8. Phytogeographic Relationships and Regional
Richness Patterns of the Cool Temperate Rainforest
Flora of Southern South America
Mary T . Kalin Arroyo, Magaly Riveros, Alejandro Penaloza,
Lohengrin Cavieres, and Ana Maria Faggi
The western margin of southern South America bears cool temperate
rainforest over a narrow landmass of some 17.5°of latitude, encompassing
great physiographic diversity. The South American rainforest zone constitutes a remarkable forest island, widely separated from the closest wet,
closed forest types on the South American continent by 1500km to
2000km. To the north, it is bound by seasonal, mediterranean-type
climate scrublands and one of the driest deserts on earth, the Atacama.
To the east , the rainforest intergrades with a narrow band of deciduous
Nothofagus or Austrocedrus chilensis coniferous forest , followed by dry
Patagonian steppe. Southward is the Antarctica continent, and westward the Pacific Ocean . In this forest island are found high productivity
levels (Schmidt & Lara , 1985), the second-longest-living tree in the
world-Fitzroya cupressoides, attaining more than 3600 years (Lara,
1993), and many obligately outbred woody species (Riveros, 1991).
Cool temperate rainforest also occurs along the Pacific coast of North
America along an analagous climatic gradient (Alaback, 1991 ; Franklin,
1988). There , however, it commences at a higher latitude on account
of the shallower temperature gradient in the Northern Hemisphere
(Alaback, 1991). As in South America, rainforest is bordered by
mediterranean-type climate vegetation type with a summer drought to
the south. However, in contrast with South America , the rainforest region
shows good eastward continuity, with extensive areas of coniferous forest
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Richness Patterns of the Cool Temperate Rainforest
Flora of Southern South America
Mary T . Kalin Arroyo, Magaly Riveros, Alejandro Penaloza,
Lohengrin Cavieres, and Ana Maria Faggi
The western margin of southern South America bears cool temperate
rainforest over a narrow landmass of some 17.5°of latitude, encompassing
great physiographic diversity. The South American rainforest zone constitutes a remarkable forest island, widely separated from the closest wet,
closed forest types on the South American continent by 1500km to
2000km. To the north, it is bound by seasonal, mediterranean-type
climate scrublands and one of the driest deserts on earth, the Atacama.
To the east , the rainforest intergrades with a narrow band of deciduous
Nothofagus or Austrocedrus chilensis coniferous forest , followed by dry
Patagonian steppe. Southward is the Antarctica continent, and westward the Pacific Ocean . In this forest island are found high productivity
levels (Schmidt & Lara , 1985), the second-longest-living tree in the
world-Fitzroya cupressoides, attaining more than 3600 years (Lara,
1993), and many obligately outbred woody species (Riveros, 1991).
Cool temperate rainforest also occurs along the Pacific coast of North
America along an analagous climatic gradient (Alaback, 1991 ; Franklin,
1988). There , however, it commences at a higher latitude on account
of the shallower temperature gradient in the Northern Hemisphere
(Alaback, 1991). As in South America, rainforest is bordered by
mediterranean-type climate vegetation type with a summer drought to
the south. However, in contrast with South America , the rainforest region
shows good eastward continuity, with extensive areas of coniferous forest
134