The characteristic feature of the region is the Araucaria
forests, which occur mainly between 400 and 1,000 m asl
along watercourses, valleys, hillsides, and grasslands on the
plateau (IBGE 1992). The presence of A. angustifolia determines
the vegetation physiognomy; these trees occur in continuous
forest habitats, as well as in patches embedded in the plateau
grasslands. The forest on the hillsides and valleys of the study
area can be considered a disturbed forest, but with a high
level of biotic integrity, since it was only selectively logged
a few decades ago. At the time of the study, the Pinus elliottii
plantation was 27 years old and the A. angustifolia plantation
areas were circa 30 years old. Both plantations were surrounded
by native forests. Thus, any species colonizing the plantations
were likely dispersed from a neighbor native forest.
Sampling design
Four areas were located within each of three different
vegetation types: native forest (NF), P. elliottii plantations
(PP), and A. angustifolia plantations (AP). The mean distance
between the areas was 8 km, and between each area in the
vegetation type, 2 km. In each sampling site, six transects (at
least 100 m from the edge) were delimited 100 m distant from
each other. Perpendicular 50 m-long lines were established
from each of the six marked transects. Within each line, five
secondary points (10 m from each other) were marked. In each
secondary point, a point-centered quarter (Cottam & Curtis
1956) was established, and the closest individual tree with a
diameter at breast height (DBH) ≥ 47 mm was sampled in each
of the four quadrants, totaling 150 points for each vegetation
type. Subsequently, the individuals were identified to species
level and the density of these was calculated. Field data was
obtained from January to April of 2009. In the plantations,
individuals that were conspecific with the planted trees were
disregarded in the analysis. This precaution was needed
because our main goal was to analyze the arrival of propagules
from outside the stands.