Tuesday, September 28, 2010

Which Type of Tree Resin/Sap is Most Flammable? Are Beetle Kill Trees Dryer Than Those Which Die of Natural Causes?

1) What type of instrument and methods could I use to determine which type of tree resin/sap is most flammable?
2) How could I determine how much drier a beetle kill tree is than a tree that died of natural causes? (Assuming the trees are of the same age and location)
Answer from Posse Member Dave McKenzie:
The bomb calorimeter is the only method I know of for getting this sort of data. There may be others. You could try some of the departments around campus, but I don't think you'll have much luck. My lab mate was trying to use one and would have had to go Denver I believe it was.

1) What type of instrument and methods could you use to determine which type of tree resin/sap is most flammable?
I can't think of any particular instrument that would be used for this, but I have an idea. You could collect similar amounts of sap and put them in some sort of metal container (beer cap or soda can bottom). Then, apply heat from a constant and repeatable heat source (long-handled lighter for example). You would measure the amount of time needed for the sap to begin to burn on its own. Never having done this, I'm not sure how much it would take or whether or not it would even work. You may have to move up to a propane torch (available for about $30 at the local hardware stores) for more heat. I'm sure you could find some sort of oven or candy thermometer that you could then apply the same amount of heat to in order to get the approximate temperature. As a forest scientist the time a particular sap takes to burn is just as interesting as which is more flammable because in forest fires the duration and intensity of the flames both play a role in tree mortality.
2) How could you determine how much drier a beetle kill tree is than a tree that died of natural causes? (Assuming the trees are of the same age and location)
This one is pretty manageable. You could take needles or wood in equal amounts (volumetric) from several trees. For this, wood would be easier because it's hard to calculate the volume of needles without getting them wet. Use a scale to measure the mass of each sample. You will want to use a scale that measures in grams and goes out to several decimal places. I think thousandths would be the minimum, but use what you can get your hands on. Weigh the samples as soon as you can after cutting them. Then, put them in a drying oven set to probably 90 degrees C. Dry them for several days, taking a mass measurement every other day. Once the mass levels off you can assume the samples are totally dry. The difference in mass between the fresh sample and the dry sample is water (and other volatiles) that evaporated through drying. If you use several samples (as many as you can handle actually), you will be able to come up with an average difference, making your study much better. You could use needles for this, but you would have to calculate the volume after you dried the samples. Even with the wood, you will still want to correct for exact volume. In the end you want to be able to compare percent moisture loss. For example: "The living tree was 15% moisture by mass, the beetle killed tree was 8% and the naturally killed tree 12%. Thus, the beetle killed tree was the driest."

I hope this helps. Let me know if you have any other questions.
-Dave

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