Environment, Ecosystem and Agriculture

Ecosystem

An ecosystem is a community of living things interacting with the non-living environment (Tansley, 1935 coined the term).

• Biotic (living) and abiotic (non-living: soil, water, light, temperature). Producers (autotrophs): plants. Consumers: herbivores (primary), carnivores (secondary and tertiary), omnivores. Decomposers: bacteria and fungi (recycle nutrients).
• Natural ecosystems: forest, grassland, desert, pond, lake, river, ocean. Artificial: garden, crop field, aquarium.
• Food chain: grass, grasshopper, frog, snake, eagle. Food web is many linked chains. Trophic levels: producer, primary consumer, secondary consumer, tertiary consumer.
• Energy flow (10 per cent law, Lindeman): only about 10% of energy passes to the next trophic level; the rest is lost as heat. So food chains are short (3 to 5 levels); a vegetarian diet uses energy more efficiently.
• Pyramids: of number, biomass and energy. Energy pyramid is always upright.
• Biomagnification: harmful chemicals (DDT, mercury) increase in concentration along the food chain; the top consumer is most affected.

Biogeochemical cycles

• Water (hydrological) cycle: evaporation, condensation, precipitation. Transpiration adds to it.
• Carbon cycle: photosynthesis takes CO2; respiration, burning and decay return it. Carbon sinks: forests and oceans.
• Nitrogen cycle: nitrogen fixation (Rhizobium, lightning), nitrification, assimilation, denitrification (returns N2 to the air).
• Oxygen cycle links photosynthesis and respiration.

Biodiversity and conservation

• Biodiversity is the variety of life. India is a mega-diverse country, with four hotspots: Himalaya, Western Ghats, Indo-Burma and Sundaland (Nicobar).
• In situ conservation: in natural habitat: national parks, wildlife sanctuaries, biosphere reserves. Ex situ: outside: zoos, botanical gardens, seed banks, gene banks.
• In J&K: Dachigam National Park (home of the hangul or Kashmir stag), Kishtwar National Park, Hemis National Park (Ladakh) (snow leopard), Overa-Aru, Salim Ali National Park, Dal Lake, Wular Lake, Hokersar wetland (Ramsar site).
• IUCN Red List classifies endangered species (tiger, snow leopard, Great Indian Bustard, hangul, Asiatic lion, one-horned rhino). Project Tiger (1973), Project Elephant (1992), Project Snow Leopard. Wildlife Protection Act, 1972.
• Extinct: dodo, passenger pigeon, Indian cheetah (re-introduced from Africa in 2022 to 2023 at Kuno National Park).
• Forests: deforestation causes soil erosion, floods and climate change. Chipko movement (Sunderlal Bahuguna, Uttarakhand) saved trees; Van Mahotsav (July). Joint Forest Management.
• Sacred groves and Bishnoi community protect nature.

Pollution

• Global warming is from the greenhouse effect; the Kyoto Protocol (1997), Paris Agreement (2015) aim to limit it. Ozone hole over Antarctica.
• Acid rain: SO2 and NO2 dissolve in rain; harms the Taj Mahal (marble cancer).
• Smog: smoke + fog. Photochemical smog forms from vehicle exhaust in sunlight.
• Tests and measures: Air Quality Index (AQI); National Green Tribunal (2010); Environment Protection Act, 1986; World Environment Day: 5 June; Earth Day: 22 April; World Water Day: 22 March; World Wildlife Day: 3 March; International Day of Biodiversity: 22 May.
• Waste management: segregate (wet and dry), compost, recycle, reduce plastics; Swachh Bharat Mission (2014).
• Renewable resources (air, water, forests) and non-renewable (coal, petroleum).

Agriculture and animal husbandry

• Crop seasons in India: Kharif (June to Oct; sown with the monsoon): rice, maize, cotton, jowar, bajra, soybean, groundnut; Rabi (Oct to Mar; winter): wheat, barley, gram, mustard, peas; Zaid (summer): watermelon, cucumber, vegetables.
• Steps: preparation of soil, sowing, adding manure and fertilisers, irrigation, weeding, harvesting, threshing, storage.
• Green Revolution (1960s) under M. S. Swaminathan (father of the Indian Green Revolution) with Norman Borlaug: high-yield wheat and rice. White Revolution (Operation Flood): milk, Verghese Kurien. Blue Revolution: fish. Yellow Revolution: oilseeds. Pink Revolution: prawn and meat. Silver Revolution: eggs and poultry.
• Manure is organic (compost, vermicompost, green manure); fertilisers are chemical (urea). Crop rotation and mixed cropping keep fertility. Organic farming avoids chemicals.
• Irrigation: canal, tube well, drip and sprinkler (save water).
• Weeds (Parthenium, Cyperus) are controlled with weedicides (2,4-D). Pests: insecticides; biopesticides like neem.
• Animal husbandry: cattle (indigenous: Sahiwal, Gir; exotic: Jersey, Holstein), poultry (broilers, layers), fisheries (pisciculture; aquaculture), apiculture (bee-keeping, honey and wax), sericulture (silk; mulberry silkworm).
• Kashmir saffron (Crocus sativus; Pampore), apples, walnuts, almonds, Basmati of R.S. Pura and pashmina (from Changthangi goat) are J&K products with GI tags.
• Food preservation and storage reduce post-harvest loss. Buffer stock is kept by FCI.
• Types of soil in India: alluvial (most fertile; widest), black (regur; cotton), red, laterite, desert, mountain.