Ecological succession on the sand dune is called...............

Explanation

**Step-by-Step Solution:**

1. **Understanding Ecological Succession**: Ecological succession refers to the process by which ecosystems change and develop over time. It involves a series of stages, starting from pioneer species to a climax community.

2. **Identifying the Environment**: In this case, we are focusing on sand dunes, which are unique ecosystems characterized by sandy soil, high winds, and limited water availability.

3. **Pioneer Species**: The first organisms to colonize a barren environment like sand dunes are known as pioneer species. These are typically hardy plants that can survive in harsh conditions, such as certain grasses and lichens.

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