The Galápagos Islands xeric scrub, also known as the Galápagos Islands scrubland mosaic,
[ is a terrestrial ]deserts and xeric shrublands
Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this ...
ecoregion
An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of l ...
that covers the Galápagos Islands
The Galápagos Islands (Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuador ...
. The Galápagos Islands are volcanic in origin, and remote from continents and other islands. The ecoregion is well known for its unique endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
species, including giant tortoises, birds, and marine iguanas, which evolved in isolation to adapt to islands' environments.
Geography
The Galápagos Islands lie in the Pacific Ocean, about 960 km west of the South American mainland. They are politically part of Ecuador
Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...
.
The Galápagos archipelago consists of 128 named islands. There are 13 islands larger than 10 km2, 19 larger than 1 km2, 42 islets smaller than 1 km2, and at least 26 emergent rocks.[ The total land area of the archipelago is 8032 km2.][ Isabela is the largest and highest island, with an area of 4,588 km2 and reaching an elevation of 1,707 meters.][
The islands are volcanic in origin, formed by the ]Galápagos hotspot
The Galápagos hotspot is a volcanic hotspot in the East Pacific Ocean responsible for the creation of the Galápagos Islands as well as three major aseismic ridge systems, Carnegie, Cocos and Malpelo which are on two tectonic plates. The hots ...
. The eastern islands are generally older, dating back 3 to 6 million years, while the western islands are less than 1 million years old. Surface geology consists of volcanic rock, typically basalt, and includes pumice, ash, and tuff ejected from volcanoes. The landscape has volcanic features like crater lakes, lava fields, lava tubes, fumaroles, and sulfur vents. Soils are generally young and thin.[
Four islands – Isabela, Santa Cruz, San Cristóbal, and ]Floreana
Floreana Island (Spanish: ''Isla Floreana'') is an island of the Galápagos Islands. It was named after Juan José Flores, the first president of Ecuador, during whose administration the government of Ecuador took possession of the archipelago. ...
– are permanently inhabited. The islands have approximately 30,000 permanent residents. There are docks on all the inhabited islands, and an airport on San Cristóbal. Baltra Island
Baltra Island (Spanish language, Spanish: ''Isla Baltra''), is a small island of the Galápagos Islands. Also known as South Seymour (named after Lord Hugh Seymour), Baltra is a small flat island located near the center of the Galápagos. It was ...
has an airport, military base, tourism dock, and fuel facilities.["Galápagos Islands". UNESCO World Heritage Centre. https://whc.unesco.org/en/list/1/?][
]
Climate
The climate is tropical, oceanic, and semi-arid, influenced by the annual movements of ocean currents. There are two main seasons. The dry or ''garúa'' (misty) season generally lasts from May to December, influenced by the cool Humboldt Current
The Humboldt Current, also called the Peru Current, is a cold, low- salinity ocean current that flows north along the western coast of South America.Montecino, Vivian, and Carina B. Lange. "The Humboldt Current System: Ecosystem components and pr ...
coming from the south. The dry season is characterized by cooler temperatures and lower rainfall. Mist and drizzling rain, known as ''garúa'', occurs during this season, particularly in the highlands. August is typically the coolest and driest month, with temperatures as low as 18°C and as little as 5 mm of rainfall.[
The hot and wet season extends December to May, influenced by the warm Panama Current from the north shifting to surround the islands. This season brings warmer temperatures and higher rainfall. March is typically the warmest and wettest month, with temperatures as high as 30°C and as much as 80 mm of rainfall.][
Temperature and rainfall vary with elevation, creating a range of microclimates on the higher islands. Average annual temperature declines an average of 0.9°C for every 100 meters of elevation, and rainfall increases. Average annual rainfall for the archipelago is 356 mm at sea level and 1092 mm at 200 meters elevation.][
]
Flora
Most of the Galápagos is covered in semi-desert vegetation, including shrublands, grasslands, and dry forest. A few of the islands have high-elevation areas with cooler temperatures and higher rainfall, which are home to humid-climate forests and shrublands, and montane grasslands, or ''pampas'', at the highest elevations. There are about 500 species of native vascular plant
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They al ...
