29
meristematic tissues and even leave injuries that can be recorded in tree rings as
anatomical anomalies. Frost rings were reported in some native conifers with latespring frosts having more incidence (Rojas-Badilla et al. 2017; Hadad et al. 2019).
The marked patterns in the annual precipitation, together with the gradual
decrease in the mean annual temperatures from north to south, determine the occurrence of different forest formations. At northern latitudes, between 35° S and 37°
20′ S in Chile occurs the district of the deciduous warm temperate Nothofagus forests, mainly at the coastal range. These forests are the transition between the evergreen sclerophyllous shrublands of Northern Chile and the southern temperate
forests and are dominated by deciduous species like Nothofagus glauca and
Nothofagus obliqua (San Martin and Donoso 1995). Temperate Valdivian rain forests prevail from 37° 45′ S to 43° 20′ S and are followed by the North Patagonian
temperate humid forest, from about 43° 20′ S to 47° 30′ S. Finally, the Magellanic
humid forest covers the surfaces to the southern tip of the continent (Veblen et al.
1995b). The main forestland occurs in Chile, but smaller extensions enter Argentina
in the wetter sections.
Biodiversity declines from north to south, accompanying the decrease in temperature and growing season length. Accordingly, the Valdivian rain forest represents the hotspot of species richness, including evergreen broadleaved trees (e.g.,
Laurelia sempervirens), evergreen conifers (e.g., Austrocedrus chilensis, Fitzroya
cupressoides, Saxegothaea conspicua) and the deciduous Nothofagus alpina (=
N. nervosa) and N. obliqua (Veblen et al. 1981; Donoso 1993). The evergreen species Nothofagus dombeyi and Nothofagus nitida prevail in the North Patagonian
temperate humid forests in association with a few broad-leaved and conifer species.
The Magellanic humid forest is characterized by the presence of N. betuloides,
Pilgerodendron uviferum, and Drimys winteri. Finally, the deciduous N. pumilio
and N. antarctica are the emblematic tree species of the Subantarctic forests, since
they occur within all the Andean forest districts mentioned above (Veblen et al.
1995b; Chap. 5).
On the other hand, the west-east sharp precipitation gradient promotes a vegetation change from temperate humid forests, through cool temperate Nothofagus forests, to open forests and shrublands in the ecotone with the Patagonian steppe
(Fig. 2.1). These cool temperate forests occur more extensively in the eastern side
of the Andes (Argentina), from 37° 30′ S to 55° S, and in their north portion include
the eastern drier forests characterized by the conifers Austrocedrus chilensis and
Araucaria araucana (Veblen et al. 1995a).
Finally, an altitudinal gradient develops along the slopes of the mountains, particularly at northern latitudes where the Andes display higher heights. Elevational
gradients impose strong adaptive challenges for plant species because of the marked
changes in environmental conditions over relatively short distances (i.e., decreasing
temperature, frost, shorter growing season). At around 40° of latitude, Nothofagus
pumilio grows from 1000 to 1700 m asl, where it conforms the tree line. Along this
elevation range, the species shows a marked variation in the growth habit distinguishing three morphotypes: arboreal, shrubby, and crawling. A genetic base for
these differences was analyzed based on genetic markers and quantitative traits
2 Temperate Subantarctic Forests: A Huge Natural Laboratory
meristematic tissues and even leave injuries that can be recorded in tree rings as
anatomical anomalies. Frost rings were reported in some native conifers with latespring frosts having more incidence (Rojas-Badilla et al. 2017; Hadad et al. 2019).
The marked patterns in the annual precipitation, together with the gradual
decrease in the mean annual temperatures from north to south, determine the occurrence of different forest formations. At northern latitudes, between 35° S and 37°
20′ S in Chile occurs the district of the deciduous warm temperate Nothofagus forests, mainly at the coastal range. These forests are the transition between the evergreen sclerophyllous shrublands of Northern Chile and the southern temperate
forests and are dominated by deciduous species like Nothofagus glauca and
Nothofagus obliqua (San Martin and Donoso 1995). Temperate Valdivian rain forests prevail from 37° 45′ S to 43° 20′ S and are followed by the North Patagonian
temperate humid forest, from about 43° 20′ S to 47° 30′ S. Finally, the Magellanic
humid forest covers the surfaces to the southern tip of the continent (Veblen et al.
1995b). The main forestland occurs in Chile, but smaller extensions enter Argentina
in the wetter sections.
Biodiversity declines from north to south, accompanying the decrease in temperature and growing season length. Accordingly, the Valdivian rain forest represents the hotspot of species richness, including evergreen broadleaved trees (e.g.,
Laurelia sempervirens), evergreen conifers (e.g., Austrocedrus chilensis, Fitzroya
cupressoides, Saxegothaea conspicua) and the deciduous Nothofagus alpina (=
N. nervosa) and N. obliqua (Veblen et al. 1981; Donoso 1993). The evergreen species Nothofagus dombeyi and Nothofagus nitida prevail in the North Patagonian
temperate humid forests in association with a few broad-leaved and conifer species.
The Magellanic humid forest is characterized by the presence of N. betuloides,
Pilgerodendron uviferum, and Drimys winteri. Finally, the deciduous N. pumilio
and N. antarctica are the emblematic tree species of the Subantarctic forests, since
they occur within all the Andean forest districts mentioned above (Veblen et al.
1995b; Chap. 5).
On the other hand, the west-east sharp precipitation gradient promotes a vegetation change from temperate humid forests, through cool temperate Nothofagus forests, to open forests and shrublands in the ecotone with the Patagonian steppe
(Fig. 2.1). These cool temperate forests occur more extensively in the eastern side
of the Andes (Argentina), from 37° 30′ S to 55° S, and in their north portion include
the eastern drier forests characterized by the conifers Austrocedrus chilensis and
Araucaria araucana (Veblen et al. 1995a).
Finally, an altitudinal gradient develops along the slopes of the mountains, particularly at northern latitudes where the Andes display higher heights. Elevational
gradients impose strong adaptive challenges for plant species because of the marked
changes in environmental conditions over relatively short distances (i.e., decreasing
temperature, frost, shorter growing season). At around 40° of latitude, Nothofagus
pumilio grows from 1000 to 1700 m asl, where it conforms the tree line. Along this
elevation range, the species shows a marked variation in the growth habit distinguishing three morphotypes: arboreal, shrubby, and crawling. A genetic base for
these differences was analyzed based on genetic markers and quantitative traits
2 Temperate Subantarctic Forests: A Huge Natural Laboratory