Bioclimatic and phytosociological diagnosis of the ...

International Journal of Geobotanical Research, Vol. nº 1, December 2011, pp. 1-20

Bioclimatic and phytosociological diagnosis of the species of the Nothofagus genus (Nothofagaceae) in South America Javier AMIGO(1) & Manuel A. RODRÍGUEZ-GUITIÁN(2) (1) Laboratorio de Botánica, Facultad de Farmacia, Universidad de Santiago de Compostela (USC). E-15782 Santiago de Compostela (Galicia, España). Phone: 34-881 814977. E-mail: [email protected] (2) Departamento de Producción Vexetal. Escola Politécnica Superior de Lugo-USC. 27002-Lugo (Galicia, España). E-mail: [email protected] Abstract The Nothofagus genus comprises 10 species recorded in the South American subcontinent. All are important tree species in the extratropical, Mediterranean, temperate and boreal forests of Chile and Argentina. This paper presents a summary of data on the phytocoenotical behaviour of these species and relates the plant communities to the measurable or inferable thermoclimatic and ombroclimatic conditions which affect them. Our aim is to update the phytosociological knowledge of the South American temperate forests and to assess their suitability as climatic bioindicators by analysing the behaviour of those species belonging to their most representative genus.

Keywords: Argentina, boreal forests, Chile, mediterranean forests, temperate forests.

Introduction The South American subcontinent is usually associated with a tropical environment because this is in fact the dominant bioclimatic profile from Panamá to the north of Argentina and Chile. However, south of the 30th parallel, grosso modo, more variable climatic conditions arise. Surrounding Río de La Plata there is an area with a Temperate bioclimate forming a large semicircle facing the Atlantic ocean and extending from the southernmost outskirts of Brasil, Uruguay and the province of BuenosAires to the Colorado river mouth. In addition, beyond a long and extremely arid strip of land –the so-called “Arid Diagonal”– extending from Perú to the Argentinian Patagonia, there is a territory with not only peculiar flora and vegetation but also with ecosystems adapted to the 3 large macrobioclimatic categories (other than the Tropical one) according to RIVAS-MARTÍNEZ (1993, On-line): Mediterranean, Temperate and Boreal This territory shows, on a much smaller scale, the same macroclimatic series as seen in the northern hemisphere, from the Palaeotropical Kingdom to the North Pole: i. a desert or hyperarid zone (where the change from a Tropical to a Mediterranean bioclimate takes place); ii. a zone with a variably and progressively more humid, Mediterranean climate, to such an extent that the increasing summer rains from the Pacific Ocean even-

tually give rise to a temperate territory with rainfall rates as high as those of regions with a Tropical pluvial bioclimate; iii. finally, towards the apex of the American Southern Cone, this temperate territory progressively gives way to a strip of land with a Boreal bioclimate. This parallelism between the climatic sequences in the northern and the southern hemispheres presents a significant difference, however. As a result of the increasingly narrower strip of land at the southern tip of South America, genuinely continental bioclimates never arise and all the variants of the Mediterranean, Temperate or Boreal climates range from hyperoceanic to oceanic subtypes. The singular character of the flora of the American Southern Cone has been squarely captured in the descriptive name of “biogeographical island” frequently given to the Chilean territory (ARMESTO ET AL. 1996). The Atacama desert to the north, the impressive and continuous Andean Cordillera to the east, the subantarctic ice to the south and the Pacific Ocean to the west have induced a scenario where the plant biota has evolved independently from the rest of the continent since the time when Australia and Antarctica separated from the American Southern Cone and the Andean barrier emerged in the Eocene-Miocene epochs (STUESSY & TAYLOR, 1995).

Correspondence: Javier Amigo. Laboratorio de Botánica, Facultad de Farmacia, Universidad de Santiago de Compostela (USC). E15782 Santiago de Compostela (Galicia, España). Phone: 34-881 814977. E-mail: [email protected] ISSN: 2253-6302 print/ISSN 2253-6515 on line ©Editaefa DOI: 10.5616/ijgr110001

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J. Amigo & M. A. Rodríguez-Guitián

This territory, the Austro-American Subkingdom in the biogeographical mapping of RIVAS-MARTÍNEZ & NAVARRO (1994) and RIVAS-MARTÍNEZ ET AL. (2011), exhibits a flora with a high endemicity rate, as high as 46% at species level (MARTICORENA 1991). The Nothofagus genus is one of the most outstanding groups in this peculiar flora and links the southern half of Chile with the Holantarctic Floristic Kingdom (sensu TAKHTAJAN 1986). The genus is included in the monotypic Nothofagaceae family and in the order Fagales, whose morphological similarities with the Fagaceae of the northern hemisphere earned them the geobotanical name of “southern beech trees”. The Nothofagus genus with its 36 known species has been considered as one of the key genera in showing the migration and evolutionary patterns of the southern hemisphere biota. The genus is of great interest for palaeobotany on account of three relevant features: 1) it is made up of tree species which are usually important components of the climatophilous forests; 2) the fruit has low dispersal ability which largely limits its propagation to land routes; and 3) there are abundant fossil records of the genus, and particularly of its unmistakable pollen grains (HILL & DETTMANN, 1996). There are 10 species belonging to the Nothofagus genus which can be found in the South American extratropical territory (either Mediterranean, Temperate or Boreal). They are the following (the order corresponds more or less to the occurrence of the species from north to south): 1. Nothofagus macrocarpa 2. N. glauca 3. N. alessandri 4. N. obliqua 5. N. alpina 6. N. dombeyi 7. N. nitida 8. N. betuloides 9. N. pumilio 10. N. antarctica The species can also be arranged to reflect the 3 large ecological groups involved (RAMÍREZ 1987): i. largeleaved, deciduous species peculiar either to the “Mediterranean region” or to areas with a submediterranean-like summer (species 1 to 5); ii. perennial species associated with the “Valdivean region” (6 to 8); and iii. smallleaved, deciduous species peculiar to the “Subantarctic region” (9 and 10). Although some publications by Chilean authors support the existence of an eleventh taxon, viz., Nothofagus leonii Espinosa, considering it a forest species on account of its distinct morphological features (RAMÍREZ ET AL. 1997) and auto-ecological profile (DONOSO 2006), in all cases they have recognized its hybrid character. The taxon is the result of the natural crossing of N. obliqua and N. glauca, and has obviously been found where these two species overlap. For this reason we have not included it in our study nor have we included other hybrids that do not always have an orthodox name, despite having begun to be recognized and described in the last decades (DONOSO & ATIENZA 1984; DONOSO ET AL. 1990; GRANT & CLEMENT 2004; QUIROGA ET AL. 2005).

Background Given the significant contribution of the Nothofagus species to the Chilean and Argentinian temperate forests, there is no shortage of studies dealing with the ecological and dynamic features of the natural populations. This is particularly true not only of the timber-yielding species growing in rainy, temperate areas (for a summary, see VEBLEN ET AL. 1996), but also of species occurring in the Chilean mediterranean territory (DONOSO 1996). Since all these species are of great interest for the timber industry (DONOSO 1998), the quantitative aspects of their autoecology (DONOSO 2006), genetic variability (DONOSO ET AL. 2004), ecophysiology (ALBERDI ET AL. 1985; ALBERDI 1996) and even palaeohistory (MARKGRAF ET AL. 1996) have already been studied. The phytosociological behaviour of each of these Nothofagus species has also been studied. Since OBERDORFER (1960) clearly established the syntaxonomical arrangement of the mediterranean and temperate vegetation of Chile, some later contributions by Argentinian authors, such as ESKUCHE (1968, 1969, 1973, 1999, 2002) or ROIG (1998), and Chilean authors, such as PISANO (1970, 1977), DOLLENZ (1982a), RAMÍREZ ET AL. (1983, 1989), SAN MARTÍN ET AL. (1984, 1991b, 1991c), have described particular associations for clearly-defined territories. However, a great variety of names of associations (RAMÍREZ ET AL. 1987; SAN MARTÍN & RAMÍREZ 1987), communities (GAJARDO 1994) or vegetation belts (LUEBERT & PLISCOFF 2006) have been published in wide-ranging studies dealing with large territories but no supportive relevés have been published to adequately support those names or has there been adequate nomenclatural validation. To avoid possible misinterpretations, there is urgent need of a careful syntaxonomical revision using the International Code of Phytosociological Nomenclature (WEBER ET AL. 2000). This paper provides a description of the phytosociological behaviour of the South American Nothofagus species and co-relates their communities with the bioclimatic belts suggested by RIVAS-MARTÍNEZ (1993, Online). Brief description of the territory In Chilean territory the Nothofagus forests extend right across the country, from latitude 33° south to Tierra del Fuego (Figure 1). Meanwhile, on the other side of the Andean Cordillera, in Argentina, their presence is restricted to a narrow strip of land that originates at latitude 35° south and runs parallel to the impressive Andean range up to the south apex of the continent. In Chile, in addition to the Andes, there is the so-called Cordillera de la Costa, a group of mountain ranges running parallel to the Pacific coast. This cordillera is much older than the Andes and, consequently, the peaks are much lower as a result of long-term erosion. In the land strip between latitudes 32° and 37° south the Andean Cordillera has imposing peaks. These are the Mediterranean Andes, with peaks above 5,000 and 6,000 masl (for example, Aconcagua, 6,959 m). Going south, between latitudes 37° and 41° south, we find the socalled Andes de la Araucanía, with peaks above 2,000 and 3,000 m. The territory is punctuated with a conside-

Bioclimatic and phytosociological diagnosis of the species of the Nothofagus genus (Nothofagaceae) in South America

raable number of volcanoes which have been active in historic times. Finally, southwards from the latitude of Puerto Montt the Patagonian Andes form the frontier between Chile and Argentina. Although these peaks are very rarely above 2,500 m, they are permanently covered by more than 18,000 km2 of ice. Despite the progressively decreasing height of the great cordillera, the westto-east rain shadow effect induced by the topography inevitably restricts the occurrence of temperate forests in Argentinian territory to a 10 to 45 km wide land strip to the east of the frontier. On the other side of that land strip, the bioclimate changes abruptly from Temperate oceanic to Mediterranean xeric conditions.

