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Pruning regimens IN STUMP TEAK PLANTATIONS
Although teak is an established high-value tree for commercial planting, the resulting
timber may not produce the expected quality and yield (Tze 1999). Pruning has been a
common, though empirically developed, silvicultural technique used to obtain high quality
timber (Hubert and Courrand 1988). Knots are widely considered as the most determinant
defect for wood quality classification; to the point of influencing the origin and magnitude
of other defects such as pith eccentricity, stem-form deviation from the geometric cylinder
shape, and bending (Rosso and Ninin 1998).
International grading rules have strict standards for classifying high-quality timber,
including the appearance of knots (number, frequency, diameter, sound or unsound). Yield
and market prices decrease considerably for trees without pruning interventions, since
lumber must be almost free of knots in order to be sold at attractive prices. For instance,
international grading rules do not allow the presence of knots on timber wood of “special”
grade. For first quality or grade 1, the permissible amount of knots is one per linear meter,
with a maximum diameter of 1.25 cm. For the lowest grade within international standards
(grade 3), a total of three knots per linear meter with a maximum of 3.81 cm of diameter is
allowed (Tanteak 1995). Market prices for teak timber may vary from 400 to 2500 US$ m-3,
depending on the grading rate assigned to the product.
Torres et al. (1995) carried out a silvicultural evaluation of tree plantations in Costa
Rica, and found that pruning is more often considered to be a cleaning activity rather than a
silvicultural technique. More often is the practice of drastic pruning (removal of almost all
the branches) of young trees in teak farms and even in medium-size companies. There are
few recommendations for pruning intensities for timber species in Costa Rica. In general, it
is recommended to prune trees up to 50% of the total height just after the first thinning
(Keogh 1987, Chaves and Fonseca 1991, Galloway 1993), or according to commercial log
sizes, i.e. up to 2.5 m sections (Murillo and Camacho 1997). Majid and Paudyal (1992)
16
consider that pruning should be done at early stages in order to minimize knotty cores.
Moreover, early pruning (at 2 or 3 years of age for tropical species) should be performed on
all trees to avoid suppression by neighboring trees. Hubert and Courrand (1988),
Hochbichler et al. (1990), and Raets (1964) consider that the diameter at pruning height
should be three times greater at harvesting than it was at pruning, in order to make the
activity economically profitable.
In many countries where large-scale teak plantations have been established recently, the
importance of intensive and on time pruning interventions is not yet clear. In Central
America, for instance, pruning is carried out arbitrarily, i.e. executed after visual
assessment using subjective criteria, without considering important scientific and
economical criteria such as maximization of volume free of knots vs. costs of pruning. The
pruning of teak trees must be carried out intensively during early plantation stages, since
later the costs of the activity increase while the benefits decrease
FURTHER DETAILS CONTACT
BALAKRISHNA MUTHUKURI
MOTHER AGRI BIOTECH INDIA PVT. LTD.
BANGALORE.
+919035003471
Although teak is an established high-value tree for commercial planting, the resulting
timber may not produce the expected quality and yield (Tze 1999). Pruning has been a
common, though empirically developed, silvicultural technique used to obtain high quality
timber (Hubert and Courrand 1988). Knots are widely considered as the most determinant
defect for wood quality classification; to the point of influencing the origin and magnitude
of other defects such as pith eccentricity, stem-form deviation from the geometric cylinder
shape, and bending (Rosso and Ninin 1998).
International grading rules have strict standards for classifying high-quality timber,
including the appearance of knots (number, frequency, diameter, sound or unsound). Yield
and market prices decrease considerably for trees without pruning interventions, since
lumber must be almost free of knots in order to be sold at attractive prices. For instance,
international grading rules do not allow the presence of knots on timber wood of “special”
grade. For first quality or grade 1, the permissible amount of knots is one per linear meter,
with a maximum diameter of 1.25 cm. For the lowest grade within international standards
(grade 3), a total of three knots per linear meter with a maximum of 3.81 cm of diameter is
allowed (Tanteak 1995). Market prices for teak timber may vary from 400 to 2500 US$ m-3,
depending on the grading rate assigned to the product.
Torres et al. (1995) carried out a silvicultural evaluation of tree plantations in Costa
Rica, and found that pruning is more often considered to be a cleaning activity rather than a
silvicultural technique. More often is the practice of drastic pruning (removal of almost all
the branches) of young trees in teak farms and even in medium-size companies. There are
few recommendations for pruning intensities for timber species in Costa Rica. In general, it
is recommended to prune trees up to 50% of the total height just after the first thinning
(Keogh 1987, Chaves and Fonseca 1991, Galloway 1993), or according to commercial log
sizes, i.e. up to 2.5 m sections (Murillo and Camacho 1997). Majid and Paudyal (1992)
16
consider that pruning should be done at early stages in order to minimize knotty cores.
Moreover, early pruning (at 2 or 3 years of age for tropical species) should be performed on
all trees to avoid suppression by neighboring trees. Hubert and Courrand (1988),
Hochbichler et al. (1990), and Raets (1964) consider that the diameter at pruning height
should be three times greater at harvesting than it was at pruning, in order to make the
activity economically profitable.
In many countries where large-scale teak plantations have been established recently, the
importance of intensive and on time pruning interventions is not yet clear. In Central
America, for instance, pruning is carried out arbitrarily, i.e. executed after visual
assessment using subjective criteria, without considering important scientific and
economical criteria such as maximization of volume free of knots vs. costs of pruning. The
pruning of teak trees must be carried out intensively during early plantation stages, since
later the costs of the activity increase while the benefits decrease
FURTHER DETAILS CONTACT
BALAKRISHNA MUTHUKURI
MOTHER AGRI BIOTECH INDIA PVT. LTD.
BANGALORE.
+919035003471
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