435
considering sites with higher probability (Fig. 16.3b) and then discarding the sites
that are known to have already been transformed from forests to crops or urban
developments, thus reaching a final area of 1,030,000 ha (Fig. 16.3c). It is interesting to note that this modeled distribution also serves to identify potential areas for
cultivation of the species.
A given group of selected individuals represents each zone. So far, 133 individuals were selected in both Argentinean rainforests (Fig. 16.1). The locations belong
to the Iguazú National Park, private reserves, and forest growers or companies. In
the case of the NWA region, the populations were selected based on previous reports
about presence and density (Ledesma 2014), and no evidence of the occurrence of
the species was found south of 24° S.
The choice of phenotypically superior trees for the conformation of the base
population is a key component of any genetic improvement program, as the set of
selected trees will be the basis of future forest generations. This makes it necessary
to reach a compromise vis-à-vis achieving outstanding genotypes in terms of desirable traits and preserving the population genetic variability, which will make it possible to accomplish improvement and conservation goals, respectively. Since the
individuals were selected in the natural forest, which in this case is a complex ecosystem with difficult accessibility, this initial part of the program required the
investment of high experimental efforts. The selection criteria were health, vigor,
proportion of heartwood, and stem straightness (Rodríguez and Barth 2014). Vigor
was estimated by a minimum DBH of 30 cm and a bole height over 6 m. The proportion of heartwood was measured by Pressler borer (only in the trees selected in
NWA) (Fornes et al. 2016).
The selected trees were vegetatively propagated by grafting in the nurseries of
the two experimental stations of INTA involved in this breeding program: Yuto and
Monte Carlo. The development of vegetative propagation techniques is a highly
useful tool for improvement programs. The use of indole butyric acid (IBA) hormone in doses lower than 1000 ppm was found to promote rooting rates of 96% in
apical cuttings of C. trichotoma (Gonzalez et al. 2016), an extraordinary success
rate that would make clonal forestry possible in the future. In addition, different
types of grafts were evaluated, as well as the time between the scion harvest (from
the canopy) and the moment of grafting. The best grafting performance was achieved
using the apical full cleft technique, within 24 hours after scion harvesting, in order
to prevent dehydration (Fornes et al. 2016).
With the clones of the trees selected in the Yungas, a Clonal Seed Orchard was
installed in 2014 in Yuto Experimental Station (23° 35′ 22.15″ S; 64° 30′ 38.97″ W;
350 m asl), including 600 ramets corresponding to 69 genotypes of 7 provenances
from the Yungas. Three years later, a new Clonal Seed Orchard was established in
Laharrague Experimental Station of INTA (26° 33′ 35.61″ S; 54° 40′ 25.45″ W;
260 m asl) with 304 ramets corresponding to 64 genotypes of 7 provenances from
the Alto Paraná Rainforest.
16 Peteribí (Cordia trichotoma), Lapacho Rosado (Handroanthus impetiginosus)...
considering sites with higher probability (Fig. 16.3b) and then discarding the sites
that are known to have already been transformed from forests to crops or urban
developments, thus reaching a final area of 1,030,000 ha (Fig. 16.3c). It is interesting to note that this modeled distribution also serves to identify potential areas for
cultivation of the species.
A given group of selected individuals represents each zone. So far, 133 individuals were selected in both Argentinean rainforests (Fig. 16.1). The locations belong
to the Iguazú National Park, private reserves, and forest growers or companies. In
the case of the NWA region, the populations were selected based on previous reports
about presence and density (Ledesma 2014), and no evidence of the occurrence of
the species was found south of 24° S.
The choice of phenotypically superior trees for the conformation of the base
population is a key component of any genetic improvement program, as the set of
selected trees will be the basis of future forest generations. This makes it necessary
to reach a compromise vis-à-vis achieving outstanding genotypes in terms of desirable traits and preserving the population genetic variability, which will make it possible to accomplish improvement and conservation goals, respectively. Since the
individuals were selected in the natural forest, which in this case is a complex ecosystem with difficult accessibility, this initial part of the program required the
investment of high experimental efforts. The selection criteria were health, vigor,
proportion of heartwood, and stem straightness (Rodríguez and Barth 2014). Vigor
was estimated by a minimum DBH of 30 cm and a bole height over 6 m. The proportion of heartwood was measured by Pressler borer (only in the trees selected in
NWA) (Fornes et al. 2016).
The selected trees were vegetatively propagated by grafting in the nurseries of
the two experimental stations of INTA involved in this breeding program: Yuto and
Monte Carlo. The development of vegetative propagation techniques is a highly
useful tool for improvement programs. The use of indole butyric acid (IBA) hormone in doses lower than 1000 ppm was found to promote rooting rates of 96% in
apical cuttings of C. trichotoma (Gonzalez et al. 2016), an extraordinary success
rate that would make clonal forestry possible in the future. In addition, different
types of grafts were evaluated, as well as the time between the scion harvest (from
the canopy) and the moment of grafting. The best grafting performance was achieved
using the apical full cleft technique, within 24 hours after scion harvesting, in order
to prevent dehydration (Fornes et al. 2016).
With the clones of the trees selected in the Yungas, a Clonal Seed Orchard was
installed in 2014 in Yuto Experimental Station (23° 35′ 22.15″ S; 64° 30′ 38.97″ W;
350 m asl), including 600 ramets corresponding to 69 genotypes of 7 provenances
from the Yungas. Three years later, a new Clonal Seed Orchard was established in
Laharrague Experimental Station of INTA (26° 33′ 35.61″ S; 54° 40′ 25.45″ W;
260 m asl) with 304 ramets corresponding to 64 genotypes of 7 provenances from
the Alto Paraná Rainforest.
16 Peteribí (Cordia trichotoma), Lapacho Rosado (Handroanthus impetiginosus)...