Included here are the so-called Atlantic forests of the southeastern coast of Brazil and its associated islands including the archipelago of Fernando de Noronha and adjacent areas of Argentina and Paraquay. The forests can be broadly divided into coastal forest and various inland forests.

Atlantic Coastal Rainforest of Brazil (Southern Bahia)

These forests represent one of the last strongholds of Atlantic lowland forest in eastern Brazil. They are structurally similar to Amazonian forest although compared with Amazonia there are far fewer buttressed roots. They are also taxonomically similar but include a high degree of endemism in their own right. Another interesting feature is the large number of primitive plants and are especially well known for their primitive bambusoid grasses. Stratification appears to vary but at least two tree layers have been recognized in southern Bahia including emergent and canopy layers. The most frequent trees include Diploon cuspidatum, Eriotheca macrophylla and the endemic Macrolobium latifolium (Caesalpiniaceae) and Rinorea bahiensis (Violaceae). Other endemic trees include Actinostemon concolor, Mabea glaziouvii, Pausandra morisiana (Euphorbiaceae), Affonsea densiflora, Calliandra bella, Inga blanchetiana, Stryphnodendron pulcherrimum (Mimosaceae), Andira nitida, Swartzia apetala, Vataireopsis araoba (Fabaceae), Aniba intermedia, Licaria bahiana (Lauraceae), Arapatiella emarginata, Chamaecrista bahiae, Harleyodendron unifoliolatum (Caesalpiniaceae), Attalea funifera, Euterpe edulis, Geonoma pauciflora (Arecaceae), Banara kuhlmannii, Carpotroche brasiliense, Casearia bahiensis (Flacourtiaceae), Couepia belemii, Hirtella angustifolia, Licania bahiensis (Chrysobalanaceae), Dulacia papillosa (Olacaceae), Elvasia tricarpellata (Ochnaceae), Eschweilera alvimii (Lecythidaceae), Guarea blanchetii, Trichilia ramalhoi (Meliaceae), Hornschuchia brytrophe (Annonaceae), Hortia arborea, Pilocarpus riedelianus (Rutaceae), Jacaratia heptaphylla (Caricaceae), Lacistema robustum (Lacistemataceae), Manilkara longifolia, Micropholis gardneriana (Sapotaceae), Miconia octopetala, Mouriri bahiensis, Tibouchina elegans (Melastomataceae), Paypayrola blanchetiana (Violaceae), Sloanea alnifolia (Elaeocarpaceae), Stephanopodium blanchetianum (Dichapetalaceae) and Virola officinalis (Myristicaceae). Tree diversity is extremely high and comparable to some of the most species rich forests in Amazonia. The epiphytic flora is also very rich. A recent study showed that up to 80% of trees supported at least some epiphytes on their trunks. These include many species of fern and Araceae but it is the Bromeliaceae that dominate the epiphytic flora in South Bahia, especially those that store water in leaf rosettes. Conspicuous are the ‘large tank’ species such as Aechmea conifera and Hohenbergia blanchetti. Other smaller but more abundant species include Aechmea lingulata, Araeococcus parvifolius and Guzmannia lingulata. Others epiphytes include the endemic Heteropsis oblongifolia, Philodendron williamsii, Rhodospatha latifolia (Araceae) and Rhipsalis pachyptera (Cactaceae). An unusual epiphyte is Codonanthe uleana (Gesneriaceae) with its large root-ball inhabited by ants. Lianas are less conspicuous. Studies show that only about 37% of trees support them. Nevertheless, there are a number of endemic species such as Forsteronia leptocarpa and Mandevilla permixta (Apocynaceae). The shrub layer includes species such as the endemic Aphelandra blanchetiana, Ruellia affinis (Acanthaceae), Baccharis singularis (Asteraceae) and Erythroxylum columbinum (Erythroxylaceae). The herb layer also includes many endemic species such as Anthurium bellum, Asterostigma riedelianum, Dracontioides descisens, Zomicarpa steigeriana (Araceae), Becquerelia clarkei, Pleurostachys gaudichaudii (Cyperaceae), Begonia subacida (Begoniaceae), Dichorisandra leucophthalmos (Commelinaceae) and Justicia symphyantha (Acanthaceae).