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the Cordillera Pelada (40° south) and 800 m in the Cordillera Piuchué (Isla Grande de Chiloé, 42° south). From that point to the south the coastline is indented with numerous inlets. The Cordillera de la Costa disappears as such and there remain only a few recognizable geological outcrops as far as 47º south. Nearer Cape Horn the coastline adopts the form of a series of islands and fiords as a result of Holocene glacial activity. The orographical profile of this emerged land is remarkable only for the extensive cover rate of the pristine vegetation, namely, peatlands and hyperhumid forests. In Chile there is a plain between the Andean Cordillera and the Cordillera de la Costa. This is the Valle Central, which constitutes a uniform landscape of lowlands made up of Terciary and Quaternary deposits extending from the capital city of Santiago to Puerto Montt, 1,000 km to the south. The territory is excellent for extensive agriculture and live-stock rearing. For this reason, this strip of land has the most densely populated urban settlements and the highest replacement rate of natural vegetation. In this man-induced landscape allochthonous trees are more abundant than aboriginal trees. As you cross the Andes towards Argentina the mountain ranges disappear fairly quickly and give way to sedimentary piedmonts. After a few kilometres the hyperhumid ombroclimate changes to semiarid and, towards the east, the disappearance of forests and scrublands with Nothofagus signals the transit to a Mediterranean macroclimate and the extensive Patagonian plains. Methods This is an in situ study of a wide variety of communities with different species of the Nothofagus genus. The study area covers a large biogeographical area, from the 33rd to the 53rd parallel. Our sampling technique and ecological interpretation approach has always followed the phytosociological method of BRAUN-BLANQUET (1979), updated by GÉHU & RIVAS-MARTÍNEZ (1981). For each Nothofagus species we provide: + Information of each one of the species, summarized in the form of:

Figure 1: Map showing latitudinal and longitudinal position of Chilean territory with indication of the administrative Chilean regions and neighbour Argentinian provinces. Thick-dotted lines mark borders between macrobioclimatic territories (sensu RIVAS-MARTÍNEZ ET AL. 2011). Green straight lines show the precise route whose vegetation is detailed along 1 to 4 West-East Transects.

The Cordillera de la Costa has its highest points, about 2,000 masl, at the latitude of the Chilean capital (La Campana, for example, is 33° south), where the ombroclimate ranges from semiarid to dry at basal level. Further south, the cordillera exhibits a discontinuous profile with lower peaks. These peaks reach 1,500 in the Cordillera de Nahuelbuta (38° south) where the climate conditions are temperate and hyperhumid, or 1,000 m in

A) A biotype with an evaluation of the size range. For this purpose, besides the distinction deciduous/ evergreen, in line with the classification of ELLENBERG & MÜELLER-DOMBOIS (1967) we have also distinguished mesophanerophytes (5-50 m high), microphanerophytes (2-5 m) and nanophanerophytes (< 2 m). B) The recorded distribution area plotted on individual maps with the logical limitations as far as the display scale is concerned. The main sources of these graphical data correspond to relatively recent publications, such as DONOSO (2006), CONAF (1998), ALBRIEU & FERRARI (2000), GARCÍA & ORMAZABAL (2008), or have been prepared in-house. Unfortunately, these are not the result of an exhaustive monitoring of bibliographical records or herbaria, since geobotanists have not yet produced a published map with a detailed and georeferenced distribution of the trees of Chile. As frequently happens with biogeographical surveys dealing with Chilean territory, numerical references are usually expressed in degrees of latitude south.

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+ A classification of the communities involved. This includes: C) The type of bioclimate and bioclimatic belts (thermo- and ombroclimatic) where these communities occur. For this purpose, we have used the climatic criteria and parameters of the classification suggested by RIVAS-MARTÍNEZ (1993, On-line). The bioindicator capability of each species has been estimated in terms of the co-relation recorded between their communities and the particular bioclimatic conditions involved. There are not sufficient weather stations for all the areas where Nothofagus communities occur and all the less for Andean areas. Consequently, the presumed relationship between particular climate conditions and the presence of a given forest association, at a latitude and for a measurable altitude range, must not be interpreted as a categorical but as a probabilistic statement. The fundamental point here is that the most reliable bioclimatic indicator is not the particular Nothofagus species, but the plant community in which that species takes place in each territory. Climate data from different weather stations all over Chile and heavily reliant on the bioclimatic indices used in the classification of RIVAS-MARTÍNEZ (op. cit.) can be obtained from LUEBERT & PLISCOFF (2006). D) The plant communities in which the tree is one of the dominant species or, at least, occurs as a member of the forest canopy. In this respect, we have used preferably phytosociological associations if available, or higher rank phytosociological categories if not. With regard to all this information, which constitutes the main body of our paper, we have only considered associations either validly published or supported by a published table of relevés. In some cases, the surplus of associations with phytosociological names already published has led us to adopt the syntaxonomical rank at alliance or order level, in the hope that further studies will eventually clarify the character of the particular associations validly published and recognizable in nomenclatural terms. The literature dealing with these Chilean-Argentinian forests sometimes includes an excessive number of associations for forests whose undisputable floristic and biogeographical variations cannot, in our opinion, justify such a nomenclatural diversity. However, we do not intend to solve these problems here. That aim would require an extensive and monographic study with a previous collection of tables of relevés and a comparison of nomenclatural typus, etc. We simply aim at providing a general overview for world phytosociologists not particularly acquainted with these Nothofagus forests and Chilean-Argentinian knowledgeable experts already acquainted with them but still unfamiliar with phytosociological sistematics. Needless to say, the main source of information has been the publications by botanists who conducted explorations and systematic surveys in our study area using European methods. However, despite the fact that the first Code of Phytosociological Nomenclature was published over three decades ago (BARKMAN ET AL. 1976), not all the researchers have complied with the standards of the orthodox nomenclature. For a list of the main references, see the Background subsection.

Results and Discussion In compliance with the species arrangement given in the Introduction, here we provide the phytosociological and bioclimatic allocation ascribed to each of the genus species. The mention of a bioclimate or a bioclimatic belt (thermoclimate or ombroclimate) in brackets means that the species has been recorded in it only exceptionally or out of its optimum location. In our view the “optimum location” is applied to plant communities in which the species is a member and has developed in a climatophilous position in a particular territory, in contrast with other possibilities: edaphoxerophilous or edaphohygrophilous. That means, when the Nothofagus species is included in or is the dominant tree in a woodland community which is found on mature soils in accordance with the mesoclimate and only receives rain water. The non-optimum positions take place in edaphoxerophilous communities (xerophytic soils, lithosols, rocky slopes, etc.) or in edaphohygrophilous ones (wet soils in river beds, banks of lakes and ponds, peat bogs, etc.). Well defined concepts applied to vegetation series can be found in RIVAS-MARTÍNEZ (2005).

Figure 2: Map showing the distribution of three Chilean endemic Nothofagus. Red dotted line marks Temperate/Mediterranean border

The schematically plotted transects 1 to 4 shown in Figure 1 are intended to reflect the spatial catenae of many of the communities dealt with here. 1. Nothofagus macrocarpa (DC.) F.M.Vázquez & R.A. Rodr. (Roble de Santiago) Life form: summergreen mesophanerophyte. Distribution area: Figure 2


Bioclimate: Pluviseasonal oceanic Mediterranean Bioclimatic belts: Meso–Supramediterranean subhumid-humid Communities: Elymo andini-Nothofagetum macrocarpae (Oberdorfer 1960) corr. This is the northernmost species. Its presence in the Cordillera de la Costa around latitude 33° south marks the absolute northern limit of the Nothofagus genus in the American continent. It gives rise to interesting deciduous forests on the shady hill slopes in the region of Valparaíso (Vª). This is the case of the Cerro La Campana, included in the National Park of the same name. Although the southern limit of its distribution area is unclear, there is no doubt that it is found in the Andean Cordillera, at the approximate latitude of the region of Maule (VIIª), i.e., just beyond latitude 35° south, in contact with the dividing line between the Mediterranean and the Temperate bioclimates. At that latitude N. macrocarpa can occur in catenal contact with three other deciduous species of the same genus: at lower altitudes, with N. glauca; and near the upper limit of the forest, with N. pumilio and even N. antarctica (SAN MARTÍN ET AL. 1991c; see Transect 1/ Figure 3). In addition, when the topography is favourable enough, the evergreen N. dombeyi can also occur at a similar altitudinal level. In forestry, the formations of this species endemic to Chile have been traditionally regarded as the northernmost version (the mediterranean version) of the oak forests of Chile. This viewpoint was further supported by the fact that the species was taxonomically considered as a mere variant of that oak tree, namely: Nothofagus obliqua (Mirb.) Oerst. var. macrocarpa (DC.) Reiche (see DONOSO, 1982). In phytosociological terms there is only one association dominated by this species. It is represented by 2 relevés taken in Sierra de Bella Vista, in the region of O’Higgins (VIª). The association was correctly subordinated to the Wintero-Nothofagetea class. However, both the subordination to order and alliance, and the association’s name itself are still under revision. Some published data on its formations in the northernmost sites of its distribution area (VILLASEÑOR & SEREY 1980) support the inclusion in Elymo andini-Nothofagetum, as LUEBERT & PLISCOFF (2006) suggest. However, further sampling and more relevés are needed for the rest of its area of distribution to check either the invariability of the floristic composition or the suitability of recognizing more than one association for these mediterranean oak forests. Some samples have been already taken in the south of the Metropolitan Region, but the compilatory work still remains unpublished (AVILEZ, 2001).. There are as yet no reliable records as to its bioclimatic behaviour. Weather stations are extremely rare in the mountainous areas of Chile (AMIGO & RAMÍREZ 1998). As with other Nothofagus species, in the case of these forests we have inevitably to infer, by extrapolation of the presumed altitudinal variation, their bioclimatic features from the data provided by weather stations located at lower altitudes. In their northernmost sites of occurrence, the documented N. macrocarpa forests present a subhumid rainfall pattern. Their lower catenal

