- Timber cruise
A Timber Cruise is a sample measurement of a stand that is used to determine an estimate of the amount of timber that the forest contains. These measurements are collected at sample locations called plots or quadrants. Each of these individual plots is one observation in a series of observations called a sample. These plots are generally laid out in some random fashion usually in the form of a
line plot survey . Depending on the size of the plot and the number of plots measured, the data gathered from these plots can then be manipulated to achieve varying levels of certainty for an estimate that can be applied to the entire timber stand. This estimate of stand conditions, species composition, volume and other measured attributes of a forest system can then be used for various purposes.Types of sample plots
Fixed area plot
Fixed area plot sample measurements are taken so that they are a fraction of the entire timber stand. This means that the numbers are all proportional to the actual stand values and that by multiplying by the correct corresponding value you can obtain the actual tract values. These plots are taken randomly so that each sample point has an equal probability of being included in the
random sample .Variable size plots
A variable size plot is more dependent of the size of the trees. The tract is measured on a series of points and the trees are tallied for being in or out depending on their size and location relevant to the plot center. Usually an
angle gauge or awedge prism are used to gather data for this type of plot. This allows for a very quick estimate of the volume and species of a given tract.References
http://www.fs.fed.us/fmsc/measure/cruising/index.shtml
Avery and Burkhart, "Forest Measurements". 5th ed. McGraw Hill, New York, 2002
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