Puerto Rican dry forests
Encyclopedia
The Puerto Rican dry forests are a subtropical dry forest
Tropical and subtropical dry broadleaf forests
The tropical and subtropical dry broadleaf forest biome, also known as tropical dry forest, is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive several hundred centimeters of rain per year, they have long dry seasons...

 ecoregion located in southwestern and eastern Puerto Rico
Puerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...

 and on the offshore islands. They cover an area of 1300 km² (501.9 sq mi). These forests grow in areas receiving less than 1000 mm (39.4 in) of rain annually. Many of the trees are deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...

, losing their leaves during the dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...

 which normally lasts from December to July.

Distribution

Dry forests exist in two areas on the island of Puerto Rico - along the south coast of the island (in the dry orographic rain shadow
Rain shadow
A rain shadow is a dry area on the lee side of a mountainous area. The mountains block the passage of rain-producing weather systems, casting a "shadow" of dryness behind them. As shown by the diagram to the right, the warm moist air is "pulled" by the prevailing winds over a mountain...

 of the Cordillera Central) and in the northeastern corner of the island near Fajardo
Fajardo, Puerto Rico
Fajardo is a small city in Puerto Rico located in the east region of the island, bordering the Atlantic Ocean, north of Ceiba and east of Luquillo.Fajardo is spread over 7 wards and Downtown Fajardo , which serves as the administrative center of the city...

, where the combination of low elevation and strong winds off the ocean (Northeast Trade Winds
Trade wind
The trade winds are the prevailing pattern of easterly surface winds found in the tropics, within the lower portion of the Earth's atmosphere, in the lower section of the troposphere near the Earth's equator...

) result in a dry environment. Dry forests also exist on the adjacent off-shore islands of Vieques, Culebra
Culebra
Culebra may refer to:* Culebra, Puerto Rico, an island* Isla Culebra, the Spanish name of Sedge Island, part of the Falkland archipelago* Culebra Peak, the southernmost fourteener in Colorado, United States...

, Mona
Mona, Puerto Rico
Mona is the third largest island of the archipelago of Puerto Rico, after the main island of Puerto Rico and Vieques. It is the largest of three islands located in the Mona Passage, a strait between the Dominican Republic and Puerto Rico, the others being Monito Island and Desecheo Island...

, Monito
Monito Island
Monito Island is an uninhabited island about 5 kilometers northwest of much larger Mona Island. Monito is the masculine diminutive form of Mona in Spanish. It is one of three islands in the Mona Passage, and part of the Isla de Mona e Islote Monito barrio, a subdivision of the municipality of...

, Desecheo
Desecheo Island
Desecheo is a small uninhabited island of the archipelago of Puerto Rico located in the northeast of the Mona Passage; 21 km from the west coast of the main island of Puerto Rico and 50 km northeast of Mona Island. It has a land area of 1.5 km² . Politically, the island is...

, Caja de Muertos and Cayo Santiago
Cayo Santiago
Cayo Santiago, also known as Isla de los monos , is an uninhabited island, located at , 950 m southeast of Punta Santiago, Humacao, Puerto Rico.-Geography:...

.

The vast majority of studies have focused on the south coast - almost nothing has been published about the northeastern dry forest. Studies of the offshore islands have been limited to species lists and qualitative descriptions of the vegetation.

Ecology

Puerto Rican dry forests (like Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

 dry forests in general) consist of short-stature (usually <5 m (16.4 ft) tall), multi-stemmed trees. The canopy is largely evergreen (dominated by Gymnanthes lucida
Gymnanthes lucida
Gymnanthes lucida, commonly known as Shiny Oysterwood, is a species of flowering plant in the spurge family, Euphorbiaceae, that is native to southern Florida in the United States, the Bahamas, the Caribbean, Mexico, and Central America. It is a tree, reaching a height of ....

(Euphorbiaceae
Euphorbiaceae
Euphorbiaceae, the Spurge family are a large family of flowering plants with 300 genera and around 7,500 species. Most are herbs, but some, especially in the tropics, are also shrubs or trees. Some are succulent and resemble cacti....

