Individual tree parameters are an important concept in forest mensuration.
By understanding what are parameters to be measured for individual tree parameters, analysts are able to make insight and conclusions from the data.
For this article, we’re going to take a look more deeply into tree diameter as an individual tree parameter and start to understand how tree diameters are measured.
Individual tree parameters are as follows, such as tree age, trees diameters, cross-sectional areas, height, form, and crown parameters.
Age is an important factor because it’s related to growth and yield as a variable in evaluating site quality.
5.2 Tree Diameters and Cross-Sectional Areas
By being able to measure tree diameter correctly and in a standardized way, we are then able to calculate surface area and also a tree volume. Tree diameters measurement can widely vary, so then we need a certain kind of standardized measurement. In the United States, the diameters of standing trees are measured at 4.5 ft or 1.3 m. This is widely known as Diameter at Breas Height (d.b.h).
In measuring d.b.h in the field, the following standard procedures are recommended:
- when trees are on slope, dbh should be calculated above the ground on the uphill (Fig. 1b and c)
- when a tree is leaning, breast height is measured parallel to the leaning on the high side of the tree. The diameter is measured perpendicular to the longitudinal axis of the stem (Fig. 1d)
- when a tree has a limb, a buldge or some abnormality. Breast height should be calculated above the abnormality (Fig. 1e and f)
- when a tree consits of two or more stems forking below breast height, measure each stem separately (Fig. 1h).
- when a tree forks at or above breast height, measure it as one tree. If the fork occurs at breast height or slighlty above, measure diameter below the enlargement caused by the fork (Fig. 1g).
- when a tree has buttress that extends higher than 3ft or 1m, it is common to measure the stem at a fixed distance above the top of the buttress, usually 30cm (Fig. 1i)
Height is a linear distance between the ground and the tip of the tree. Height is an important tree parameter since volume calculation also can be derived by knowing the height of the tree. Tree height needs to be clearly defined first.
The form of the main stems of the trees varies due to differences in rates of diminution in diameter from the base to the tip. The diminution in diameter known as taper which varies with species, dbh, and age of the trees and with sites, is the fundamental reason for variation in volume.
5.5 Crown Parameters
The crown parameter is a factor that is involved in forest growth and yield. Crown dimensions are useful for predicting wildlife habitat value and monitoring forest health.