Location and General Description
Caatinga moist forest enclaves (regionally called "brejos") represent well-defined patches of Atlantic forest surrounded by the Caatinga dry forest and the Cerrado savannalike vegetation in northeast Brazil. The climate is tropical with an annual rainfall around 1,000 to 1,300 mm. The dry period is from July through December (Lyra 1984). Forest enclaves are found mostly on four major regional plateaus (Chapada do Araripe, Serra de Ibiapaba, Serra de Baturité, and Serra da Borborema), whose rocks are very diversified in origin, varying from the Cretaceous to the Silurian (IBGE 1985). Forest covers the windward slopes and plateaus between 600 and 800 m elevation. The main type of vegetation is Atlantic semi-deciduous forest, with four strata of vegetation and emergent trees taller than 30 m (Veloso et al. 1991). The emergent and canopy layers are rich in tree species of Leguminosae (Peltophorum dubium), Meliaceae (Cedrella fissilis) and Apocynaceae (Aspidosperma pyricollum) (Andrade-Lima 1957). Habitats of transition between Atlantic forest, Caatinga dry forest and Cerrado vegetation are also found. A combination of tree species from Amazonian forest (Apeiba tibordou), Caatinga (Croton campestris), Cerrado (Parkia platycephala) and from the south portion of Atlantic forest (Podocarpus sellowii) sets this ecoregion apart from other portions of the Brazilian Atlantic forest.
Enclaves exist as forest islands within the semi-arid caatingas that surrounds them (Bigarella et al. 1975, Andrade-Lima 1982). Plant and animal species reached these forested areas at times of greater humidity when continuous forest existed (Andrade-Lima 1982, Sales et al. 1998). Examples of currently confined tree species are Podocarpus sellowii (Podocarpaceae), Prunus sphaerocarpa (Rosaceae), and Manilkara rufula (Sapotaceae). Today, forest enclaves are extraordinary natural laboratories in which confined populations of plants and animals are passing through a process of differentiation. In fact, some isolated populations have already differentiated enough to be recognized as species. Examples are found in plants, amphibians, lizards, and birds. The most extraordinary examples are some amphibians and birds. The amphibian example is given by Hoogmoed et al (1994) that described two interesting species of the genus Adelophryne, a forest frog. One species is endemic to Serra do Baturité (A. baturitensis) whereas the other closely related species is restricted to Serra de Maranguape (A. maranguapensis), located some kilometers apart. The bird example is the Araripe's manakin (Antilophia bokermanni), a wonderful bird recently discovered on the forest slopes of Chapada do Araripe. Forest enclaves are diverse; approximately 900 vascular plant species were recorded on of Chapada do Araripe. The richest plant families are Rubiaceae, Euphorbiaceae, Asteraceae, and Orchidaceae (Sales et al. 1998). Even with their considerable biological importance, forest enclaves remain poorly studied. Forest enclaves are of tremendous importance for regional populations, because they play the essential function of controlling the water cycle in a region where water is a critical resource (Cabral 2000).
Because of their more comfortable climate, Caatinga moist forest enclaves receive much stronger human pressure than their semi-arid surroundings. Consequently, these forests have been reduced in area by 96 percent (SOS MATA ATLÂNTICA 1993). Forest conversion into c still persists at alarming rates (Coimbra-Filho & Câmara 1996). Remaining natural vegetation is represented by 1,915.7 km2 of semi-deciduous forest, with the last largest blocks of habitat (10 to 20 km2) restricted to the areas with difficult access for people (SOS MATA ATLÂNTICA 1993).
Types and Severity of Threats
Four protected areas (from only 0.11 to 382 km2) cover 399 km2 of semi-deciduous forest (SOS MATA ATLÂNTICA 1993, Lima & Capobianco 1997). Subsistence agriculture and forest harvesting to provide wood for fuel threaten the remaining vegetation.
Justification of Ecoregion Delineation
These patches of moist forest are very distinct floristically and faunistically from the surrounding caatinga xeric shrublands, and occur on isolated mountains and ridges. Delineation’s were derived from the IBGE (1993) map following the classification of secondary "open ombrophilous forest", which occur as habitat islands in the greater caatinga ecoregion. Linework was reviewed and modified by expert opinion at a priority setting workshop (10-14 August, 1999).
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Prepared by: Jose Maria C. da Silva
Reviewed by: In process