Age of a tree can be estimated by
1 diameter of its heartwood
2 its height and girth
3 biomass
4 number of annual rings

Options

A. diameter of its heartwood
B. its height and girth
C. biomass
D. number of annual rings

Answer

To determine the age of a tree, we can analyze the options provided in the question step by step:

1. **Understanding the Growth of Trees**: Trees grow in layers, and these layers are formed due to the activity of the cambium, a tissue responsible for secondary growth. Each year, a new layer of secondary xylem (wood) is produced, which results in the formation of annual rings.

2. **Examining the Options**:
- **Option 1: Diameter of its heartwood**: Heartwood is the central part of the tree that is composed of older, dead xylem. While it can indicate the size of the tree, it does not provide direct information about the tree's age. Therefore, this option is incorrect.
- **Option 2: Its height and girth**: While height and girth can give an idea about the tree's growth, they do not directly correlate to the age of the tree. Thus, this option is also incorrect.
- **Option 3: Biomass**: Biomass refers to the total mass of living matter in a given area. It does not provide any specific information regarding the age of the tree. Hence, this option is incorrect as well.
- **Option 4: Number of annual rings**: Each year, a tree adds a new layer of growth, which appears as a ring. Counting these rings provides a direct estimate of the tree's age. Therefore, this option is correct.

3. **Conclusion**: The age of a tree can be accurately estimated by counting the number of annual rings present in its cross-section.

**Final Answer**: The age of a tree can be estimated by the number of annual rings (Option 4).

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