Tese em PDF - departamento de engenharia florestal - ufpr ...

of the Jacuí River. For each sample’s unit, all woody plants with a diameter at breast
height ≥ 5 cm were measured and identified, and surface soil samples were collected
for fertility and granulometric composition analysis. In this study, 16 soil classes were
determined up to the fourth categorical level in 12 geomorphological and soil
compartments, and 3757 individuals belonging to 95 species were sampled. The
richest families in species are: Myrtaceae (16), Myrsinaceae (6), Fabaceae (5),
Euphorbiaceae (4), Rubiaceae (4) and Sapotaceae (4). In the floristic similarity
analysis, three major groups were classified, and they had high correlation with
environmental conditions and spatial distribution on the topographic gradient. For
each group, the representation of the species was determined through the ecological
guilds of dispersion, stratification and regeneration, as well as via the geographical
contingent of the species. The geographical contingent and ecological patterns of the
species were different between groups. The ordination analysis of the environment
(NMS) revealed significant differences between the sampling points of the plain and
slopes. Elevation, slope, soil texture, H + Al and CEC were the most important
variables in the analysis. The floristic ordination analysis (DCA) complemented the
cluster analysis by strengthening the existence of three major tree communities,
spatially correlated with the relief position, at different stages of conservation,
diversity and phytosociology. These were termed formation, submontane (FS),
alluvial (FA), and the area dominated by both teams (FA/FS). The FA/FS area proved
to be more diverse than the others, with lower ecological dominance in narrow
fragments. The submontane presented the highest density of individuals in larger
diameter and height classes, due to the protected location in small valleys, with high
ecological dominance by a particular shadow species, Actinostemon concolor. The
alluvial was characterized by smaller trees and the overwhelming presence of
Sebastiania commersoniana in narrow corridors. The patterns of the forest typologies
of the watershed were sorted mainly by environmental gradients and relief forms, the
sizes of the fragments linked to the disturbances, conditioning different successional
stages, that impact on the light gradient within the fragments and on environmental
control over soil moisture. This set of variables determined the distribution of the
main species and communities in the watershed.
Keywords: Pampa Biome, community ecology, forest dynamics, soil-plant
relationship, arboreal species, forest soils.
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