The Saint Helena scrub and woodlandsecoregion covers the volcanic island of Saint Helena in the South Atlantic Ocean. The island's remote location gave rise to many endemic species. First discovered and settled in the 1500s, the island has been degraded by human activities. Most of its native habitat has been destroyed, and many of its unique plants and animals are extinct or endangered.[1]
Saint Helena is in the South Atlantic Ocean, 1,950km west of the Angola on the African mainland.
The island is approximately 122km2 in area. It is the eroded summit of a composite volcano, first formed by the Mid-Atlantic Ridge over 14 million years ago. Volcanic activity ceased about 6 million years ago.[3]
Millions of years of volcanic deposition and erosion have created coastal cliffs and dramatic landscape features. The island's year-round streams have eroded steep-sided valleys. Diana's Peak is the highest point on the island at 823 meters elevation.[1]
The climate of the island is dry and subtropical. Average monthly temperatures range from 15 to 32°C. Mean annual rainfall is 152mm, and higher in the island's windward hills.[1]
The middle elevations of the island were once covered with dry woodlands and forests. Principal trees included gumwood (Commidendrum robustum), bastard gumwood (Commidendrum rotundifolium), dwarf ebony (Trochetiopsis ebenus), and false gumwood (Commidendrum spurium). The Saint Helena olive (Nesiota elliptica) became extinct in the wild in 1994, and the last living specimen died in 2003. The native tree fern Dicksonia arborescens grows up to 3 metres high. The island is notable for native species in the composite family (Asteraceae). The composites are mostly herbaceous, but on St. Helena evolved woody into woody trees and shrubs. The native composite trees and shrubs include species of Pladaroxylon, Lachanodes, Commidendrum, Melanodendron, and Petrobium.[3]
Native plants are now limited to a few sheltered and inaccessible locations, including a small gumwood stand at Peak Dale. Prosperous Bay Plain is a 150-hectare semi-desert area which is home to the native shrub Suaeda fruticosa, the endemic annual plant Hydrodea cryptantha, most of the remaining habitat of the endemic barn fern (Asplenium haughtonii), along with many endemic invertebrates, some of which are known only from this location. A portion of the plain was destroyed to build Saint Helena Airport.[1]
The present-day vegetation of the island is mostly of naturalized non-native plants. Approximately 260 species of non-native plants are now naturalized on the island. Over half the island is covered by wasteland of bare soil and sparse scrub of mostly exotic plants. Other areas are covered with pasture and abandoned flax plantations. Regenerating shrubland and woodland includes many exotic species, with prickly pear (Opuntia ficus-indica), common lantana (Lantana camara), Brazilian pepper tree (Schinus terebinthifolia), Chrysanthemoides monilifera, Bermuda cedar (Juniperus bermudiana), green-aloe (Furcraea gigantea), maritime pine (Pinus pinaster), cape cheesewood (Pittosporum viridiflorum), iceplant (Carpobrotus edulis), yellow trumpetbush (Tecoma stans), and wattle (Acacia longifolia) prominent. The Millennium Forest, on the east side of the island, is a 250-hectare reserve where thousands of native trees have been replanted.[1]
The Saint Helena plover or wirebird (Charadrius sanctaehelenae) is the island's sole surviving endemic bird species. It is found on interior pasturelands and the Prosperous Bay Plain's shrublands.[1]
Fossil and subfossil remains of several extinct land birds have been found on the island – the Saint Helena rail (Aphanocrex podarces), Saint Helena crake (Zapornia astrictocarpus), Saint Helena dove (Dysmoropelia dekarchikos), Saint Helena cuckoo (Nannococcyx psix), and Saint Helena hoopoe (Upupa antaios). Most are thought to have been present when the first human settlers arrived there.[1][3]
The islands have no known native mammals, amphibians, or terrestrial reptiles. There are many native and endemic invertebrates. 157 endemic beetles have been recorded, including the endangered ground beetle Aplothorax burchelli.[1] The giant Saint Helena earwig (Labidura herculeana) is likely extinct.
