The Osa Conservation Area encompasses several protected areas: The most famous of them and the crown jewel of the protected areas in Costa Rica is Corcovado National Park.
Corcovado National Park
Corcovado National Park encompasses 45,757 terrestrial ha and 5,375 marine ha and contains a variety of ecosystems including forests, beaches, coral reefs, and mangrove and freshwater swamps. Corcovado includes the entire drainage of the Corcovado plain, a sediment-filled embayment between Punta Llorona and Punta Salsipuedes that extends 5-10 km (3,1-6.25 miles) inland. The Corcovado plain covers about 10,000 ha (24,710 acres) ringed with steep and broken uplands on three sides and the Pacific Ocean on the southwest. Intense geological weathering has produced a topography of narrow ridges, long and steep slopes, and a drainage network that dominates practically all of the uplands except for an undulating plateau in the northwest part of the park.
The climate of Corcovado is hot, humid, and rainy. Although no weather station exists in the park, vegetation patterns suggest that the Corcovado plain receives an average annual rainfall between 3,000 and 3,800 mm, while the tropical wet forest uplands receive more than 4,000 mm. However, the annual rainfall in the high interior could be as high as 5,000 to 6,000 mm (Hartshorn 1983). The average mean temperature of the Park is approximately 27° C (80,6 F).
The unique topography and weather patterns of the park have led to the development of at least thirteen major ecosystems within Corcovado. These ecosystems support an array of plant and animal life, which is described in more detail below.
Corcovado is distinguished from other areas in Central America and worldwide by the variety and uniqueness of its flora. Approximately one third of the trees in Costa Rica can be found in the Corcovado area, including one-half of the endangered trees in the Country.
It has been estimated that there are 4,000 to 5,000 vascular plant species in the Osa Peninsula .
The lowlands of southern Costa Rica are the only wet forests still extant on the Pacific side of Central America. The abundant rainfall coupled with a short three-month dry season seems to be ideal for tree growth, which helps explain why Corcovado has the most impressive forests in Central America.
Corcovado’s forests exemplify the popular conception of the tropical rain forest, with a multitude of species, very tall trees, spectacular buttresses, large woody lianas, and abundant herbaceous vines. Holdridge et al. (1971) report that the most outstanding feature of their study site in the Osa Peninsula is the extreme height of the forest; they encountered 22 species over 50 m tall, five species that exceeded 60 m, and one, Minquartia guianensis, that reached 73 m. Possibly the largest tree in Central America, an example of Ceiba pentandra measuring 80 m tall, 3 m in diameter, and with 10 m tall buttresses, occurs on the Corcovado plain.
The Corcovado Lagoon is one of Corcovado’s notable hydrological features, and encompasses approximately 10 km near the center of the park. An extensive floating mat of herbaceous vegetation, dominated by a Pennisetum sp., surrounds the relatively small, open-water section of the lagoon. As the depth of water decreases, more heterogeneous vegetation is rooted in the muck soil. The slightly higher natural levees of the streams feeding the lagoon support a large stand of Inga vera. Surrounding the herbaceous swamp is an extensive area dominated by the Yolillo palm (Raphia taedigera) estimated by Vaughan (1979) to vary between 200 m (600 feet) and 1,500 m (4500 feet) in radius. The Yolillo palm forms mono-specific stands in areas receiving appreciable floodwaters for a few months each year. The Raphia swamp dries out during the dry season to the stage that it is relatively easy to walk on the mucky swamp soil. The vegetation outside the Raphia swamp takes on the appearance of typical swamp forests with large, well-buttressed canopy trees, stilt rooted sub canopy trees, and a fairly open understory of abundant palms.
