Elevational gradient on the arboreal flora on Moutain Cuscuzeiro, Ubatuba (SP) : a phytogeographic, phytosociologic and floristic analysis / A vegetação arborea em um gradiente altitudinal no Morro Cuscuzeiro, Ubatuba (SP) : uma analise floristica, fitossociologica e fitogeografica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The classification and delimitation of different vegetational formations into a phytogeographic system in Brazil has been a challenge to ecologists, botanists, and phytogeographers. The current distribution of these formations is related to historical process of land use and complex environment gradients, occurring in horizontal (latitude, longitude and edafic) and vertical (altitude) ways. The aims of this study were (a) to describe the changes in floristic composition and structure of tree species along an elevational gradient on Morro do Cuscuzeiro, Ubatuba (SP), and to verify the occurrence of a Cloud Forest that can be discriminated by floristic and structural paremeters; and (b) to analyze the phytogeographic position of the communities found in this mountain in relation to other surveys of the Atlantic Rain Forest domain in Southern and Southeastern Brazil. Mountain Cuscuzeiro is located in the Serra do Mar State Park (at 23° 18 14" S, 44° 47 16" W it is 1277m in height). A survey of tree species was made in four elevational levels, 820m, 970m, 1120m, and 1270m, using 10 samples of 10x10m on each level, except on the higher one, which was sub-divided in two sub-levels whith five samples on each. The sampling criterion was 4,8cm of DBH (except in the two higher sub-levels, where 3,2cm of DBH was used). The analysis resulted in consistent groups at the different levels, indicating a strong altitude influence on the floristic composition. An abrupt change of the vegetation was identified at 1120m, from where a typical Ombrophilous Dense Forest (slope forest from 820m to 970m) shifted into a Cloud Forest formation (1120m to 1270m). These two formations were inserted in a matrix made by a total of 1546 species of 112 surveys from 78 locations of Atlantic Rain Forest domain in southern and southeastern Brazil. The multivariate analysis resulted in five groups of samples: 1- The Cloud Forest; 2- The coastal province (further subdivided into (a) the slope forests and (b) a subgroup composeded by the mountaintop and the coastal plain forests); 3- The Araucaria Forest; 4-The Semi-Deciduous Forest; and 5- The Montane Semi-Deciduous Forest. The formations found on Mt. Cuscuzeiro were included in the groups of the Cloud Forest (from 1120m to 1270m) and of the Coastal Province (from 820m to 970m), which reinforced the results of the local elevational gradient analysis, showing that minor changes on altitude can lead to abrupt changes in community composition due to the occurrence of species with disjunct distribution that are shared with other Cloud Forest formations of southern and southeastern Brazil

ASSUNTO(S)

gradiente altitudinal cloud forest elevational gradient floresta nebular atlantic forest (brazil) phytogeography plant communities fitogeografia comunidades vegetais

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