Delhi has the distinction of being one of the few metros in the world that possesses a city forest. The Delhi Ridge and its forest, is the tail end of Aravalli hills – one of the oldest mountain system in the world and Delhi’s oldest natural heritage. The ridge is 2.5 billion years old forming about only 6% of the landmass of Delhi. At present the Ridge is well regarded for being a green lung, controller of pollution, climate moderator, and groundwater recharge, prevents soil erosion besides being a bird and wildlife habitat.
It not only shields the city from the hot winds of the deserts of Rajasthan to a great extent but also brings respite to the people from soaring temperatures by retaining moisture and bringing down the temperature in this region. It can prove to be a haven from the scorching heat during peak summers. One Sq.Km. of dense tree area emanates approximately 3 tones of 0xygen and absorbs 2.5 tons of carbon dioxide. These trees are responsible for the rains that the city so desperately needs and also maintains the water table of Delhi.
An astonishing variety of wildlife, including 120 species of plants, 100 species of birds, 25 species of mammals, amphibians, reptiles, and an innumerable species of arthropods are known to inhibit the area.
The following variety of species exist in the ridge forest:
a) Plants:
The vegetation of the Ridge forest is semi-arid open scrub. The gazetteer of Rural Delhi(1991) lists some native ridge forest plants to be the Babul (Acacia nilotica), Karil (Caparis decidua), and Ber (Ziziphus numularia), Phylahi (Acacia modesta), Bulahi, Katha, Rong (Acacia sp.), Dhak (Butea monosperma), Pilu (Salvadora persica), Hingot (Balanites aeqyptiaca), etc. Amongst the Shrubs are Bansa (Adhatodavasica), Heens (Capparis sepiaria) Ramchana (Grewia tenax) Jangli Karaunda (Carissa spinarum) Khatai (Flacourtia indica) and Kakera (Maytenus seneqalensis). Forestation of the Ridge began in as early as the 14th century. Some of the exotic species introduced in the ridge include Mexican Kikar (Prosipis juliflora), Salvodara persica, Prosopis glandulosa, Parkinsonia (Parkinsonia aculeata), Albizia lebbek, Neem (Azadrachta indica), Kaith (Feronia limonia), Barna (Crataeva nuivula), and Dalberqia latifolig.
b) Fauna:
Even today the dense areas of Ridge are a home to many mammals, amphibians, reptiles, arthropods and about 200 spececies of resident and migratory. Some of the animals found are the Mongoose, Indian Hare, Indian Gerbils, Longeared Hedgehog, five stripped palm squirrel, Indian bull Frog, Nilgai, Rhesus Macaque, Mices, Foxes, Jackals.
c) Birds:
The unbridled encroachments into the Ridge have resulted in depletion of a number of rare species like the Barn Owl, Paradise Flycatcher and Shirker cuckoo. They are disappearing fast. Even the more common peacocks and partridges — birds that nest in the undergrowth are becoming rare sights, thanks to the periodic ‘cleaning’ of the Ridge to make way for the parks. Common birds of the ridge are the weaver bird or baya, grey shrike, five species of babblers, two species of bulbuls, four species of mynas and sunbirds, while birds migrating from the Himalayas include the pintails, shoveller, brahminy duck, common teal, bar headed goose, white eyed pochard etc.