Ogden,Utah, was a College Teacher Participant on aNational Science Foundation grant. Labor,was performed by crews of the MiramonteConservation Camp, Willard Haley,Superintendent. This article is reprinted fromthe February, 1968, issue of CaliforniaAgriculture by courtesy of that publication

Biswell, Gibbens and Buchanan. 1968. Fuel Conditions and Fire Hazard Costs in a Giant Sequoia Forest. California Agriculture 22:2-4.

Above, the result of understory manipulation to reduce wildfire hazards and to improve estheticvalue of giant sequoia at the University of California’s 320-acre Whitaker’s Forest adjacent toKing’s Canyon National park.

Biswell, Gibbens and Buchanan. 1968. Fuel Conditions and Fire Hazard Costs in a Giant Sequoia Forest. California Agriculture 22:2-4.

The material is disposed of by burning insmall piles below the canopy of largertrees in the fall and spring months whenthe danger of wildfire is minimal. Largeamounts of material have been removedand the continuous vertical distributionof fuels broken up by this treatment.Because the treatment does notappreciably affect those trees indominant- or subdominant-crownclasses, the composition of the forest isnot changed significantly for the present.

In the second phase of the manipulation(yet to be done) it is planned to removesome of the intermediate sized incense

cedars and white fir (which seeded infollowing the logging of the 1870’s)growing within about six feet ofsequoias. This will not be a thinning topromote growth of incense cedars andfirs; rather, the purpose will be to reducecompetition to – and open up views of –the sequoias and to further reduce firehazards.

At a later date prescribed burning will betested in the different types of fuels onthe forest floor. These treatments aredesigned to result in more pines inn theforest and fewer incense cedars, and torestore plant patterns and successions

Biswell, Gibbens and Buchanan. 1968. Fuel Conditions and Fire Hazard Costs in a Giant Sequoia Forest. California Agriculture 22:2-4.

that prevailed in the primitive conditionbefore the white man intervened.Increasing the reproduction of giantsequoia is not a special objective of themanipulation on this forest, althoughsome may result from the disturbances.The forest is well stocked with second-growth redwood, far more than arenecessary to replace those which werelogged off.

To determine the man-hours of laborrequired to perform the minimumtreatment, four tenth-of-an-acre plotswere marked off for manipulation. Plotswere selected where debris, dead trees,or understory trees were fairlyrepresentative of maximum conditionsencountered. A careful record was madeof the time required to perform each stepin the manipulation operation. Weight ofmaterial to be burned was estimated,after a period of training with scales.

The results obtained are presented in thetable above. Assuming a labor cost of$2.38 per hour and chain-saw cost of$2.00 per hour, the calculated costranged from $114 to $146 per acre. Thisdoes not include costs of supervision,etc. These figures approach themaximum cost since few areas wouldhave more material to dispose of. Theaverage amount of fuel removed fromthe four plots was 44,040 pounds peracre. The average number of trees cutper acre was: living, 945; dead, 550.

While the cost of treatment appearshigh, it should be borne in mind that themanipulation removed 80 years’accumulation of debris and lowered thefire hazard conditions for many years tocome. Also, there has been an

improvement in esthetic values. Nomonetary value can be placed on giantsequoias because they are a pricelessheritage to be preserved at almost anycost.

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Biswell, Gibbens and Buchanan. 1968. Fuel Conditions and Fire Hazard Costs in a Giant Sequoia Forest. California Agriculture 22:2-4.