One consideration when evaluating potential harvest value is JAS conversion or where your export logs weighed in tonnes are paid for by JAS.
If you are weighing up export as a destination in your stumpage calculation then you need to understand what it means to get paid in JAS.
For the domestic market log output is typically measured by weight and expressed in tonnes; however for the export market log output is measured or scaled in volume. The scaled volume is expressed in JAS which is an acronym for Japanese Agricultural Standard. Often people mistake JAS for an adjusted weight measurement; however JAS is a method of expressing the cubic meter equivalent of a load of wood. Normally to calculate the volume of a cylinder you would multiply its base area by its height; i.e. volume = π r²h. Unfortunately it is not that simple when it comes to scaling logs, as a log is not a true cylinder – logs taper, sweep and can have swelling or fluting.
These factors are taken into consideration when calculating JAS volume. Typically logging and cartage contractors are paid per tonne, so when wood is sold by JAS it is necessary to keep track of the reciprocal tonnages. This results in a handy conversion factor that can be used to determine how well your wood transforms from tonnes to JAS. The higher these figures are the better, but determining the JAS conversion pre-harvest is more of an art than a science as it is impossible to effectively calculate the exact weight, taper and cross section of each stem.
Live information, inventory data, photo analysis and historical data are used to project weight estimates. Jas conversions are then projected from historical data by region and taking age factors into account. Whenever we appraise the value of a potential stumpage block or client managed sale we draw on 20 years of conversion factors across 3 million tonnes of export sales across the country.
This is because the weight of a load of wood decreases over time due to the difference between the greenwood and drywood density. If overseas buyers paid by weight they would be paying for tonnage in the form of water vapour which evapourates in transit. Good for the seller but not the buyer.
If your wood is to be sold as export and paid by JAS volume, each load will take a trip to the port via the scaling yard where the logs are individually measured by qualified scalers. JAS calculations are based on each log’s SED or small end diameter using a special bar-coded scaling ruler and scaling wand. Each log is then barcoded for identification purposes. This barcoded information is e-mailed to the supplier next morning in the form of a CSV report which then gets loaded for reporting to the client and monitoring in relation to value recovery.
When you see the actual JAS conversions coming through they should replicate what you have been advised in your block’s value proposition and most importantly you should understand them.