Question

In forest trees, provenance variation and tree to tree differences accounts for nearly _______ of all the variation observed.

• A. 10%
• B. 90%
• C. 50%
• D. 60%

Hint:

This high natural variation (\(90\%\)) highlights the importance of provenance testing in tree improvement programs to select the best seed sources for reforestation.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Phenotypic variation in wild forest stands is shaped by genetic differences (including origin or provenance) and environmental factors.

Step 2: Detailed Explanation:
- In forest genetics, provenance refers to the geographical origin of a seed source.
- Because forest trees are wild, outcrossing, and long-lived, they maintain high levels of genetic variation.
- Population genetics studies (such as those by Zobel and Talbert) show that provenance differences combined with individual tree-to-tree genetic variation account for approximately \(90\%\) of the total observed phenotypic variation in most forest tree species.
- Environmental and micro-site factors account for the remaining \(10\%\).

Step 3: Final Answer:
Provenance variation and tree-to-tree differences account for nearly \(90\%\) of the observed variation.