Vietnam War: Forest Fire as a Military Weapon - Paperless Archives

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SECRET 100 80 FIG. 31 FLAME HEIGHTS IN LITTER AND SHRUB FUELS BENEATH FOREST STANDS 0.33 0.5 1 2 3 4 6 $10 15 20 30 60 40 200 20 m0 FLAME HEIGHT (FT. 0 .5 1 4680 2 1.0 0.01 0.02 0.04 0.06 0.1 0.2 0.4 0.6 1.0 AVAILABLE FUEL WEIGHT (GROUND FUELS ONLY) (LB./Ft?) S~SECRET 43
SECRET Aerial observers have a natural tendency to overestimate shrub cover because they are misled by looking at conditions along the edges of roads and clearings where shrubs are always unusally dense. Observers should be instructed to try to look through small gaps in the tree crowns to check the portion of the ground occupied by low-growing vegetation. Pilots should fly into the shadows (generally north to south), and keep ground speeds as low as practical. An altitude of about 1500 feet is optimum unless aircraft speeds are so high that altitude must be increased to allow the observer enough time to scan each spot. The maximum altitude from which accurate understory determinations can be made without binoculars is about 3500 feet. For aerial photographic interpretation of understory shrub density, Ektachrome film Type 2448 at a scale of 1:8000 and flown at right angles to the shadows (generally east to west) is optimum, but photos at any scale between 1:2500 and 1:18,000 are usable. When using aerial photos, the interpreter should pick out the shrub color and texture characteristics by looking at clearing edges, and then estimate understory shrub density by slowly moving his view into the tree stand. 15J WEATHER CHARACTERISTICS Since the moisture content of the fuel is the overriding determinant of forest fire behavior, it is not surprising that weather variables are primarily important for the manner in which they affect fuel moisture. Temperature, humidity, wind and precipitation all affect the moisture content of woody materials-acting directly on dead wood, and indirectly off living plants by influencing the physiological moisture regulating processes. 16 The moisture content of living plannrvts. changes relatively slowly. The effect of weather on living fuel moisture has already been discussed in the section on climate. But dead twigs, leaves and other litter depends more on the weather of the moment than it does on the seasonal climate. The following weather variables have a direct effect on the drying of dead forest fuels. Precipitation: Obviously, rain or snowfall will greatly increase the moisture content of forest litter. Since water holding capacity differs among various forest fuels, the amount of rainfall required to saturate forest litter varies with both 3 the amount and type of litter. Table 7 shows the rainfall requirements for each of the standard vegetation types. Not all rainfall reaches the forest floor. A substantial amount is caught on the twigs and foliage of the upper canopy, and evaporates without ever reaching the ground. The amount thus lost depends on the amount of surface area in the foliage and on the amount of rain in the storm. Table 7 also shows the interception losses that can be expected in each of the vegetation types, and the amount of rain needed to saturate both light and heavy litter accumulations. As shown in the last column, it takes nearly twice as much rain to saturate a dense accumulation of shrub or hardwood litter as it does for an equal weight of grass or conifers. 15/ More complete guidelines and photo interpreter's keys can be found in Lund, H. G. and G. R. Fahnestock. Color aerial photography for interpreting understory vegetation. USDA-Forest Service. Final Progress Report PNW-2103: FA-2.2. /9 pp., illus. July 1968 1N The detailed mechanics of wood-moisture relations are beyond the scope of this paper. Three excellent references are available: For dead wood, see Simard, A. J., The moisture content of forest fuels - I: A review of basic concepts. Forest Fire Research Institute, Ottawa, Ontario. Information Report FF-X-14. 47 pp. July 1968. For living vegetation, see Kozlowski, T. T., Water metabolism in plants. Harper and Row, N.Y. 227 pp. 1964 For living plants under drought stress, see Zgurovskaya, L N. and Yu. L. Tsel'niker., The influence of irrigation after a prolonged drought on transpiration and on the condition of the absorbing roots of arboreal species in the Derkul' Steppe. (Translated from Russian). Office of Tech. Svcs., U.S. Department of Commere., PSTCat. No. 311. 10 pp. 1961. SECRET 44
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VIETNAM WAR Forest Fire as a Milita
Page 4 and 5: Forest Fire as a Military Weapon A
Page 6 and 7: OF7 A iD5S Hil'---0 __ = IIIII- _w
Page 8 and 9: SECRET FOREST FIRE AS A MILITARY WE
Page 10 and 11: SECRET INDEX (Continued) Page Weath
Page 12 and 13: SECRET FOREST FIRE AS A MILITARY WE
Page 14 and 15: SECRET detailed and timely intellig
Page 16 and 17: SECRET I I I i it FI.I FIG. 2 I I B
Page 18 and 19: I SECRET I I I I I S....... '•FIG
Page 20 and 21: SECRET FI.I TYIAIRONFR BEOR FIG.FIG
Page 22 and 23: SECRET REQUIREMENTS FOR SUCCESSFUL
Page 24 and 25: I I SECRET heating adjacent unburne
