The Physical Environment of Rupestrian Grasslands (Campos Rupestres) in Brazil: Geological, Geomorphological and Pedological Characteristics, and Interplays

Abstract

The Rupestrian Grassland is a vegetational complex with grassy to shrubby formations that occur throughout the high mountains of Brazil, usually formed by structurally resistant rocks, little affected by late tectonics, and strongly eroded and weathered under long term geological stability. RGC is closely associated with high altitude landsurfaces, in which several factors have a determinant role: (1) extreme oligotrophy, and acid, nutrient-depleted parent materials; (2) resistance to weathering and erosion (chemical and physical); (3) constant wind exposure; (4) intense fire regime. Variations of RG phytophysiognomies are basically due to soil depth (edaphic factor), drainage and landscape stability and evolution. Landforms (geomorphological attributes) affect the RGC at continental scales (high landsurfaces), regional scales (regional landforms, such as escarpments, valleys, slopes) and local scales (soil depth, stoniness, rockiness, drainage). The most common occurrence of RGC in Brazil is on Quartzite and metarenites, followed by canga and other Fe-rich substrates, igneous rocks and metamorphics, hence displaying a high diversity of substrates, with a major trait of extreme soil oligotrophy and acidity, and crucial variations in soil depth. The occurrence of well-documented areas of RG on Granitic and gneissic terrains imply that even richer rocks, submitted to long term weathering and erosion, can lead to similar soils on Highlands, where rock outcrops are also common (e.g. Caparaó, Itatiaia, Brigadeiro, Serra dos Órgãos). RGC can occur immersed in different domains (Atlantic Forest, Caatinga, Cerrado), regardless of present day climates, since it represents an edaphic climax of long-term development. The widespread distribution of comparable RGC, from Amazonia (Carajás, Roraima, Pacaás Novos, Cachimbo) to the Central Plateau (Santa Barbara, Ricardo Franco, Pirineus) and Northeastern and Southeastern Brazil (Caparaó, Espinhaço, Sincorá, Jacobina, Itatiaia, Serra dos Órgãos, Brigadeiro, Carangola) raises the unresolved question of phylogenetic ancestry, age and similarities (floristic, structural) between those isolated islands of Rupestrian vegetation. These aspects are central to the evolution of Brazilian Biomes, representing key issues to resolve the late Quaternary Refuge Theory controversy, and test the validity of island biogeographical isolation theories.

Appendix 1

Picture illustrations of phytophysiognomies and landscape features of Rupestrian Grassland Complex (RGC) on different lithologies in Brazil. The striking similarities between widely separate geographical sits, very contrasting parent-materials, indicate a notable convergence of edaphic/landscape features at different localities. (a) Itatiaia highlands at Campo Belo Valley (2400 m) on syenite (alkaline rocks) (mark 20 in Fig. 2.14). (b) Caparaó highlands at Upper Crystal Valley (above Terreirão Plateau), with Chusquea sp. on granitoid rocks (mark 17 in Fig. 2.14). (c) Serra do Brigadeiro Plateau Pedra do Pato, migmatites/granites Paraíba do Sul headwaters. (d) Shrubby rupestrian grassland in Serra do Espinhaço, Diamantina, Minas Gerais States, with Syagrus sp. (Palmeira da Serra), on micaceous quartzites (mark 12 in Fig. 2.14). (e) Sempre-Vivas National Park, shrubby rupestrian grassland on quartzite (mark 12 in Fig. 2.14). (f) Canastra National Park, open rupestrian grassland with Vellozia sp. on micaceaus quartzites/conglomerates (mark 19 in Fig. 2.14). (g) Ibitipoca State Park, with open rupestrian grassland on micaceous quartzites and metapelits (mark 23 in Fig. 2.14). (h) São Francisco River headwaters at Canastra National Park, with shrubby rupestrian grassland a quartzite plateau (mark 19 in Fig. 2.14). (i) Shrubby ferruginous rupestrian grassland on Fe-rich canga of Carajás Plateau, Santa Rita Durão, (see Caraça quartzite at background) (1000 m) (mark 8 in Fig. 2.14). (j) General view of ferruginous rupestrian grassland on the Fe-ich itabirite/canga on Serra Sul Plateau of Carajás (900 m) (mark 8 in Fig. 2.14). (k) Ferrugineous rupestrian grassland on the Fe-rich Itabirite/canga of Alto do Conta História (1600 m), Iron Quadrangle, Minas Gerais States (mark 16 in Fig. 2.14). (l) Exposed itabirite saprolite with overlying canga on the Moeda Plateau, with ferruginous rupestrian grassland (shrubby/open) (1380 m) (mark 16 in Fig. 2.14). (m) Open rupestrian savanna on metapelites from Serra de Grão Mogol (1200 m) (mark 12 in Fig. 2.14). (n) Open rupestrian grassland on conglomeratic quartzites of Diamantina Plateau, Minas Gerais States (mark 12 in Fig. 2.14) at 1420 m. (o) Sempre-Vivas National Park with open rupestrian grassland on quartzite with Lychnophora sp. (mark 12 in Fig. 2.14) at 1130 m. (p) Serra de São José Environmental Protected Area, Tiradentes, Minas Gerais States, with open rupestrian grassland on micaceous quartzite and schists at 1200 m (q) Pico da Neblina, the highest RG site in Brazil (close to 3000 m) on metarenites of Roraima Group, Amazonas State (mark 1 in Fig. 2.14). (r) Serra do Sol, at 2250 m altitude, on quartzites of the Roraima Group, Roraima State (mark 1 in Fig. 2.14). (s) Serra dos Pacaás Novos, with an altitude of 1050 m, an isolated spot of RG in the middle of the Amazon Forest domain, with metarenites to metapelitic rocks (mark 3 in Fig. 2.14). (t) (mark 1 in Fig. 2.14). (u) Serra Ricardo Franco, in the Brazil-Bolivia border, at Mato Grosso State, where RG occurs on metarenites (mark 4 in Fig. 2.14) at 1030 m. (v) Monte Roraima highest surface (mark 1 in Fig. 2.14), the largest Rupestrian Plateau in the Brazilian Amazonia (Roraima State), at 2850 m. (w) Monte Roraima top surface (2800 m), on Quartzite of the Roraima Group (mark 1 in Fig. 2.14). (x) Serra da Seringa, southeastern Pará State, an isolated RGC on Felsic Granites in the middle of the Caiapó Indigenous Land (mark 7 in Fig. 2.14).

Fig. 2.14

Phytophysiognomies and landscape features of Rupestrian Grassland Complex (RGC) on different lithologies in Brazil