This study was carried out in part of riparian forest along "Rio das Mortes (Rio das Pedras basin)" in the Municipality of Guarapuava, Paraná State, Brazil (25o19'30''S and 51o23'55''W). Analysis of the floristic composition and phytosociological structure of the arboreal component of the area and of soil macrofauna in specific points were, performed. Another objective of this research was to assess the green biomass of the arboreal component of the 15 most important species in terms of VI. It was also possible to test mathematical models capable of estimating the tree green biomass. Analysis of floristic composition and phytosociological structure of the arboreal component were analysed on base of 1,047 individual trees in 33 plots of 200m2 with DBH > 5cm, distributed in 39 species and 24 families. The Shannon-Weaver diversity index value was 2.21 nat/ind and the equability index of Pielou was 0.604. The total density found was 1,586.36 indivíduous/ha, and the medium DBH and height were 12.79cm and 7.25m, respectively. Acording to the parameters the most important species are Sebastiania commersoniana (Baillon) L.B Smith and R.J. Dows; Araucária angustifólia (Bertol) Kuntze; Allophylus edulis (A.St.–Hil., Cambess. E A. – Juss.) Radlk.; Prunus brasiliensis Shott ex Spreng, Illex brevicuspis Reissek; Zanthoxylum rhoifolium Lam. and Illex paraguariensis A.S.St.-Hil. The macrofauna study was based on 1,850 captured individuals (764 in the winter and 1,086 in the summer) in specific points, a total of 29,600 individuals/m2. These organisms have showed different behaviors according to the time of collection and the soil depth. Green biomass determinated was found to be around 276,08 tonnes/ha. From this total 48.39% corresponds to the trunk, 34.28% to the branchs, 15.64% to the root and 1.69% to the leaves. Mathematical model was adjusted for the estimate of the green biomass of the arboreal component for each studied species.
