Nature

The pattern of life in Sri Lanka depends directly on the availability of rainwater. The mountains and the southwestern part of the country, known as the 'wet zone,' receive ample rainfall, with an annual average of 250 centimetres. Most of the southeast, east, and northern parts of the country comprise the 'dry zone,' which receives between 120 and 190 cm of rain annually. Much of the rain in these areas falls from October to January; during the rest of the year there is very little precipitation, and all living creatures must conserve precious moisture. The arid northwest and southeast coasts receive the least amount of rain 60 to 120 cm per year.

In the wet zone, the dominant vegetation of the lowlands is a tropical evergreen forest, with tall trees, broad foliage and a dense undergrowth of vines and creepers. Subtropical evergreen forests resembling those of temperate climates flourish in the higher altitudes. Varieties of flowering acacias are well adapted to the arid conditions and flourish on the Jaffna Peninsula. Among the trees of the dry-land forests are some valuable species, such as satinwood, ebony, ironwood and mahogany.

Forests at one time covered nearly the entire island, but by the late 20th century lands classified as forests and forest reserves covered only one-fifth of the land. During the Mahaweli Ganga Program of the 1970s and 1980s in northern Sri Lanka, the government set aside four areas of land totalling 1,900 sq km as national parks. Ruhunu National Park in the southeast protects herds of elephant, deer and peacocks, and Wilpattu National Park in the northwest preserves the habitats of many water birds, such as storks, pelicans, ibis and spoonbills. The island has three biosphere reserves, Hurulu, Sinharaja, and the Kanneliya-Dediyagala-Nakiyadeniya.