Analise multivariada da distribuição geografica de especies de orquideas dos campos rupestres do Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

The geographical distribution of 72 orchid species from the "campos ruprestres" vegetation of Brazil, was analysed using multivariate methods, inc1uding c1ustering and ordination. The data set used was constructed by first creating a data bank with informations on the distribution (latitude and longitude) and habitat of each based on herbarium material and citations in floras and floristic studies. A series of six data matrices was created, based on 5 X 5 and 2 X 2 latitude / longitude squares for three habitat combinations - epiphytic, terrestrial and complete (combined). Group mean (UPGMA) and Ward s method c1ustering were used with Jaccard and Jaccard complement coefficients for c1ustering. CA and DCA were used as ordination techniques. TWINSPAN analysis was also used for some data sets. The c1ustering methods suggested that some floristic elements could be recognized, but TWINSPAN analysis showed very little agreement with these, except in the 5 X 5 epiphyte matrix. The ordination methods gave interpretable results, mainly on first two axes. Although some elements could be recognized, a large number of species could not be assigned with confidence to any of the designated elements, and it was c1ear that no simple overall c1assiftcation of floristic elements was possible. There was no obvious difference between epiphytic and terrestrial species. Results of analyses were greatly influenced by the size of square used, and by overall frequency of occurrence of the species as reflected in the number of squares they occupied.

ASSUNTO(S)

orquideas - brasil fitogeografia analise multivariada

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