vegetative cover and geolithology. The Himalayas serve as the source of natural resources for the population residing in the hills as well as in the plains. As human population expands in the hills, forests are being depleted for the extension of agricultural lands, introduction of new settlements, roadways, etc. The growing changes coming in the wake of urbanisation and industrialisation leave deep impressions on the hill ecosystem. The economy of Darjeeling hill area depends on tea production, horticulture, agriculture, forestry and tourism. The major portions of the forests are today found at elevations of and above. The area in between is cleared either for tea plantation or cultivation. About 30 percent of the forest covers found in the lower hills are deciduous. Evergreen forest constitutes only about 6 percent of the total forest coverage. Shorea robusta remains the most prominent species of tropical moist deciduous forest along with heavy undergrowth. Teesta, Rangeet, Mechi, Balason, Mahananda and Rammam are the important rivers of the district. Climate Area Subdivisions Darjeeling District comprises four subdivisions: Darjeeling Sadar subdivision Kurseong subdivision Mirik subdivision Siliguri subdivision Assembly constituencies The district was previously divided into six assembly constituencies. As per the order of the Delimitation Commission in respect of the delimitation of constituencies in West Bengal, the district had been divided into six assembly constituencies. Kalimpong has become a separate district from 14 February 2017, so the number of assembly constituencies in Darjeeling district is now five. Darjeeling (assembly constituency no. 23) Kurseong (assembly constituency no. 24) Matigara-Naxalbari (SC) (assembly constituency no. 25) Siliguri (assembly constituency no. 26) Phansidewa (ST) (assembly constituency no. 27) Phansidewa constituency is reserved for Scheduled Tribes (ST) candidates. Matigara-Naxalbari constituency is reserved for Scheduled Castes (SC) candidates. Along with one assembly constituency from Kalimpong district and one assembly constituency from Uttar Dinajpur district, the five assembly constituencies of this district form the Darjeeling Lok Sabha constituency. Demographics According to the 2011 census Darjeeling district has a population of 1,846,823, roughly equal to the population of Kosovo. This gives it a ranking of 257th in India (out of a total of 640). The district has a population density of . Its population growth rate over the decade 2001-2011 was 14.77%. Darjeeling has a sex ratio of 970 females for every 1000 males, and a literacy rate of 79.56%. After Kalimpong district was separated its population was 1,595,181. Scheduled Castes and Scheduled Tribes