Question

In establishing new ecosystem on rock the pioneers are
A. Lichens
B. Phytoplanktons
C. Trees
D. Animals

Answer 1

Hint: We have to remember that an ecosystem is a geographic area where plants, animals, and additional species work jointly to form a bubble of life, as well as the climate and environment. Ecosystems include biotic or living elements, as well as abiotic or non-living components. Rocks, temperature, and moisture are abiotic variables.

Complete answer:
As we know that each organism needs a soil to build a new environment, but lichens colonize in bare rock and secrete acid, which causes rock breakdown and creates the soil. That is why lichens on rocks are considered pioneer species.
Whereas, the primary succession in water is formed by the phytoplankton and phytoplanktons are replaced by free-floating angiosperms, then the hydrophytes and finally the trees with time.
The pioneer organisms in the succession of hydrarch are called phytoplanktons.
We have to remember that lichen is a composite organism which arises in a mutually advantageous symbiotic relationship from algae or cyanobacteria living among the filaments (hyphae) of the fungi. Fungi benefit from the photosynthesis of carbohydrates formed by algae or cyanobacteria.
So,' Lichens' is the right answer.

So, the correct answer is “Option A”.

Note:
We have to remember that the lichens emit acids over the rocks that are able to gradually remove it, helping with weathering and soil formation. This provides nutrients and the environment that are suitable for the growth of small plants capable of maintaining the soil, such as bryophytes. These plants are followed by larger plants that eventually contribute to a forest population of climax. Here, xerophytic habitat is transformed into mesophytic habitat over time. The created climax group is a mesophytic one. If there is an environmental transition, it stays in equilibrium.