Introduction to the ecosystems of the Osa Conservation Area (ACOSA)

On this web page one may consult the first results of an ecological study on Costa Rica's Osa Conservation Area (ACOSA), which was conducted between 1998 and 2000 by the ECOMAPAS Project. This project was designed and implemented as a joint effort by Costa Rica's National Biodiversity Institute (INBio) and the National System of Conservation Areas (SINAC). It represents the project's first digital on-line contribution. The first data on the area's ecosystems and vegetation are reported here, on basis of an intense geographical and ecological inventory and mapping process.

ACOSA is one out of eleven Conservation Areas in Costa Rica and includes 17 protected wildlife areas. This Conservation Areas comprises the Osa Peninsula and its surroundings along the Pacific coast, from Dominical down to Burica Point. It maintains an extra-ordinary species richness in plants, animals, fungi and microorganisms. According to INBio's database (the Atta system), there are at least 2659 vascular plant species in ACOSA, distributed over 203 families and 1029 genera. The ECOMAPAS Project has been able to report a total of 794 vascular plant species in ACOSA, being 7.7 % of the 10.350 plant species recorded for Costa Rica and 30.9 % of the vascular flora known from ACOSA, according to INBio's Atta database. At this moment, only 44.7% of ACOSA is still covered with forest, mainly concentrated in the Corcovado and Piedras Blancas National Parks.
The ecosystem classification system we applied was developed on basis of the International System for the Classification of the World's Vegetation as proposed by the UNESCO in 1973. We implemented the modifications that were recommended by the USGS-NPS Vegetation Mapping Program (The Nature Conservancy, 1994) and adapted the system to the particular situation of Costa Rica as an extraordinarily species-rich country. Classification systems that have been applied in Costa Rica in the past were taken into account during the development of the current ecosystem classification system. This system is hierarchical, can be applied at multiple scales and makes use of different levels of classification, among which the physiognomic, floristic, climatic, hydrologic and anthropogenic levels prevail. It is a flexible system, which is easy to use, scientifically rigorous, usefull at the international level, compatible with other international classification systems, efficient and effective.
The vegetation and other types of land use are jointly considered to be one of the most important components in ecosystem description, while also being one of the most clear indicators of ecosystem health condition. For this reason, land cover and in particular the existing vegetation, are used as basic ecosystem attributes which help most in their identification, characterization, mapping, monitoring, conservation and sustainable use.

The floristic data gathered at 184 sample points in ACOSA were analyzed. Thus, on basis of identification in the field and collection of 316 botanical specimens, a total of 794 vascular plant species were recorded. A total of 59 species were new records according to the Atta information system, which stores the taxonomic information generated by INBio. There were at least 82 endemic plant species in ACOSA. As a result, 38 ecosystems were identified, distributed over 28 natural and semi-natural, and 10 cultural ecosystems, ranging from different types of dense forest to coffee and rice plantations.
The geographic and ecological data presented in the corresponding book (see: source), were incorporated into a Geographical Information System (GIS), which permits a great flexibility in the design and production of thematic maps on land cover, ecosystems and vegetation. This GIS may easily be extended, updated or modified, depending on the needs of the different sectors of society.
This information may be used by both its collectors and administrators, as well as by other national and international bodies, thus contributing to the conservation and sustainable use of Costa Rica's biodiversity. The information presented here will particularly put a basis for a monitoring process that will focus on spatial changes in ecosystem conditions in time. This will be fundamental for formulating necessary recommendations related to decision-making in planning, management and sustainable use of biodiversity at the long term.

Kappelle, M., M. Castro, H. Acevedo, L. González, & H. Monge. 2002 (in press). Ecosystems of the Osa Conservation Area, Costa Rica. Ministerio de Ambiente y Energía (MINAE) & Instituto Nacional de Biodiversidad (INBio). INBio, Santo Domingo de Heredia, Costa Rica.