How does the removal of a ring of bark and wood from the trunk of a tree kills it ?

Options

A. Mineral salts cannot go up
B. Immediate stoppage of potosynthesis
C. food and water cannot be translocated
D. The exposed part dies due to heat

Answer

### Step-by-Step Solution:

1. **Understanding Girdling**: The removal of a ring of bark from the trunk of a tree is known as girdling or ringing. This process involves taking away a complete ring of bark, which includes various tissues.

2. **Identifying Bark Components**: Bark consists of all the tissues outside the vascular cambium, primarily the phloem layer (both primary and secondary), cork layer, secondary cortex, pheloderm, and outer endodermis.

3. **Role of Phloem**: The phloem is crucial for transporting nutrients, particularly sucrose (a form of sugar produced during photosynthesis), and plant hormones. When the phloem is removed, these essential substances cannot be transported.

4. **Consequences of Bark Removal**: When a ring of bark is removed, the phloem is disrupted. This leads to an inability for the tree to transport food (sucrose) and hormones from the leaves (where photosynthesis occurs) to the roots and other parts of the plant.

5. **Swelling of the Tree**: After girdling, the areas above the cut will accumulate sugars and other substances because they cannot move downwards. This accumulation causes swelling above the girdled area.

6. **Impact on the Tree's Health**: Eventually, the parts of the tree below the girdled area will die due to a lack of nutrients and water, as they are not receiving the necessary substances transported by the phloem.

7. **Conclusion**: The removal of a ring of bark kills the tree because it prevents the translocation of food and water, leading to starvation and death of the tissues below the girdled area.