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contact is sclerophyllous forests of a dry ombroclimate The N. macrocarpa forests represent the rainfall standards of a subhumid character up to their northernmost limit (Parque Nacional La Campana), because even there their lower catenal contact is sclerophyllous forests under a dry ombroclimate. However, in their southernmost formations (with altitudes as high as 1,600 m) records clearly correspond to a humid rainfall pattern. This is the case, for example, of the Reserva Natural Altos de Lircay. 2. Nothofagus glauca (Phil.) Krasser (Hualo) Life form: summergreen mesophanerophyte. Distribution area: Figure 2 Bioclimate: Pluviseasonal oceanic Mediterranean Bioclimatic belts: Meso–(Supra)Mediterranean humid Communities: Bomareo salsillae-Nothofagetum glaucae Amigo, San Martín & Quintanilla 2000 This is another species endemic to Chile which cannot occur on the eastern side of the Andes because the territory in Argentina does not provide the bioclimatic conditions required, namely, a mesomediterranean belt and a humid ombroclimate. It is basically located throughout the region of Maule (VIIª), where it gives rise to forests where it dominates both in the Cordillera de la Costa and the Andes. Along the coastal cordillera it also extends through the region of O’Higgins (VIª), where it reaches its northernmost limit, and along the Andean Cordillera it reaches the north of the region of Bío-Bío (VIIIª) as its southernmost limit. Latitudes 34° and 37° south can be taken as the limits of the distribution area of this plant which is nowadays regarded as one of the vulnerable species of the Chilean flora. Capable of producing one-species forest masses, it can also occur in combination with N. obliqua and N. macrocarpa. In the coastal cordillera it also occurs embedded in the forest masses of N. alessandri. The main association described for the forests dominated by N. glauca is Bomareo-Nothofagetum glaucae, which belongs to the Laurelietalia philippianae order, included in the Wintero-Nothofagetea class. In other words, the association exhibits a clearly mediterranean profile, but the components of its flora are indisputably temperate in origin and character (AMIGO ET AL. 2000). For that reason, and very noticeably, it presents a seral scrub community peculiar to the vegetation class of the sclerophyllous forests of the Mediterranean territory of Chile: the Lithraeo-Cryptocaryetea class. It thrives ideally at altitudes ranging between 100 m and 1,000 masl, particularly where the territory lies within the mesomediterranean belt, and reaches the lower limits of the supramediterranean belt in the Andean Cordillera. The ombroclimate records remain within humid standard levels but in hyperoceanic environments they can also reach subhumid levels in the Cordillera de la Costa. (Figure 3/Transect 1).

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Figure 3: Transect 1: Middle Chilean-Patagonian Region, Central Chilean Province. Potential natural vegetation at latitude 35º 50’ south. Horizontal coloured stripes show thermoclimatic belts: Mesomediterranean (dark orange), Supramediterranean (light yellow) and Oromediterranean (olive green). Gap at Central Valley means the complete natural woodland absence by human activities. 1/ Sclerophyllous woodland (Lithraeo-Cryptocaryetea). 2/ Nothofagetum alessandri. 3/ Bomareo-Nothofagetum glaucae. 4/ ScirpoNothofagetum antarcticae (edaphohygrophilous). 5/ Pitavio-Nothofagetum dombeyi (edaphohygrophilous). 6/ Nothofagus macrocarpa woodland. 7/ Austrocedrus chilensis (edaphoxerophylous) intermixed with Nothofagus macrocarpa. 8/ Nothofagus pumilio at timberline. 9/ Nothofagus antarctica dwarf woodland. 10/ Orophilous and xerophythic shrubland.

3. Nothofagus alessandrii Espinosa (Ruil) Life form: summergreen mesophanerophyte. Distribution area: Figure 2 Bioclimate: Pluviseasonal oceanic Mediterranean Bioclimatic belts: Mesomediterranean subhumid-humid; hyperoceanic Communities: Nothofagetum alessandrii San Martín, Figueroa & Ramírez 1984 This is another species endemic to Chile and one of the most endangered tree species of all the Chilean native forests and consequently, it has been labelled “Critically endangered” (HECHENLEITNER ET AL. 2005) according to the threat assessment criteria used by the IUCN (2001). Its distribution area is restricted to a strip of land barely 100 km long and 20 km wide in the Cordillera de la Costa. Once over the 35th parallel south, the area extends across the region of Maule, where N. alessandri occurs with a punctuated pattern. The species grows on slopes exposed to the humid wind coming from the Pacific Ocean. The plant formations, located within a strip of land at a distance of between 7 and 60 km from the coastline, never grow at altitudes above 450 m (OLIVARES ET AL. 2005). (Figure 3/Transect 1). The deciduous character and leaf size of N. alessandrii are not very suitable for the mesomediterranean belt environments where the plant develops. These features relate it to a more humid and warmer climate and support the idea that the species is a relict of ancient times. Two decades ago the covering area of these forests was estimated at less than 350 ha (SAN MARTÍN ET AL. 1991a). On account of the bioclimatic location of these forests, they are a privileged combination of species of the

mostly temperate Wintero-Nothofagetea class (where the Nothofagetum alessandrii association is included) and the mediterranean Lithraeo-Cryptocaryetea class. These are multi-stratum forests dominated by N. alessandrii, which is accompanied by N. glauca and several evergreen tree species, such as Cryptocarya alba, Aextoxicon punctatum, Gevuina avellana, Persea lingue and Peumus boldus. As is usual in a humid bioclimate with intense oceanity, there are a great variety of lianas and some epiphytes. Given that, of all the genus, it is the species with the most restricted area of occurrence in South America, its bioclimatic location can be easily defined: its belt is lower mesomediterranean, its ombroclimate ranges from upper subhumid to humid, and the corresponding continentality index reveals hyperoceanic standards. The exploitation of large areas of the Cordillera de la Costa for the cultivation of exotic plants, most particularly, Pinus radiata, has contributed dramatically to the critical situation of this species. Only the 42 ha integrated in the Natural Reserve of “Los Ruiles” can be considered as under protection (BUSTAMANTE & CASTOR 1998). 4. Nothofagus obliqua (Mirb.) Oerst. (Roble, roble-pellín) Life form: summergreen mesophanerophyte. Distribution area: Figure 4 Bioclimate: hyperoceanic Temperate; oceanic Temperate; oceanic Pluviseasonal Mediterranean Bioclimatic belts: (Thermo) Mesotemperate-Supratemperate humid & hyperhumid; Mesomediterranean (sub)-humid


Communities: Boldo-Cryptocaryetum nothofagetosum obliquae Oberdorfer 1960; Nothofago obliquae-Perseetum lingue Oberdorfer 1960; Dioscoreo brachybotryae-Nothofagetum obliquae Eskuche 1999; Nothofago obliquae-Prumnopitydetum andinae Amigo, Rodríguez-Guitián & Ramírez 2010

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peculiar to the sclerophyllous forest (Cryptocarya alba, Peumus boldus, Quillaja saponaria) growing in the mesomediterranean belt (in the most oceanic versions, with an ombroclimate which is at least upper subhumid), the species becomes dominant in large formations of deciduous forest of the mesotemperate belt. This versatility makes it the most frequent tree in the temperate submediterranean territory. When the climate becomes colder and with more intense contrasts in the valleys of the Andean Cordillera, it still forms a community with an endemic conifer (Prumnopitys andina) at the beginning of the supratemperate belt (AMIGO ET AL. 2010). However, when climate conditions become more severe, it can give way to the oak forests of Dioscoreo-Nothofagetum between the Chilean region of Araucanía (IXª) and the Argentinian province of Neuquén. To the south, as submediterranean conditions disappear, this last community will progressively give way to hyperhumid forests. Eventually, these deciduous oak forests are replaced by likewise deciduous forests of raulí (N. alpina) or increasingly mixed combinations of raulí with the evergreen N. dombeyi. 5. Nothofagus alpina (Poepp. & Endl.) Oerst. (Raulí)

Figure 4: Map showing the distribution of Nothofagus obliqua. Red dotted line marks Temperate/Mediterranean border.

