3.4. Volume increment
The total volume of all species increased by
38% between 1981 and 1992 (Table 6), and a
similar increase (37%) was observed for the
commercial species. As expected, the periodic
annual increment in volume followed the general
declining trend observed for the PAIdbh.
In 1992, there were only six trees and 18 m3
ha- I larger than 45 cm dbh (the commercial size
according to the Brazilian forestry regulations)
represented on the 1979 commercial species list,
and only a few smaller trees of these species appeared
to be candidates for the next harvest.
However, since the forest was logged, many additional
species have been accepted by the timber
market, and a revision of the species list revealed
a further 29 species that could be
designated commercial.
These additional 29 species boost the commercial
volume in 1992 to 54 m3 ha-’ in 15 trees
per hectare, and more than double the anmtal increment
including ingrowth (Table 6). This is
comparable with other silvicultural systems in
Suriname (Jonkers and Schmidt, 1984) and in
Malaysian dipterocarp forest (Thang and Yang,
1989 ). Even though the initial logging was considered
heavy by regional standards, growth to
date suggests that a second cut of similar inten-
sity may be possible after 30-35 years. Remeasurements
of the permanent sample plots should
continue on a regular basis for the next 30 years
or more, to confirm this assertion and to provide
a better basis for forest management
prescriptions.