Question:
Crop height is determined by the following formula
Crop height is determined by the following formula
Show Hint
Lorey's height is widely used in forest inventories because it correlates closely with the total merchantable volume of a stand, making it a reliable variable for growth models.
Updated On: Jul 21, 2026
- Smalian's formula
- Quarter girth formula
- Lorey's Formula
- Cotta's formula
Show Solution
Verified By Collegedunia
The Correct Option is C
Solution and Explanation
Step 1: Understanding the Concept:
In forest mensuration, calculating the average height of a forest stand (crop height) is essential for estimating volume, assessing site quality, and modeling stand growth.
A simple arithmetic mean of tree heights is often inaccurate, as it does not account for differences in tree size and volume.
Key Formula or Approach:
Lorey's Formula calculates the mean height of a forest stand by weighting the height of individual trees by their basal area.
The formula is expressed as:
\[ H_L = \frac{\sum (g_i \cdot h_i)}{\sum g_i} \]
where:
- $H_L$ is Lorey's mean height.
- $g_i$ is the basal area of an individual tree.
- $h_i$ is the height of an individual tree.
Step 2: Detailed Explanation:
Let us review the applications of the other formulas listed in the options:
- Smalian's Formula: This is used to estimate the volume of logs by averaging the cross-sectional areas of both ends and multiplying by the log length ($V = \frac{A_1 + A_2}{2} \cdot L$).
- Quarter Girth Formula: This is a traditional method used to estimate the usable timber volume of a log based on its girth ($V = (\frac{G}{4})^2 \cdot L$).
- Cotta's Formula: This is used to calculate the volume of standing timber.
- Lorey's Formula: Because this formula weights tree heights by their basal area, it is less affected by small, suppressed understory trees. As a result, it provides a much more accurate representation of the dominant canopy height and overall stand volume.
Step 3: Final Answer:
Crop height is determined using Lorey's Formula, corresponding to option (C).
In forest mensuration, calculating the average height of a forest stand (crop height) is essential for estimating volume, assessing site quality, and modeling stand growth.
A simple arithmetic mean of tree heights is often inaccurate, as it does not account for differences in tree size and volume.
Key Formula or Approach:
Lorey's Formula calculates the mean height of a forest stand by weighting the height of individual trees by their basal area.
The formula is expressed as:
\[ H_L = \frac{\sum (g_i \cdot h_i)}{\sum g_i} \]
where:
- $H_L$ is Lorey's mean height.
- $g_i$ is the basal area of an individual tree.
- $h_i$ is the height of an individual tree.
Step 2: Detailed Explanation:
Let us review the applications of the other formulas listed in the options:
- Smalian's Formula: This is used to estimate the volume of logs by averaging the cross-sectional areas of both ends and multiplying by the log length ($V = \frac{A_1 + A_2}{2} \cdot L$).
- Quarter Girth Formula: This is a traditional method used to estimate the usable timber volume of a log based on its girth ($V = (\frac{G}{4})^2 \cdot L$).
- Cotta's Formula: This is used to calculate the volume of standing timber.
- Lorey's Formula: Because this formula weights tree heights by their basal area, it is less affected by small, suppressed understory trees. As a result, it provides a much more accurate representation of the dominant canopy height and overall stand volume.
Step 3: Final Answer:
Crop height is determined using Lorey's Formula, corresponding to option (C).
Was this answer helpful?
0
0
Top ICAR AIEEA Forestry Agroforestry Silviculture Questions
- Read the following statements of silvicultural system followed in tree species and choose the correct answer from the following options:
Statement (I): Anogeissus latifolia is worked only as a component species of mixed forests as coppice-with-standards.
Statement (II): Terminalia arjuna tree is not a regular component of forest stand and is usually worked under selection and coppice with standards.
Choose the correct answer from the options given below: - The most important single factor affecting natural regeneration of Shorea robusta is the time lag between the falling of seed and the commencement of the ________.
- Read the following statements and choose the correct answer about silvicultural system/s adopted for the management of Shorea robusta:
Statement (I): Under clear felling system, a rotation age is fixed and the entire area clear felled and the crop is of uniform age.
Statement (II): Selection system is adopted for areas which are badly eroded and where regeneration is problem and regeneration is obtained by natural means, which may be supplemented by planting.
Statement (III): In coppice with standards system, a few standards are retained and the other trees above the exploitable diameter are clear felled and regeneration is obtained by means of coppice.
Choose the correct answer from the options given below: - Which of the following type of soil is the best for plant growth?
- A biosphere reserve conserves and preserves the following variety of life and choose the correct option of variety of life:
(A). Wild animals
(B). Wild land
(C). Natural vegetation
Choose the correct answer from the options given below:
View More Questions
Top ICAR AIEEA Forest Mensuration Questions
- Read the following statements on methods of point sampling in forestry and choose the correct answer from the below given two options.
Statement (I): Horizontal point sampling (HPS) measures mean stand height which is developed by Bitterlich
Statement (II): Vertical point sampling measures basal area per ha which is developed by Japanese forester Hirata
In light of the above statements, choose the most appropriate answer from the options given below. - What is the theme of International Day of Forests 2024?
- Find the area in hectare of each permanent periodic block, if the area of each felling series is 2400 hectare, rotation age is 120 years and period is 30 years.
- Von Mantel's formula of regulation of yield, which is based on the relationship between volume and increment is applicable to _______
- The value of m.a.i is never zero and in no circumstances it is _______ like the c.a.i.
View More Questions
Top ICAR AIEEA Questions
- Which of the following statements is false?
- Which of the following is an example of an inventory?
- According to Adam Smith, productivity gains could be brought about through .
- The supply curve for an artificially scarce good is .
- Which of the following would not be considered an opportunity cost of paid employment?
View More Questions