This is a widely distributed tree species that extends, farthest to the north, through the mediterranean territory of the region of Maule. There, it is present in the most oceanic areas of the Cordillera de la Costa, where it mingles with the elements peculiar to a sclerophyllous forest (Boldo-Cryptocaryetum nothofagetosum). From that point it extends southwards, and throughout the bioclimatically temperate Valle Central (Nothofago-Perseetum, see Figure 5/Transect 2) to the northern part of the region of Los Lagos (Xª), the species is overwhelmingly dominant. From that point onwards, hyperhumid ombroclimate conditions also prevail in the Valle Central. As a result, the forests dominated by deciduous trees give way to a combination of evergreen taxa traditionally depicted as “Valdivean Forest”. In terms of latitude, the species is present from a strip of land before the 35th parallel south to beyond the 41st south. Although commonly associated with low altitudes, it is also capable of enduring more continental and colder conditions. When entering Argentinian territory, for example, it forms remarkable oak forest areas on the eastern slopes of the Andes (Dioscoreo-Nothofagetum). Although accompanied by evergreen thermophilous trees peculiar to temperate forests (Persea lingue, Laurelia sempervirens, Gevuina avellana), or even by trees

[N. procera Oerst.; N. nervosa (Phil.)Krasser] Life form: summergreen mesophanerophyte. Distribution area: Figure 6 Bioclimate: hyperoceanic Temperate, oceanic Temperate; (oceanic Pluviseasonal Mediterranean). Bioclimatic belts: Meso-Supratemperate humid & hyperhumid; (Supramediterranean humid). Communities: Dasyphyllo diacanthoides-Nothofagetum alpinae (Frank & Finckh) Pollmann 2001; Nothofagetum procerae Oberdorfer 1960 + Nothofagetum dombeyi-alpinae Eskuche 1999 This is another species recorded in both cordilleras and in Argentinian territory, and has a cover rate even higher than that of N. obliqua. Although present in topographically suitable mediterranean enclaves of the regions of Maule and Bío-Bío, whose northernmost frontier lies close to the 35th parallel south, the biggest populations, i.e., the most extensive forests are found in the Andean Cordillera, where they reach the 41st parallel south and beyond. The name of the species has long been disputed. Here we follow the criterion suggested by RODRÍGUEZ & QUEZADA (2003). GRANT & CLEMENTS (2004) have also endorsed this, but their arguments have not been universally conclusive. Recent works, particularly those by Argentinian authors, have maintained the biname system, i.e., N. nervosa or N. procera. The species can be found in formations dominated by the taxon itself. In the most thermophilous variants of these formations, N. alpina mingles with tree species peculiar to the oak forests of N. obliqua, such as Persea lingue, Dasyphyllum diacanthoides, or Laurelia sempervirens in the humid mesotemperate belt (DasyphylloNothofagetum). At higher altitudes these species disappear and N. alpina may form one-species forests or appear increasingly combined with an evergreen Nothofagus: N. dombeyi. This fact has led to the idea of two different associations catenally juxtaposed in the Andean

8


Figure 5: Transect 2: Valdivean-Magellanian Region, Valdivean Province. Potential natural vegetation at latitude 38º 40’ south. Basal coloured bands show thermoclimatic belts: Thermotemperate (orange), Mesotemperate (light green), Supratemperate (dark green) and Orotemperate (violet). Gap at Central Valley means the practically complete natural woodland absence by human activities. 1/ Lapagerio-Aextoxiconetum (evergreen woodland without Nothofagus). 2/ Nothofago obliquae-Perseetum lingue. 3/ Dasyphyllo-Nothofagetum alpinae. 4/ Nothofagetum procerae+ Nothofagetum dombeyi-alpinae. 5/ Carici-Araucarietum 6/ Nothofagus pumilio + Araucaria araucana woodland. 7/ Orophilous dwarf Nothofagus antarctica woodlands. 8/ Austrocedrus chilensis woodland

altitudinal cliseries: firstly, Nothofagetum procerae [a name taken by its descriptor, Oberdorfer, in 1960, from an invalid homonym, viz., N. procera (Poepp. & Endl.) Oerst.], and, secondly, Nothofagetum dombeyi-alpinae, at a higher altitude. Both associations occur in the Chilean Araucanía and in the Argentinian Neuquén. However, we think that closer analysis could eventually reveal that they are simply two variants of the same association. To sum up, moving from north to south through the Valle Central, the Mediterranean bioclimate becomes Temperate at the 38th parallel south, although in the Andean Cordillera the Chilean slopes already exhibit temperate conditions from at least the 36th parallel south. Once in the area of the Temperate bioclimate, the low altitude territory is dominated by the oak forest of Nothofago-Perseetum and the next forests to be seen in the altitudinal catena towards the supratemperate belt in the band 36°-38° south are variable combinations of Nothofagus obliqua until, when finally entering the orotemperate belt, other trees comes onto scene. This is because of the submediterranean Temperate climate of that land strip of the Andean Cordillera. However, from the parallel 38°-38° 30’ south, summer drought episodes are less intense and the transect Valle Central-Andes undergoes the replacement of the oak forests of Nothofago-Persee-

tum by communities dominated by raulí (DasyphylloNothofagetum, Nothofagetum procerae + Nothofagetum dombeyi-alpinae) before ultimately giving way to the orotemperate forests of araucaria and lenga (Nothofagus pumilio) (Figure 5/Transect 2). 6. Nothofagus dombeyi (Mirb.) Oerst. (Coihue) Life form: evergreen mesophanerophyte. Distribution area: Figure 7 Bioclimate: hyperoceanic Temperate, oceanic Temperate; (oceanic Pluviseasonal Mediterranean). Bioclimatic belts: Meso-Supratemperate humid & hyperhumid; (Meso-Supramediterranean edaphohygrophilous). Communities: Pitavio punctatae-Nothofagetum dombeyi San Martín & Ramírez ex Stoll 2008 n.n.; Nothofagetum procerae Oberdorfer 1960+ Nothofagetum dombeyi-alpinae Eskuche 1999; MyrceugenioNothofagetum dombeyi Eskuche 1999; AustrocedroNothofagetum dombeyi Eskuche 1999; Nothofago dombeyi-Eucryphietum cordifoliae Oberdorfer 1960; Laurelio-Weinmannietum trichospermae Oberdorfer 1960; Chrysosplenio valdivici- Nothofagetum dombeyi Oberdorfer 1960


This is the evergreen species most widely distributed throughout the temperate territories of Chile and Argentina. It is very abundant from the beginning of the Valdivean-Magellanian Region, i.e., from the 36th parallel south (in the Andean Cordillera) or the 38th parallel south (in the Valle Central), crossing the 47th parallel south in the region of Aisén (XIª). It is also not infrequent in the foothills of the Andes of the mediterranean territory between the 35th and 36th parallels south (region

9

could be interpreted as one single association). Relevés of this community have already been published, both in Chile and Argentina (ESKUCHE 1999; POLLMANN 2001). The variable physiognomical profiles recorded reveal forests under the dominance of N. alpina but also under the overwhelming dominance of N. dombeyi.

Figure 6: Map showing the distribution of Nothofagus alpina. Red dotted line marks Temperate/Mediterranean border.

of Maule), even scattered at humid spots slightly further north (region of Libertador O’Higgins). An interesting community (Pitavio-Nothofagetum dombeyi) has even been described for its edaphohigrophilous formations in the topographically suitable sites of the hyperoceanic, mesomediterranean territory of the region of Maule. In these sites it co-dominates the forest with very interesting, endangered relict trees, such as Pitavia punctata or Gomortega keule (STOLL ET AL. 2006) (see Transect 1/ Figure 3). Besides these occurrences in the mediterranean territory, once in the Temperate bioclimate, Nothofagus dombeyi can occur in a submediterranean environment in combination with the oak forests of N. obliqua. In this case, clearly visible as an evergreen species intermingled with deciduous forests, it always signals a topographically more humid location. As we go south and to higher altitudes in the Andean Cordillera, the temperate climate is less and less submediterranean and the deciduous forest, dominated by raulí (N. alpina), combines increasingly with N. dombeyi. As a result, new climatophilous associations of Nothofagetum procerae + Nothofagetum dombeyi-alpinae emerge (as already said, these two

Figure 7. Map showing the distribution of Nothofagus dombeyi. Red dotted lines mark Temperate/Mediterranean and Temperate/Boreal borders.

