This research had as objective evaluation the floristic and structural of a Mixed Rain
Forest and arboreal vegetation under an Araucaria angustifolia stand of 60 years,
located in the National Forest of Irati, Paraná State - Brazil. A research area (A) of 10
ha was installed in an araucária stand, and other (B) of 25 ha in a forest. This areas
was structured in continuous blocks of 1 ha (100 x 100 m) divided in plots of 0,25 ha
(50 x 50 m). Using control strips of 10 x 50 m in the plots, each arboreal individual
was numbered, identified, mapped, and measured DBH above 10 cm. They were
found 124 species in the total, 79 in the area A and 108 in the area B, of which 63
species in common. Ilex paraguariensis, Ocotea odorifera and Araucaria angustifolia
were the species of larger occurrence in the area B, while the area A presented
Myrsine umbellata, Psychotria vellosiana and Casearia sylvestris. The Shannon’s
indices calculated for the 10 blocks in the area A were statistically equals, and for the
25 blocks in the area B, presented significant differences, tested by analysis of
variance. The Hutcheson test showed statistical difference among the Shannon’s
indice of area A (H'=3.17) and of area B (H’=3.55). The diametric distribution from
arboreal individuals under the araucária stand (A) was shown less variable than
individuals of Mixed Rain Forest (B), being more concentrated in first diameter class
(10 to 15 cm). Appling the Kolmogorov-Smirnov test, it was verify statistically that the
10 blocks in area A presented none similar diametric distribution to the 25 blocks of
area B. The araucária planting had unimodal distribution, typical of even age forest,
with 297 trees/ha with basal area of 30.2 m²/ha, while in natural environment (area B)
the specie did not possess define distribution, being the frequency smaller than the
area A (42.1 trees/ha) and as consequence basal area 7.68 m²/ha. With clustering
analysis 6 groups with similar covering values were constituted. With discriminant
analysis it was selected by stepwise 12 variables (species) being able to discriminate
the ambient (formed groups). Accomplishing the fitossociological analyses of the
formed groups the following associations were identify: association with Araucaria
angustifolia stand I and II, association Nectandra grandiflora, association Ocotea
porosa, association Ocotea odorifera and association Matayba elaeagnoides. In each
group a block was selected for spatial structure analysis using Ripley’s K function.
The groups of the area A had spatial random when appraised all the individuals,
while the clustering pattern was identified in the groups of the Forest. It was identified
a regular pattern of the araucárias in the two groups of the research area A, in a
scale of up to 10 m. In the area B, the appraised species accompanied the pattern of
distribution of the groups in general. The spatial dependence was revealed in some
cases showing tendencies to attraction between two species and repulse for others.
