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Q.Explain the ecosystem of pond. OR Describe the ecological succession on bare rocks.
Madhya Pradesh MpbseMP Board Higher Secondary 2023Subjective· 5mImportance★★★★★
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Start your 14-day free trial to unlock the full solution →A pond is a classic self-sustaining freshwater ecosystem with clear trophic structure; succession on bare rock is a slow, stepwise colonisation from lichens to a climax forest.
Part 1 — Ecosystem of a pond: A pond is a small, self-sustainable, and complete functional unit of nature, containing both abiotic and biotic components interacting with each other.
- Abiotic components: water and dissolved nutrients/minerals, dissolved oxygen and carbon dioxide, sunlight penetrating the water, and temperature — all of which govern the productivity and distribution of organisms in the pond.
- Biotic components, organised into trophic levels:
- Producers: phytoplankton (algae), and floating/submerged aquatic plants like Hydrilla, Lemna, and water lilies, which fix solar energy via photosynthesis.
- Primary consumers (herbivores): zooplankton and small herbivorous insects/fish that feed on the producers.
- Secondary/tertiary consumers (carnivores): carnivorous fish, frogs, and water birds that feed on the primary consumers and each other.
- Decomposers: bacteria and fungi that break down dead organisms and waste, releasing nutrients back into the water for reuse by producers. Energy flows unidirectionally from producers through the various consumer levels (with loss at each step), while nutrients are cycled repeatedly between the biotic and abiotic components, making the pond a complete, if small, ecosystem.
Part 2 (OR) — Ecological succession on bare rock (primary succession/xerosere): Bare rock has no soil and represents an extremely harsh starting point for life, so succession here is a primary succession, proceeding slowly through distinct stages (seres):
- Pioneer community — lichens: crustose lichens are the first colonisers; they secrete acids that help weather and break down the rock surface, and their accumulated remains begin to form a thin layer of soil. …
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