101
the entire trial was 53 cm, being Epulauquen the population with, on average, the
smallest seedlings. The effects of both population and family were significant; family explained 5% of the total variance. Accordingly, intrapopulation variation was
low (mean h
2
= 0.19), whereas differentiation resulted moderate (Q ST = 35%). It is
noteworthy that the estimation of Q ST after excluding the Epulauquen population
fell down to 17%.
During 2004, a field trial including ten natural N. obliqua provenances was
installed at Lake Lácar, Lanín National Park (40° 07′ 48″ S, 71° 28′ 48″ W, 920 m
asl) with the aim of evaluating genetic variation at growth traits and survival,
beneath a mixed forest of Nothofagus dombeyi (Mirb.) Oerst, N. obliqua and
N. alpina (Azpilicueta et al. 2014). The site is characterised by volcanic soils and a
mean precipitation of 2200 mm/year. Survival and height were measured at the first
and fourth years from trial installation, and both measurements were used to calculate growth rate. Tree survival was high (94% and 91% at the first and fourth year
after installation, respectively), according to the optimal environmental conditions
of the trial site. Analysis of variance revealed that the population effect gave rise to
significant differences for both years of measurements regarding total height and
relative growth. According to Tukey’s tests, mean plant height was significantly
lower for Epulauquen than for all other analysed populations, except for two of
them also belonging to the north of the species range. On the other hand, Epulauquen
exhibited the highest relative growth rate, significantly different from all the other
populations except for two northern populations belonging to the watersheds of
Quillén and Ñorquinco.
Another field trial was installed in 2009 in Bariloche Experimental Station of
INTA (Instituto Nacional de Tecnología Agropecuaria) (41° 07′ 21.17″ S; 71° 14′
56.95″ W; 795 m asl) with the aim of analysing genetic variation in early traits
(Barbero 2014). It was composed by 40 open-pollinated families from four environmentally contrasting natural populations of Argentina (Epulauquen, Pilo lil, Yuco,
Catritre; 24 seedlings per family; N = 960). It had a randomised complete block
design, with single-tree plots and seedlings distributed at high density, with a plantation frame of 25 × 25 cm, with the purpose of reducing the environmental noise.
In order to analyse growth traits, during the second growing season, the height of
each sapling was measured every 10 days so as to build an individual growth curve
for each sapling by means of nonlinear regressions (Boltzmann model). On average,
growth initiated (t 10 : time to reach 10% of the season growth) in the 332 day of the
year (DOY) (November 27); whereas growth ceased (t 90 : time to reach 90% of the
season growth) in the 388 DOY (January 22). Differences for t 10 were proved only
for Epulauquen population, which was the last to initiate growth, thus evidencing a
low interpopulation differentiation for this trait (Q ST = 11%). The significance of the
family factor could not be proved. The variation for t 90 was higher, but the pattern
was similar: family was also not significant, and the most different population was
Epulauquen which, on average, was the first to cease its growth. Differentiation in
this case resulted moderate to high (Q ST = 47%).
4 Roble pellín (Nothofagus obliqua): A Southern Beech with a Restricted…
the entire trial was 53 cm, being Epulauquen the population with, on average, the
smallest seedlings. The effects of both population and family were significant; family explained 5% of the total variance. Accordingly, intrapopulation variation was
low (mean h
2
= 0.19), whereas differentiation resulted moderate (Q ST = 35%). It is
noteworthy that the estimation of Q ST after excluding the Epulauquen population
fell down to 17%.
During 2004, a field trial including ten natural N. obliqua provenances was
installed at Lake Lácar, Lanín National Park (40° 07′ 48″ S, 71° 28′ 48″ W, 920 m
asl) with the aim of evaluating genetic variation at growth traits and survival,
beneath a mixed forest of Nothofagus dombeyi (Mirb.) Oerst, N. obliqua and
N. alpina (Azpilicueta et al. 2014). The site is characterised by volcanic soils and a
mean precipitation of 2200 mm/year. Survival and height were measured at the first
and fourth years from trial installation, and both measurements were used to calculate growth rate. Tree survival was high (94% and 91% at the first and fourth year
after installation, respectively), according to the optimal environmental conditions
of the trial site. Analysis of variance revealed that the population effect gave rise to
significant differences for both years of measurements regarding total height and
relative growth. According to Tukey’s tests, mean plant height was significantly
lower for Epulauquen than for all other analysed populations, except for two of
them also belonging to the north of the species range. On the other hand, Epulauquen
exhibited the highest relative growth rate, significantly different from all the other
populations except for two northern populations belonging to the watersheds of
Quillén and Ñorquinco.
Another field trial was installed in 2009 in Bariloche Experimental Station of
INTA (Instituto Nacional de Tecnología Agropecuaria) (41° 07′ 21.17″ S; 71° 14′
56.95″ W; 795 m asl) with the aim of analysing genetic variation in early traits
(Barbero 2014). It was composed by 40 open-pollinated families from four environmentally contrasting natural populations of Argentina (Epulauquen, Pilo lil, Yuco,
Catritre; 24 seedlings per family; N = 960). It had a randomised complete block
design, with single-tree plots and seedlings distributed at high density, with a plantation frame of 25 × 25 cm, with the purpose of reducing the environmental noise.
In order to analyse growth traits, during the second growing season, the height of
each sapling was measured every 10 days so as to build an individual growth curve
for each sapling by means of nonlinear regressions (Boltzmann model). On average,
growth initiated (t 10 : time to reach 10% of the season growth) in the 332 day of the
year (DOY) (November 27); whereas growth ceased (t 90 : time to reach 90% of the
season growth) in the 388 DOY (January 22). Differences for t 10 were proved only
for Epulauquen population, which was the last to initiate growth, thus evidencing a
low interpopulation differentiation for this trait (Q ST = 11%). The significance of the
family factor could not be proved. The variation for t 90 was higher, but the pattern
was similar: family was also not significant, and the most different population was
Epulauquen which, on average, was the first to cease its growth. Differentiation in
this case resulted moderate to high (Q ST = 47%).
4 Roble pellín (Nothofagus obliqua): A Southern Beech with a Restricted…