Farming and tourism are the primary livelihood options for mountain people in the Hindu Kush-Himalayan region. Tourism in Sikkim, a small Indian state in the eastern Himalaya, has become popular only since 1990; the main focus is on ecotourism. Only a small segment of the population is engaged in this sector, however. More than 80% of the population depends on agriculture. The developmental measures of the "green revolution" implemented in other Indian states were not successful in the Himalayan region because adequate fertilisers were never available on time, irrigation could not be developed, and soils are very fragile. Population growth and consequent fragmentation of farmland in Sikkim have caused a reduction in per capita holdings. This has forced farmers to cultivate cash crops such as potatoes (Solanum tuberosum), ginger (Zingiber officinale), and mandarin oranges (Citrus reticulata). The latter two have caused rapid nutrient depletion of the soil. Production of another cash crop, large cardamom (Amomum subulatum), a plant native to the Sikkim Himalaya, has been a boon to the mountain people of the area. Large cardamom is a perennial cash crop grown beneath the forest cover on marginal lands. Its cultivation is an example of how a local mountain niche can be exploited sustainably.