Atlantic Mountain Grasslands

In the highlands of the Itatiaia Range at altitudes between about 2000-2400 m grasslands almost exclusively dominate well-drained areas. They generally grow to about 20 cm in height and typically include Andropogon incanus, Calamagrostis montevidensis, Danthonia montana, Panicum demissum, P. setifolium and the endemic Briza braziliensis and Bromus brachyanthera (Poaceae) together with species of Deschampsia, Festuca and Trachypogon. Isolated woody species may also occur with gnarled trunks and irregular open crowns. They are invariable associated with large boulders presumably as a form of shelter. Among other characteristic species are Clethra laevigata, Roupala gardneriana, R. lucens, R. schwackeana and the endemic Weinmannia discolor (Cunoniaceae). On well-drained slopes particularly where there are low levels of organic matter in the soil dense swards of the endemic dwarf bamboo Chusquea pinifolia (Poaceae) can be found. These can reach heights of 2 m and are almost impenetrable in places. In the flatter, poorly drained areas, grasslands dominated by the tall, endemic grass Cortaderia modesta (Poaceae) usually form the main vegetation type. These tall, bunch-grass formations can range in height from 1-2 m, but individual clumps are often separated by up to 1 m.

Atlantic Mountain Wetlands

In the Itatiaia Mountain Range most of the bogs are dominated by graminoids but usually have a ground layer of Sphagnum moss. In the wettest areas the upper layer is typically dominated by Cladium ensifolium, but when slightly dryer conditions prevail the endemic grass Cortaderia modesta (Poaceae) usually becomes the main species. Associated species include Alstroemeria isabellana, Blechnum schomburgkii, Polystichum quadrangulare and Rhabdocaulon coccineus. The many small swamps are also largely dominated by graminoides particularly of the genera Bulbostylis and Fimbristylis. Sphagnum again dominates the lower stratum but small plants such as Anagallis tenella, Ranunculus montevidensis and the local endemic Hydrocotyle itatiaiaensis (Apiaceae) may also be present. Ponds and lagoons such as Lagoa Bonita, locally referred to as ‘pozzinas’ usually have bottom dwelling species like Isoetes gardneriana and I. martii, while the emergent vegetation typically include Juncus microcephalus and the endemic Juncus ustulatus (Juncaceae) together with several species of Eriocaulaceae. Creeping plants like Lilaeopsis ulei and the local endemic Boopis itatiaiae (Calyceraceae) may also be present. Stream margins are typically dominated by shrubby vegetation in which Azara uruguayensis, Leucothoe rivularis and Myrica hispida usually predominate, while the ground layer of these communities is typically dominated by creeping plants such as Blechnum pennamarina and the endemic Geranium brasiliense (Geraniaceae) and Itatiaia cleistopetala (family?).

