Island off ChileIsle of Chile
Archipelago off the Pacific Ocean coastline of Chile | Eco-regions
Juan Fernández Island is the only eco-region in the Juan Fernández islands. Like on most oceans, its habitat has a different set of fish than on the continent. It is unavoidable that the island has an unrepresentative sampling of the near continent types because of the difficulty of reaching the island and because each continent type has different distribution capabilities.
This forest contains a high proportion of indigenous vegetation and has the only indigenous colibri known for its islets. Originally, these are the most beautiful species of taxi, developed after the formation of the island, valued in 1-5 years. In 1574, these small island were explored by the Spaniard Juan Fernández and are also known as Robinson Crusoe Island, because the Scotish seafarer Alexander Selkirk himself was exposed there for over 4 years and his experience inspired Daniel Defoe's work.
The Juan Fernández is 667 km off the Chilean coastline in the southeast of the Pacific and is one of the few areas of the globe where there were no sustainable man-made communities before the sixteenth century (Wester 1991). The island consists of three major islands:
The Isla Robinson Crusoe (= Masatierra) at 33º 13' C, 78º 50' W, nearest to the coast, Santa Clara, 1 km to the southwest of Isla R. Crusoe, and Isla Alejandro Selkirk (= Masafuera) at 33º 45'S, 80º 46'W, 181 km further on. They are of vulcanic origins and are said to have built up above a "hot spot" in the earth's rust and then shifted eastward, as the Nazca plate was subduced under the Latin America continen.
The age-groups for the island were indicated by radiometric datings (Stuessy et al., 1984): 5th Santa Clara, 8 million years old, R. Crusoe, 3.8-4. 2 million years old, and A. Selkirk, 1.0-2. 4 million years old. Each island's territory is (Stuessy 1995): Selkirk (50 km2), Crusoe (48 km2) and Santa Clara (2. 2 km2).
Its highest point (1319 metres, Los Inocentes) is on Isla A. Selkirk. The Isla R. Crusoe is 916 metres (El Yunque), while Santa Clara is only 350 metres high. The landscape comprises impressive steep rocks and deep gorges. On Isla A. Selkirk frost sometimes appears. On the lower west side of Isla R. Crusoe and Isla Santa Clara are very arid and only receive rains during tropic wind.
The over 500 metre high areas of the two large isles are often affected by precipitation every day, but only for a brief period. Occasional disruption of marine and coastal flows leads to abnormal climate change on the island, as in 1973, when hot seawater helped to prolong the rainy period, probably as part of the general Pacific El Niño-Southern Oscillation anomaly.
Like most of the ocean iceland, this eco-region has an exceptional biotope with exceptional concentrations of marine life and a high degree of endemicity. Nevertheless, the wealth of its vegetation is in contrast to the scarcity of its wildlife. Even though the vegetation of the island is small (about 150 blooming and 50 ferns; Stuessy et al. 1992; Marticorena et al. 1998), the island contains a high proportion of native vegetation (about 62.5%), 12 of which are genus and one family:
Furthermore, the endemic densities and densities are higher than on any other ocean island: 2.08 species/km2 and 0.98 endemite/km2 respectively. Moreover, these types are of significant importance, not only because they can be a major source of early anger sperm irradiation, but also because several types can supply fundamental tools for studying evolving in certain groups (Stuessy et al., 1998).
Asteraceae are the most species-rich families, which have experienced a wide diversity of the first colonisers on these isles: they comprise the four indigenous genera: There are other indigenous genera: Most of the angiosperms have very small or small blossoms. The most types are hermaphrodite, 9% are two-home and 9% mono-home.
Some 14% of the plants show that 85% of these plants are self-tolerant, but their degree of autogamicity is low. They have a much less spectacular marine life than the island's wildlife. No indigenous animals, amphibia or reptile; a indigenous Mexican Pleuroderma sp. from Chile was probably imported by people.
Fernandetian insects are also small (Kuschel, 1952; Wilson 1973), and there is a lack of flora (Skottsberg 1928; Anderson et al. 2001). Of the 296 nesting birds of Chile, only eleven are native, five of which are limited to the Juan Fernández Islands (Hahn 1996).
Therefore, this eco-region is of great importance for Chile's wildlife. There are seventeen land and sea bird breeds in the Juan Fernández area. Eight of these types and subtypes are indigenous, and four further types brood outside the island only on the isles of Mocha or Desventuradas (Hahn, 1996). Indigenous bird life at speciational scale are: the Juan Fernández fire crown, Sephanoides Fernandsis (the only indigenous colibri known on the Ocean iceland; Colwell 1989; Roy et al.
1998 ), the "Rayadito" from Masafuera, Aphrastura massafuerae, the Juan Fernández tit-tyrant, Arlairetes ferandezianus and the indigenous subspecies: the Juan Fernández Red-backed Buzzard, Buteo panosoma exsul and the Juan Fernández sparrowhawk, Falco spverius ferandensis. Marsh ear-ows, Asio flammmeus, the green-backed fire crown, Sephanoides separhaniodes, the southern buzzard, Eurasian turtle, and the southern Eurasian blackbird, Guracus kuraeus, are divided with mainland Chile.
There are no or only a few flower-goers on these island woods (Skottsberg 1928; Anderson et al. 2001; Bernardello et al. in press), except the two hummingbirds named. Approximately 9% of the existing vegetation is hummingbirds and it is believed that about 47% is germinated by winds (Bernardello et al. in press).
