Question

In India diameter or girth at breast height is measured at ____whereas, in Europe, UK and other commonwealth countries it is measured at \rule{1.5cm}{0.15mm}.

• A. 1.37 m ; 1.30 m
• B. 1.30 m ; 1.37 m
• C. 1.37 m ; 1.20 m
• D. 1.37 m ; 1.20 m

Hint:

Remember: India = I.37m. Most international metrics use 1.30m, but India sticks to the colonial 4'6" standard converted to metric. Always ensure you are on the uphill side when measuring!

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
This question pertains to forest mensuration, specifically the standardized height at which the diameter or girth of a standing tree is measured, known as the Diameter at Breast Height (DBH). Different countries follow different standards based on historical precedents and average human height.
Key Formula or Approach:
The approach involves identifying the specific standards adopted by the Indian Forest Service versus those used in European and Commonwealth nations. DBH is a critical parameter for calculating timber volume, growth, and basal area.

Step 2: Detailed Explanation:

• Indian Standard: In India, the standard height for measuring breast height is fixed at 1.37 meters (equivalent to 4 feet 6 inches) above the ground level. This standard was established during the British colonial era and has been maintained for consistency in forest inventories.

• Global Standards: In many European countries, the United Kingdom, and various Commonwealth nations, the standard height is set slightly lower at 1.30 meters. Some other countries, like the USA, may use 4.5 feet (1.37m), similar to India.

• Purpose of Measurement: Measuring at a fixed height (Breast Height) eliminates the irregularities caused by buttresses or root swelling near the base of the tree. It also provides a convenient height for foresters to use callipers or diameter tapes without bending or reaching excessively.

• Measurement on Slopes: It is important to note that if a tree is growing on a slope, the measurement is typically taken from the uphill side. If the tree has a lean, the measurement is taken along the underside of the lean.

• Technical Significance: The choice of a consistent height is vital for calculating the basal area of a stand (\(BA = \pi \times D^2 / 40000\) for sq.m) and for applying volume tables that are calibrated to specific DBH measurements.

Step 3: Final Answer:
In India, the standard DBH height is 1.37 m, whereas in Europe and the UK, it is 1.30 m.