To the south, in the Argentinian provinces of Neuquén and Río Negro, as the supramediterranean belt becomes more and more clearly hyperhumid, the deciduous-evergreen community of Nothofagetum procerae + Nothofagetum dombeyi-alpinae gives way to forests clearly dominated by the evergreen N. dombeyi with the association Myrceugenio-Nothofagetum dombeyi. However, east of the Andean Cordillera, the decreasing rainfall

Bioclimatic and phytosociological diagnosis of the species of the Nothofagus genus (Nothofagaceae) in South America 11

Figure 8: Transect 3: Valdivean-Magellanian Region, Valdivean Province. Potential natural vegetation at latitude 40º 45’ – 41º 00’ south. Horizontal coloured stripes show thermoclimatic belts: Mesotemperate (light green), Supratemperate (dark green) and Orotemperate (violet). Gaps at Central Valley are the result of natural woodland absence by human activities. 1/ Lapagerio-Aextoxiconetum (evergreen woodland without Nothofagus). 2/ Laurelio-Weinmannietum (occasionally including N. dombeyi). 3/ Luzuriago-Nothofagetum nitidae. 4/ Nothofago dombeyi-Eucryphietum. 5/ Nothofago obliquae-Perseetum lingue. 6/ Chrysosplenio-Nothofagetum dombeyi. 7/ “Nothofagetum pumilionis”. 8/ Orothilous and discon tinuous dwarf shrubland. 9/ “ Nothofagetum antarcticae” (edaphohygrophilous or as N. dombeyi woodland succesional stage). 10/ Myrceugenio-Nothofagetum dombeyi. 11/ Austrocedro-Nothofagetum dombeyi. 12/ Gavileo-Austrocedretum chilensis (without Nothofagus).

gradient is very intense, the increasingly drier hyperhumid rainfall pattern eve ntually reaches humid standards and the coihue forests g ive rise to a commu nity that reveals again the presence of a s ubmediterranean scenario with the association Austrocedro-Nothofagetum dombeyi (Figure 8/ Transect 3). In this latter association, the presence of Austrocedrus chilensis, a Cupressaceae, indicates lower rainfall rates an d the transition to the submediterranean cypress forests. After these forests, the tree vegetation will d ecline dramatically to give way to the typical scrub-like pampas of A rgentinian Patagonia. Here the conditions are clearly those of a Mediterranean, dry or semiarid bioclimate. On the other hand, in Chile, when the Temperate bioclimate becomes hyperhumid, even at t he lowest altitudes, the deciduous oak forest of N. obliqua is replaced by an evergreen forest, without deciduous taxa. This formation is an in tegral part of the so-called Valdivean Forest. This phenomenon occurs from latitude 39° south on the slopes of both cordilleras. The forest formed in this way has been ascribed to two ass ociations which alternate in the altitudinal cliseries. At lo wer and warmer altitudes but still with in the range of t he mesotemperate belt, we find Nothofago dombeyi-Eucryphietum cordifoliae, with the presence of coihue (N. dombeyi) and other evergreen taxa of similar size, such as the ulmo (Eucryphia cordifolia) or the tepa (Laureliopsis philippiana). At altitudes above those of Nothofago-Eucryphietum the evergreen forest takes th e form of an other association: LaurelioWeinmannietum. The name reveals the important role played by two large-sized trees, such as the tepa (Laure-

liopsis philippiana = Laurelia philippiana) and the tineo (Weinmannia trichosperma), but there is al so a sign ificant, although variable, presence of coihue (N. dombeyi) Finally, in the Andean catena, between the 38th and th 40 parallels south and still i n Chile, a supratem perate, hyperhumid forest c ommunity, floristically different from the Argentinian Myrceugenio-Nothofagetum, can be found. It is described as an i ndependent association with the name of Chrysosplenio-Nothofagetum dombeyi and is a one-s pecies coihue forest, which makes altitudinal contact with the orotemperate deciduous forests of Nothofagus pumilio. 7. Nothofagus nitida (Phil.) Krasser (Coihue de Chiloé) Life form: evergreen mesophanerophyte. Bioclimate: hyperoceanic Temperate, oceanic Temperate. Bioclimatic belts: (Meso)Supratemperate hyperhumid & ultrahyperhumid. Distribution area: Figure 9 Communities: Luzuriago polyphyllae-Nothofagetum nitidae Amigo, Ramírez & Quintanilla 2004; Pilgerodendronetum uviferi Oberdorfer 1960; Fitzroyetum cupressoidis Oberdorfer 1960 As with ot her evergreen Nothofagus species, it has the common name of coihue. The geographical tag of de Chiloé in the name reveals in this case the geographical territory where the species is particularly a bundant as a substitute to the northern coihue (N. dombeyi). N. nitida is another large-sized tree th at either produces one -spe-


cies forests or occurs in combination with other evergreen taxa commonly found in the Valdivean Forest. This latter is a forest which can occur at supratemperate altitudes in both cordilleras (C. de la Costa and the Andes) from latitude 40° south and reaches beyond 48° south. From this last point southwards, the forest gives way to the forests of the third Chilean coihue, namely, N. betuloides.

Temperate climate, which explains why this species endemic to Chile does not cross the Andes to colonize territory in Argentina. A climatophilous association, Luzuriago polyphyllaeNothofagetum has been recognized. In this association the dominance of N. nitida is accompanied by other broad-leaved, evergreen taxa, such as Laureliopsis philippiana or Drimys winteri and even some conifers, such as Podocarpus nubigena. The species is not at all infrequent either in edaphohigrophilous locations, which can be even found in its northern distribution area, e.g., the provinces of Llanquihue and Palena. In this type of sites it can intermingle with associations commonly seen in terrains with blocked drainage, a habitat particularly suitable for swamp gymnosperms. This is the case of the community named Pilgerodendronetum uviferi and also of frequent instances of the Fitzroyetum cupressoidis, which is dominated by an emblematic and magnificent Cupressaceae, viz., Fitzroya cupressoides, the Chilean larch. Larch formations thrive in the supratemperate, ultrahyperhumid bioclimate; but Fitzroya cupressoides can grow even under orotemperate conditions. So that in the rainiest areas of the region of Los Lagos the larch forests usually colonize altitudes higher than those recorded for Luzuriago polyphyllae-Nothofagetum (AMIGO ET AL. 2004). However, both communities (Fitzroyetum and Luzuriago-Nothofagetum) converge perfectly in topographically flat sites, such as valleys carved by glaciers. These formations form the so-called “FitzroyaNothofagus nitida-forest” (HILDEBRAND-VOGEL ET AL. 1995). In the form of a climatophilous community, the N. nitida forests tend to occur in the supratemperate belt. However, these forests are not unusual in the upper mesotemperate belt on account of their variable adaptations as an edaphohigrophilous forest. This is particularly true on the southern edge of the region of Los Lagos (43° south). HOLDGATE (1961) studied N. nitida forests in combination with the swamp Myrtaceae Tepualia stipularis. His survey covered sites as far from each other as the western coast of the Island de Chiloé (42° south) and the most southerly limit of the species (49° south). In both extremes of this territory the soils presented a thick peat layer and low pH values. This explains the abundance of N. nitida all over the islands and ultrahyperhumid channels of the indented Chilean coast to the south of Isla Grande de Chiloé (from 43° south). From the 45th parallel south onwards, the presence of a supratemperate belt at sea level provides conditions even better suited to the species (AMIGO ET AL. 2007). 8. Nothofagus betuloides (Mirb.) Oerst. (Coihue de Magallanes)

Figure 9: Map showing the distribution of Nothofagus nitida. Red dotted lines mark Temperate/Mediterranean and Temperate/Boreal borders.

Another peculiarity of N. nitida is that its forests develop with rainfall records ranging from hyperhumid to ultrahyperhumid standards and cover large areas. This is the case of some areas in the south of the region of Los Lagos, where annual rainfall records range from 5,000 to 6,000 mm. (M.O.P. 1987). On the other hand, its distribution area reveals a strong liking for a hyperoceanic

Life form: evergreen mesophanerophyte. Distribution area: Figure 10. Bioclimate: hyperoceanic Temperate, oceanic Temperate; hyperoceanic Boreal. Bioclimatic belts: Supra-Orotemperate hyperhumid & ultrahyperhumid; Thermo-(Meso) Boreal humid-ultrahyperhumid. Communities: Nothofagetum betuloidis Oberdorfer 1960; Pilgerodendronetum uviferi Oberdorfer 1960; Nothofagion betuloidis Roig, Dollenz & Méndez 1985

12 J. Amigo & M. A. Rodríguez-Guitián

Figure 10: Map showing the distribution of Nothofagus betuloides. Red dotted lines mark Temperate/ Mediterranean and Temperate/Boreal borders.

South of latitude 49° south, the forests of coihue de Chiloé are replaced by other evergreen, (ultra) hyperhumid taxa dominated by the coihue de Magallanes. These can be found throughout the hyperoceanic islands of the channels and fiords of the Chilean coast as far as Tierra del Fuego. OBERDORFER (1960) was the first to provide a phytosociological name for these forests. He ascribed all these formations to one single association, which he named Nothofagetum betuloidis, and supported his viewpoint with floristic arguments. However, he did not provide any relevés of his own but simply used relevés of other authors (REICHE 1907; SKOTTSBERG 1916; ROIVAINEN 1954). These relevés covered the area from

