Estimating Timber Volume
Once the forest inventory data is collected, foresters can estimate the timber volume present in commercial stands. In terms of timber, the volume of wood in a trunk – up to a specified top diameter – is considered ‘sellable,’ but this can vary dependent on market appetite. Accurate volume estimates mean more sustainable forest management, commercial harvesting, conservation, and trade.
Several methods are used for this purpose, and the choice depends on the forest type, species, and available resources. Some of these methods are below:
Volume equations are mathematical formulas developed based on statistical sample data analysis. These equations relate tree characteristics (e.g., DBH and height) to timber volume. When applied to the entire stand, they provide estimates of the total timber volume.
Cruising involves physically measuring sample trees to determine their volume. This can be done using relascope, Biltmore stick, or similar instruments. The aggregated measurements from sample trees are then extrapolated to estimate the total volume of the timber stands in the form of a cruise report. Alongside total volume and trees per acre, this report also provides the range of tree species, sort, grade, age and other information.
Remote Sensing and GIS:
In recent years, remote sensing technologies, such as satellite and aerial imagery, have been increasingly used to estimate timber volume. Coupled with Geographic Information Systems (GIS), these tools provide accurate and efficient assessments over large forest areas. The bigger impact of these technologies is the creation of national forest resource maps to improve forestry management and sustainability at a local and, eventually, global scale. Global and local datasets that incorporate the use of stereo satellite imagery to capture height data from space as well as point cloud data from LiDAR and Drone data as well as some Radar datasets are also being utilised in the forestry industry more and more to make inventory studies better.