Learn some advanced options for the GI method.
The GI method allows for some advanced options that surveyors may find useful. The following options allow surveyors some flexibility in using the GI method.
In order to reduce between plot variation, surveyors may wish to measure more than one GI sample tree per plot. Surveyors must increase plot size in order to collect more than one sample tree per plot. The following stipulates the appropriate plot radius for the corresponding number of sample trees:
To compile data when more than one sample tree per plot is measured, SI is estimated for each tree and the SI values are averaged.
It is possible to estimate SI from a portion of the total growth above breast height if the SI species has distinct annual branch whorls. This method is less accurate than the method based on ring count and total height. However, it can be used during the growing season. It is suitable for quick reconnaissance work.
To estimate SI from partial growth, surveyors follow these five steps (Figure 6.1):