The method we follow in this paper attempts to draw comparisons among several previous report of this type and other types.
Taking into account the importance of nomenclature, this report presents flora and fauna according to the Linnean naming system to facilitate understanding in a scientific context.
This report includes a considerable volume of scientific information as documental groundwork was carried out by technicians with prior experience relating to STP flora and fauna and the problems of biodiversity in the country. Data came from investigative reports undertaken per the ECOFAC (Forest Ecosystems in Central Africa) program for the Conservation and Rational Use of Dense Ecosystems and the reports on preservation by several government authorities. The information available was complemented by on-site research to better understand preservation of environment and resources as well as the impact of steps already taken in São Tomé and Príncipe.
Considering that available publications are an important source of information, it was difficult to gather data for this report. Figure 7 illustrates ecosystems and habitats under threat in the archipelago.
Synopsis of Information on São Tomé and Príncipe
The scheme below concisely presents a descriptive overview of São Tomé and Príncipe according to ENPAB data.1
São Tomé and Príncipe are the two main islands of this archipelago country located on the Gulf of Guinea. 380km off mainland Africa, the main geographical coordinates are: Latitute 0o 25’N, longitude 6o 20’E. The islands present a land surface of roughly 1,001 square kilometers (859km2 for São Tomé island, 142km2 for Príncipe island).
Fig. 1: Maps of the geographical situation of São Tomé and Príncipe
The islands are part of a volcanic range that includes Pagalu to the southwest and Bioko on the northeast, extending to the African mainland via Cameroon Mountain and reaching Lake Tchad. The islands have never been physically connected to each other or the African mainland.
The archipelago has arisen from relatively old volcanic activity (3 million years). The landforms are diverse, including peaks reaching 1500 meters. The highest is the Pico de São Tomé, 2024m above sea level (see charts in annexes I and II). Most of the country, however, is under 800m.
Annual average rainfall is 2,000 to 3,000mm/year, and up to 7,000m/year in mist forests.
There is a humid tropical climate with two seasons: a hot rainy season lasting about 9 months, and a dryer season from June through September. Annual average rainfall is 2,000 to 3,000mm/year, and up to 7,000m/year in mist forests. The average annual temperature is 26º C. (see maps 7 and 8)
To assess the vulnerability of soil vis-à-vis climactic changes, we must consider the following basic concepts:
tropical soil, especially forest soil, is not very fertile — fertility is heavily dependent on vegetable covering that ensures a cycle of mineralization for organic matter;
Besides existing nutrients, soils are fertile when they possess an optimum physico-chemical structure for the exchange of cations and the circulation of water and oxygen;
The way soil has been used also defines its productive capability: several years of intense cultivation, or never being used for agricultural purposes, will result in different soil profiles.
Regarding the orographic and eco-climatic situation, as well as the history of soil use, the most vulnerable to climate changes are tropical fersialitic and black clay soils (see figure 2, below).
Fig. 2: Illustration of soil most vulnerable to climate change
Source: Study on vulnerability to climate changes - forest and soil sector
CHAPTER II – GENERAL DESCRIPTION
As shown in the table below, S. Tomé is home to a great number of species: birds, amphibians, superior plants, bats, reptiles, butterflies and mollusks, distributed throughout different ecosystems and habitats.
2.1. Groups of Organisms in São Tomé and Príncipe — number of non-endemic and endemic species
(Source: ENPAB-Agriculture 2002; Ogonovszky 2003, World Bank 2003).
Source: ENPAB-Agriculture 2002; Ogonovszky 2003, World Bank 2003).1
As stated above, the islands on the Gulf of Guinea are a part of the western African sub-region related to the Congo River basin, and are known for high rates of endemism.
Both São Tomé and Príncipe exhibit a rate of endemism around 14%, the highest in the Gulf of Guinea.
This is due to the following factors: small size of the islands, isolation and diverse habitats.
The most representative families in the land angiosperm groups are: Rubiaceae (27 species), Orchidaceae (35 endemic), Euphorbiaceae (11 endemic), Melastomataceae (8 endemic in a total of 17, i.e., 47% endemism), Begoniaceae (6 endemic in a total of 11, i.e., 55% endemism).2
As for taxonomic diversity, there are pteridophytes, including ferns, lycopods, psilophytes and field horsetails. The latter group is not found in S. Tomé and Príncipe. There are a total 157 pteridophytes.3 As for ferns, there are 13 endemic species on both islands (see table 2 below).
The diversity of spermatophytes comprises 113 families represented by 791 taxa at specific or intra-specific levels (10). There are 683 taxa in São Tomé and 330 in Príncipe.
Orchids are a privileged family on the islands, with a rate of endemism around 23%. The total number of species is 135, and 35 are endemic. The polystachia and bulbophyllum genera present the largest number of species.
Certain groups of organisms are better known than others, so there must be further research. The best-studied groups are vascular plants.
The list of endemic plants on both islands is comprised of 148 endemic taxa, 123 in S. Tomé and 50 in Príncipe.4
These 148 endemic taxa have been assessed with the IUCN categories adapted to the archipelago. 14,9% endemic species on São Tomé and Príncipe are deemed extinct (EX), 12,8% are critically endangered (CR), 10,8% are endangered (EN), 41,9% are vulnerable (VUD2), 12,2% are near threatened (NT) and 7,4% are of least concern (LC).
46% of species in non-protected areas of São Tomé have been deemed extinct, 41% in the buffer zone are threatened and may disappear if no action is taken, and 39% of threatened species are located within the bounds of Park Obô. The latter will be effectively protected is the park’s boundaries are legalized and protected.
The number of threatened animal species is: 16 bird species, 10 insect species, 4 mollusk species and three mammal species (see table 12 below).