There is a few studies on soil seed bank in the Amazonian forests, a very few in logged
forest. A series of 180 soil samples were collected from an area where a reduced impact
logging was applied in the Rio Capim Forest Management Unit, which belongs to Cikel
Brazil Verde Madeiras Ltda., municipality of Paragominas, PA. Three treatments were
randomly distributed in 36 50mx50m plots: T0 – unlogged area; T1 – logged area,
where only the commercial boles were collected; and T2 - logged area, where the
commercial boles plus the coarse woody debois were collected. Each one of the 36
plots were divided in 25 10mx10m subplots, from which 5 were chosen to be collected
the soil samples in plots of 25cm x 25cm x 5cm. The samples were put in a green house
and monitored during a six-month period to evaluate the germination from the soil seed
bank. The seedlings were counting and identified monthly. The foristic composition of
the soil seed bank in the three forest conditions (treatments) together is constituted of
113 species from 94 genera and 51 families. In the logged forest where only the
commercial boles were collected (T1) there are 74 species, In the logged forest where
the boles plus the coarse woody debois were collected (T2) there are 67 species and in
the unlogged forest (T0) there are 72 species. The variation between treatments is very
small, indicating that the intensity of logging applied in the area has not influenced
significantly in the floristic composition of the seed bank. The total number of seedlings
was 4.323, being higher in the unlloged forest, followed by the logged area where only
the commercial boles were collected (T1) and the logged area where both the
commercial boles and the coarse woody debois were collected (T2). There was no
significant difference among the three forest conditions, although the logged area
collecting boles plus coarse woody debois (T2) had presented a smaller number of
seedlings. That same tendency was observed on the species frequency, therefore
showing that the logging has not influenced significantly the abundance or the species
distribution on area. Among the ecologically most important species in the area, 57%
belong to tree life form and, because of that, they can be used in the timber industries,
but studies are needed involving natural regeneration of these species, as well as their
young and adult populations. Also there is a need to study the technological
characteristics of the species to inform about their timber and non-timber uses, mainly
for those species most important on abundance and distribution on area, including
shrubs, herbs and lianas. The tree species Cecropia obtusa and Heisteria densifrons
are the most abundant and mort frequent species in the study area. Bixa arborea and
Glycidendron amazonicum which also are among the most abundant and the most
frequent species have already their wood properties studied and some use were
identified, so atentiou must be payed to those especies during the planning of
management and use of the forest resources in the study area.