s on the islands, including 90 species of ferns. About 180 vascular plant species are endemic.[
Coastal plant communities are generally low-growing shrubs and herbs which are tolerant of drought and salt spray. Typical plants include the shrubs saltbush ('' Cryptocarpus pyriformis'') and '' Maytenus octagona''. Herbaceous seashore plants include the widespread beach morning glory ('']Ipomoea pes-caprae
''Ipomoea pes-caprae'', also known as bayhops, bay-hops, beach morning glory or goat's foot, is a common pantropical creeping vine belonging to the family Convolvulaceae. It grows on the upper parts of beaches and endures salted air. It is one ...
'') and ''Sesuvium portulacastrum
''Sesuvium portulacastrum'' is a sprawling perennial herb that grows in coastal areas throughout much of the world. It is commonly known as shoreline purslane or (ambiguously) " sea purslane," in English, ''dampalit'' in Tagalog and 海马齿sl ...
'', and the endemic Galápagos carpet weed ('''').[
]Mangrove
A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evoluti ...
s grow in calm inlets and lagoons. Typical species include red mangrove (''Rhizophora mangle
''Rhizophora mangle'', the red mangrove, is distributed in Estuary, estuarine ecosystems throughout the tropics. Its Vivipary, viviparous "seeds", in actuality called propagules, become fully mature plants before dropping off the parent tree. Th ...
''), black mangrove (''Avicennia germinans
''Avicennia germinans'', the black mangrove, is a shrub or small tree growing up to 12 meters (39 feet) in the acanthus family, Acanthaceae. It grows in tropical and subtropical regions of the Americas, on both the Atlantic and Pacific Coasts, ...
''), and white mangrove (''Laguncularia racemosa
''Laguncularia racemosa'', the white mangrove, is a species of flowering plant in the leadwood tree family, Combretaceae. It is native to the coasts of western Africa from Senegal to Cameroon, the Atlantic Coast of the Americas from Bermuda and ...
'') and button mangrove (''Conocarpus erectus
''Conocarpus erectus'', commonly called buttonwood or button mangrove, is a mangrove shrub in the family Combretaceae. This species grows on shorelines in tropical and subtropical regions around the world.
Range
Locations it is known from inc ...
'').[
The arid zone lies inland of the coastal zone and extends to 200 meters elevation or higher. It covers most of the archipelago. It includes trees, shrubs, cacti, and herbs adapted to dry conditions. Common trees include the palo santo ('']Bursera graveolens
''Bursera graveolens'', known in Spanish as ("Holy Stick”), is a wild tree native from the Yucatán Peninsula to Peru and Venezuela.
''Bursera'' ''graveolens'' is found in the seasonally dry tropical forests of Peru, Venezuela, Colombia, Ecu ...
'') and paga paga (''Pisonia floribunda
''Pisonia'' is a genus of flowering plants in the four o'clock flower family, Nyctaginaceae. It was named for Dutch physician and naturalist Willem Piso (1611–1678). Certain species in this genus are known as catchbirdtrees, birdcatcher trees o ...
''), and the endemic trees guayabillo ('' Psidium galapageium'') and '' Bursera malacophylla'', which is found only on Seymour, Baltra and Daphne islands. Cacti
A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...
include several endemic species of ''Opuntia
''Opuntia'', commonly called prickly pear or pear cactus, is a genus of flowering plants in the cactus family Cactaceae. Prickly pears are also known as ''tuna'' (fruit), ''sabra'', ''nopal'' (paddle, plural ''nopales'') from the Nahuatl word f ...
