4. Conclusions
Logging and the resulting changes in canopy
structure altered the composition of the stand,
reducing the number of shade tolerant species
and stimulating light demanding species. There
has been a nett increase in stem numbers and
stand basal area during the 11 year observation
period, and this trend has been echoed by most
of the individual species. The stand basal area 13
years after logging was about 75% of that in a
comparable unlogged primary forest. Logging
stimulated growth, but this effect was short-lived,
lasting only about 3 years, and current growth
rates are similar to those in unlogged primary
forest. Tree growth and timber production may
be enhanced by periodic silvicultural treatment
to release trees from competition and this should
be considered as a mechanism to reduce the cutting
cycles in the Brazilian Amazon.
The recognition of 29 additional species of
commercial importance raised the commercial
volume increment to 1.8 m3 ha-’ year-‘, but
further work will be necessary to confirm that this
production can be sustained on a 30-35 year cutting
cycle.
Results from the experiment reported here and
in related works, provide the first quantitative
information for management planning in the Ta