Comoros, Land and Resources
largest craters, Mwali, Karthala, Intensive cultivation, calderas
The three islands of Comoros cover 1,862 sq km (719 sq mi), Njazidja being the largest with an area of 1,147 sq km (443 sq mi). All three are of volcanic origin and are mountainous. The highest peak in Comoros is Karthala, which rises to 2,361 m (7,746 ft) on Njazidja. Karthala has one of the largest craters, or calderas, of any active volcano. The most recent major eruptions occurred in 1965 and 1977. The highest peak on Nzwani is N’Tingui at 1,596 m (5,235 ft). The island shores are rocky, with offshore islets and a steeply sloping seabed. There are no good beaches on Nzwani, and although a few exist in northern Njazidja, only Mwali has many large expanses of sand.
The islands, which lie within the region of the Indian Ocean monsoons, experience a dry season between April and October, and they receive heavy tropical rains accompanied by cyclones between November and March. Daily temperatures seldom rise above 30°C (85°F), and 5,080 mm (200 in) of rain per year fall on the slopes of Karthala, the site of the heaviest rainfall in Comoros. In spite of the heavy rainfall, the porous nature of the volcanic rock means that no water is retained on Njazidja, and the islanders have traditionally built cisterns to store rainwater for the dry season. Mwali and Nzwani, however, have streams that flow from the mountains throughout the year.
Njazidja has virtually no topsoil, but the volcanic rocks nevertheless support a dense rain forest on the slopes of Karthala. The other islands have soils that are rich in minerals and are very fertile, providing ideal conditions for the growth of sugarcane, ylang-ylang trees (the blossoms of which are used to make a perfume), vanilla, cloves, and a wide variety of tropical fruits and flowers. Intensive cultivation, however, has stripped the forest cover from all but the mountain peaks, leading to heavy soil erosion; it has also destroyed the habitat of many species of plants and animals. A variety of flycatcher called Humblot’s flycatcher breeds only on Njazidja. The seas off the Comoros are the home of the famous coelacanth, a fish that was thought to be extinct for millions of years until 1938, when one was caught off the eastern coast of South Africa. In 1952 the coelacanth was discovered to live and breed off the Comoros.
About 53 percent (1999) of the country’s land area is devoted to cropland, and soil degradation and erosion have resulted from crop cultivation on slopes without proper terracing. A relatively high proportion of the islands’ limited biodiversity is threatened, and fishing and tourism are damaging coral reefs.
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