Hummingbird food contains 14 indigenous plants (Bernardello et al. 2000; Anderson et al. 2001). Every island has its own, slightly different type of flora (Stuessy 1995). The Isla R. Crusoe has grassland (0-100 metres altitude), established bushes (100-300 metres), high woods (300-500 metres), lower mountain woods (500-700 metres), ferns (700-750 metres) and high scrub on rocky outcrops (500-850 metres).
The Isla Santa Clara is naked by bushy bushes and is mostly made up of grass-covered mountains. The Isla A. Selkirk has meadow sides (0-400 m) and gorges ("quebradas", 0-500 m), lower mountain woods (400-600 m), higher mountain woods (600-950 m), high scrub (950-1100 m) and an "alpine zone" (1100-1300 m).
Grasslands with indigenous and imported herbs and other herbic tundra occupy much of the lower elevations of the two large islets, as well as almost the entire island of Santa Clara. Anthoxanthum ororatum is the most abundant type of grassland on Isla A. Selkirk. On Isla R. Crusoe, the oval form of caena is widely spread together with the two most harmful insects on the island, Aristotelia chillensis ("maqui") and Rubus utmifolius ("zarzamora").
The conferti folia of Drimy (on both major islands), Myrceugenia ferandeziana (on Isla R. Crusoe) and M. schulzei (on Isla A. Selkirk). The lower mountain wood contains dressimys perfertifolia and myrceugenia ferandeziana, together with Boehmeria Excelsa, Coprosma olive, C. Pyrrifolia and two types of Fagara (F. mightu on Isla R. Crusoe and F. externna on Isla A. Selkirk).
In Isla A. Selkirk D. Berteriana is substituted by D. externa. Types in this area are Berberis sparertioides, Colletia sparertioides, Dendroseris marginalata, Eryngium buupleuroides, Ochagavia Elegans, Pernettya rigidida and Robinsonia Ganana. In 1935 the National Park of Juan Fernández was designated by the National Park of Chile an the International Union for the Conservation of Nature in 1977 (Wester 1991) as the World Biosphere Reserve, which is classified as "most threatened".
They are also classified by Bird Life to be a maintenance critique and appear in the WWF/IUCN worldwide WWF/IUCN survey on centres for plant diversity and endemism (Davis et al. 1997). The CONAF is working hard to rescue Chilean endemics with the help of the Chilean government and several non-governmental organisations.
The restorations, however, do not seem to be enough to halt the impact of many aggressively imported varieties. Indigenous vegetation is characterised by low fire tolerances and bad adaptability to herbivores (Skottsberg 1953b). Most of the rare plants in these woods have very few population and in some cases only a few survivors (Stuessy et al. 1997).
It has a negative effect on the propagation of plants: a) the densities of the other species are essential to promote a higher flow of air between the plants, and b) the breeding performance is dependent on the amount and qualitiy of the actual pollinating visit, and both are likely to be dependent on the frequency of visit. Wildlife is the greatest menace, as it has a disastrous impact on the island's habitat, especially on Isla A. Selkirk, where there are several thousand geese (Mann, 1975).
Razorbills are the biggest menace on the other two islets, where several thousand are found in the arid regions (Saiz and Ojeda 1988). Feral hounds and swine were exterminated from the island (Wester 1991). The grazers used to migrate throughout Isla R. Crusoe, but are now confined near the only hamlet of San Juan Bautista that surrounds Cumberland Bay.
Indigenous wood was harvested to supply wood for sailboats, but also for building materials and fuel. The opening of lower altitude woods has led to a number of colonising bushes indigenous to the continental and imported to the island invading large parts of the troubled woodland in competition with indigenous varieties.
Ullmifolius rubuses and Chilean aristotelia occupy large areas where no other indigenous plant can competiton. Either type regenerates from truncated dies, making monitoring harder. Surprisingly, 227 imported and naturalised varieties have been recorded so far, much more than indigenous and indigenous varieties, and in supplement to these weeders, Lantana Camara and Lonicera Japanica have the capacity to be heavy pest organisms (Swenson et al., 1997).
When producing nektar and being attended by hummingbirds (as many do), their wealth can also result in a decreased visiting quota and a decreased actual dusting of the endemites (Bernardello et al. in press). As an example, the indigenous hummingbirds visit the higly invertebrate Rubus Ulimifolius as a nektar spring and seem to be better able to eat this type of plants than the indigenous hummingbirds (Brooke 1987; Colwell 1989).
One of the reasons for this is that the indigenous hummingbirds have benefited differently at the cost of the indigenous hummingbirds, whose population declines (Colwell 1989). Finally, the depletion of the island's delicate living space by man is worth mentioning. Mittermeier et al. (1999) noted that man-made changes in the oceans have occurred on a larger scale than in most of the continent's system.
Because of these conditions at least one type of plants became extinct in historic periods (the indigenous Santalum ferandezianum sandals, which were threatened with disappearance at the beginning of the twentieth c. because of their fragrant wood), and some others, gathered with very few specimens or not at all from the beginning of the c. centr. are about to disappear (Stuessy et al. 1997).
Because of the very impressing degree of phytodermism - at the peculiar, general and family level - in a very small country area, together with some indigenous bird species - including the only indigenous hummingbirds known from the ocean islands - the Juan Fernández Islands are clearly a centre of global interest and make them a centre of independent bio-diversity.
Juan Fernandez differs from other eco-regions in the long distances of the island from the land and other island and in the number of existing native birds, among them 3 birds (Stattersfield et al. 1998). Farming system and pollinating of select indigenous crops in the Juan Fernandez isles.
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