The species that invades a bare area is called ___________

The correct answer is Option (4) → Pioneer species

Ecological succession is the gradual, predictable change in the species of an area until a stable climax community forms. When it starts on a bare area with no life, it is primary succession.

Option (1) Seral stage — Incorrect. A seral stage is any one of the stages of the succession (the sere). It is a stage, not the first species.

Option (2) Alien species — Incorrect. Alien species are brought in from another region, often by humans, such as water hyacinth or the African catfish. They are a cause of biodiversity loss.

Option (3) Endemic species — Incorrect. Endemic species are found only in one region and nowhere else.

Option (4) Pioneer species — Correct. The first species to invade a bare area are the pioneers. On bare rock these are usually lichens; in water they are small phytoplankton.

Note: This question is from the topic “Succession of Plants” in Chapter 14, Ecosystem, of the pre-rationalised NCERT book. This portion is not in the present NCERT book, where the chapter is now Chapter 12, Ecosystem. The extract below is from the pre-rationalised edition.

NCERT Extract (Pre-rationalised edition, Chapter 14, Ecosystem):
Succession of Plants – “… The species that invade a bare area are called pioneer species. In primary succession on rocks these are usually lichens which are able to secrete acids to dissolve rock, helping in weathering and soil formation. These later pave way to some very small plants like bryophytes, which are able to take hold in the small amount of soil. They are, with time, succeeded by higher plants, and after several more stages, ultimately a stable climax forest community is formed.”