The influence of reduced impact logging were evaluated on the growth phases of a terra firme forest in the
Paragominas region, state of Pará, that was logged considering two intensities of timber harvesting. Data
were collected in 36 permanent sample plots (0.25ha) randomly distributed among treatments (T1 – Logged
forest, harvesting the stem of commercial trees; T2
– Logged forest, harvesting the stem and coarse woody
debris) and control (T0
unlogged forest). Three growth phases of the forest were considered: mature (DBH
> 40cm); building forest (10cm < DBH < 40cm); and gaps (occurrence of a canopy gap and a few or no
tree with DBH > 10cm). The homogeneity of variances of sub-plots between treatments, growth phases
and years was tested by the Bonferroni test, according to the statistics of Bartlett and Levene. An analysis
of variance was applied on the number of sub-plots by phases, years and treatments at a 0.005 significance
level. The Tukey test was applied for analyzing the interaction between the phases and years. Before logging
the percentage of growth phases were: 57.0% building forest, 38.9% mature forest and 4.1% canopy gaps.
Logging reduced the areas of mature forest and building forest, increasing the number of canopy gaps, but
this increase had no statistical difference. One year after logging the area of mature forest (38.4%) and
building forest (53.1%) increased while the areas of gaps (8.4%) decreased. Three years after logging the
percentage of mature forest (37.1%), building forest (57.9%) and gaps (5.0%) were similar to those found
before logging. The forest growth phases were not influenced by logging, over the study period. The study
forest showed that it is able to grow, closing the canopy gaps, even in a short period of time.
|
