Terrain shapes and bedrock
According to COUNTRYAAH, Tonga encompasses about 170 islands, most in two rows in the north-north-south-west, parallel to the Tongagraven further east. The islands form the peaks of volcanoes and are higher in the western line due to repeated volcanism. Four of them are active and several have a hard lava surface, e.g. Late 518 m and the highest island, Kao 1,031 m above sea level. Others formed by more explosive eruptions consist of ash and pumice, which are more easily eroded by the waves.
The islands of the eastern line are low and covered by coral lime, which also protects against degradation, e.g. the largest island, Tongatapu, which is an elevated atoll.
Tonga has a hot and humid climate; humidity is increasing north. The average temperature in December – January is 27 °C and in June – July 16–21 °C. The average annual rainfall varies between 1,600 mm and 2,200 mm, but is on the northernmost islands 2,570 mm. These can also be affected by typhoons between December and April.
Plant-and animal life
The tropical rainforest that originally covered large parts of the islands is now largely decomposed and replaced with cultivations of mainly coconut. Of the almost 500 species of vascular plants, of which just over 100 are ferns, about 25 are endemic. There are representatives for eg. families elaeocarpusväxter, karakanötsväxter and spoon shrub plants (Cunonia’ceae).
Especially on the low islands are coral reefs with rich wildlife. The species of palolomask of interest for its special reproduction is found on shallow water. The land fauna is poor. There are no frogs or freshwater fish. Of reptiles, there are geckos, hams and figs. There are also snakes (fijiboor, Candoia [-dɔ in ʹa]), but these are probably introduced by man.
Of birds, 39 species breed (of which 15 land birds), and another 13 species are seen regularly. Among the species are two species of tropical birds, red-footed sole, three species of dove terns, fetus, four species of pigeons and two species of parrots, of which only bluish-crowned lori (Viʹni austraʹlis) is native. In addition to the mammals introduced there are only Polynesian rats (Raʹttus eʹxulans) and the fly dog Pteʹropus tongaʹnus.
Tonga has three designated national parks.
Tonga is located on the eastern edge of the Indo-Australian plate, which is pushed up by the Pacific plate. This one moves down the eastern side of Tonga, forming one of the Pacific’s deepest pits, the Tonga pit (about 10,800 m deep). The islands are peaks of volcanoes, the highest islands are those in the west due to repeated volcanism. At its peak, the island of Kao reaches the Ha’apai group, with 1031 m asl. In the east there are rows of low coral islands. The largest island, Tongatapu, is also a coral island.
Read more about Plant and Wildlife at Tonga.
The islands have a tropical, maritime climate with annual mean temperatures ranging from 23 ° C in the south to 27 ° C in the north. Precipitation increases from south (1500 mm) to north (2700 mm); most rainfall in January-March during the southern movement of the equatorial rain belt, at least in May-September when the southeast passage dominates.
Plant and wildlife at Tonga
Lush tropical rainforest covers those areas that are not cultivated.
The only land mammals are the introduced black and brown rats, both a major threat to the bird fauna. Fossil finds show that at least 20 terrestrial birds, a number of reptiles and a bat species have disappeared since the Polynesians arrived.
20 terrestrial birds, including two native (endemic) species: Tonga whistles and Tonga furnace, the latter live on Niuafo’ou and hatch the eggs using volcanic heat. Many seabirds, including large colonies of the Soters and well odes.
The reptiles include 20 species: 9 geckos, 9 hams, a boa and an iguana. The latter, Fijiiguan, also lives on Fiji and is believed to have reached the islands by sea from America. Amphibians do not occur.