Page 26 and 27: I SECRET FUEL TYPE 8o e1 82 83 84 I
Page 28 and 29: I SECRET I ii 11 I S~FIG. 17 | GRAS
Page 30 and 31: I I SECRET I I FIG. 18 SHRUB TYPE I
Page 32 and 33: Relative Humidity SECRET Table 2 "S
Page 34 and 35: I U I I I I I SECRET I FIG. 21 CONI
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Page 40 and 41: SECRET In developing recommended pr
Page 42 and 43: U SECRET The yearly sums of (+) val
Page 44 and 45: I Fireclimate Classification SECRET
Page 46 and 47: SECRET TABLE 5 KEY TO IDENTIFICATIO
Page 48 and 49: SECRET SHumid, long bum season (HUL
Page 50 and 51: I SECRET Table 6 Surfac,,/Volume Ra
Page 52 and 53: I SECRET FIG. 29 AVAILABLE FUEL WEI
Page 56 and 57: I SECRET I Table 7 Precipitation Ef
Page 58 and 59: I SECRET FIG. 32 EQUILIBRIUM MOI$TU
Page 60 and 61: •Sunshine: SECRET Solar radiation
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Page 64 and 65: Technique"s for Kdlin, D•rming an
Page 66 and 67: SECRET I t '4Pi I I FIG. 35 * AERIA
Page 68 and 69: SECRET FIG.36 EFFECTS OF OVERSTORY
Page 70 and 71: SECRET FIG. 37 TYPICAL EFFECT OF CO
Page 72 and 73: I .SECRET Use of Systemic Desiccant
Page 74 and 75: SECRET 6. Effectiveness of foliar s
Page 76 and 77: SECRET Example of a Desiccation Pla
Page 78 and 79: SECRET If a lighted match is droppe
Page 80 and 81: SECRET 0 0 ----- 0" E I- -- z -- o
Page 82 and 83: SECRET The advantages of multiple i
Page 84 and 85: SECRET DISCUSSION The deliberate in
Page 86 and 87: 1 SECRET U MINH FOREST FIRES PROLOG
Page 88 and 89: SECRET Spread Analysis: Spread to K
Page 90 and 91: SECRET HEADQUARTERS US ARMY ADVISOR
Page 92 and 93: I SECRET MACV-IVC-2 24 May 1968 SUB
Page 94 and 95: SECRET NAVAL GUNFIRE MISSIONS DATE
Page 96 and 97: SECRET Rach Gia - Kien Giang Hourly
Page 98 and 99: SECRET APPENDIX B Pertinent Incendi
Page 100 and 101: SECRET Major vegetation type: Tropi
Page 102 and 103: SECRET CLIMATE FF-HUSB FROSTFREE WI
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SECRET FIG. B2 CLIMATE FF-HUSB HANO
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SECRET Soil appiicat ion: Apply 20
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SECRET CLIMATE FF-NHLB FROSTFREE WI
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SECRET CLIMATE FF-DRYL FROSTFREE WI
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SECRET CLIMATE MI-HUYL MILD WINTER;
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SECRET FIG. B6 CLIMATE MI-HUYL NEW
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SECRET Soil application: Apply 15 p
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SECRET CLIMATE MI-HULB MILD WINTER;
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SECRET FCa. W8 CLIMATE MI-HULB RHOD
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SECRET FIG. B9 CLIMATE MI-NHSB AUST
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SECRET Dates for examl ocationAU.s
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SECRET CLIMATE MI-DRYL MILD WINTER;
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* climates& j SECRET CLIMATE CL-HUY
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SECRET FIG. 512 CLIMATE CL-HUYL COL
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SECRET Dates for example location (
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SECRET t (IIMATI (L HILD ('(X)I WIN
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SECRET (1lMAU- (L NH.% 41()1. *INTI
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I SECRET (IIM-AIF ( Hl•Nt1 ( Wl W
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SECRET FIG. 816 CLIMATE CL-NHLB GRA
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SECRET FIG. 817 CLIMATE CL-DRYL LAS
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Foliar sTray: Apply per acre: SECRE
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Warm continental climates SECRET CL
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SECRET FIG. B19 CLIMATE SC-HUSB MT.
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SECRET Dates for cxampre location (
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SECRET CLIMATE SC-NHYL SHORT COLD W
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SECRET FIG. B21 CLIMATE SC-NHYL PAR
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SECRET FIG. 522 CLIMATE SC-NHSB SAN
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SECRET FIG. 823 CLIMATE SC-NHLB REN
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SECRET Foliar Žpxa: Apply per acre
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SECRET CLIMATE LC-HUSB LONG COLD WI
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SECRET Foliar spray: Apply during t
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"SECRET CLIMATE LC-NHLB LONG COLD W
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SECRET CLIMATE VC-HUYL VERY COLD WI
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I SECRET FIG. 827 CLIMATE VC-HUYL D
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SECRET "CLIMATE VC-NHSB VERY COLD W
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SECRET I Publiction-,: Protect EMOT
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