Included here is the so-called Atlantic forest zone on 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 but other vegetation types occur including sand dune vegetation.

Atlantic Coastal Sand Dunes

Dunes on the Atlantic coast of Brazil comprise of a large variety of different vegetation zones ranging from foredunes to primary and secondary dune scrub and flooded dune forest.

Foredunes
This zone extends from the upper part of the beach to the top of the foredune crest and may be inundated by seawater during exceptionally high tides. It is therefore dominated by prostrate, largely succulent halophytes. The main species is Blutaporon portulacoides but other frequent species include Alternanthera maritima and Sesuvium portulacastrum.   

Primary Dune Zone
This zone can extent from five to a few hundred metres inland and is normally less than 2 m high but can reach heights of up to 100 m on the north-eastern coast where it is frequently mobile and unvegetated. It is typically composed of a creeping psammophytic zone which in places gives way to low closed thicket.

Creeping Psammophyte Primary Dune Zone
This zone is mainly dominated by grasses and sedges such as Mariscus pedunculatus, Panicum racemosum and Sporobolus virginicus but also includes broad-leaved creeping plants like Canavalia rosea, Ipomoea littoralis and Ipomoea pes-caprae. In southern latitudes Spartina ciliata becomes the main species. Plant height rarely exceeds more than about 30 cm (about 1 m in the case of Spartina) and plant cover is usually less than 20%.  

Low Closed Thicket Primary Dune Zone
In certain areas such as along the coast of Rio de Janeiro and southern Espirito Santo where there has been less of a human impact the creeping psammophyte zone gives way to dense, dune shrub vegetation. This can reach heights of up to 3 m in the back-dune zone. The most abundant species are Bumelia obtusifolia, Schinus terebinthifolius and the endemic Jacquinia brasiliensis (Theophrastaceae). The zone also includes a number of cacti and bromeliads and the liana Aristolochia macroura.

Swale Zone
Between successive beach ridges are low areas known as swales. These zones are usually less than 300 m but support a huge diversity of species ranging from typical hydrophytes to wet forests. At least four communities have been recognised. These include sedge swamp, periodically flooded forest, permanently flooded forest and Ericaceae open scrub. These all appear to relate to differing ground-water levels

Swamp Sedge Swale
These zones are inundated for most of the year but water depth is usually less than 20 cm. Sedges such as Eleocharis subarticulata, Rhynchospora corymbosa and Rhynchospora holoschoenoides are the dominant species but grasses, such as Panicum pumilum and Paspalum arenarium are common while Tibouchina urceolaris and Xris jupicai are conspicuous along the edges of the flooded zones.

Periodically Flooded Forest Swale
Reaching no more than about 15 m in height these forests are typically dominated by Calophyllum brasiliensis and Symphonia globulifera. The understory usually includes Psychotria carthaginensis and Rheedia brasiliensis while Aechmea pineliana is a frequent herb layer bromeliad. Also frequent is the understory palm Geonoma schottiana.

Permanently Flooded Forest Swale
Dominated by Tabebuia cassinoides, which forms a canopy up to 8 m high, these forests are otherwise relatively poor in species. The few other species include the palm Bactris setosa and small specimens of Symphonia globulifera, while in the understory the fern Acrostichum danaefolium is a characteristic feature.

Ericaceae Open Dune Scrub
These distinctive scrublands are most extensively found on the north-eastern plains of the Rio de Janeiro coast.  They are typically found on slightly elevated area where termite hills occur. The characteristic species include Andira legalis, Esterhazya splendida, Gaylussacia brasiliensis, Protium icicariba and the endemic Leucothoe revolute (Ericaceae) and Ocotea notata (Lauraceae).  In some areas the area between scrub is covered by a dense stand of the low shrub Marcetia taxifolia. The herbaceous layer typically comprises dense stands of Vriesea procera, and Catasetum discolor is a characteristic ground orchids.

Secondary Dunes
This zone can extend from about 500 m from the ocean inland for several kilometres but in exceptional circumstances can form a zone up to 25 km wide. It eventually grades into Atlantic rainforest. The zone can be resolved into three communities: Myrtaceae closed thicket, Clusia open scrub, and palm open scrub.

Secondary Dunes with Myrtaceae Closed Thicket
Reaching about 4 m in height this zone is dominated by species of the family Myrtaceae with Eugenia and Myrcia being the most important genera. These 2 genera contribute up to about 12 of the species. Other important shrubs are Aspidosperma pyricollum, Cupania emarginata, Esenbeckia rigida, Gomidesia maritime, Melanopsidium nigrum, Myrrhinum atropurpureum, Pouteria psammophila, Rheedia brasiliensis and Zollernia falcate. The herbaceous layer largely comprises Aechmea lingulata, Billbergia amoena and the endemic Quesnelia quesneliana (Bromeliaceae). Bromeliads are reported to be important colonisers of these open dunes.

Secondary Dunes with Clusia Open Scrub
Forming dense often hemispherical thickets interspersed with bare patches these open scrublands can reach heights of up to 4 m. Clusia is the most important genus but species composition varies from site to site. Typical species include Clusia australis, Clusia fluminensis, Clusia lanceolata and the endemic Clusia hilariana (Clusiaceae). Other characteristic shrubs include Cassia australis, Erythroxylum ovalifolium, Eugenia nitida, Gomidesia fenzliana, Manilkara subsericea, Myrica lundiana and Tapirira guianensis.  Also characteristic are various climbing plants such as Mandevilla funiformis, Passiflora mucronata, Peixotoa hispidula and the endemic Paullinia weinmanniaefolia (Sapindaceae). The sparse herbaceous layer is characterised by various Anthurium and Polypodium species together with various bromeliads and cacti.  Terrestrial bromeliads, such as Aechmea nudicaulis, Vriesea procera and the endemic Neoregelia cruenta, are often found in the borders around thickets. In the sparsely vegetated areas between thickets isolated plants of many species can be found. The most characteristic of these are Allagoptera arenaria, Cassia ramose, Pilosocereus arrabidae, Stachytarpheta schottiana and Stigmaphyllon paralias.

Secondary Dune with Palm Open Scrub
Whenever other forms of secondary dune vegetation is burned on the Rio de Janeiro coast a low scrub community dominated by the palm Allagoptera arenaria often becomes the dominant vegetation. This disclimax can often cover up to 30% of any devastated area. Other important species include Axonopus barbigerus, Byrsonima sericea and Vriesea neoglutinosa.

References

Lucerda, L. D. D., Araujo, D. S. D. D. & Maciel, N. C.  1993. Dry Coastal Ecosystems of the Tropical Brazilian Coast. In: Ecosystems of the World. 2B. Dry Coastal Ecosystems. Africa, America, and Oceana. Ed. Eddy van der Maarel. Elsevier.