Certified Forester Practice Exam

Which of the following is a drawback of using site index to measure forest productivity?

1. It is effective for uneven-aged stands

2. It provides a comprehensive estimate of growing capacity

3. It may not apply to mixed stands or open land

4. It is a suitable method for all tree species

The correct answer is: It may not apply to mixed stands or open land

Using site index to measure forest productivity has the notable drawback of potentially not applying well to mixed stands or open land. Site index is based on the height of the dominant tree species at a given age, typically for a specific species. This method assumes a certain level of homogeneity in tree species, age, and site conditions, which is often not the case in mixed stands where various species may have different growth rates and optimal growing conditions. In mixed stands, the presence of different species can complicate the interpretation of site index measurements, as some may thrive better than others depending on their specific environmental needs and competition with adjacent trees. Similarly, in open land where tree cover is sparse or non-existent, the concept of site index becomes less relevant as there are no dominant trees to measure. Consequently, while site index can be a useful tool for certain forest conditions, its application becomes limited in more diverse or unconventional forest environments.