2.2. Experimental design
The study was carried out within the LTSRP plots established at
INPA by the Instituto Boliviano de Investigacio´n Forestal. At INPA,
there are 8 plots with an average size of 21.25-ha, grouped in two
blocks. Each block was established in a different logging
compartment logged in a different year, using a randomized block
design, for a total of 160 ha of study plots. All plots were first
delineated on the ground using an inventory map to select areas
with similar densities of harvestable trees. Plots were then
randomly assigned to one of four treatments, except that the
control treatment plots were located so as to maximize the area of
adjacent unharvested forest.
Plots received one of four treatments that vary in management
intensity consisting of: (a) unharvested, ‘‘control’’; (b) harvested
following the technical norms of the Bolivian forestry law, which
requires the application of reduced-impact logging techniques,
‘‘normal’’; (c) ‘‘light silviculture’’ plots harvested as the normal
treatment but with application of additional, low-intensity
silvicultural treatments; and, (d) ‘‘intensive silviculture’’ plots
that were harvested at twice the intensity of the normal treatment
and with application of more intensive silvicultural treatments
(Table 1). The more intensive treatments were intended to enhance
the growth of potential commercially marketable individuals,
especially FCTs. FCTs are individuals of commercial species
(Table 2) that are too small to be harvested in the first cutting
cycle (i.e., 10–50 cm DBH for current commercial species and 20–
50 cm DBH for potentially commercial species) but that have
adequate form (excellent to good stem quality and perfect to
tolerable crown form; see Section 2.3 for more details) and are
expected to be harvested in the future. In the intensive silviculture
treatment, a longer species list based on expected future marketability
was used for defining FCTs (Table 2).
LTSRP plots have a nested design in which trees 40 cm in DBH
are included in the entire plot, trees 20 cm in DBH in the central