During ecological succession

Options

A. the gradual and predictable change in species composition occurs in a given area
B. the establishmnt of a new biotic community is very fast in its primary phase
C. the numbers and types of animals remain constant
D. the changes lead to a community that is in near equilibrium with the environment and is called pioneer community

Answer

**Step-by-Step Solution:**

1. **Understanding Ecological Succession**:
- Ecological succession refers to the gradual and predictable change in the species composition of a given area over time. This process can occur in various environments, leading to changes in both plant and animal communities.

2. **Analyzing the Options**:
- **Option A**: "The gradual and predictable change in species composition occurs in a given area."
- This statement accurately describes ecological succession. It highlights the gradual nature of the changes and the predictability of the process.

- **Option B**: "The establishment of a new biotic community is very fast in its primary phase."
- This statement is incorrect. While some changes can occur rapidly, ecological succession is generally a gradual process, especially in the early stages.

- **Option C**: "The number and types of animals remain constant."
- This statement is also incorrect. During ecological succession, both the number and types of animals change as new species establish and others decline or disappear.

- **Option D**: "The changes lead to a community that is near equilibrium with the environment and is called pioneer community."
- This statement is misleading. The pioneer community refers to the first species that colonize a barren environment, while the climax community is the stable end point of succession.

3. **Conclusion**:
- Based on the analysis of the options, **Option A** is the correct answer as it accurately reflects the definition of ecological succession.

**Final Answer**: Option A is correct.

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