48° south to 53-54° south in Tierra del Fuego. Except for the relevés taken at latitude 48° south, where N. nitida is also present, no other forest includes any other Nothofagus species. After the contribution of OBERDORFER (op. cit.), up to 3 forest associations dominated by N. betuloides were described. These were different stages of shrub degradation as a result of human action. All these variants were described across a transect from the Pacific to the Atlantic along latitude 51°-52° south (ROIG ET AL. 1985b). Although these forest associations dominated by the coihue de Magallanes need to be correctly re-arranged and probably simplified, we support the proposal of the Argentinian authors. They defend the existence of an alliance, viz. Nothofagion betuloidis, for this set of hyperoceanic and hyperhumid most southerly associations, whose borderline with the Boreal macroclimate still needs to be properly determined according to the floristic, structural and dynamic changes observed in the composition of these forests. N. betuloides thrives ideally in a Boreal macroclimate. Not surprisingly, it is in Tierra del Fuego, the southernmost part of the continent, where the species tolerates the widest range of ombroclimates. According to MCQUEEN (1976), the species is found in a full range of forests along the Straits of Magellan, where rainfall rates range from upper humid standards to hyperhumid records to the west of Punta Arenas (Figure 11/Transect 4). From this boreal territory the species also extends to the north, but always in ombroclimatically hyper- and ultrahyperhumid conditions. It occurs on coastal hyperoceanic slopes and in the foothills of the Andean Cordillera, altitudinally on top, in the hyperoceanic temperate territory, of the forests of N. nitida, and appearing in some scattered spots as far as the Cordillera de la Costa at parallel 40° south. At this latitude, the northernmost limit of the species, ultrahyperhumid larch forests of Fitzroyetum cupressoidis are intertwined in a hilltop position with vegetation of Magellanic origin. There we can find small patches of N. betuloides and Magellanic peatlands belonging to the class Myrteolo-Sphagnetea, which is dominated by sod-forming vascular plants, with Donatia fascicularis as the most prominent representative taxon (RAMÍREZ & RIVEROS 1975). The identification of such northerly instances with the same association Nothofagetum betuloidis (RAMÍREZ & FIGUEROA 1987) needs further discussion. 9. Nothofagus pumilio (Poepp. & Endl.) Krasser (Lenga) Life form: summergreen (micro)-mesophanerophyte. Distribution area: Figure 12. Bioclimate: hyperoceanic Temperate, oceanic Temperate; (oceanic Boreal). Bioclimatic belt: (Supra)-Orotemperate humid & hyperhumid; (Mesoboreal subhumid –humid) Communities: Ad eno cau lo- No tho fag e ta lia pum i l io n is Oberd. 1960 em. Hildebrand-Vogel, Godoy & Vogel 1990; Violo magellanicae-Nothofagion pumilionis Roig, Anchorena, Dollenz, Faggi & Méndez 1985


Figure 11: Transect 4: Valdivean-Magellanian Region, Boreal-Austromagellanian Province/Temperate Magellanian Province. Vegetation at latitude 53º 30’ south. Coloured basement shows bioclimate territories: Boreal (green) and Temperate (violet). 1/ Magellanic moorland (Myrteolo-Sphagnetea). 2/ Escallonio-Nothofagion antarcticae 3/ Nothofagion betuloidis 4/ Violo-Nothofagion pumilionis. 5/ Agropyro-Nothofagion antarcticae 6/ Patagonian graminoid steppe (Festucetea gracillimae).

This is the most widely distributed of all the tree species growing in the South American extratropical territory. It can be found from the middle of the region of Maule, i.e., from latitude 35° 30’ south to Tierra del Fuego, at the southernmost tip of the continent beyond 55° south. Consequently, it covers about 20 latitudinal degrees. In this immense geographical area the species usually appears forming one-species forests and its presence always signals the altitudinal limit for the forests throughout the Andean Cordillera. These one-species lenga forests, the most orophilous of all temperate forests, are ideal bioindicators for the orotemperate belt (AMIGO ET AL. 2007). In this belt we can only find N. pumilio forests frequently accompanied in the timber-line by chaparrals of the same species in the form of dwarf groves. Only four other tree species can be seen in these orotemperate forests: A) Nothofagus antarctica in its shrub-like, stunted morphotype. Occasionally, on mountain peaks, the highest limit of an orotemperate lenga forest is edged with scrublands of this species of 2 m or less (RAMÍREZ ET AL. 1985). B) Araucaria araucana, which forms mixed forests where this gymnosperm easily surpasses the height of the lengas. These mixed orotemperate forests can only be found in the latitudinal strip ranging from 37° 30’ to 39° 40’ south, i.e., the north and south borderlines respectively of this Chilean-Argentinian gymnosperm (see Figure 5/Transect 2). The association Carici trichodes-Araucarietum araucanae, previously described by OBERDORFER (1960), was intended to reflect this situation. However, some associations combining Araucaria araucana and Nothofagus pumilio have since been published and we now need a syntaxonomical reconsideration of the question. C) Fitzroya cupressoides. In mountain environments in ultrahyperhumid conditions, stunted lenga groves can also grow on the highest slopes, either in contact or even intertwining with larch forests (Fitzroyetum cupressoidis). These formations can only be found in the narrow

Andean land strip where these larch forests have been recorded, that is, between latitudes 41° and 43° south. There are records of these formations, for example, in the region of Los Lagos, in the National Park of Vicente Pérez Rosales, around latitude 41° (VILLAGRÁN 1980). D) N. betuloides. Where the ultrahyperhumid conditions reach the Andean Cordillera in the region of Los Lagos (40°- 43° south), the orotemperate lenga forests can occasionally make contact with this species. But these contacts are more frequent in the Magellanian territory, where a decreasing rainfall gradient from the fiords and western islands to the border between Chile and Argentina provides suitable conditions for the massive occurrence of ultra- and hyperhumid, boreal forests of Nothofagion betuloidis to the west and south, and humid or subhumid lenga forests to the east and north. In the transitional land strips lenga forests can co-exist with intrusions of N. betuloides. Near the city of Punta Arenas, at latitude 53° south, some cases of this kind have already been studied (DOLLENZ 1982b). At latitude 37° south the orotemperate belt typically associated with the one-species lenga forest occurs from 1,700 m. However, at latitude 52° south we find the same conditions at sea level. As one would expect, given the lower altitudinal limit of these lengales, N. pumilio and other dominant Nothofagus species of the catenally lower forests (N. dombeyi, N. alpina, N. obliqua; see Transect 3/ Fig. 8) intertwine. However, these scenarios must be interpreted as “variants of N. pumilio”, perhaps as a subassociation in some cases, of the corresponding supratemperate forests. The syntaxonomical debate There are numerous communities already described which can be used to make a syntaxonomical analysis of these lenga forests. However, this group of vegetation badly needs a detailed revision to clarify, in the first place, how many distinct units are involved and how they should be named. Two are the most widely used criteria, namely:


Figure 12: Map showing the distribution of Nothofagus pumilio. Red dotted lines mark Temperate/ Mediterranean and Temperate/Boreal borders.

1) that lenga forests must be ascribed to a class other than the most common one of temperate forests (viz., Wintero-Nothofagetea), a class given the name Nothofagetea pumilionis-antarcticae by OBERDORFER (1960). However, following the proposal of FREIBERG (1985), the possibility of breaking this unit down into two classes, namely, Nothofagetea pumilionis and Nothofagetea antarcticae, received some consideration. However, this proposal is clearly invalid, since it does not comply with Article 5 of the ICPN. 2) that the already recognized lenga forests can be divided into two large units, each with the rank of an order and differentiated according to a biogeographical

criterion: Adenocau lo- No tho fag e talia pum ilion is for the communities of the Valdivean Province, and No tho fagetalia pum ilion is -an tarctic ae for the Magellanian Province. This last unit was floristically depicted in a classic study by ROIG ET AL. (1985a). These authors provided data on the lenga forests growing in Chile and Argentina within the latitudinal strip between the 51st and 52nd parallels south. However, as far as the Valdivean lengales are concerned, the syntaxonomical debate became more and more complicated with every new study of these forest communities. First, ESKUCHE (1968) reformulated the original Oberdorfer’s invalid name (“Pumilietalia”) as Nohofagetalia pumilionis-dombeyi to include not only the Argentinian forests of N. dombeyi but also those of Austrocedrus chilensis. Subsequently, after taking relevés on the slopes of the volcanoes within the Chilean land strip between 38° 50’ and 41° 50’ south, FREIBERG (1985) divided the class into Nothofagetea pumilionis and Nothofagetea antarcticae, accepted the name of the order suggested by ESKUCHE (op. cit.) –but as included in his Nothofagetea pumilionis– and finally put forward the proposal of up to 7 associations of lenga forests as members of one single alliance. In his research, Freiberg also defended the existence of a new association. Soon after, HILDEBRAND-VOGEL ET AL. (1990) proposed a more correct name for the order, Adenocaulo-Nothofagetalia pumilionis, and recognized 6 associations for the lengales studied between the 38th and 45th parallels south. These same authors also defended the existence of a new association. Later, FINCKH (1996), in a detailed study conducted in the National Park of Villarrica uses the name Nothofagetalia pumilionis for the order. However, Finckh recognized 5 associations of Nothofagus pumilio forests in the Andean strip between parallels 39° 18’ and 39° 38’ south, and put forward two new associations for such small a territory. In a later review made from the perspective of an Argentinian phytosociologist, ESKUCHE (2002) defended the name of Nothofagetalia pumilionis encompassing, in the same latitudinal strip between parallels 38° and 45° south, up to 11 associations of Argentinian-Chilean lenga forests (with the inclusion of two associations dominated by Araucaria araucana). In his review, Eskuche proposed 3 new associations. More recently, FLORES & HILDEBRAND-VOGEL (2006) recognized 3 associations of lengales in Chile between latitudes 40° and 43° south. Two of these associations would be new and the third one has a clearly invalid name. Against this background, we urgently need to clarify the phytocoenotical biodiversity involved in the lengales of the Valdivean Province and adopt an orthodox nomenclature for a stable and uniform syntaxonomy. By contrast, only two associations have been mentioned for the Magellanian Province and, in accordance with the impoverishment of the flora towards the southern apex of the continent, it is not likely that the present phytocoenotical diversity of these forests will change significantly with new findings. Nevertheless, we must bear in mind that in this biogeographical territory there are lenga forests growing not only in a Temperate bioclimate but also in a Boreal bioclimate, and a detailed phytosociological


