420
According to the genetic structure analysis, more variable or differentiated fragments should be prioritized. Likewise, management of the plantation should ensure
its natural regeneration. Understory cleanings could be scheduled for the productive
pollen years in order to favor the development of seedlings after seed dispersion,
thus contributing to the natural regeneration of the species.
On the other hand, in view of the scarce natural regeneration observed in the
Argentinean stands (Fassola et al. 1999; Latorre et al. 2013), an ex situ conservation strategy must be considered. The ex situ production of seeds for the active
restoration of native forests would be recommendable as well, based on the aerobiological pollen background presented in this chapter. Limitations of pollen
transport for effective pollination in A. angustifolia, a direct relationship between
pollination and seeds abundance, and the influence of temperature on the different
reproductive stages of the species were confirmed. Simón et al. (2018) concluded
that A. angustifolia stands growing in a temperate climate with cold winters produce a greater amount of pollen that leads to enhanced seed production. Also, they
observed that the current climate conditions of the southern extreme of A. angustifolia natural range do not favor pollen production, thus affecting its reproduction. On the contrary, the temperate climate of the north center of the Province of
Buenos Aires (like that of 25 de Mayo) could be a suitable location for the establishment of an ex situ seed production area. Ex situ conservation banks would be
a good complementary strategy to the in situ reserves, becoming a “safeguard” of
the genetic variability of the fragments in unprotected areas or close to the region
of great demographic pressure (Bittencourt and Higa 2004). Thus, conservation
banks and seed production areas can be combined in ex situ plantations located in
appropriate sites. Consequently, a replicate of the CSO of A. angustifolia of
Manuel Belgrano Forest Station was installed in 2020 in the 25 de Mayo Forest
Station of INTA, 1450 km further south. It is constituted by 196 ramets of 30 of
the 64 genotypes present in the CSO installed in Manuel Belgrano Forest Station,
which were replicated by grafting.
In the context of climate change, progressive warming affecting the natural range
of A. angustifolia (IPCC 2001–2007) has a deep impact into its regeneration.
Therefore, the alternative of an assisted migration southward from its place of origin, to temperate climates where the environmental conditions favor its seed productivity, should be discussed. This strategy has been decided for the conservation
of Araucaria araucana in Chile, where the natural populations of this sister species
are being decimated by the occurrence of a foliar damage presumably related to the
climate change (Ipinza 2017, Chapter 7A). In any case, it is advisable to maintain
the existing plantations in temperate environments (i.e., 25 de Mayo, Buenos Aires)
as genetic reservoirs and ex situ seed production areas for native forest enrichment
or restoration programs, as well as for reforestation purposes in the Argentinean
range of the species, where natural regeneration is minimal (Pinazo et al. 2016). In
situ and ex situ conservation units are effective tools to prevent the extinction of the
species natural populations.
M. E. Gauchat et al.
According to the genetic structure analysis, more variable or differentiated fragments should be prioritized. Likewise, management of the plantation should ensure
its natural regeneration. Understory cleanings could be scheduled for the productive
pollen years in order to favor the development of seedlings after seed dispersion,
thus contributing to the natural regeneration of the species.
On the other hand, in view of the scarce natural regeneration observed in the
Argentinean stands (Fassola et al. 1999; Latorre et al. 2013), an ex situ conservation strategy must be considered. The ex situ production of seeds for the active
restoration of native forests would be recommendable as well, based on the aerobiological pollen background presented in this chapter. Limitations of pollen
transport for effective pollination in A. angustifolia, a direct relationship between
pollination and seeds abundance, and the influence of temperature on the different
reproductive stages of the species were confirmed. Simón et al. (2018) concluded
that A. angustifolia stands growing in a temperate climate with cold winters produce a greater amount of pollen that leads to enhanced seed production. Also, they
observed that the current climate conditions of the southern extreme of A. angustifolia natural range do not favor pollen production, thus affecting its reproduction. On the contrary, the temperate climate of the north center of the Province of
Buenos Aires (like that of 25 de Mayo) could be a suitable location for the establishment of an ex situ seed production area. Ex situ conservation banks would be
a good complementary strategy to the in situ reserves, becoming a “safeguard” of
the genetic variability of the fragments in unprotected areas or close to the region
of great demographic pressure (Bittencourt and Higa 2004). Thus, conservation
banks and seed production areas can be combined in ex situ plantations located in
appropriate sites. Consequently, a replicate of the CSO of A. angustifolia of
Manuel Belgrano Forest Station was installed in 2020 in the 25 de Mayo Forest
Station of INTA, 1450 km further south. It is constituted by 196 ramets of 30 of
the 64 genotypes present in the CSO installed in Manuel Belgrano Forest Station,
which were replicated by grafting.
In the context of climate change, progressive warming affecting the natural range
of A. angustifolia (IPCC 2001–2007) has a deep impact into its regeneration.
Therefore, the alternative of an assisted migration southward from its place of origin, to temperate climates where the environmental conditions favor its seed productivity, should be discussed. This strategy has been decided for the conservation
of Araucaria araucana in Chile, where the natural populations of this sister species
are being decimated by the occurrence of a foliar damage presumably related to the
climate change (Ipinza 2017, Chapter 7A). In any case, it is advisable to maintain
the existing plantations in temperate environments (i.e., 25 de Mayo, Buenos Aires)
as genetic reservoirs and ex situ seed production areas for native forest enrichment
or restoration programs, as well as for reforestation purposes in the Argentinean
range of the species, where natural regeneration is minimal (Pinazo et al. 2016). In
situ and ex situ conservation units are effective tools to prevent the extinction of the
species natural populations.
M. E. Gauchat et al.