Bark beetle infestations in western North
America have severe negative biogeophysical and biogeochemical impacts that affect areas of forestry in the US of an area approximately equal to the State of Washington. The beetles kill apparently healthy trees by attacking en masse to overcome host tree resistance, and then adequately space themselves to limit interspecies competition. Through the release of pheromones, the pioneer beetle control the location of other beetles.
In order to protect high value stands, forest managers use synthetic pheromones to repel or attract beetles to traps. By adequately placing synthetic attractants and anti-aggregation semiochemicals, forest managers can protect trees and forested areas from bark beetle attacks. However, there is a lack of information to guide them.
In this experiment, we set up a simulation to graph the correspondence between tracer gas concentration and atmospheric stability. Within the Tukey
Cherry Orchard, we set up three sonic anemometers to measure the wind and temperature in order to produce distribution profiles from the measurements.
Concurrently, we set up the Tracer Gas
Automated Profiling System or T-GAPS to measure sulfur hexafluoride: an inert gas that is not commonly found in ambient air and is easily traceable. The release is set within the canopy with sampling tubes surrounding it in a concentric circle. This allows us to analyze the tracer sample continuously with five minute average measurements. concentration
In analyzing the data, hourly averages were taken from the 5 minute average values in order to filter out noise or spikes . In doing so, there are better trends observed within the data.
Design a tracer gas dispersion experiment to measure on-site meteorology.
Find and verify the relationship between plume distribution and atmospheric stability through continuous data collection.
From the data collected, we observed high concentration with respect to a stable atmosphere and low concentration with respect to an unstable atmosphere. Within an unstable atmosphere there are higher
TKE than within a stable atmosphere. This means there is an inverse relationship between stability and dispersion which can seen by looking at the turbulent kinetic energy (TKE) against max concentration values .
Further research needs to be done in this area in order to obtain a big picture of the relationship between dispersion and stability. The data collected here is for five days which is not sufficient enough to see a relationship between day and night time trends.
Edburg S, Allwine G, Lamb B, and Stock D. 2010. A Simple
Model to Predict Scalar Dispersion Within A Successively
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Thistle, Harold W.; Peterson, Holly; Allwine, Gene; Lamb,
Brian; Edburg, Steve; Strom, Brian. 2005. The Influence of Stand
Thinning on Surrogate Pheromone Plumes. Proceedings, 16th
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Gypsy Moth and Other Invasive Species 2005, U.S. Department of Agriculture, Forest Service, Northeastern Research Station:
83-85.
Thistle HW, Strom B, Strand T, Peterson HG, Lamb B,
Edburg S, and Allwine G. 2011. Atmospheric Dispersion from a
Point Source in Four Southern Pine Thinning Scenarios: Basic
Relationships and Case Studies. Transactions of the ASABE
54(4): 1219-1236.
Thistle, H., Peterson, H., Allwine, G., Lamb, B., Strand, T.,
Holsten, E., and P. Shea. 2004. Surrogate Pheromone Plumes in
Three Forest Trunk Spaces: Composite Statistics and Case
Studies. Forest Science 50(55): 610-625.
This work was supported by the National Science Foundation’s
REU program under grant number AGS-1157095.
Special thanks goes out to Alejandro A. Prieto, Deb Pehrson, and Tukey Orchard for the assistance and contributions with this experiment.