analysis (see for example PISANO, 1977) could eventually lead to changes in an updated syntaxonomy for these forests. 10. Nothofagus antarctica (G. Forst.) Oerst. (Ñirre, Ñire) Life form: summergreen (nano)-micro-mesophanerophyte. Distribution area: Figure 13. Bioclimate: hyperoceanic Temperate, oceanic Temperate; oceanic Boreal. (oceanic Pluviseasonal Mediterranean) Bioclimatic belt: (Meso)-Supra-Orotemperate subhumid-hyperhumid; Mesoboreal humid. (Mesomediterranean edaphohygrophilous). Communities: Nothofagetum antarcticae Oberdorfer 1960; Lomatio hirsutae-Nothofagetum Berberido-Nothofagetalia antarcticae Eskuche 1968, Nothofagetalia pumilionis-antarcticae Oberdorfer 1960 Similarly to the previous species, N. antarctica is also very widely distributed. It can be found from antarcticae Eskuche 1969 in Luebert et al. 2003; latitudes 35° to 56° south and on both sides of the Andean Cordillera. Thus, these two deciduous species, N. antarctica and N. pumilio, have been taken as genuine representatives of the subantarctic forest or Magellanian forest, particularly in the description of the northernmost instances of that forest (SAN MARTÍN ET AL. 1991c), which are located in sites with a macroclimate very different from that of Tierra del Fuego in the Magellanian Province. The most distinctive feature of the especies, usually a scrub plant up to 5 m high but sometimes a tree up to 15 m high, is its high endurance of extreme conditions. Thanks to this endurance, the plant has colonized the coldest environments peculiar to temperate or even boreal forests. Records of the plant have been taken in Tierra del Fuego, at latitude 55° south, in the upper limits of the Andean forest, for example in Puyehue (RAMÍREZ ET AL. 1985), at latitude 40° 45’ south, or in the northernmost limit of that species, at 2,000 m masl. (SAN MARTÍN ET AL. 1991c). The plant can also tolerate severely limiting soil conditions, such as those imposed by volcanic ash or highly hydromorphic soils. For this reason, Nothofagus antarctica has long been known under the nickname of ‘the beggar’: in the Patagonian forests no other species is able to accept habitats as extreme as those colonized by N. antarctica (KALELA 1941). An analysis of the natural regeneration patterns of all the Chilean Nothofagus species (WEINBERGER 1973) has revealed that this is a particularly continental species, capable of enduring day-long summer frosts, remarkably heliophilous and very abundant in environments with high air humidity saturation deficits. For all these reasons, it is the species of the genus most suited to endure the rain shadow conditions to the east of the Andean Cordillera, where the temperate forests progressively give way to the treeless landscape of Patagonia. The extraordinary ecological plasticity exhibited by the specimens ascribed to the species N. antarctica becomes apparent through its enormous and long recognized morphological diversity, as RAMÍREZ ET AL. (1985)

emphasized. These authors distinguished 3 morphotypes: (a) the tree-like morphotype thrives in supratemperate environments; (b) the shrub-like and stunted morphotype is peculiar to orotemperate conditions, either in the upper limit of the forests or in sites transitional to the cold and drier steppes of the Patagonian south and Magallanes; and (c) the chamaephytic morphotype, up to 1 m high, that thrives on peat soils. Studies on reproductive fertility, isoenzymatic and even genetic variability have revealed very significant interpopulational variability rates. Tests have proved that the morphological traits remain even outside the habitat associated with the corresponding morphotype (DONOSO ET AL. 2006). In specimens of the shrub-like morphotype developed in the upper limits

Figure 13: Map showing the distribution of Nothofagus antarctica. Red dotted lines mark Temperate/Mediterranean and Temperate/Boreal borders.


of the forest, cases of hybridization have been confirmed between N. antarctica and N. pumilio; hybrid which is morphologically closer to the first species mentioned (QUIROGA ET AL. 2005). Consequently, the existence of different taxa under the current concept of Nothofagus antarctica, cannot be fully dismissed. A positive confirmation of this hypothesis would surely have an impact on the syntaxonomical position of the communities involved. Syntaxonomical position As with the lenga forests, the ñirrantales also present a complex syntaxonomical allocation in need of clarification. First, OBERDORFER (1960) made the proposal of the association Nothofagetum antarcticae with the supporting evidence of only two relevés made, respectively, at latitudes 39° and 45° south. This led to the use of that association name in surveys conducted in Chile for native, either tree-like or shrub-like, ñirre formations both for the Magellanian Province, at the 54th parallel (PISANO 1977), and for the northernmost populations of the species in the Andean Cordillera, that is, at latitude 35° 36’ south (SAN MARTÍN ET AL.1991c). New proposals were also made for the following situations: + For formations of a tree-like morphotype in the region of Los Lagos (latitudes 40°-41° south) on badly drained volcanic soils (locally known as “ñadis”), some authors defended the existence of the association ”Chusqueo (tenuiflorae)-Nothofagetum antarcticae” (RAMÍREZ & FIGUEROA 1987). The corresponding belt is humid mesotemperate. + For clearly finicolous and edaphohigrophilous sites in steep and hyperoceanic valley bottoms within the mesomediterranean territory, another community was published, viz. ”Scirpo (cernui)-Nothofagetum antarcticae” (SAN MARTÍN ET AL. 1988) (latitude 35° 50’ south, see Transect 1/ Fig. 3). + For a hilltop community in the Cordillera de la Costa at latitude 40° south (Cordillera Pelada, above 1,000 m), dominated by a shrub-like morphotype in upper supratemperate, ultrahyperhumid environments, another association name, viz., ”Baccharido (magellanicae)-Nothofagetum antarcticae”, was also published (RAMÍREZ ET AL. 1996). However, all these 3 community names were invalidly published, because they did not comply with Articles 5 and 7 of the ICPN. For this reason these 3 phytosociological names appear in inverted commas and the final syntaxonomical scheme does not include them (see Appendix II). For the Argentinian territory of the Valdivean Province ESKUCHE (1969) described communities of copses and scrublands which corresponded to serial stages of the Argentinian temperate forests growing between latitudes 38° and 43° south (North Patagonian for the author). Among these communities Eskuche proposed up to 13 associations as varied as microforests with an absolute dominance of ñirre in its tree-like variant, different combinations of this taxon with other shrubs (Schinus patagonicus, Maytenus boaria, Ribes sp. pl., Berberis sp. pl., Escallonia sp. pl. etc.), and even scrublands whe re N. antarctica was completely absent. ESKUCHE (op. cit.)

arranged these associations into three alliances (two of them with provisional names). For these alliances Eskuche proposed a special order, viz., Berberido-Nothofagetalia antarcticae, which he included in the class Nothofagetea pumilionis-antarcticae, to which he had ascribed all the Argentinian temperate forests. Some years later an extensive, classic work on the vegetation of the Magellanian Province was published (ROIG ET AL. 1985a). It covered a land transect crossing South America from the Pacific to the Atlantic along the latitudinal strip between parallels 51°-52° south. The ñirre communities described were arranged, with ecological and climatic justification, into two phytosociological alliances. On the one hand, the hyperhumid ñirrantales of the islands of the Chilean channels located in the macrobioclimatical transition Boreal/Temperate were ascribed to the alliance Escallonio-Nothofagion antarcticae. Meanwhile, the humid, temperate ñirrantales in contact with lengales, and even those subhumid ones growing in the easternmost limit of the South Patagonian forests, were ascribed to the alliance Agropyro-Nothofagion antarcticae. As has so often happened, the proposed names were invalidly published (Article 5 of the ICPN). Almost at the same time, FREIBERG (1985) proposed the creation of an independent class, viz., ”Nothofagetea antarcticae”, to allocate two orders: one for the Valdivean scrublands already studied by ESKUCHE (1969) in Argentina, and another for the Magellanian ñirrantales dealt with by ROIG ET AL. (op. cit.). Apart from the fact that the nomenclature was invalid (Article 5 of the ICPN), the proposal made by FREIBERG (op. cit.) was not taken up by any Argentinian phytosociologists, despite the fact that the communities intended for his class “Nothofagetea antarcticae” had been recorded mainly in territories to the east of the Andes. As far as we know, in Argentina all the papers dealing syntaxonomically with temperate forests have ascribed the different North Patagonian Nothofagus forests (i.e., of the Valdivean Province) to an order: ”Nothofagetalia pumilionis-dombeyi” (CONTICELLO ET AL. 1996; ROIG 1998; ESKUCHE 1999). But the authors who have dealt with the South Patagonian forests of N. pumilio or N. antarctica (Magellanian Province) defend the existence of another order, viz., Nothofagetalia pumilionis-antarcticae (ROIG 1998). In both cases, the two orders were ascribed to the same class, the Nothofagetea pumilionis-antarcticae. There have not been many phytosociological surveys recently. However, some studies have occasionally recorded the presence of ñirre forests and ascribed them to a particular phytosociological association: in the National Park of Copahue in Argentina at latitude 37° 50’ south (GANDULLO 2003), and in the National Park of Tolhuaca, in Chile, at latitude 38° 10’ south (LUEBERT ET AL. 2003). In these two sources the authors mention supratemperate hyperhumid ñirre forests and accept the existence of an association published by ESKUCHE (1969): Lomatio-Nothofagetum in the Chilean park and Ribesi-Nothofagetum in the Argentinian park. Only in the survey dealing with the park of Tolhuaca is the presence of an association, viz., Lomatio hirsutae-Nothofagetum antarcticae, supported by relevés. In this case the particular lectotypus of the association is taken from the original contribution of ESKUCHE (1969).


