Wood Survey
In 1996, the owner of Wood Frog Farm considered the possibility of establishing some kind of business based on trees abundant on the property. Some could be cut and sold to timber companies or the Oriented Strand Board (OSB) plant in Drayton Valley. Others could be turned into firewood. The first step in the business plan was to determine just how much wood there was on one quarter section of land. This was not expected to amount to much. Several farmers in the area had been buying forested land and paying for the trees to be bulldozed into huge piles and burned to make space for crops.
Because Wood Frog Farm is a highly diverse property, it was divided into 16 zones for the wood survey (labelled A to P on an outline map made from an aerial photo). Five zones were identified as containing commercially valuable wood.
Zone areas were determined with a Numonics 2200 graphics tablet sending its output to a 386SX computer running the Jandel SigmaScan morphometry program. Calibration was done by assuming one boundary of a quarter section is 880 yards (804.7 metres). On the tracing this translates into a scale where 1cm = 31.7m or 100m = 3.16cm. Area of the entire quarter should therefore be (805m)2 = 648,025m2 = 64.8ha. This compares closely with the standard definition of a quarter section as 160 acres = 64.75ha.
Because Wood Frog Farm is a highly diverse property, it was divided into 16 zones for the wood survey (labelled A to P on an outline map made from an aerial photo). Five zones were identified as containing commercially valuable wood.
Zone areas were determined with a Numonics 2200 graphics tablet sending its output to a 386SX computer running the Jandel SigmaScan morphometry program. Calibration was done by assuming one boundary of a quarter section is 880 yards (804.7 metres). On the tracing this translates into a scale where 1cm = 31.7m or 100m = 3.16cm. Area of the entire quarter should therefore be (805m)2 = 648,025m2 = 64.8ha. This compares closely with the standard definition of a quarter section as 160 acres = 64.75ha.
Survey Results
The result of the survey was a surprise. There was one heck of a lot of wood on Wood Frog Farm and it was worth over $100,000 at the current market value of the time. Despite this discovery, it was decided that cutting down trees is a very dangerous business, and that the greatest value of the land is its natural beauty. Accordingly, the chain saw was sold and no wood business was started. The results of the 1996 survey are given in the table below:
| Zone | Area (ha) | Aspen | Birch | White Spruce | Jack Pine | Black Spruce | Larch |
|---|---|---|---|---|---|---|---|
| Vireo Woods | 9.63 | 4386 stems (1200 m3) |
3604 | 510 (202 m3) |
34 (32 m3) |
0 | 0 |
| Fairyland Woods | 22.04 | 4340 (1445 m3) |
2765 (142 m3) |
2275 (866 m3) |
2345 (514 m3) |
a few | a few |
| Whitetail Woods | 3.91 | 1360 (343 m3) |
300 (17 m3) |
20 (8 m3) |
220 (55 m3) |
0 | 0 |
| Thrush Woods | 4.83 | 1176 (210 m3) |
a few | 504 (99 m3) |
644 (176 m3) |
0 | 0 |
| Black Spruce | 5.58 | a few | some | a few | 0 | many | some |
| Slopes of Creeks | 9.84 | many | many | a few | a few | 0 | 0 |
| Meadows | 8.91 | many small | many small | many small | a few small | 0 | 0 |
| Total | 64.8 | 11,200 stems (3,200 m3) |
6,600 (370 m3) |
3,300 (1,100 m3) |
3,200 (770 m3) |
not counted |
not counted |
Current values will be considerably greater after 17 years of additional growth. The methods use to arrive at the estimates are shown below.
