OTCPK:TOUBF - Post by User
Post by
repap_nbon Sep 16, 2011 8:18pm
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Post# 19052721
Measuring Forest
Measuring Forest
Measuring the forest involves 2 levels:
1. Determine the hectares of forest "stands" usually through aerial photos, maps or ownership doc's - A stand can be a mixture of trees homogeneous over an area or a single species as we would see in a plantation.
2. Calculate Yield per hectare of these stands. (metric - Cubic Meters per Hectre or M3/Ha)
If PWC/OSC are just interesed in confirming the Hectares (1.) , much faster process - If they want to confirm volumes (2.), lot more work required.
Hectares:
Typically a company would have a database of holdings that delineate the forest stands (Maps for ex or GIS preferably)
If PWC wants Hectares, this is all they need - maps or ownership docs showing land bases. To validate in this day, google earth could be used to look at the areas to see if trees exist. Few months perhaps for 3-4 people to validate the the entire landbase. the other part is validting ownership which is slow as we see.
Volumes:
Area of similiar types are pooled over a land base and these similar types are randomly sampled (using statistical confidence intervals) for species, diameter and perhaps height depending on the quality of the volume tables available (A Volume table provides average volume per tree for each diameter class - ex: A 14 cm tree may have an average volume of 0.08 M3 - this would have been validated by measuring a number of sample trees in detail for height and diameter and calculating their volume) .
The sampling would determine the number of trees per hectare of each diameter class which can then be used to calculate the volume per hectare. The average volume per hectare is then multiplied by the hectares of that type of forest to determine total volume available for that type. Different types are summed over the entire landbase to determine total volume or "Growing Stock"
How many samples? Complex answer due to the sampling can be plots (establish a center point and measure all trees within a 10 m radius) or plotless (prism sampling) where points are measured every (for ex) 50 m on 50 m spaced lines.
In even-aged Plantations a lot less sampling would be required than say southern US mixedwood stands or coastal old growth stands to have the same level of statistical confidence. As with most statistical sampling methods, a subsample would be done to look for uniformity and from that the total number of samples required would be calcuated.
On 800,000 hectares, this is a slow process as a sampling regieme is set up, stands have to be randomly sampled and the results tabulated. A crew of 10-12 would be many many months to do this sampling.
Hope it helps a bit even though I know it does not answer the how long Q.