Question

What will be the increment percent (P) according to Pressler's formula when the volume at the age of 70 years be 100 m$^3$ and the volume ten years ago be 70 m$^3$, but a thinning was carried out at 5 years ago and yielded 10 m$^3$ ?

• A. 5.44
• B. 4.44
• C. 6.44
• D. 7.94

Hint:

Pressler's formula is highly valued in forest magement because it provides a reliable estimate of growth rate while accounting for intermediate harvests (thinning) within the period.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Pressler's formula is a standard mathematical equation used in forest mensuration to calculate the volume increment percent of a tree or forest stand over a given period.
It relates the current volume, past volume, and any thinning yields removed during the period to calculate the average annual growth rate.
Key Formula or Approach:
The modified Pressler's formula accounting for intermediate thinning yields (\(T\)) removed during the period is:
\[ P = \frac{V - v + T}{V + v + T} \times \frac{200}{n} \]
where:
- \(V\) is the current volume of the stand (\(100\text{ m}^3\)).
- \(v\) is the past volume of the stand at the start of the period (\(70\text{ m}^3\)).
- \(T\) is the volume of wood removed during thinning (\(10\text{ m}^3\)).
- \(n\) is the length of the period in years (\(10\text{ years}\)).

Step 2: Detailed Explation:
Let us substitute the given values into Pressler's formula:
- Current volume (\(V\)) = \(100\text{ m}^3\)
- Past volume (\(v\)) = \(70\text{ m}^3\)
- Thinning volume (\(T\)) = \(10\text{ m}^3\)
- Period (\(n\)) = 10 years
Plugging these into the equation:
\[ P = \frac{100 - 70 + 10}{100 + 70 + 10} \times \frac{200}{10} \]
\[ P = \frac{40}{180} \times 20 \]
\[ P = \frac{4}{18} \times 20 = \frac{80}{18} \]
\[ P = 4.44\% \]
Thus, the volume increment percent of the stand during this 10-year period is \(4.44\%\).

Step 3: Fil Answer:
According to Pressler's formula, the calculated increment percent is \(4.44\).
Hence, the correct option is (B).