Forest inventory
Encyclopedia
Forest inventory is the systematic collection of data and forest information for assessment or analysis. It is also commonly known as timber cruising
. It is important for owners to cruise the timber to get an estimate of the value and possible uses of the timber
. When taking forest inventory the following are important things to measure and note: species, diameter at breast height
(DBH), height, site quality, age, and defects. From the data collected one can calculate the number of trees per acre, the basal area
, the volume of trees in an area, and the value of the timber. Inventories can be done for other reasons than just calculating the value. The timber can be cruised to determine potential fire hazards and the risk of fire. The results of this type of inventory can be used in preventative actions and also awareness. Wildlife surveys or inventories can be taken to determine the number and type of wildlife within a forest.
The aim of the statistical forest inventory is to provide comprehensive information about the state and dynamics of forests for strategic and management planning.
(the main source of fuel) would run out. The first information was organized into maps used to plan out usage. In the early 19th century forest harvesters estimated the volume and dispersal of trees within smaller forests with their eyes. More diverse and larger forests were divided into smaller sections of similar type trees that were individually estimated by visual inspection. These estimates were related together to figure out the entire forest’s available resources. As the 19th century progressed so did the measurement techniques. New relationships between diameter, height, and volume were discovered and exploited. These newfound relationships allowed for a more accurate assessment of wood types and yields of much larger forests. By 1891, these surveys were conducted through sample-based methods involving statistical averages and more sophisticated measuring devices were implemented. In the 20th century, the statistical method of sampling had become well established and commonly used. Further developments, such as unequal probability sampling, arose. As the 20th century progressed, an understanding of co efficients of error became clearer and the new technology of computers combined with the availability of aerial as well as satellite photography, further refined the process.As a result sampling accuracy and assessment values became more accurate and allowed for modern practices to arise.
Timber cruise
A timber cruise is a sample measurement of a stand used to estimate the amount of standing 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...
. It is important for owners to cruise the timber to get an estimate of the value and possible uses of the timber
Timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...
. When taking forest inventory the following are important things to measure and note: species, diameter at breast height
Diameter at breast height
Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements....
(DBH), height, site quality, age, and defects. From the data collected one can calculate the number of trees per acre, the basal area
Basal area
Basal area is the term used in forest management that defines the cross-sectional area of a tree at DBH, inside the bark.In most countries, this is usually a measurement taken at a specimen's breast height above the ground and includes the entire diameter of every tree, including the bark...
, the volume of trees in an area, and the value of the timber. Inventories can be done for other reasons than just calculating the value. The timber can be cruised to determine potential fire hazards and the risk of fire. The results of this type of inventory can be used in preventative actions and also awareness. Wildlife surveys or inventories can be taken to determine the number and type of wildlife within a forest.
The aim of the statistical forest inventory is to provide comprehensive information about the state and dynamics of forests for strategic and management planning.
History
Surveying and taking inventory of trees originated in Europe in the late 18th century out of a fear that woodWood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
(the main source of fuel) would run out. The first information was organized into maps used to plan out usage. In the early 19th century forest harvesters estimated the volume and dispersal of trees within smaller forests with their eyes. More diverse and larger forests were divided into smaller sections of similar type trees that were individually estimated by visual inspection. These estimates were related together to figure out the entire forest’s available resources. As the 19th century progressed so did the measurement techniques. New relationships between diameter, height, and volume were discovered and exploited. These newfound relationships allowed for a more accurate assessment of wood types and yields of much larger forests. By 1891, these surveys were conducted through sample-based methods involving statistical averages and more sophisticated measuring devices were implemented. In the 20th century, the statistical method of sampling had become well established and commonly used. Further developments, such as unequal probability sampling, arose. As the 20th century progressed, an understanding of co efficients of error became clearer and the new technology of computers combined with the availability of aerial as well as satellite photography, further refined the process.As a result sampling accuracy and assessment values became more accurate and allowed for modern practices to arise.
Stand examination
Today, the most common type of inventory is one that uses a random sampling technique which groups similar forests into one category based on age, stand structure, species, and location. The next step would be to begin from a random place and measure circular plots that are equidistant from one another. When taking inventory, a decision has to be made about which types of plots to measure. There are several different types of plots. The two most common types are fixed radius and variable radius, also known as prism radius. In a fixed radius plot, the forester finds the center of a plot and every tree within a certain fixed distance away from that point is measured. Variable radius plots are used more for inventory of volume. During this method, an angle is created and projected from the plot center and all trees that are larger than the projected angle are measured.See also
- Reducing Emissions from Deforestation and Forest Degradation (REDD)
- National forest inventory (NFI)