(a) What is unique of Indian plant biodiversity ? Discuss briefly the threats and various conservation strategies. 5+15=20 (b)…

(a) Uniqueness, threats and conservation of Indian plant biodiversity India is a megadiverse country with over 45,000 plant species, about 18,000 flowering plants, of which roughly a third are endemic. Its uniqueness lies in four biodiversity hotspots (Himalaya, Indo-Burma, Western Ghats–Sri Lanka and Sundaland including Nicobar) and diverse biomes: rich orchids and rhododendrons in the north-east, endemic palms (Pinanga) and Dipterocarps in the Western Ghats, mangroves in the Sundarbans, and ancient lineages such as cycads (Cycas) and conifers. Crop wild relatives of rice, banana, citrus, brinjal and Rauvolfia make it a centre of origin. Threats: habitat loss through deforestation, shifting cultivation, dams and mining; over-exploitation of medicinal plants (Saussurea costus, Podophyllum); invasive alien species (Lantana, Parthenium); grazing, fires, climate change and pollution. Conservation: in-situ through national parks, sanctuaries, biosphere reserves, sacred groves and community reserves; ex-situ through botanical gardens, seed and gene banks (NBPGR), cryopreservation and tissue culture of orchids such as Vanda. Legal framework: Wildlife (Protection) Act 1972 (Schedule VI plants), Forest (Conservation) Act 1980 (now Van (Sanrakshan Evam Samvardhan) Adhiniyam), Biological Diversity Act 2002 and the Protection of Plant Varieties and Farmers’ Rights Act 2001.

(b) Social forestry Social forestry is raising trees on community, public and private waste or marginal land by and for local people, to meet fuelwood, fodder and small timber needs and relieve pressure on natural forests, as promoted by the National Commission on Agriculture (1976). Types: farm forestry (trees on farmers’ fields and bunds), community forestry (village woodlots on common land), extension forestry (roadsides, canal banks, railway tracks, tank foreshores) and urban forestry (parks, avenues, greenbelts). Species: neem, babool (Acacia nilotica), eucalyptus, Casuarina, shisham, subabul (Leucaena), bamboo. Benefits: fuelwood, fodder, timber and non-timber produce; rural employment and income; soil and moisture conservation and shelterbelts against wind erosion; reduced pressure on reserved forests; carbon sink and cooler microclimate. Programmes include the National Afforestation Programme and state social forestry projects (Gujarat, West Bengal, Uttar Pradesh).

(c) Ecological pyramids and ecological factors An ecological pyramid is a graphic representation of trophic structure, with producers at the base. The pyramid of numbers (upright in grassland, inverted for a single tree supporting many insects), the pyramid of biomass (upright on land, inverted in oceans where phytoplankton turn over fast) and the pyramid of energy (always upright, about 10% transfer between levels) show these relations. Ecological factors are the environmental components acting on organisms. Climatic or abiotic factors: light (photoperiod, sun and shade plants), temperature, water and humidity (hydrophytes, xerophytes), wind and fire; edaphic factors: soil texture, pH, minerals; topographic factors: altitude, slope; biotic factors: competition, predation, parasitism, mutualism, pollination. Liebig’s law of the minimum and Shelford’s law of tolerance explain how a limiting factor controls distribution, growth and productivity of plants.