In addition to Corcovado lagoons, the Park contains a variety of freshwater ecosystems. Some of the larger rivers include Rio Madrigal, Rio Claro, Rio Sirena, Rio Corcovado, and Rio Llorona. In addition, there is an extensive network of smaller streams and brooks. Mangroves occur in association with the tidal estuaries of the Llorona, Corcovado, and Sirena rivers. These environments support an array of birds and aquatic life. You can read more about Corcovado National park at.
http://www.costarica-nationalparks.com/corcovadonationalpark.html
The Golfo Dulce Forest Reserve:
Located between Corcovado and Piedras Blancas National Park, the Golfo Dulce Forest Reserve is a large protected area with rivers, secluded beaches and exuberant forest.
Most of the lowlands surrounding the Golfo Dulce are characterized by tall evergreen forest. The area near Golfito includes some of the highest-storied (100 - 140 ft) forests in Central America. One of the wettest places in the world, the region receives an average annual rainfall of 150 - 200 inches.
The fragmented, dense evergreen forests provide a biological corridor, connecting multiple wildlife refuges and national parks surrounding the Golfo Dulce. The calm waters along the beaches and bays of the Golfo Dulce Costa Rica have great attraction to tourists seeking peaceful swimming, wildlife, nature and birdwatching.
Caño Island Biological Reserve
Isla del Caño is located about 17 km off the Pacific coast at the north end of Corcovado National Park and is clearly visible from the shore. The island is approximately 320 ha in area; it forms a rough triangle 3-km long and 2-km wide at the base. The island is a heavily forested rock mesa about 100-m high dissected by small ever-flowing creeks. The beaches are sand and rock and lack mangroves due to the high-energy environment. The upland part of the island contains undisturbed rainforest, while the triangle’s apex contains various ages of secondary growth following clearing for banana plantations, an aborted airstrip, and some cultivated areas. The slopes down to the sea contain undisturbed vegetation similar to that on the sea-facing cliffs of northern Corcovado National Park.
The climate of the island is characterized by high precipitation; the mean annual rainfall for the zone is 5150 mm (15 feet) annually. The rainy season is from May to December, and the peak of precipitation is in October. The dry season is from December to April. The temperature in the island is very consistent ranging between 26-27° C (78,8 – 80,6 Fahrenheit) and there is almost always 100% relative humidity.
Like most islands, species richness is lower than on the mainland and a few species are the most abundant. In terms of plant species, 158 species of vascular plants and ferns exist on the island. The area is characterized as humid tropical forest, and the majority of the species are perennials. The tree species vaco (Brosimum utile), aguacaton (Ocotoea ira) and pilon (Hieronima alchornioides) dominate the upper strata of the forest while the juco (Trema micranta) and rubiacea (Penhagoa gymnopoda) dominate the underbrush. The abundance of the vaco in the center of the island suggests the possibility of its introduction by the Quepos and Cotos Indians for religious reasons. Thus, the vegetation associations on the island have archaeological as well as ecological significance. There is little vegetation along the periphery of the island, due to the abruptly steep terrain.
Piedras Blancas National Park
Piedras Blancas National Park is found in the Puntarenas Province of southern Costa Rica near the town of La Gamba. It protects rainforests and beaches near the Golfo Dulce on the Pacific Coast. It used to operate as part of the Corcovado National Park called the Esquinas Sector from 1991 before becoming a separate park in 1999.
The rugged mountains and watersheds of both the Esquinas and Piedras Blancas rivers are covered in dense evergreen forest that is home to a number of rare tropical trees and the habitat of many species of birds, mammals and reptiles.
Some of the park has remained in private hands, however a charitable organization Rainforest of the Austrians (Regenwald der Osterreicher) has been raising funds and purchasing these, which up to 2005 had moved 31 km² of land in the area into public ownership. More about Piedras Blancas at piedrasblancasnationalpark
Other protected areas in Osa:
Carate Wildlife Refuge
Donald Peters Hayes Wildlife Refuge
Golfito Wildlife Refuge
Osa Wildlife Refuge
If you would like to find more information about these protected areas you can visit
http://www.costarica-nationalparks.com/osaconservationarea.html