Atlantic Mountain Rupicolous Formations

These upland rupicolous or rocky plant formations occur in isolated patches in a number of the Atlantic Serras. On the high plateau of Itatiaia, for example, there are good examples. Here this vegetation can vary considerably over very short distances. Vegetation islands dominated by the local endemic mat-forming species Fernseea itatiaiae (Bromeliaceae) or Pleurostima gounelleana (Velloziaceae) are often in close proximity to wetland species such as Juncus microcephala and the endemic Utricularia reniformis (Lentibulariaceae) and Xyris teres (Xyridaceae), and woody plants like Eupatorium alpestre and the endemic Baccharis stylosa (Asteraceae). On talus slopes, the endemic tank bromeliad Vriesea itatiaiae (Bromeliaceae) is often the main species. These upland areas provide harsh condition for plant life. There is increased exposure to wind and the rocky substratum has low levels of nutrients and water retention. The specialist flora includes species with various adaptations. Some, for example, (mostly members of the Cyperaceae and Velloziaceae in South America) are know as ‘resurrection’ plants in that they are capable of rehydrating desiccated leaves. Other adaptations to the lack of water include atmospheric roots, bulbs and tank-forming leaves. In fact, geophytes, such as the endemic Alstroemeria foliosa (Alstroemeriaceae), Hippeastrum morelianum (Amarylidaceae) and Stevia camporum (Asteraceae) are among the most abundant species with a high frequency in all microhabitats. Therophytes, on the other hand, are rare. The low nutrient budget and short growing season is thought to preclude any rapid establishment and growth. Many other species are endemic to these rocky upland areas and a number of these such as Begonia lanstiakii (Begoniaceae), Briza itatiaiae, Chusquea microphylla (Poaceae), Leiothrix argyroderma, Paepalanthus itatiaiensis (Eriocaulaceae), Salvia itatiaiensis (Lamiaceae), Senecio arygrotrichus (Asteraceae), Viola uleana (Violaceae), Xyris wawrae (Xyridaceae) and the fern Doryopteria feei (Pteridaceae) are confined to Itatiaia. In the Serra das Cabaças part of the Serra do Mantiqueira, cushions of Trilepis lhotzkiana dominate many of the so-called monocotyledonous mats that cover many of the granitic outcrops. Other common associates include Nanuza plicata, Rhynchospora emaciata, Stevia claussenii and the endemic Vellozia candida (Velloziaceae). The most important mat forming plants are species of Bromeliaceae and Velloziaceae, and these mats act as an important substratum for other species to colonize. Other endemic species found here include Baccharis stylosa (Asteraceae) and Sininga magnifica (Gesneriaceae). A defining feature of these communities is their so-called oligarchic structure. In other words, they have few dominant species but support many locally rare species. Similar formations are found on the Gneiss-granite outcrops around Rio de Janeiro (Serra do Mar). Trilepis lhotzkiana is again the most frequent species closely followed by Nanuza plicata, Epidendron elongatum, Pleurostima purpurea, Selaginella convoluta, S. sellowii and the narrow endemic cactus Cephalocereus fluminensis (Cactaceae). Plant endemism is again incredibly high. In fact, certain separated narrow endemics are within seeing distance of each other highlighting the insular character of these outcrops. Among the many narrow endemics are Alcanterea geniculata (Bromelaceae), Anthurium sucrii (Araceae), Manihot leptopoda (Euphorbiaceae), Paliavana racemosa (Gesneraceae), Pleurostima seubertiana (Velloziaceae), Rhipsalis cereoides (Cactaceae), Trilepis ciliatifolia (Cyperaceae) and Vernonia longo-angustata (Asteraceae). 

Atlantic Summit Formations

In the summit zones of the Itatiaia Range at altitudes ranging from about 2400-2770 m, even the most favourable, sheltered areas are subject to extremes of wind and temperature. In the most extensive formations, the endemic bamboo Chusquea pinifolia (Poaceae) typically dominates, and can stand up to a height of 1 m. In high, shady, often humid valleys between the highest peaks there are dense shrubby formations growing up to 2 m in height. Typical species here include Griselina ruscifolia, Myrica hispida, Purpurella hospita and the endemic Leandra sulfurea (Melastomataceae). Often mixed with these shrubs is the endemic Fuchsia campos-portoi (Onagraceae). Crevices provide habitat for various low growing herbs and shrubs, a number of which form tight cushions. Typical species include Achyrocline satureoides, Chionolaena glomerata, Lepechinea speciosa and Leuchopholis capitata. On relatively flat areas where the rock has become broken up, such, as on Aqulhas Negras and Prateleiras, there are interesting, compact carpets of Oxalis calva and Zygocactus obtusangulus, which can be up to 10 cm thick.

References

Anon. 1996. Habitats of South America. Institute of Terrestrial Ecology and Intitut Royal Des Sciences Naturelles De Belgique.

Caiafa, A. N. & Da Silva, A. F. 2007. Structural analysis of the vegetation on a highland granitic rock outcrop in Southeast Brazil. Revista Brasileira De Botanica, 30: 657-664.

Jacobi, C. M., do Carmo, F. F., Vincent, R. C. & Stehmann, J. R. 2007. Plant communities on the ironstone outcrops: a diverse and endangered Brazilian ecosystem. Biodiversity and Conservation, 16: 2185-2200.

Meirelles, S. T., Pivello, V. R. & Joly, C. A. 1999. The vegetation of granite rock outcrops in Rio de Janeiro, Brazil, and the need for its protection. Environmental Conservation, 26: 10-20.

Porembski, S., Martinelli, G., Ohlemüller, R. & Barthlott, W. 1998. Diversity and ecology of saxicolous mats on inselbergs in the Brazilian Atlantic rainforest. Diversity and Distribution, 4: 107-119.

Ribeiro, K. T., Medina, B. M. O. & Scarano, F. R. 2007. Species composition and biogeographic relations of the rock outcrops flora on the high plateau of Itatiaia, SE-Brazil. Revista Brasiliera de Botânica, 30: 623-639.

Segadas-Vianna, F. 1965. Ecology of the Itatiaia Range, Southeastern Brazil. Arqu. Mus. Nacional, LIII: 1-30.