 

Atlantic Interior Forest of Paraguay

These forests rarely form large continuous stands but tend to alternate with areas of savanna. They are also influenced along their margins by other floras including the Chaco flora in the west, the Cerrado flora in the north and Pampas flora in the south. Nevertheless, they still constitute a major centre of endemism particularly for bird species. They typically comprise three well-differentiated tree strata and the canopy or upper stratum can reach heights of up to 40 m. The main canopy trees include Anadenanthera colubrina, Apuleia leiocarpa, Cordia trichotoma, Patagonula americana, Peltophorum dubium, Pterogyne nitens and the endemic Balfourodendron riedelianum (Rutaceae) and Cedrela fissilis (Meliaceae), Many of these have important commercial value. An intermediate tree stratum ranges in height from 10-20 m and commonly includes Holocalyx balansae. Other under storey trees include Cecropia pachystachya, Chrysophyllum gonocarpum, Diatenopteryx sorbifolia, Guarea guidonia, Hennecartia omphalandra, Inga affinis, Jacaratia corumbensis, Nectandra angustifolia, Pilocarpus pennatifolius, Plinia rivularis, Sorocea bonplandii, Trichilia catigua and the endemic Campomanesia xanthocarpa (Myrtaceae). Many of these under story trees produce edible fruits and provide an important resource for local fauna. Common shrub layer species include Piper hispidum and Piper medium together with bamboos such as Chesquea ramosissima, Merostachys claussenii and Olyra micrantha. At ground level there are various herbs and terrestrial ferns. The latter include Adianthopsis radiata, Blechnum brasiliense, Didymochlaena truncatula and Pteris denticulata. Other endemic species of these forests include Annona amambayensis (Annoniaceae), Aspidosperma polyneuron (Apocynaceae), Astronium fraxinifolium (Anacardiaceae), Cabralea canjerana (Meliaceae), Euterpe edulis (Arecaceae), Myrocarpus frondosus and Tabebuia heptaphylla (Bignoniaceae). Another important feature are the occasional almost exclusive stands of the arborescent ferns species Alsophila cuspidata and Cyathea atrovirens. These can grow to heights of up to 7 m and are often associated with slopes or streams or certain soil conditions. Associated species may include Cecropia pachystachya, Luehea divaricata and Peltophorum dubium. These areas often have an extremely rich epiphytic flora of ferns, cacti and orchids giving them an almost ‘magic’ appearance.

 

Atlantic Interior Forest of Argentina (with Rosewood & Assai Palm)

These forests found in the extreme north of Misiones on the Iquazú and Paraná river plains were once characterized by an abundance of the two endemic trees Aspidosperma polyneuron Rosewood (Apocynaceae) and Euterpe edulis Assai Palm (Arecaceae), but these have now been reduced to almost relict status. Several local endemic plant taxa occur including Begonia descoleana (Begoniaceae), Cyperus andreanus var. yguazuensis (Cyperaceae), Peperomia misionense (Piperaceae) and Podostemum comatum (Podostemaceae). (To be completed).

 

Atlantic Interior Forest of Argentina (with Laurel and Guatambu)

Forests characterized by an abundance of Nectandra species (laurels) and the endemic Balfourodendron riedelianum (Rutaceae) are found in the north and central parts of Misiones. In the west they are bordered by the Paraná River, in the east by mountains, and in the south they merge into campos. Parts of this formation occur in the gullies and flood valleys of the Paraná and its tributaries. Here along the banks of the rivers Sapindus saponaria and the endemic or near endemic bamboo Guadua paraquayana (Poaceae) typically occur.

 

References

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