Estudo floristico e fitossociologico de um trecho de mata ciliar do Rio Paraguai, Pantanal-MS, e suas relações com o regime de inundação

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

A floristic and phytosociological study was carried out in a galIery forest of the Paraguay river near Corumbá and Ladário - MS, Brazil. Structural aspects of the forest were correlated to the flooding of the river, and the dynamics and some caracteristics of dispersion of the species were evaluated. The floristic survey comprised an area of about 22 km along the river, between 18° 59 51"S; 57°39 17" W and 19° 01 12" S; 57° 26 44" W, including trees, shrubs and vines, inside the area of influence of the Lagoa Negra basin. The phytosociological survey was accomplished in an area between coordenates 19° 01 16" S; 57° 27 01"W and 19° 01 12" S; 57° 26 44"W. 106 contiguous 10x10m quadrats were established. AlI individuaIs with more than 15 cm PBH were surveyed. After two years the sampled individuaIs which had died were verified. The floristic survey totalIed 113 species, 39 families. Legurninosae was the most representative family, with 24 species; Bignoniaceae with 9; Convolvulaceae with 7; Arecaceae with 5; Apocynaceae, Euphorbiaceae, Myrtaceae, Malpighiaceae, Polygonaceae and Rubiaceae with 4 species each. Trees and shrubs occurred in the proportion of 59,73%, while the proportion of the vines was 30,93%. The study area presented a floristic composition characteristic of transition between amazonian forest and the wet environrnents of the "Chaco". In the phytosociological survey 716 individuals of 37 species and 29 families were sampled. The Shannon index (H ) found for the species was 2,63 and this value is in accordance with the values found for sites with high flooding levels. The highest values of IV (Importance Value) was found for Inga vera ssp affinis, Triplaris gardneriana, Ocotea suaveolens, Crataeva tapia, Vochysia divergens, Cecropia pachystachya, Eugenia cf polystachya, Tabebuia heptaphylla, Myrcia cf mollis and Albizia polyantha, with a great advantage for Inga vera ssp affinis which showed values much higher than the other species in alI of the evaluated parameters. The study forest presented a canopy between 6 and 10 meters, sometimes reaching 13 m, with discontinuous understorey. Some individuaIs of Tabebuia heptaphylla, were found reaching 14m. It was observed that the species were distributed according to a topographicaI leveI, resulting from the flooding to which they were subjected. The more frequent species were grouped in: high places species (found in places which remained flooded a maximum of 10% of days); intermediate high places species (found flooded between 6 and 30% of days); intermediate low places species (found flooded between 10 and 48% of days) and low places species (found flooded between 30 and 48% of days). The total mortality index between the years 1994 and 1996 was 4,2%. For the individuals with a diameter higher than 15 cm, it was 3,56% and for those with diameters between 5 and 15 em, it was 4,6%. This elevated mortality index was associated to the exeptionally high flooding that happened in 1995. The study forest is a pioneer community that is in sucession apparently controlled by the levels of flooding. Twenty-eight of the 37 species found in the phytosociological study are apparently dispersed by animals, confirming a tendency to this kind of dispersion in regularly flooded evironrnents

ASSUNTO(S)

pantanal mato-grossense mata ciliar ecologia vegetal

ACESSO AO ARTIGO

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