ARBOREAL VEGETATION ASPECTS ON A SEASONAL STEPPE SAVANNA REMAINING, IN BARRA DO QUARAÍ, RS STATE, BRAZIL

• Published in: Ciência florestal 2014-05, Vol.24 (1), p.23-36
• Main Authors: Farinha Watzlawick, Luciano, Longhi, Solon Jonas, Schneider, Paulo Renato, Guimarães Finger, César Augusto
• Format: Article
• Language: eng ; por
• Subjects: Aspidosperma quebracho-blanco; Parque do Espinilho; Prosopis; Vachelia caven; Vachellia caven
• ISSN: 0103-9954; 1980-5098
• DOI: 10.5902/1980509813320

The purpose of this study was to evaluate the floristic composition, the horizontal and vertical structures, as well as the spatial distribution patterns of the tree component in a Steppe Savanna Park located at 'Parque do Espinilho', in Barra do Quaraí, Rio Grande do Sul state, Brazil. Floristic composition and phyto-sociological analysis were carried out in a four (04) ha permanent plot (40 000 m2), where all individuals which circumference (C) was ≥ 15.7 cm, measured 30 cm from the ground, were sampled and had their circumference and total height measured. A mean of 145 individuals/ha was found, distributed in 11 species, 10 genera and eight (08) families, with basal area of 4.06 m2/ha. The Shannon Diversity Index (H') for the tree vegetation was 1.86, and the species with the highest importance values were Prosopis nigra (25.86%), Aspidosperma quebracho-blanco (24.57%), Prosopis affinis (24.30%) and Vachellia caven (10.51%), representing 85.26% of the total. The tree vegetation has two strata, the lower one with 93.3% of the trees and the upper one with only 6.7% of total. The species Aspidosperma quebrachoblanco dominated with 70.0% of trees in this stratum. Regarding the spatial distribution pattern of the species, Aspidosperma quebracho-blanco presented a grouped tendency, whereas the other ones were grouped. The savannah steppe park studied is mainly characterized by the occurrence of Aspidosperma quebracho-blanco, Prosopis nigra, Prosopis affinisand Vachellia caven, constituting a unique combination of species in Brazil, presenting question of rarity in terms of species composition and structure. O presente estudo teve por objetivo avaliar a composição florística, a estrutura horizontal e vertical, bem como os padrões de distribuição espacial do componente arbóreo e agrupamento de espécies em uma amostra de Estepe Estacional Savanícola localizada no Parque do Espinilho, Barra do Quaraí - RS. Para o levantamento florístico e análise fitossociológica foi instalada, em uma área de ocorrência de Aspidosperma quebracho-blanco , uma unidade permanente de 4 ha (200 x 200 m), onde todos os indivíduos com circunferência (C) ≥ 15,7 cm a 30 cm do nível do solo foram amostrados e medidas a circunferência e altura total. Foram encontrados 145 indivíduos/ha, distribuídos em 11 espécies, 10 gêneros e 8 famílias, com área basal de 4,06 m2/ha. A vegetação arbórea apresentou Índice de Diversidade de Shannon estimado em 1,86, sendo que as espécies com os maiores val