56
extensively logged, mainly during the first half of the twentieth century, causing a
dramatic reduction of its forests (Donoso and Lara 1995; Gonzalez Peñalba
et al. 1997).
Raulí is endemic to the temperate forests of Chile and Argentina. It occurs in
Chile between 35° and 41° 30′ S in both, the Andes and Coastal Mountains (Donoso
1993). In Argentina, it has a very small range along the Andes Mountains (39° 25′ –
40° 35′S), which covers only 55,000 hectares in a narrow fringe of c. 120 km in
length and c. 40 km in maximum width, following the numerous west-east lake
basins of glacial origin (Fig. 3.1; Sabatier et al. 2011). It grows between 800 and
1000 m asl, although it can go down following humid micro-basins to 650 m asl,
for example, in the Lake Lácar basin, where it enters the predominant area of
N. obliqua, as also up to 1250 m asl at some locations where N. pumilio is the dominant species. Along the Andes Mountains, the species develops on soils of volcanic
origin, while in the Coastal Range, in Chile, it does so on granitic soils (Donoso
1993). The natural range in Argentina expands from an average annual rainfall of
around 1200 mm in the east towards more than 3000 mm to the west.
Raulí is a large tree that reaches heights between 25 m and 30 m, sometimes even
40 m (Fig. 3.2a) (Donoso 1993), whose trunk can exceptionally exceed 2 m in diameter. It has a deciduous habit, turning the leaves reddish during the fall (Fig. 3.2b).
It is a monoecious species, with anemophilous and anemochorous dispersion. The
male flowers are pedunculated, solitary or in clusters of two or three, with numerous
stamens. The female flowers are axillary, in number of three, wrapped by a short
pedunculated pubescent involucre: bifid style in the central flower and trifid in the
lateral ones (Dimitri and Milano 1950). The pollination takes place between the
months of October and November, and seeds fall between February and April. Each
involucre contains three seeds (achene fruits; Fig. 3.2c): flat the one of the middle
and triquetrous the other two.
The forests of raulí in Argentina are mature, with individual ages between 100
and 150 years, being able to reach 300 years (Dimitri and Milano 1950). These
forests are one of the most productive in terms of commercial biomass, with growths
of 12 m
3
/ha/year in some places (Chauchard et al. 1997, 2012). Fire represents one
of the most important factors in the dynamics of these forests, and large recurrent
low-frequency fires cause pulses of post-fire regeneration at the landscape scale
(Gallo et al. 2000). Raulí requires moderate open spaces for natural regeneration,
since it does not tolerate total exposure; therefore, regeneration occurs in protected
sites with partial shadow of other vegetation.
3.2 Genetic Structure: Patterns of Genetic Variation
at Neutral Markers
3.2.1 The Legacy of the Glacial Ages
Past climatic changes induced vegetation shifts in different areas around the globe,
including the southern Patagonian Andes (e.g. Folguera et al. 2011). However, glaciations affected the two hemispheres in different ways, having a lower impact in
P. Marchelli et al.
extensively logged, mainly during the first half of the twentieth century, causing a
dramatic reduction of its forests (Donoso and Lara 1995; Gonzalez Peñalba
et al. 1997).
Raulí is endemic to the temperate forests of Chile and Argentina. It occurs in
Chile between 35° and 41° 30′ S in both, the Andes and Coastal Mountains (Donoso
1993). In Argentina, it has a very small range along the Andes Mountains (39° 25′ –
40° 35′S), which covers only 55,000 hectares in a narrow fringe of c. 120 km in
length and c. 40 km in maximum width, following the numerous west-east lake
basins of glacial origin (Fig. 3.1; Sabatier et al. 2011). It grows between 800 and
1000 m asl, although it can go down following humid micro-basins to 650 m asl,
for example, in the Lake Lácar basin, where it enters the predominant area of
N. obliqua, as also up to 1250 m asl at some locations where N. pumilio is the dominant species. Along the Andes Mountains, the species develops on soils of volcanic
origin, while in the Coastal Range, in Chile, it does so on granitic soils (Donoso
1993). The natural range in Argentina expands from an average annual rainfall of
around 1200 mm in the east towards more than 3000 mm to the west.
Raulí is a large tree that reaches heights between 25 m and 30 m, sometimes even
40 m (Fig. 3.2a) (Donoso 1993), whose trunk can exceptionally exceed 2 m in diameter. It has a deciduous habit, turning the leaves reddish during the fall (Fig. 3.2b).
It is a monoecious species, with anemophilous and anemochorous dispersion. The
male flowers are pedunculated, solitary or in clusters of two or three, with numerous
stamens. The female flowers are axillary, in number of three, wrapped by a short
pedunculated pubescent involucre: bifid style in the central flower and trifid in the
lateral ones (Dimitri and Milano 1950). The pollination takes place between the
months of October and November, and seeds fall between February and April. Each
involucre contains three seeds (achene fruits; Fig. 3.2c): flat the one of the middle
and triquetrous the other two.
The forests of raulí in Argentina are mature, with individual ages between 100
and 150 years, being able to reach 300 years (Dimitri and Milano 1950). These
forests are one of the most productive in terms of commercial biomass, with growths
of 12 m
3
/ha/year in some places (Chauchard et al. 1997, 2012). Fire represents one
of the most important factors in the dynamics of these forests, and large recurrent
low-frequency fires cause pulses of post-fire regeneration at the landscape scale
(Gallo et al. 2000). Raulí requires moderate open spaces for natural regeneration,
since it does not tolerate total exposure; therefore, regeneration occurs in protected
sites with partial shadow of other vegetation.
3.2 Genetic Structure: Patterns of Genetic Variation
at Neutral Markers
3.2.1 The Legacy of the Glacial Ages
Past climatic changes induced vegetation shifts in different areas around the globe,
including the southern Patagonian Andes (e.g. Folguera et al. 2011). However, glaciations affected the two hemispheres in different ways, having a lower impact in
P. Marchelli et al.