'' – '' Opuntia echios, O. helleri'', and others – and the endemic genera ''Jasminocereus
''Jasminocereus'' (meaning "jasmine-like cereus", referring to the flowers) is a genus of cacti with only one species, ''Jasminocereus thouarsii'', endemic to the Galápagos Islands, territorially a part of Ecuador. In English it is often called ...
'' and ''Brachycereus
The lava cactus is a species of cactus, ''Brachycereus nesioticus'', the sole species of the genus ''Brachycereus''. The plant is a colonizer of lava fields – hence its common name – where it forms spiny clumps up to tall. Its solitary whit ...
''. Ground cover plants include low shrubs, like the endemic bitterbush (''Castela galapageia
''Castela'' is a genus of thorny shrubs and small trees in the family Simaroubaceae. Members of the genus are native to the Americas, especially the tropical regions. The generic name honours the French naturalist René Richard Louis Castel. ''C ...
'') and species of the endemic genus ''Lecocarpus'', and herbaceous plants. Herbaceous arid zone species include the endemic genera ''Tiquilia
''Tiquilia'' is a genus of flowering plants in the borage family, Boraginaceae. The 27 species in this genus are known by the common name crinklemat. They are native to the Western Hemisphere and are mostly found in desert regions.
Selected spe ...
'' and ''Chamaesyce
''Chamaesyce'' is a genus of plants in the family Euphorbiaceae. Recent phylogenetic studies have shown that ''Chamaesyce'' is deeply nested within the broader ''Euphorbia''. Specifically, ''Chamaesyce'' is very closely related to plants like '' ...
'', Galápagos tomato ('' Solanum galapagense''), and stinking passion flower (''Passiflora foetida
''Passiflora foetida'' (common names: stinking passionflower, wild maracuja, bush passion fruit, wild water lemon, stoneflower, love-in-a-mist, or running pop) is a species of passion flower that is native to the southwestern United States (south ...
'').[
On islands that reach higher elevations, there is transition zone between the arid and humid zones between 200 and 300 meters elevation. Transition zone plants include ''Pisonis floribunda'' and ''Psidium galapageium'' at lower elevations, and ''P. galapageium'' with '']Scalesia
''Scalesia'' is a genus in the family Asteraceae endemic to the Galapagos Islands. It contains fifteen species that grow as shrubs or trees. This is unusual, because tree species are uncommon in Asteraceae. The genus ''Scalesia'' resulted from a ...
'' trees closer to the humid zone.
The humid zone lies above 300 meters elevation. It has higher rainfall than lower-elevation areas, and the dry-season ''garua'' fogs reduce plants' loss of moisture through evaporation and provide some moisture from condensation. Woodlands of ''Scalesia
''Scalesia'' is a genus in the family Asteraceae endemic to the Galapagos Islands. It contains fifteen species that grow as shrubs or trees. This is unusual, because tree species are uncommon in Asteraceae. The genus ''Scalesia'' resulted from a ...
'' trees, 5 to 15 meters tall, are predominant from 300 to 500 meters elevation, with over 20 species of the endemic genus across the high islands of the archipelago.
The low tree cat's claw (''Zanthoxylum fagara
''Zanthoxylum fagara'' or wild lime, is a species of flowering plant that—despite its name—is not part of the genus ''Citrus'' with real limes and other fruit, but is a close cousin in the larger citrus family, Rutaceae. It is native to sout ...
'') is most abundant between 500 and 600 meters elevation, in the transition between the ''Scalesia'' woodlands below and the ''Miconia'' shrublands above. The endemic shrub '' Miconia robinsoniana'' is predominant between 600 and 700 meters elevation, particularly on Santa Cruz and San Cristóbal islands, forming shrublands 3 to 4 meters high.[
High-elevation grasslands, known as ''pampa'', are found above 900 meters elevation. The pampa is lush with grasses, ferns, ]sphagnum moss
''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, peat moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store wa ...
