Researchers in the Dept. of Wood Science and Engineering at Oregon State University (OSU) have started research on wood quality of Valley Ponderosa Pine in comparison to Eastern Oregon Ponderosa Pine. Laurent Bouffier, a French student on a five-month internship to OSU, is working with professor Barb Gartner to look at the woods' density, its anatomy, and how resistant it is to drought. It's just a pilot project because the duration is so short, but if there are interesting differences other students will be encouraged to follow suit and work on Valley Ponderosa.
Laurent used an increment borer to get
cores from about 20 trees at each of four sites. The two valley sites are near
Brownsville and Albany along the Calapooia River. The eastside sites are near
Gilchrist and Bend. The increment borer with its hollow center extracted a core
of wood about ¼" in diameter. This core contains a sample of the annual
growth rings for the tree.
Laurent x-rayed the cores with an x-ray densitometer, which gave a trace of wood density all along the core, from which he could computer percentage latewood (which is the dark band of dense wood produced in the summer), ring by ring density, and ring by ring density of just the early wood or just the latewood. For the four sites, he will be able to answer the question, is the wood the same? Do they have the same amount of latewood? Is the latewood the same in both sites, or does it vary in density? These questions are important because they affect many of wood's properties, ranging from strength to pulp yield.
The
early results based on these 4 sites are interesting. They show that after a few
rings from the pith, the trees in the Willamette Valley sites appear to get
denser and denser ring by ring, but the Eastern Oregon trees stay about the
same! We don't know if it's environment, genetics or a poor sample (or all
three). Based on these limited results additional sampling maybe done.
Laurent will go back to some of the trees to take a larger-diameter core and then look at the cells-their diameters and cell wall thicknesses, to better understand from where the density differences come. Time permitting, he'll also do some analyses on twigs and roots that are designed to tell how well the wood can transport water under drought. You start by measuring how permeable a sample is (how much water comes through it when you push it in with a given force? standardized by length and sample diameter). Then you put the sample in conditions that simulate having a mild drought (i.e., similar to having 1 MPa of tension in the water-as if the water is being pulled, or stretched, the way it is in a slight drought). You measure conductivity again, then put 2 MPa tension in the water, etc. Eventually, you construct a curve showing how much the sample lost in conductivity as a result of varying degrees of drought (tension in the water column). They expect that the valley plants may be better adapted to rapid water transport, but less well adapted to transport during drought, than the east side trees. Time will tell!
