Timber Inventory


An accurate and up-to-date inventory of forest resources is the foundational step for timber valuation and is vital in maximizing a property’s productivity. Knowing the value of a capital asset is a crucial component of the management process. Timberland owners in South Carolina have trusted the land experts at Henderson & Associates, Inc. to perform periodic assessments of forest products for over 35 years.

A timber inventory is a systematic data collection process that assesses the quantity and product classification of premerchantable and merchantable timber and other forest resources on a property at a specific time. Comprehensive timber cruises and evaluations also provide landowners with growth estimates, and help determine the overall productivity of a particular tract. Inventories can assist in making important forest management decisions, such as in scheduling harvests, thinnings, and reforestation, evaluating soil health and fertility, and preventing disease or reducing stocking levels. Timber inventory is necessary for a variety of reasons including:

  • Land management planning
  • Timber sales
  • Timberland acquisition
  • Investment analyses
  • 1031 exchanges
  • Estate planning

Inventory Methods

The professionals of Henderson & Associates utilize several different inventory methods and strategies, including strip, fixed-plot, variable radius, and 100-percent cruises. The appropriate inventory method is determined by a variety of contributing factors including the characteristics and size of the property, the scale and intensity that the inventory project requires, and the expectations and objectives of the landowner.

Generally speaking, a systematic sample is taken by collecting data at uniformly-spaced increments in the inventory area in order to get an accurate record of all forested areas. Field distance measurements are determined in survey “chain” increments, where a single chain is equal to 66 feet.

Fixed Radius Plot Cruise

The most commonly used inventory method by the professionals at Henderson & Associates, Inc. is the fixed-radius plot cruise. This method is often employed in timber appraisals, estate planning, and harvest management planning. When a plot cruise is utilized, individual tree measurements and product classifications are made for all trees that lie within a fixed-radius plot. Plots can range from 1/100th of an acre to 1/5th of an acre, depending upon inventory requirements. Spacing between the plots in a fixed-radius cruise is determined by the variability of the timber types in the cruise area, as well as the desired intensity of the cruise. Data collected within those plots are then expanded to estimate the volume of timber in the entire sampling region. Sampling rates, depending on desired cruise intensity and other factors, typically range between 6 and 20 percent.

Variable Radius Cruise (Prism Cruise)

Best suited in uniform timber stands, a variable-radius cruise, or prism cruise, provides another method of determining merchantable timber volume that can aid in making important forest management decisions. Variable-radius cruises utilize a glass prism, typically a 10-factor prism, which the cruiser uses to determine which trees to measure and quantify in a 360-degree radius from a fixed sample point. Light shining through the prism refracts the tree’s image which is used to determine which trees are measured and which are excluded. Tree diameter and distance from the point center are the main variables in determining which trees are refracted less than 100 percent by the prism. Data collected within the sample points are expanded by the prism factor represent the volume of the entire region.

100 Percent Cruise

Sometimes high variability among forested stands on a tract requires that high intensity cruises be conducted in order to determine more exact volume figures. Though the are less efficient much more labor-intensive, one hundred percent cruises are sometimes employed on small sample areas wherein every tree is measured, tallied, and categorized by grade and product classification.

An up-to-date, accurate timber inventory is the foundation for conducting sales of any forest resource, and can be a vital tool in maximizing the return on your timberland investment. Have questions or ready to get started with a timber inventory and land management strategy? Contact the experts at Henderson & Associates today.

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