, and orchids. '' Purthieva maculata'' is one of 11 species of orchids found here. The endemic tree fern '' Cyathea weatherbyana'' is a ''pampa'' native.[
]
Fauna
The Galápagos is home to many endemic species of reptiles, birds, mammals, land snails, insects.[
There are 19 resident seabird species, including five endemic species. Endemic seabirds include the ]Galapagos penguin
The Galápagos penguin (''Spheniscus mendiculus'') is a penguin endemic to the Galápagos Islands, Ecuador. It is the only penguin found north of the equator. Most inhabit Fernandina Island and the west coast of Isabela Island. The cool wate ...
(''Spheniscus mendiculus''), waved albatross
The waved albatross (''Phoebastria irrorata''), also known as Galapagos albatross,Remsen Jr., J.V. (2008) is the only member of the family Diomedeidae located in the tropics. When they forage, they follow a straight path to a single site off the ...
(''Phoebastria irrorata''), flightless cormorant
The flightless cormorant (''Nannopterum harrisi''), also known as the Galapagos cormorant, is a cormorant endemic to the Galapagos Islands, and an example of the highly unusual fauna there. It is unique in that it is the only known cormorant t ...
(''Nannopterum harrisi''), swallow-tailed gull
The swallow-tailed gull (''Creagrus furcatus'') is an equatorial seabird in the gull family, Laridae. It is the only species in the genus ''Creagrus'', which derives from the Latin ''Creagra'' and the Greek ''kreourgos'' which means butcher, al ...
(''Creagrus furcatus''), and lava gull
The lava gull (''Leucophaeus fuliginosus''), also known as the dusky gull, is a medium-sized gull and a member of the "hooded gull" group. It is most closely related to the Laughing gull and Franklin's gull and is the rarest gull in the world. It ...
(''Leucophaeus fuliginosus'').[
The islands are home to 29 native species of land birds, 24 of which are endemic. Endemic species include the ]Galapagos hawk
The Galápagos hawk (''Buteo galapagoensis'') is a large hawk endemic to most of the Galápagos Islands.
Description
The Galapágos hawk is similar in size to the red-tailed hawk (''Buteo jamaicensis'') and the Swainson's hawk (''Buteo swainso ...
(''Buteo galapagoensis''), Galapagos dove (''Zenaida galapagoensis''), Galapagos rail (''Laterallus spilonota''), Galápagos martin
The Galápagos martin (''Progne modesta'') is a species of bird in the family Hirundinidae, endemic to the Galápagos Islands.
Its natural habitats are subtropical or tropical dry shrubland, subtropical or tropical seasonally wet or flooded lowla ...
(''Progne modesta''), and four species of mockingbirds from genus ''Nesomimus
''Mimus'' is a bird genus in the family Mimidae. It contains the typical mockingbirds. In 2007, the genus ''Nesomimus'' was merged into ''Mimus'' by the American Ornithologists' Union. The genus name is Latin for "mimic".
The following species ...
''.[ There are about 18 distinct species of endemic tanagers on the island, collectively known as ]Darwin's finches
Darwin's finches (also known as the Galápagos finches) are a group of about 18 species of passerine birds. They are well known for their remarkable diversity in beak form and function. They are often classified as the subfamily Geospizinae or t ...
.
There are 22 endemic reptile species in the Galápagos. Notable species include the giant Galápagos tortoise
The Galápagos tortoise or Galápagos giant tortoise (''Chelonoidis niger'') is a species of very large tortoise in the genus ''Chelonoidis'' (which also contains three smaller species from mainland South America). It comprises 15 subspecies (13 ...
(''Geochelone'' spp.), which evolved 14 or 15 distinct species, of which 11 remain. Other endemic reptiles include the marine iguana
The marine iguana (''Amblyrhynchus cristatus''), also known as the sea iguana, saltwater iguana, or Galápagos marine iguana, is a species of iguana found only on the Galápagos Islands (Ecuador). Unique among modern lizards, it is a marine repti ...