Zones with merchantable wood (total of about 49.2 ha)
A 9.63ha Vireo woods - mainly aspen and birch with somespruce and a very few jack pine
B&C 3.21ha East and west banks of Beaver Creek, where beaver have cut many aspen
E 22.04ha Fairyland and vicinity - spruce, pine, aspen, birch
I 3.91ha Whitetail woods - mainly aspen; some pine
N 4.83ha Thrush woods - mainly pine and spruce
O 5.58ha Black spruce fen
Meadows that could be planted and harvested (total of about 8.96 ha)
D 5.26ha Cabin and Spring meadows
F 0.45ha Driveway
G&H 3.25ha House site, Aspen grove and Strawberry meadow
Areas claimed by beavers; no possible use value (total of about 6.63 ha)
J 0.90ha North bank of Pigeon Creek - willows
K 0.88ha Willow/alder scrub
L 0.94ha Grassy north bank of Pigeon Creek
M 2.02ha South bank of Pigeon Creek
P 1.89ha The two creeks and beaver ponds
Zones with merchantable wood (total of about 49.2 ha)
A 9.63ha Vireo woods - mainly aspen and birch with somespruce and a very few jack pine
B&C 3.21ha East and west banks of Beaver Creek, where beaver have cut many aspen
E 22.04ha Fairyland and vicinity - spruce, pine, aspen, birch
I 3.91ha Whitetail woods - mainly aspen; some pine
N 4.83ha Thrush woods - mainly pine and spruce
O 5.58ha Black spruce fen
Meadows that could be planted and harvested (total of about 8.96 ha)
D 5.26ha Cabin and Spring meadows
F 0.45ha Driveway
G&H 3.25ha House site, Aspen grove and Strawberry meadow
Areas claimed by beavers; no possible use value (total of about 6.63 ha)
J 0.90ha North bank of Pigeon Creek - willows
K 0.88ha Willow/alder scrub
L 0.94ha Grassy north bank of Pigeon Creek
M 2.02ha South bank of Pigeon Creek
P 1.89ha The two creeks and beaver ponds
Transects for Tree Survey
Because of the diversity of the habitat within each zone, line plots were used rather than circular or square patch plots. Transects were set up arbitrarily without regard to any geographical landmark by drawing lines across the entire quarter at 45 degree angles, starting at the NW corner and plotting a transect every 100m along the N and W boundaries. Every other transect was surveyed for the final results, which meant at least two transects were used for each major zone containing useful wood. The survey was started at one of the defined points along a boundary with aid of the map, and it continued on a 45 degree angle with aid of a compass (adjusting for declination of magnetic North). The point where the actual walked line emerged from the zone was noted and the actual length of the transect was found by measuring this line on the diagram. Width of the measured zone was 4m as determined by a 2m rod. Diameter at breast height (DBH) for every tree over 8cm DBH was measured with a metric square, and height in meters was determined for a few trees at each DBH with a spirit level and a 45 degree vertical angle on the square. Final determination of wood resources for a zone was made by adding the results of two or more transects.
Estimating Merchantable Volume
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This was done with a computer program (WOOD.C) that assumed each tree was a perfect cone. This assumption yields an underestimate of volume for aspen and pine but may be quite good for birch and spruce (as compared with Alberta Land and Forest Services Individual Tree Volume Tables; see Huang, S., S.J. Titus, and D. Wiens, 1992. Comparison of nonlinear height-diameter functions for major Alberta tree species. Canadian Journal of Forest Research 22:1297-1304.). A minimum top diameter of 10cm was used for aspen, pine and spruce (5cm for birch). Minimum OSB bolt length for aspen was 2.55m, and minimum sawlog length for pine and spruce was 5m.
If a tree did not meet these criteria, it was regarded as too small to be of current use. Wood left over at the top of aspen was presumed to be useful for firewood after even-dimensioned bolts were cut. A tally all trees of each species with each diameter was done by walking each transect. Then the program multiplied frequency by the appropriate volume from the table and added volumes for each species separately. A table for this purpose was used. Volume was estimated assuming the tree is a perfect cone, using the formula VOLUME = (hr2)/3. .. where h is height in m and r is radius in m. Heights were based on previous measurements at Wood Frog Farm in 1996. A diagram shows this method. |
Beaver-logged aspen in zones B & C was surveyed by measuring each downed stem, noting its base diameter and length to a top height of 10cm. There were 127 aspen one or two years old and not yet rotten, and their volume was 22.6 m3, making about 10 cord of firewood.
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