History
The island was discovered by Portuguese navigator João da Nova in May 1502, close to the feast day for St. Helena. Goats were introduced soon afterwards to provide food for passing ships. In 1588 the English seacaptain Thomas Cavendish visited the island, and discovered large herds of goats. It soon became a port of call for vessels traveling between Europe and ports on the Indian Ocean. In 1659 the East India Company claimed control of the island and established a fort and settlement near the site of present-day Jamestown. The island's first inhabitants were English traders and settlers, along with slaves from South and Southeast Asia and Madagascar. In 1673 nearly half of the island's inhabitants were slaves. The island's slaves were emancipated between 1826 and 1836.[1]
In 1659 the woodlands were fragmented by overgrazing, although large wooded areas still remained, including the Great Wood on the northeastern corner of the island. Portions of the island were cleared for agriculture, including orchards and fields, and native woodlands harvested for timber and firewood. Pigs, sheep, and cattle were also introduced to the island.[1]
In 1709 Governor Roberts reported to the East India Company's Court of Directors that the island's native timber, notably the endemic Saint Helena ebony (Trochetiopsis ebenus) was rapidly disappearing, and recommended limiting the grazing of goats on the island. The Directors refused to order the goats' removal.[4]
Between 1723 and 1727 a stone wall was constructed around a remnant of the Great Wood to protect it from grazing cattle, goats, and timber harvesting. The Great Wood Wall enclosed 6km2, but proved ineffective in protecting the wood. The wood was mostly cleared of trees, and maintenance of the wall was abandoned.[4]
Napoleon was exiled to St. Helena from 1815 to 1821. Other prisoners exiled there included Zulu warriors after the Anglo-Zulu War in the 1870s, and Boer prisoners during the Boer Wars at the end of the 19th century.[1]
By the 19th century the native woodlands had mostly disappeared. Plantations of New Zealand flax (Phormium tenax) were established after 1900 to produce fiber for string and rope. Demand for flax fiber collapsed in the 1960s, and most of the flax plantations were abandoned.[1]
Conservation and threats
Most of the wild habitat on the island has been lost to overgrazing, conversion to pasture and agriculture, and introduced species. Some interior areas are still covered in New Zealand flax.[1]
Peaks National Park was created in 1996, and protects 81 hectares on the central ridge of the island, including the island's three highest peaks, Diana's Peak, Cuckold Point, and Mount Actaeon. The park protects forests of black cabbage tree (Melanodendron integrifolium) and other native plants. The park has an endemic plant nursery that propagates island native plants.
In 2000 the Millennium Forest project was initiated. It involves reforesting a denuded area on the eastern side of the island with native trees, to restore a portion of the Great Wood which once covered the middle of the island. About 250 hectares have been planted with thousands of gumwood and other native trees.[5]
The California chaparral and woodlands is a terrestrial ecoregion of southwestern Oregon, northern, central, and southern California and northwestern Baja California (Mexico), located on the west coast of North America. It is an ecoregion of the Mediterranean forests, woodlands, and scrub biome, and part of the Nearctic realm.
The ecology of California can be understood by dividing the state into a number of ecoregions, which contain distinct ecological communities of plants and animals in a contiguous region. The ecoregions of California can be grouped into four major groups: desert ecoregions, Mediterranean ecoregions, forested mountains, and coastal forests.
The Saint Helena olive is an extinct species of flowering plant. It is the only member of the genus Nesiota. It was endemic to the island of Saint Helena in the South Atlantic Ocean. Despite its name, it is unrelated to the true olive, but is instead a member of the family Rhamnaceae, the family which contains buckthorns and jujube. The last remaining tree in the wild died in 1994, and the last remaining individual in cultivation died in December 2003, despite conservation efforts. It is thus a prime example of recent plant extinction. The Saint Helena olive belongs to the tribe Phyliceae, which are mostly endemic to Southern Africa.
Melanodendron is a genus of trees in the family Asteraceae, with only one species, Melanodendron integrifolium, native to the island of Saint Helena. It is related to the Saint Helenan gumwoods and is the most common of the remaining cabbage tree species of Saint Helena, although it is considered endangered due to the restricted population size.
The flora of Saint Helena, an isolated island in the South Atlantic Ocean, is exceptional in its high level of endemism and the severe threats facing the survival of the flora. In phytogeography, it is in the phytochorion St. Helena and Ascension Region of the African Subkingdom, in the Paleotropical Kingdom.
