Question:
Given below are two statements
Statement I: A tree species is said to be fast‐growing if it attains an average height growth of 60 cm per annum
Statement II: Fast‐growing tree species should have a minimum mean annual increment of 10 m$^3$ha$^{-1}$year$^{-1}$
In light of the above statements, choose the most appropriate answer from the options given below}
Given below are two statements
Statement I: A tree species is said to be fast‐growing if it attains an average height growth of 60 cm per annum
Statement II: Fast‐growing tree species should have a minimum mean annual increment of 10 m$^3$ha$^{-1}$year$^{-1}$
In light of the above statements, choose the most appropriate answer from the options given below}
Statement I: A tree species is said to be fast‐growing if it attains an average height growth of 60 cm per annum
Statement II: Fast‐growing tree species should have a minimum mean annual increment of 10 m$^3$ha$^{-1}$year$^{-1}$
In light of the above statements, choose the most appropriate answer from the options given below}
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Fast-growing threshold: MAI > 10 m$^3$. This is the "magic number" in plantation forestry. Height growth for such trees is usually measured in meters, not centimeters, per year!
Updated On: Aug 7, 2026
- Both Statement I and Statement II are correct
- Both Statement I and Statement II are incorrect
- Statement I is correct but Statement II is incorrect
- Statement I is incorrect but Statement II is correct
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Verified By Collegedunia
The Correct Option is D
Solution and Explanation
Step 1: Understanding the Question:
The question asks to evaluate the technical definitions of "fast-growing tree species" used in silviculture and forest policy.
Step 2: Detailed Explanation:
• Height Growth (Statement I): In the context of "fast-growing" species (especially in tropical regions like India), a height increment of only 60 cm per year is actually considered slow to moderate. Most fast-growing species used in plantations (like Eucalyptus, Populus, or Leucaena) easily attain height increments of 1.5 to 3 meters per year in their early stages. Therefore, Statement I is technically incorrect.
• Volume Increment (Statement II): The most widely accepted international and national definition of a "fast-growing" species relates to its wood volume production. A species is classified as fast-growing if its Mean Annual Increment (MAI) is at least 10 cubic meters per hectare per year (10 m$^3$ha$^{-1}$year$^{-1}$). This is the standard threshold used by FAO and Indian forestry institutions. Some "very fast-growing" species can exceed 30-40 m$^3$ha$^{-1}$year$^{-1}$. Thus, Statement II is correct.
Step 3: Final Answer:
Statement I is false because 60cm/year is too low for a "fast-growing" classification. Statement II correctly identifies the volume-based MAI threshold.
The question asks to evaluate the technical definitions of "fast-growing tree species" used in silviculture and forest policy.
Step 2: Detailed Explanation:
• Height Growth (Statement I): In the context of "fast-growing" species (especially in tropical regions like India), a height increment of only 60 cm per year is actually considered slow to moderate. Most fast-growing species used in plantations (like Eucalyptus, Populus, or Leucaena) easily attain height increments of 1.5 to 3 meters per year in their early stages. Therefore, Statement I is technically incorrect.
• Volume Increment (Statement II): The most widely accepted international and national definition of a "fast-growing" species relates to its wood volume production. A species is classified as fast-growing if its Mean Annual Increment (MAI) is at least 10 cubic meters per hectare per year (10 m$^3$ha$^{-1}$year$^{-1}$). This is the standard threshold used by FAO and Indian forestry institutions. Some "very fast-growing" species can exceed 30-40 m$^3$ha$^{-1}$year$^{-1}$. Thus, Statement II is correct.
Step 3: Final Answer:
Statement I is false because 60cm/year is too low for a "fast-growing" classification. Statement II correctly identifies the volume-based MAI threshold.
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