Identify and discuss the factors responsible for diversity of natural vegetation in India. Assess the significance of wildlife sanctuaries in rain forests regions of India.

Factors of vegetational diversity

• Latitude and the Tropic of Cancer split tropical and subtropical belts, so Kerala and Himachal cannot grow the same climax forest.
• The monsoon, its length, and rain-shadow west of the Ghats decide evergreen, deciduous, and thorn forest more than any other single factor.
• Himalayan altitude stacks tropical foothill forest, oak and conifer, and alpine meadow in a few vertical kilometres.
• Soils from alluvium, laterite, black cotton, and desert sand filter which species can root even under the same rainfall.
• Relief, aspect, and drainage create local wet pockets, such as windward Ghats versus leeward Deccan.
• Human use, fire, and grazing have replaced climax forest with savanna, scrub, and plantation, which is also a cause of the pattern we now map.

Types that follow from those factors

• Western Ghats, north-east India, and the Andaman–Nicobar islands hold tropical wet evergreen and semi-evergreen forest.
• The Gangetic and Deccan cores hold moist and dry deciduous sal and teak belts.
• The Thar and the interior Deccan hold thorn and scrub; the Himalaya and the Nilgiri heights hold montane types.

Significance of sanctuaries in rainforest regions

• Rainforest fragments hold endemic frogs, plants, lion-tailed macaque, hornbills, and trees that dry forests do not, so sanctuaries are arks for a biodiversity hotspot.
• The Wildlife (Protection) Act, 1972, lets a sanctuary limit hunting and some land use while still allowing more local rights than a national park in many cases.
• Periyar, Kalakad–Mundanthurai, Bhadra’s wet tracts, Namdapha’s buffer world, and island sanctuaries in the Andamans keep gene pools for medicine, crop wild relatives, and carbon.
• They buffer monsoon catchments that feed rivers such as the Periyar, Sharavathi, and Brahmaputra tributaries, which is water security, not only wildlife watching.
• Tribal and forest-village livelihoods in honey, cane, and fish need these patches, provided the Forest Rights Act, 2006, is not ignored at the boundary.
• Eco-sensitive zones and tiger or elephant corridors only work if rainforest sanctuaries are not islands in a sea of plantation and mine.

Limits of the sanctuary tool

• Small notified patches cannot save a Ghats slope if hydel, highway, and quarry cut the canopy.
• Tourism and exclusion without consent can turn a sanctuary into a conflict zone.

Way forward

• Notify corridors, fund anti-poaching and fire lines, and co-manage with gram sabhas in rainforest catchments.
• Keep Silent Valley-type lessons: some evergreen tracts should stay closed to dam and cash-crop conversion.