Relações solo-vegetação no Parque Nacional da Serra do Cipó, Espinhaço Meridional, Minas Gerais / Soil vegetation relationships in the National Park Serra do Cipó, in Espinhaço Meridional, Minas Gerais

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The region of Serra do Rio Cipó, in the southern part of the Serra do Espinhaço, comprises large areas of Cerrado, Atlantic forest, forest islands and one of the richest high-altitude rocky vegetation in Brazil. The ecotonal character between the Cerrado and Atlantic Forest biomes, described in many studies of regional flora and fauna, is one of the factors responsible for the remarkable biological diversity found in this ecosystem. The purpose of this study was to characterize sequences of representative soils of the Serra Cipó with different lithologies and vegetation types, describe and characterize aspects of flora and phytophysiognomy of the tree component of two "capões de mata" (forest islands within the natural grassland) and investigate the soil- vegetation relationships of the area, based on an analysis of soil and vegetation gradients of high-altitude grassland, in two "capões de mata" in the region of Alto Palácio, National Park Serra do Cipó, (Parna-Cipó) and in an area of environmental protection Morro da Pedreira. The flora of two transects (T1 and T2) was investigated in 64 plots (10 m x 10 m), with a total sampled area of 6400 m2. A total of 1535 plants were identified in the floristic survey, in these two transects, belonging to 213 species from 50 families. Trees with a CBH ≥ 15 cm (trunk circumference 1.30 cm above the ground) were included in the inventory. In 40 forest plots 887 trees of 164 tree species of 40 angiosperm families were identified. The most frequent species were Guatteria selowiana (Annonaceae), Casearia decandra (Flacourtiaceae), Coussarea contracta (Rubiaceae), Tibouchina cf. stenocarpa (Melastomataceae), Myrcia splendens, Myrcia amazonica (Myrtaceae) and Myrsine ferruginea (Myrsinaceae). The families with the greatest number of trees were Myrtaceae with 159 plants, Rubiaceae (78), Lauraceae (74), Annonaceae (67), Myrsinaceae (60) and Melastomataceae (56). The families with the greatest number of species were Myrtaceae with 30 species, Lauraceae (27 spp.), Leguminosae (8 spp.), Melastomataceae (7 spp.) Sapindaceae (7 spp.) and Sapotaceae (6 spp.). Seventeen soil profiles were opened in three high-altitude transects of grassland and forest. Underlying the capão de mata of transect 1 are soils derived from weathering metapelitic (phylite) rock, of transect 2 soils derived from weathering meta-psammitic (quartzite) rock and of transect 3 soil derived from weathering metabasic (amphibolite) rock (the data of transect 3 were used as additional information in Chapter 3 of this study). The soils of the Serra do Cipó, regardless of the geological matrix, profile depth and vegetation growing on them are generally acidic, nutrient-poor and rich in aluminum. The poor chemical status is mainly due to the nature of the prevailing geological matrix of the system and can be partly explained by leaching and erosion losses from the system in the past and present. Regardless of the parent rock, in areas with deeper soil grows shrub to tree vegetation, characterized by "capões de mata" which occur in three different situations: (i) "Capões de mata" are most frequently found on soils derived from weathering metapelitic (phylite) rocks; (ii) secondly, these forest vegetation types occur on soils derived from weathering metabasic (amphibolite) rock; (iii) while the occurrence of such forest formations on soils derived from weathering metapsammitic (quartzite) rock is rarest. Although in these places the abundance is apparently greater, the predominant soils are extremely nutrient-poor, where the "capões de mata" occur as "islands" in the midst of the surrounding grassland environment. The soil physical properties, e.g., depth and texture, favor the retention of moisture in the soil and the development of forest vegetation. In sandy soils, about 80% of the sand fraction consists of very fine sand (0.106 to 0.053 mm) that plays an important role in soil moisture retention. The mean humidity (simple mean) was 0.15 in transect 2, and 0.24 (simple mean) in the clay soils of transect 1. In terms of soil chemistry, the soils are slightly less nutrient-poor under "capões de mata" than under grassland. The moisture in the system is notably higher on the eastern side of the Serra, where the forest vegetation is related to the flora of the Atlantic Forest biome and can be characterized as rainforest fragments with elements of cloud forest. The results of this study indicate that, in view of the chemical poverty of the soil and parent rocks, the great nutrient reserve of the "capões de mata" is contained in the proper vegetation, which is highly dependent on biogeochemical cycling. The results also indicate that these capões, aside from their floristic relationships with the Atlantic Forest biome, have characteristics and an identity of their own, particularly in floristic and ecological aspects. Since they differ from other forest formations, they are a source of great interest for science and in terms of conservation.

ASSUNTO(S)

ciencia do solo vegetation gradients gradientes de solos soil gradients gradientes de vegetação ecologia de paisagens landscape ecology

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