228
At the farm level, long-term rotation between agriculture, livestock, and forestry
can be considered, maintaining productivity and soil health, and supporting productive diversification, heterogeneity of the territory and job positions. At the regional
level, territorial planning, the establishment of biological corridors, the creation of
protected areas (and the strengthening of existing ones), and the development of
forest industry clusters are desirable. Thus, native tree species are basic bricks of
this building, and genetic improvement is a necessary procedure to build with the
best bricks.
To end this chapter, we present a group of species not treated in the rest of the
book that we consider key to put in practice the reconversion of the productive systems in the Chaco. They are useful for timber and non-timber products, and at the
same time, several of them are structuring of fundamental ecosystems in the region.
However, these species are not yet the object of breeding programs. Their actual
distribution areas are not known in detail, and they do not count with basic and sufficient biological, genetic, and ecophysiological studies for the management of their
genetic resources. There are not any natural or planted seed-producing areas of
these species. Most of them have no specific protocols for DNA extraction or PCR
amplification nor have specific molecular markers been isolated.
8.5.1 Red Quebrachos: Schinopsis spp. (Anacardiaceae)
Schinopsis is a small genus that includes only seven species distributed in the tropical and subtropical dry forests of South America (Mogni et al. 2017). The red quebrachos cited for the Argentine Chaco (S. balansae, S. lorentzii, S. heterophylla, and
S. haenkeana) are the dominant species of the humid, semi-arid, and Serrano Chaco
(Fig. 8.7). Their wood of extreme density (> 1 kg/dm
3
), hardness and durability
characterizes them. They have a high content of tannins that in the heartwood can
reach 42% in S. balansae. This species was declared the “National Forest Tree” of
Argentina (decree 15190/56).
Quebrachos are trees that reach 20–25 m in height with diameters that can exceed
1.5 m. The crown has a characteristic inverted cone shape that allows it to be easily
distinguished. They have alternate, simple, or imparipinnately compound leaves;
lateral or terminal paniculate inflorescences; staminate or pistillate flowers with
vestigial ovaries or stamens depending on the case; samaroid fruits with a woody
endocarp and a persistent calyx; seeds with membranous testa (Muñoz 2000). The
genus is polygamous-dioecious, with hermaphrodite and unisexual flowers on the
same or different trees (Muñoz 2000). However, Barberis et al. (2012) in a very
detailed review of S. balansae state that this species is dioecious.
From the end of the nineteenth century to the mid-twentieth century, the largest
exploitation in history of red quebrachos occurred. Trees were felled for the production of railway sleepers and fence posts, and, to a much greater extent, for the
extraction of tannins. A single company of English origin (the sadly famous “La
Forestal”) is estimated to have exploited around 2 million ha of forests during this
A. Verga and D. López Lauenstein
At the farm level, long-term rotation between agriculture, livestock, and forestry
can be considered, maintaining productivity and soil health, and supporting productive diversification, heterogeneity of the territory and job positions. At the regional
level, territorial planning, the establishment of biological corridors, the creation of
protected areas (and the strengthening of existing ones), and the development of
forest industry clusters are desirable. Thus, native tree species are basic bricks of
this building, and genetic improvement is a necessary procedure to build with the
best bricks.
To end this chapter, we present a group of species not treated in the rest of the
book that we consider key to put in practice the reconversion of the productive systems in the Chaco. They are useful for timber and non-timber products, and at the
same time, several of them are structuring of fundamental ecosystems in the region.
However, these species are not yet the object of breeding programs. Their actual
distribution areas are not known in detail, and they do not count with basic and sufficient biological, genetic, and ecophysiological studies for the management of their
genetic resources. There are not any natural or planted seed-producing areas of
these species. Most of them have no specific protocols for DNA extraction or PCR
amplification nor have specific molecular markers been isolated.
8.5.1 Red Quebrachos: Schinopsis spp. (Anacardiaceae)
Schinopsis is a small genus that includes only seven species distributed in the tropical and subtropical dry forests of South America (Mogni et al. 2017). The red quebrachos cited for the Argentine Chaco (S. balansae, S. lorentzii, S. heterophylla, and
S. haenkeana) are the dominant species of the humid, semi-arid, and Serrano Chaco
(Fig. 8.7). Their wood of extreme density (> 1 kg/dm
3
), hardness and durability
characterizes them. They have a high content of tannins that in the heartwood can
reach 42% in S. balansae. This species was declared the “National Forest Tree” of
Argentina (decree 15190/56).
Quebrachos are trees that reach 20–25 m in height with diameters that can exceed
1.5 m. The crown has a characteristic inverted cone shape that allows it to be easily
distinguished. They have alternate, simple, or imparipinnately compound leaves;
lateral or terminal paniculate inflorescences; staminate or pistillate flowers with
vestigial ovaries or stamens depending on the case; samaroid fruits with a woody
endocarp and a persistent calyx; seeds with membranous testa (Muñoz 2000). The
genus is polygamous-dioecious, with hermaphrodite and unisexual flowers on the
same or different trees (Muñoz 2000). However, Barberis et al. (2012) in a very
detailed review of S. balansae state that this species is dioecious.
From the end of the nineteenth century to the mid-twentieth century, the largest
exploitation in history of red quebrachos occurred. Trees were felled for the production of railway sleepers and fence posts, and, to a much greater extent, for the
extraction of tannins. A single company of English origin (the sadly famous “La
Forestal”) is estimated to have exploited around 2 million ha of forests during this
A. Verga and D. López Lauenstein