FOR 306 Forest measurements Trees eight
weight Measure of the quantity of wood eight used also for: Scaling Complete tree utilization root, branches or stump Biomass Carbon content Fuel eight determined by comparing the weight of the object of interest (tree, truck with portion of stem, etc), which is unknown, with other objects whose weight is known Newton: related the weight with mass: G=mg 2
eight measurements eight can be measured by: 1. Balancing the object of interest against the gravitation force of a standard mass weighting machines 2. Measuring the acceleration of the object of interest to which a force was applied 3. Balancing against magnetic forces 4. Transducing the weight(which is a force) to the pressure of a fluid 5. Applying the weight to an elastic object and measuring the deflection Most used: weighting machines 3
Factors influencing weight Gross weight- relatively easy ry weight depends on gross weight, which is impacted by: ood density Moisture ry weight: at 103±2 C 220 F until stable weight is attained eight of wood products depends on: Bark Foreign material: mud, ice, rocks etc 4
ensity ensity = mass / volume ensity symbolized by or ρ: ensity determined using or weight: or For a specific moisture content, MC [%] density is: MC MC Specific gravity: ratio between the density of a substance and density of = 62.4 lb/ft 3 (1000 kg/m 3 ) = 1 cubic unit (ft or m) SG 1 ft 1 3 SG MC MC 1 ft 1 3 5
ensity - example Parameter Green At 12% MC Oven olume [ft 3 ] 0.65 0.57 0.50 eight [lb] 22.6 18.5 18.0 g SG 1 SG 1 SG 1 12% 12% SG 12% 12% 1 6
ensity Specific gravity refers to volume (unless otherwise specified) Specific gravity of solid wood (no air-space): 1.5 Solid wood weight: 93.6 lb/ft 3 (1500 kg/m 3 ) ood as porous structure: SG: 0.3 0.5 eight: 19 50 lb/ft 3 ensity decreases from base to tip of the stem ensity increases from pith to cambium 7
Moisture content Moisture content varies with: Species Location in the tree: along and across the stem Length of time since cutting Moisture: 1) free in cell cavities and 2) in cell wall Fiber saturation point: cell condition with no free AN cell wall is saturated 27 32 % of the weight Moisture content expressed as % of weight ry weight: at 103±2 C 220 F 8
Moisture content Example MC 100 [%]...... : MC 100...[%]... Moisture content varies across/along stem: MC smaller in heartwood than in sapwood MC on upper stem larger than on lower sections More sapwood, % wise Moisture content varies with season: winter and spring have largest MC 9
Tree weight relationships Increase use of weight as a measure of forest products and biomass lead to estimation of the weight of standing trees Two type of weight estimates: hole tree Merchantable portion of the tree Other portions of the tree have a sizable mass: Tree: dbh =12 / total height = 70 Red spruce Red maple Component Pounds % Pounds % Merchantable stem (stump-4 ) 1218 60 1224 63 Stem above merchantable portion 20 1 58 3 Branches larger 1 diameter 76 3 109 6 Root 185 15 273 14 Stump (6 above ground to large roots) 109 5 159 8 10
Bole s eight equation Similar to volume tables but use weight instead eight = f(bh, Height) Common equation used to estimate bole weight: weight = b 0 +b 1 x BH a xh b Green weight = -32.35 + 0.15544 x BH 2 xh (sycamore) Green weight = 1.1435xBH 2.0178 H 0.5726 (loblolly pine 4 top) ry weight appropriate for pulped products ry weight correlated with yield pulped products ore than weight with the same products ry weight = -17.679 + 0.06684 x BH 2 H (sycamore) 11
eight equations - Biomass Total weight of the tree eight of the tree components: bole, branches or foliage Engelmann Spruce Spur type equation Biomass = b 0 +b 1 x BH 2 [dbh cm, biomass kg] Tree component b 0 b 1 Coefficient of determination Stem wood -25.26 0.25 0.96 Branches -7.78 0.07 0.90 Foliage -0.56 0.03 0.88 12
eight equations - Biomass b 0 < 0 assume a good fit but nor for all BH BH = 10 BH = 25.4 cm Stem= - 25.26+0.25 25.4 2 = Branches =.. Foliage = 13