FOREST INVENTORY
			A forest inventory is often termed a “timber cruise”.  A timber cruise is an      inventory of a forest stand to determine the quantity of forest products that      can be derived from the stand.  In addition to timber quantity, a cruise      often contains information about species composition, age, tree quality,      site quality, topography, and operability for logging.  It also can include      data on growth, down woody material, snags, understory vegetation, and      other resources.        Click here to view or download a sample inventory report.  The report was      developed by Northwest Forestry Services for one of its clients, but the      names, dates, and legal descriptions have been changed.      Northwest Forestry Services has cruised or examined over 800,000 acres      of forestland in the Pacific Northwest.  Resources examined range from      reproduction to old growth.  Assignments have ranged from a few acres      to tens of thousands of acres.      A “typical” cruise report includes a Property Description and Timber      Inventory Data as detailed below.  Some cruises contain additional      information, as described under the “Other Inventory Data” heading.
	PROPERTY DESCRIPTION			TIMBER INVENTORY DATA	OTHER INVENTORY DATA
	KEY POINTS TO CONSIDER   Cruise results are always estimates, not precise figures.  Only a sample of trees on a property is measured.  Measuring every tree would be too time consuming and expensive. Even if every tree were measured, the results would be an estimate, because the cruiser cannot see all defects within a tree.  The cruiser estimates defect based on training and experience. The sampling error estimate in the cruise report is a measure of the precision of the volume estimate.   For cruises conducted for sale or acquisition purposes, sampling error target is a standard error of 5% to 7%.  That is, based on sampling error alone, the probability that true volume is within one standard error of cruise volume is 68 percent.  It is 95 percent that the true value is within two standard errors of cruise volume, and 99 percent that it is within three.  For cruises conducted for management planning purposes, the standard error may be 10% to 15%. Usually, the biggest factor affecting price of the cruise is sampling intensity. Obviously, the more sample plots that are installed, the more expensive is the cruise.  On the other hand, more sample plots result in a lower sampling error and consequently, a more precise volume estimate.   The volume estimate can vary depending on cruise methods.   For example, board foot volume is higher when logs are cruised in 32-foot lengths than when they are cruised in 40-foot lengths. Preferred length depends on the requirements of the log market.
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