) in areas of limestone soil), while the emergent layer is considerably more dry-season deciduous.
Guaiacum officinale
Guaiacum officinale
Guaiacum officinale, commonly known as Roughbark Lignum-vitae, is a species of tree in the caltrop family, Zygophyllaceae, that is native to the Caribbean and the northern coast of South America.-Description:...

, Coccoloba venosa, Ceiba pentandra
Kapok
Ceiba pentandra is a tropical tree of the order Malvales and the family Malvaceae , native to Mexico, Central America and the Caribbean, northern South America, and to tropical west Africa...

, and Capparis cynophallophora
Capparis cynophallophora
Capparis cyanophallophora, commonly known as the Jamaican Caper, is small tree in the caper family, Capparaceae, that is native to the neotropics.-Description:...

are common trees in coastal dry forests. Dry limestone forest species include Pisonia albida, Guaiacum sanctum
Guaiacum sanctum
Guaiacum sanctum, commonly known as Holywood or Holywood Lignum-vitae, is a species of flowering plant in the creosote bush family, Zygophyllaceae. It ranges from southern Florida in the United States and the Bahamas south to Central America and the Greater Antilles...

, and Plumeria alba
Plumeria alba
Plumeria alba is a species of the genus Plumeria . This large evergreen shrub has narrow elongated leaves, large and strongly perfumed white flowers with a yellow center. Native from Central America and the Caribbean, it is now common and naturalized in southern and southeastern Asia....

.

Although most of the forest was destroyed for agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

 prior to the 1940s, some patches of forest which pre-date that period still exist. Areas that were used for charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

 production or for fence-posts have recovered rapidly - after 50 years forests that had been used for charcoal production recovered to the point where they were indistinguishable from much older forests.

In addition, large areas of secondary forest
Secondary forest
A secondary forest is a forest or woodland area which has re-grown after a major disturbance such as fire, insect infestation, timber harvest or windthrow, until a long enough period has passed so that the effects of the disturbance are no longer evident...

 have grown back on abandoned agricultural land. Unlike areas which were only lightly used, these forests on abandoned farmland have far fewer species than do natural forests. Their path to recovery remains uncertain.

Puerto Rican dry forests are dominated by plants in the families Rubiaceae
Rubiaceae
The Rubiaceae is a family of flowering plants, variously called the coffee family, madder family, or bedstraw family. The group contains many commonly known plants, including the economically important coffee , quinine , and gambier , and the horticulturally valuable madder , west indian jasmine ,...

, Euphorbiaceae, and Myrtaceae
Myrtaceae
The Myrtaceae or Myrtle family are a family of dicotyledon plants, placed within the order Myrtales. Myrtle, clove, guava, feijoa, allspice, and eucalyptus belong here. All species are woody, with essential oils, and flower parts in multiples of four or five...

. In this regard they are similar to Jamaican dry forests
Jamaican dry forests
Jamaican dry forests are subtropical dry forests located in southern Jamaica. The most extensive dry forests are in the limestone hills of the Hellshire Hills in St. Catherine and Portland Ridge in Clarendon in southern Jamaica. These areas are dry because the lie in the orographic rain shadow of...

, but differ sharply from dry forests on the mainland of South
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 and Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

, which are dominated by Fabaceae
Fabaceae
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...

 and Bignoniaceae
Bignoniaceae
The Bignoniaceae, or Trumpet Creeper Family, is a family of flowering plants comprising about 650-750 species in 116-120 genera. Members of the family are mostly trees and lianas , shrubs and more rarely herbaceous plants. As climber plants, they are twine climbers or tendril climbers, and rarely...

.

The best example of dry forests in Puerto Rico (and probably, in the Caribbean as a whole) are in the Guánica State Forest
Guánica State Forest
The Guánica State Forest is a subtropical dry forest located in southwest Puerto Rico. The area was designated as a forest reserve in 1919 and a United Nations Biosphere Reserve in 1981...

 (Bosque Estatal de Guánica) outside the town of Guánica
Guánica, Puerto Rico
Guánica is a municipality in southwestern Puerto Rico located on southern coast, bordering the Caribbean Sea, south of Sabana Grande, east of Lajas, and west of Yauco. It is part of the Yauco Metropolitan Statistical Area....

. This site has also been the focus of the vast majority of studies of dry forests.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK