440
Station of INTA with a plantation frame of 4 × 3.5 m showed an average growth of
1.31 cm/year in DBH and 1.07 m/year in total height (0.49 m/year of shaft height),
yielding a timber volume of 1.096 m
3
/ha/year (Gil and Del Castillo 2004). Likewise,
native forest enrichment trials (under forest canopy) were also carried out in single
rows over 5 m wide strips open in the natural vegetation, with the seedlings separated by 4, 5, and 6 m in the row. At 8 years of age, the trees reached a mean DBH
of 5.9 cm, 4 cm, and 5.9 cm for each plantation density, respectively, and a mean
total height of 4.9 m, 4.4 m, and 5.4 m, respectively (Del Castillo et al. 2005).
In the abovementioned private property of Valle Morado (Province of Salta),
three trials with Handroanthus impetiginosus were installed in 2001 and 2002, with
a plantation frame of 4 × 3 m. One of them is a pure stand over an area of 1 ha. The
two other trials are mixed, in combination with other native species of the Selva
Pedemontana of the Yungas: one with C. trichotoma over an area of 2.7 ha and the
other with Pterogyne nitens over an area of 0.9 ha. In all cases the mean diametric
growth was quite promising, with 1.3 cm/year in the pure stand, 1.6 cm/year in
combination with C. trichotoma, and 1.8 cm/year in the mixed stand with P. nitens
(Balducci et al. 2009). In the first 5 years, mortality rate remained rather low, close
to 5%, thus showing the species, a good behavior when implanted in block. The
main concerns about the species growth from a genetic improvement perspective
would be the stem straightness and the narrowness of the crown.
In view of the promising behavior of the species under a cultivation system, and
parallel to the molecular diversity studies, a low-intensity breeding program was
initiated for Handroanthus impetiginosus in Famaillá Experimental Station of
INTA. The strategy decided was to select individuals in the natural forest, propagate
them vegetatively, and install clonal seed orchards. Between 2011 and 2017, 189
plus trees were selected according to criteria defined by different private and public
institutions of the forest-industrial sector, including stem straightness, self-pruning
of the first portion of the trunk (up to 7 m height), stem taper, crown diameter, heartwood proportion, and health (especially wood health).
In practice, the selection procedure took advantage of the harvesting activities of
industrial sawmills working in the natural forest, which kindly supported the breeding program. When outstanding exemplars of H. impetiginosus were harvested,
upon notification from the sawmill company, we verified the quality of the candidates and eventually went back to the harvesting site to collected material for its
vegetative propagation (Fig. 16.5). Given the harvesting activities are commonly
performed in winter and early spring (the dry season of the year), we had a 2-month
window to find branches still alive on the soil of the forest since the cutting down of
the trees (Ignacio Sosa, pers. comm.). The selection carried out in the sawmill made
it easier to consider wood features, like heartwood proportion and wood health.
Due to the selection procedure described, most of the genotypes of the base
population of the breeding program are not anymore standing in the forest. This
made necessary to preserve them in a clonal bank. Only the best individuals of the
phenotypic ranking were finally included in a clonal seed orchard.
After locating the remains of the selected trees in the forest (by means of gps
coordinates), at least 30 branches per tree were taken to the nursery in polyethylene
L. F. Fornes et al.
Station of INTA with a plantation frame of 4 × 3.5 m showed an average growth of
1.31 cm/year in DBH and 1.07 m/year in total height (0.49 m/year of shaft height),
yielding a timber volume of 1.096 m
3
/ha/year (Gil and Del Castillo 2004). Likewise,
native forest enrichment trials (under forest canopy) were also carried out in single
rows over 5 m wide strips open in the natural vegetation, with the seedlings separated by 4, 5, and 6 m in the row. At 8 years of age, the trees reached a mean DBH
of 5.9 cm, 4 cm, and 5.9 cm for each plantation density, respectively, and a mean
total height of 4.9 m, 4.4 m, and 5.4 m, respectively (Del Castillo et al. 2005).
In the abovementioned private property of Valle Morado (Province of Salta),
three trials with Handroanthus impetiginosus were installed in 2001 and 2002, with
a plantation frame of 4 × 3 m. One of them is a pure stand over an area of 1 ha. The
two other trials are mixed, in combination with other native species of the Selva
Pedemontana of the Yungas: one with C. trichotoma over an area of 2.7 ha and the
other with Pterogyne nitens over an area of 0.9 ha. In all cases the mean diametric
growth was quite promising, with 1.3 cm/year in the pure stand, 1.6 cm/year in
combination with C. trichotoma, and 1.8 cm/year in the mixed stand with P. nitens
(Balducci et al. 2009). In the first 5 years, mortality rate remained rather low, close
to 5%, thus showing the species, a good behavior when implanted in block. The
main concerns about the species growth from a genetic improvement perspective
would be the stem straightness and the narrowness of the crown.
In view of the promising behavior of the species under a cultivation system, and
parallel to the molecular diversity studies, a low-intensity breeding program was
initiated for Handroanthus impetiginosus in Famaillá Experimental Station of
INTA. The strategy decided was to select individuals in the natural forest, propagate
them vegetatively, and install clonal seed orchards. Between 2011 and 2017, 189
plus trees were selected according to criteria defined by different private and public
institutions of the forest-industrial sector, including stem straightness, self-pruning
of the first portion of the trunk (up to 7 m height), stem taper, crown diameter, heartwood proportion, and health (especially wood health).
In practice, the selection procedure took advantage of the harvesting activities of
industrial sawmills working in the natural forest, which kindly supported the breeding program. When outstanding exemplars of H. impetiginosus were harvested,
upon notification from the sawmill company, we verified the quality of the candidates and eventually went back to the harvesting site to collected material for its
vegetative propagation (Fig. 16.5). Given the harvesting activities are commonly
performed in winter and early spring (the dry season of the year), we had a 2-month
window to find branches still alive on the soil of the forest since the cutting down of
the trees (Ignacio Sosa, pers. comm.). The selection carried out in the sawmill made
it easier to consider wood features, like heartwood proportion and wood health.
Due to the selection procedure described, most of the genotypes of the base
population of the breeding program are not anymore standing in the forest. This
made necessary to preserve them in a clonal bank. Only the best individuals of the
phenotypic ranking were finally included in a clonal seed orchard.
After locating the remains of the selected trees in the forest (by means of gps
coordinates), at least 30 branches per tree were taken to the nursery in polyethylene
L. F. Fornes et al.