(''Amblyrhynchus cristatus'') and three species of snakes, the Galápagos racer
The Galápagos racer (''Pseudalsophis biserialis'') is a colubrid snake in the genus ''Pseudalsophis'' that is endemic to the Galápagos Islands. It is a mildly venomous constrictor but it is not considered aggressive or harmful to humans. The two ...
(''Pseudalsophis biserialis''), '' Pseudalsophis dorsalis'', and '' Pseudalsophis slevini''.[
There are nine known species of terrestrial mammals – four surviving and three extinct species of rice rats, and two species of bats.
The four surviving species of rice rat live on uninhabited islands – '']Nesoryzomys fernandinae
''Nesoryzomys fernandinae'', also known as the Fernandina nesoryzomys, Fernandina rice rat, or Fernandina Galápagos mouse, is a species of rodent in the genus ''Nesoryzomys'' of family Cricetidae. It is found only on Fernandina in the Galápago ...
'' and '' Nesoryzomys indefessus narboroughi'' on Fernandina, ''Nesoryzomys swarthi
''Nesoryzomys swarthi'', also known as the Santiago nesoryzomysMusser and Carleton, 2005 or Santiago Galápagos mouse, is a species of rodent in the genus ''Nesoryzomys'' of family Cricetidae. It is found only on Santiago in the Galápagos Island ...
'' on Santiago, and ''Aegialomys galapagoensis
The Galápagos rice rat (''Aegialomys galapagoensis''), also known as the Galápagos oryzomys, is a species of rodent that is endemic to the Galápagos Islands.
Description
The Galapagos rice rat is a medium-sized rodent, with a head-body lengt ...
'' on Santa Fé. The other species were driven to extinction by competition with introduced black rat
The black rat (''Rattus rattus''), also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae. It likely originated in the Indian subcontinent, but is n ...
s (''Rattus rattus'').
The hoary bat
The hoary bat (''Lasiurus cinereus'') is a species of bat in the vesper bat family, Vespertilionidae. It lives throughout most of North America (possibly including Hawaii, although this is disputed).
Taxonomy
The hoary bat was described as a ...
(''Lasiurus cinereus'') is an insect-eating species that roosts on mangroves and shrubs. It is found on Santa Cruz, San Cristóbal, Isabela, Santiago, and Floreana. The Galápagos red bat (''Lasiurus blossevillii brachyotis'') inhabits Santa Cruz and San Cristóbal, where feeds near the ground on insects.
Conservation and threats
Most of the islands' land and marine area is permanently protected. Invasive species
An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...
are considered the greatest current threat to the Galápagos' native animals and plants. Non-native species compete with native ones for habitat, and some prey on natives unadapted to predation. Non-native species have been introduced since the islands were first visited by humans, and the islands' growing human population and increasing movement of goods and people to the islands are introducing new non-native species at a high rate.[
]
Protected areas
97% of the islands' land area is in Galápagos National Park
Galápagos National Park ( es, Parque Nacional Galápagos) was established in 1959. It began operation in 1968, and it is Ecuador's first national park and a UNESCO World Heritage Site.
Park history
The government of Ecuador has designated ...
, which was created in 1959. Human settlements are limited to the remaining 3% of the islands, located on the four permanently inhabited islands. Access to the uninhabited islands is strictly controlled, and visitor numbers and itineraries are limited and planned by authorities. Approximately 170,000 people visit the islands each year.[
In 1986 the ]Galápagos Marine Reserve
The Galápagos Marine Reserve (GMR) lies a thousand kilometres from the Ecuadorian mainland and covers an area of around . The Galápagos Islands and the surrounding waters represent one of the world’s most unusual ecosystems and are rich areas ...
was created, with an area of 70,000 km2. In 1998 the marine reserve was enlarged to 133,000 km2.[
]
References
{{reflist
Ecoregions of Ecuador
Deserts and xeric shrublands
Neotropical ecoregions
Endemic Bird Areas