486
Functionality aims to attain the persistence, resilience, and stability of the
restored ecosystem, once the intervention is finished (Falk et al. 2001). Therefore, it
focuses on the current adaptation of the gene pool used and on the adaptability to
the future environmental conditions (unknown) of the implanted trees and of the
next generations that will succeed them naturally. Consequently, a high level of
genetic variation is necessary to ensure functionality, which can be detrimental to
authenticity. Some authors recommend the inclusion of non-local gene pools in the
restoration program, thus adding genetic diversity, particularly when local populations are genetically impoverished (Vergeer et al. 2004; Broadhurst et al. 2008;
Vander Mijnsbrugge et al. 2010). Others, instead of promoting the increase of
genetic diversity, focus on avoiding its loss (Basey et al. 2015), recommending management measures for all the stages of seedling production (collection, cleaning,
storage and germination of seeds, and the maintenance of seedlings in the nursery).
In any case, the solution to the authenticity vs. functionality dilemma will be a balance that the restoration program must decide in a more or less arbitrary way.
In turn, the objectives of authenticity and functionality should also be considered
in afforestation for productive purposes, provided it is carried out with a native species, that is, in a place where the same species is naturally present. In this case, the
functionality must be understood in a productive rather than ecological sense.
Adaptation to current conditions will continue to be of primary interest, but instead,
the adaptability of the next generations will lose relevance. This is not the case with
the risk of genetic contamination, which could be large if the plantation size is significant compared to the surrounding natural populations.
Several real cases of productive use of native species in the current Argentine
scenario require caution regarding genetic risks. Some of them refer to subtropical
rainforest species with disjoint distribution ranges. For example, Cordia trichotoma
is present in both the Yungas and the Alto Paraná Rainforest, and we still do not
know the level of genetic differentiation between these two regions. Until knowledge is gained, the ongoing breeding program for C. trichotoma maintains both
origins separate, in fact considering them to belong to different breeding zones, and
consequently a particular program for each of them is being developed.
Likewise, there are also cases of possible interspecific hybridization of species of
the same genus with disjoint distribution, for example, in the genera Cedrela and
Handroanthus. In fact, Cedrela fissilis from the Alto Paraná Rainforest has been
planted successfully in the Yungas, for the enrichment of degraded forests. We do
not know yet if this may have any impact on the natural populations of C. balansae,
C. angustifolia, or C. saltensis. The case of Handroanthus, with H. impetiginosus in
the Yungas and H. heptaphyllus in the humid Chaco, is of less urgent resolution
since until now, these species have only been planted as urban ornamental trees and
in experimental trials.
Another case that deserves special attention has the Chaco as its setting. The
ongoing Prosopis alba breeding program has been able to identify a provenance
M. J. Pastorino et al.
Functionality aims to attain the persistence, resilience, and stability of the
restored ecosystem, once the intervention is finished (Falk et al. 2001). Therefore, it
focuses on the current adaptation of the gene pool used and on the adaptability to
the future environmental conditions (unknown) of the implanted trees and of the
next generations that will succeed them naturally. Consequently, a high level of
genetic variation is necessary to ensure functionality, which can be detrimental to
authenticity. Some authors recommend the inclusion of non-local gene pools in the
restoration program, thus adding genetic diversity, particularly when local populations are genetically impoverished (Vergeer et al. 2004; Broadhurst et al. 2008;
Vander Mijnsbrugge et al. 2010). Others, instead of promoting the increase of
genetic diversity, focus on avoiding its loss (Basey et al. 2015), recommending management measures for all the stages of seedling production (collection, cleaning,
storage and germination of seeds, and the maintenance of seedlings in the nursery).
In any case, the solution to the authenticity vs. functionality dilemma will be a balance that the restoration program must decide in a more or less arbitrary way.
In turn, the objectives of authenticity and functionality should also be considered
in afforestation for productive purposes, provided it is carried out with a native species, that is, in a place where the same species is naturally present. In this case, the
functionality must be understood in a productive rather than ecological sense.
Adaptation to current conditions will continue to be of primary interest, but instead,
the adaptability of the next generations will lose relevance. This is not the case with
the risk of genetic contamination, which could be large if the plantation size is significant compared to the surrounding natural populations.
Several real cases of productive use of native species in the current Argentine
scenario require caution regarding genetic risks. Some of them refer to subtropical
rainforest species with disjoint distribution ranges. For example, Cordia trichotoma
is present in both the Yungas and the Alto Paraná Rainforest, and we still do not
know the level of genetic differentiation between these two regions. Until knowledge is gained, the ongoing breeding program for C. trichotoma maintains both
origins separate, in fact considering them to belong to different breeding zones, and
consequently a particular program for each of them is being developed.
Likewise, there are also cases of possible interspecific hybridization of species of
the same genus with disjoint distribution, for example, in the genera Cedrela and
Handroanthus. In fact, Cedrela fissilis from the Alto Paraná Rainforest has been
planted successfully in the Yungas, for the enrichment of degraded forests. We do
not know yet if this may have any impact on the natural populations of C. balansae,
C. angustifolia, or C. saltensis. The case of Handroanthus, with H. impetiginosus in
the Yungas and H. heptaphyllus in the humid Chaco, is of less urgent resolution
since until now, these species have only been planted as urban ornamental trees and
in experimental trials.
Another case that deserves special attention has the Chaco as its setting. The
ongoing Prosopis alba breeding program has been able to identify a provenance
M. J. Pastorino et al.