Question

The pioneer species in xerarch and hydrarch succession are respectively.
(a)Lichens and sedges.
(b)Lichens and rooted hydrophytes.
(c)Lichens and phytoplanktons.
(d)Phytoplanktons and Lichens.

Answer 1

The Pioneer species is this species that marks the beginning of a succession. Hydrarch succession occurs in wet places whereas xerarch succession occurs in dry places.

Complete answer:
The pioneer species in xerarch succession and hydride succession are phytoplanktons and lichens respectively. The universal process of unidirectional series of changes in community composition on an ecological time scale that finally leads to the establishment of a stable community is known as succession.

Additional Information: Based on habitat succession is divided into two types:
1)Xerarch succession: In this succession, the pioneer species are established on rocks or dunes. Rocks may be produced by volcano or glacier or may be eroded by rain, water, and wind as desert cracks and crevices are formed on the rock where dispose of algae or fungi settle and form the lichens. lichens accumulate the dust particle and also secrete acidic secretions which further help insolubilization of the rocks into fine particles. This will form new soil with humans and contribute to the development of new plants and animals.
2)Hydric succession: This succession occurs in freshwater ecosystems such as ponds, lakes, or even in saline water ecosystems such as mangroves. Since the pond water is poor in nutrients they can give rise only to the microscopic organisms like phytoplankton. The phytoplanktons multiply and become food for dependent animals and after the death of these animals they were decomposed and minerals were released making the pond water or aquatic habitat enriched with nutrients. Then further development occurs and rooted hydrophytes and sedges appear which ultimately develops into a complex community. e.g. phytoplankton, Hydrilla, Vallisneria
So, the correct answer is, 'lichens and phytoplanktons'.

Note: -lichens these are the symbiotic association of fungi and algae.
-phytoplanktons are microscopic organisms that move through water current; they include dinoflagellate, diatoms, and algae.
-The phytoplanktons multiply and become food for dependent animals which are later after death decomposed and nutrient materials were released.