On the other hand, a few years earlier a different criterion had been applied in a nearby territory. In the National Park of Villarrica (latitude 39° 20’, Chile), in similar thermo- and ombroclimatic belts along the 8201,280 m altitudinal strip, in contact with the forests of Nothofagus dombeyi, N. pumilio and Araucaria araucana, FINCKH (1996) described three associations dominated by Nothofagus antarctica which he maintained should be included in the “Nothofagetea antarcticae“class. In short, as a result of its adaptability to habitats unacceptable to other Nothofagus taxa, Nothofagus antarctica has received very heterogeneous syntaxonomical treatments in phytosociological literature. In our opinion, Nothofagus antarctica can be ascribed to either of the two large classes used for the temperate and boreal forests of South America. The supratemperate micro-mesoforests of the Valdivean Province and the scrublands acting probably as substitution stages of larger forests or which are capable of settlement as edaphohigrophilous or edaphoxerophilous permanent communities can be ascribed to Wintero-Nothofagetea. On the other hand, the orotemperate scrublands capable of both intertwining with orotemperate lengales in the altitudinally upper limits of the temperate forest and establishing themselves as permasigmetum in the cold areas of the Magellanian Province, either in edaphohigrophilous locations under macroclimatically Boreal conditions or in other lower subhumid Temperate conditions as far as the beginning of the xeric Magellanian steppes, can be ascribed to Nothofagetea pumilionis-antarcticae. The 3 morphotypes above mentioned when dealing with the ecological adaptability of N. antarctica can be related to 3 phytosociological classes: firstly, a tree-like morphotype with Wintero-Nothofagetea, but also with Nothofagetea pumilionis-antarcticae; secondly, a shrub-like morphotype, which must correspond only with Nothofagetea pumilionis-antarcticae; and thirdly, a chamaephytic morphotype, which must be related, on account of its peat-dwelling profile, with the Myrteolo-Sphagnetea class. Further studies on a larger scale will probably reveal that there is more than one taxon under the current name of one single species. The phytocoenotical behaviour should be correctly studied and clarified to solve this question. Conclusion The ten South American species of the Nothofagus genus are some of the best references for the study and understanding of the temperate, boreal and even mediterranean forest ecosystems of South America. The phytosociological behaviour of the genus is already relatively well known, but further review is needed to avoid misleading interpretations. An accurate study of the phytocoenoses can certainly provide more detailed knowledge of the thermoclimatic and ombroclimatic belts found in this large territory. Acknowledgements We thank the staff of the Instituto de Botánica of the Austral University of Valdivia as well as several Chilean botanists from the University of Talca, University of Concepción and University of Chile for extensive help

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Taxonomic names cited along the text Aextoxicon punctatum Ruiz & Pavón Araucaria araucana (Molina) K.Koch Austrocedrus chilensis (D.Don) Pic.Serm. & Bizzarri Cryptocarya alba (Molina )Looser Dasyphyllum diacanthoides (Less.) Cabrera Donatia fascicularis J. R. & G. Foster Drimys winteri J.R. Forst. & G. Forst. Eucryphia cordifolia Cav. Fitzroya cupressoides (Molina) I.M. Johnst. Gevuina avellana Molina Gomortega keule (Molina) Baill. Laurelia sempervirens (Ruiz & Pavón) Tul. Laureliopsis philippiana (Looser) Schodde Maytenus boaria Molina Nothofagus alessandri Espinosa Nothofagus alpina (Poepp. & Endl.) Oerst. Nothofagus antarctica (G. Forst.) Oerst. Nothofagus betuloides (Mirb.) Oerst. Nothofagus dombeyi (Mirb.) Oerst. Nothofagus glauca (Phil.) Krasser Nothofagus leonii Espinosa Nothofagus macrocarpa (DC.) F.M.Vázquez & R.A. Rodr. Nothofagus nitida (Phil.) Krasser Nothofagus obliqua (Mirb.) Oerst. Nothofagus pumilio (Poepp. & Endl.) Krasser Persea lingue Nees Peumus boldus Molina Pinus radiata D. Don Pitavia punctata (Ruiz & Pavón) Molina Podocarpus nubigena Lindl. Prumnopitys andina (Poepp. ex Endl.) De Laub. Quillaja saponaria Molina Schinus patagonicus (Phil.)I.M.Johnst. ex Cabrera Tepualia stipularis (Hook. & Arn.) Griseb. Weinmannia trichosperma Cav. Appendix I: Phytosociological typology: hierarchical relationships of the syntaxa cited in the text. When a name is marked as INQUIRENDA means either was not correctly published by its original descriptor, or could be rejected as superfluous after peer syntaxonomical revision. C l a s s W I N T E R O - N O T H O F A G E T E A Oberd. 1960 Subclass Wintero-Nothofagenea O r d e r L a u r e l i e t a l i a p h i l i p p i a n a e Oberd. 1960 A l l i a n c e N o t h o f a g o - E u c r y p h i o n Oberd. 1960 Suballiance Nothofagenion glauco-alessandrii Amigo, San Martín & Quintanilla 2000 - Nothofagetum alessandrii San Martín et al. 1984 - Bomareo salsillae-Nothofagetum glaucae Amigo, San Martín & Quintanilla 2000 Suballiance Aextoxiconenion punctate Oberd. 1960 - Lapagerio roseae-Aextoxiconetum punctati Oberd. 1960 - Nothofago obliquae-Perseetum lingue Oberd. 1960 - Dasyphyllo diacanthoidis-Nothofagetum alpinae (Frank & Finckh) Pollmann 2001 Suballiance Nothofago-Eucryphienion Oberd. 1960 - Nothofago dombeyi-Eucryphietum cordifoliae Oberd. 1960 Suballiance Nothofagenion procerae Oberd. 1960 INQUIRENDA - Nothofagetum procerae Oberd. 1960 ex Ramírez 1978 O r d e r W i n t e r o - N o t h o f a g e t a l i a b e t u l o i d i s Roig, Dollenz & Méndez 1985 Alliance Nothofago-Winterion Oberd. 1960 - Laurelio philippianae-Weinmannietum trichospermae Oberd. 1960

- Luzuriago polyphyllae-Nothofagetum nitidae Amigo, Ramírez & Quintanilla 2004 - Fitzroyetum cupressoidis Oberd. 1960 - Pilgerodendronetum uviferi Oberd. 1960 Alliance Nothofagion betuloidis (Oberd. 1960) Roig, Dollenz & Méndez 1985 - Nothofagetum betuloidis Oberd. 1960 Order Berberido trigonae-Nothofagetalia dombeyi Pollmann 2001 Alliance Austrocedro-Nothofagion dombeyi Eskuche 1968 - Gavileo-Austrocedretum chilensis Eskuche 1968 - Austrocedro-Nothofagetum dombeyi Eskuche 1968 - Nothofago obliquae-Prumnopitydetum andinae Amigo, M.Rodríguez & Ramírez 2010 Alliance Elymo andini-Nothofagion macrocarpae Oberd. 1960 prov. corr. INQUIRENDA - Elymo andini-Nothofagetum macrocarpae Oberd. 1960 prov. corr. Alliance Myrceugenio-Nothofagion dombeyi (Eskuche 1999) Pollmann 2001 - Nothofagetum dombeyi-alpinae Eskuche 1999 INQUIRENDA - Dioscoreo-Nothofagetum obliquae Eskuche (1973) 1999 - Myrceugenio-Nothofagetum dombeyi Eskuche 1999 - Chrysosplenio valdivici-Nothofagetum dombeyi Oberd. 1960 prov. Order Myrceugenietalia exsuccae Oberdorfer 1960 corr. - Pitavio punctatae-Nothofagetum dombeyi San Martín & Ramírez ex Stoll 2008 n.n. INQUIRENDA Subclass Aristotelienea chilensis Amigo, Ramírez & Quintanilla 2007 Order Berberido-Nothofagetalia antarcticae Eskuche 1969 [pro parte, excl. Bacchari-Discarion articulatae] Alliance Ribesi-Nothofagion Eskuche 1969 INQUIRENDA - Ribesi-Nothofagetum antarcticae Eskuche 1969 - Lomatio-Nothofagetum antarcticae Eskuche 1969 in Luebert, Gajardo & Estay 2003 Class NOTHOFAGETEA PUMILIONIS-ANTARCTICAE Oberd. 1960 Order Adenocaulo-Nothofagetalia pumilionis Oberd. 1960 em. Hildebrand-Vogel, Godoy & Vogel 1990 Alliance Lagenophoro-Nothofagion pumilionis Oberd. 1960 em. Freiberg 1986 - Carici trichodes-Araucarietum araucanae Oberd. 1960 Order Nothofagetalia pumilionis-antarcticae Roig, Anchorena, Dollenz, Faggi & Méndez 1985 Alliance Violo magellanicae-Nothofagion pumilionis Roig, Anchorena, Dollenz, Faggi & Méndez 1985 A l l i a n c e Escallonio-Nothofagion antarcticae Roig, Anchorena, Dollenz, Faggi & Méndez 1985 A l l i a n c e Agropyro-Nothofagion antarcticae Roig, Anchorena, Dollenz, Faggi & Méndez 1985 Class LITHRAEO-CRYPTOCARYETEA Oberd. 1960 Order Cryptocaryetalia (Schmithüsen 1954)Oberd. 1960 Alliance Cryptocaryion (Schmithüsen 1954)Oberd. 1960 - Boldo-Cryptocaryetum nothofagetosum obliquae Oberd. 1960 Class MYRTEOLO-SPHAGNETEA Oberd. 1960 Class FESTUCETEA GRACILLIMAE Roig, Anchorena, Dollenz, Faggi & Méndez 1985