Ecosystem fundamentals, India's biodiversity wealth, and the legal-institutional framework protecting it.
Ecology — the study of interactions between organisms and their environment — and biodiversity conservation form a major, consistently tested pillar of the Environment section across UPSC, APPSC and TSPSC.
An ecosystem comprises biotic (living) and abiotic (non-living) components interacting through energy flow and nutrient cycling. Key concepts include food chains and food webs (energy transfer through trophic levels, with roughly 10% energy transfer efficiency between levels per the "ten per cent law"), ecological pyramids (of number, biomass, energy), and biogeochemical cycles (carbon, nitrogen, water, phosphorus cycles) that recycle matter through the ecosystem.
A biodiversity hotspot is a biogeographic region with significant levels of biodiversity threatened by habitat loss, meeting two criteria: at least 1,500 endemic vascular plant species, and having lost at least 70% of its original habitat. India has four biodiversity hotspots (out of 36 recognised globally):
India's protected area system, established under the Wildlife (Protection) Act, 1972, includes National Parks (highest protection, no human activity permitted), Wildlife Sanctuaries (some regulated human activity permitted), Conservation Reserves and Community Reserves. Specialised programmes include Project Tiger (1973, covering Tiger Reserves under the National Tiger Conservation Authority) and Project Elephant (1992). India is also party to the international Ramsar Convention on wetlands, with a growing list of Ramsar sites.
Prelims frequently tests hotspot names/criteria, Wildlife Act schedules, and species-specific conservation programmes. Mains rewards linking biodiversity loss to development pressures (infrastructure, mining, climate change) and evaluating India's conservation governance framework.