Trochetiopsis erythroxylon, the Saint Helena redwood, is a species of plant, now extinct in the wild. It was formerly abundant enough in the upland parts of the island of Saint Helena for early settlers in the 17th century to use the timber to make their homes. It became extinct in the 1950's due to deforestation as its habitat was cleared to make way for pasture, timber and fuel.
Trochetiopsis ebenus, the dwarf ebony or Saint Helena ebony, is a species of flowering plant that is endemic to the island of Saint Helena in the southern Atlantic Ocean. It is not related to the ebony of commerce, but is instead a member of the mallow family, Malvaceae. Saint Helena ebony is now critically endangered in the wild, being reduced to two wild individuals on a cliff, but old roots are sometimes found washed out of eroding slopes. These are collected on the island a used for inlay work, an important craft on Saint Helena. A related species, Trochetiopsis melanoxylon is now completely extinct.
Commidendrum is a genus of trees and shrubs in the family Asteraceae endemic to the island of Saint Helena in the South Atlantic Ocean. The vernacular name is gumwood or scrubwood.
Trochetiopsis melanoxylon, the dwarf ebony or St Helena ebony, of the island of Saint Helena is related to Trochetiopsis ebenus but is now extinct. It differed from T. ebenus by having much smaller flowers, sepals hairless on their interior surfaces and leaves densely hairy on both surfaces.
The flowering plant genus Trochetiopsis consists of two extant and one extinct species endemic to the island of Saint Helena. They were formerly placed in the family Sterculiaceae, but this is included in the expanded Malvaceae in the APG and most subsequent systematics.
Saint Helena, Ascension Island and Tristan da Cunha, as well the other uninhabited islands nearby, are a haven for wildlife in the middle of the Atlantic Ocean. The islands are or were home to much endemic flora and fauna, especially invertebrates, and many endemic fish species are found in the reef ecosystems off the islands. The islands have been identified by BirdLife International as Important Bird Areas for both their endemic landbirds and breeding seabirds.
Commidendrum rotundifolium, the bastard gumwood, is a species of tree endemic to the island of Saint Helena. It was thought to be extinct, but one last tree was discovered in Horse Pasture in 1982. This tree, long believed to be the last, was destroyed in 1986 by a gale. However seedlings were grown from this tree before it perished. The last of these to survive in cultivation was damaged by gales in 2008 and the survival of the species was in doubt.
The Chilean Matorral (NT1201) is a terrestrial ecoregion of central Chile, located on the west coast of South America. It is in the Mediterranean forests, woodlands, and scrub biome, part of the Neotropical realm.
The Ascension scrub and grasslands ecoregion covers the dormant volcano, Ascension Island in the Atlantic Ocean. As well as shrubs and grasses wildlife on the island includes a range of unique flora and fauna. In particular the surrounding islets are important havens for many seabirds. However the seabird populations on Ascension Island itself have been severely affected by introduced species, especially cats, which were the subject of an eradication campaign between 2002 and 2006.
The Timor and Wetar deciduous forests is a tropical dry forest ecoregion in Indonesia and East Timor. The ecoregion includes the islands of Timor, Wetar, Rote, Savu, and adjacent smaller islands.
The Madagascar succulent woodlands are a xeric shrublands ecoregion in southwestern and central western Madagascar. Native plants survive in the arid climate and long dry season with adaptations like succulent leaves, water storing trunks, photosynthetic stems, and dropping leaves during the dry season. The ecoregion is threatened by various human activities.
The Crete Mediterranean forests is a terrestrial ecoregion that encompasses the Greek island of Crete.
The Madeira evergreen forests is a laurissilva ecoregion of southwestern Europe. It covers the archipelago of Madeira and some nearby islands in the Atlantic Ocean. Laurel forest, known as Laurisilva of Madeira, once covered the islands. Over centuries the laurel forests were mostly cleared. Madeira's remaining forests are now protected.
The Tristan da Cunha–Gough Islands shrub and grasslands is a terrestrial ecoregion which covers the Tristan da Cunha archipelago and Gough Island in the South Atlantic Ocean. The islands' remote location gave rise to many endemic species.
Al Hajar montane woodlands is a temperate grasslands, savannas and shrublands ecoregion in the Hajar Mountains of the eastern part of the Arabian Peninsula, which extends across portions of Oman and the U.A.E.
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