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Introduction
America are extremely isolated from other moist forest types yet have
developed and maintained a high level of species diversity. These forests
evolved under very different conditions than in North America , since
they were once a part of a large, cool rainforest type that was continuous
with tropical rainforests and they were subject to much less climatic
variation than North American rainforests . Chilean rainforests have a
much greater richness of unique specialized species than in analogous
forests in North America. Woody genera also dominate southern rainforests to a much greater degree than in North America. Chilean rainforests are likely to be more sensitive to environmental stresses caused by
climatic change and human activities than North American rainforests.
Veblen and Alaback study the role of natural disturbance in determining
forest structure and composition in temperate forests in both hemispheres.
Infrequent large-scale catastrophic disturbances as well as small-scale
localized disturbances play key roles in structuring rainforests in both
hemispheres. Windstorms are pervasive as chaotic disturbance agents in
both hemispheres, but stem breakage is the dominant mechanism for tree
mortality in North America , whereas rootthrow dominates in South
America. Some disturbances, such as earthquakes and landslides, are of
greater significance in South America, but others, such as wildfires and
snow avalanches, are more important in North America . While a large
degree of similarity exists between the material disturbance regimes of
rainforests in North America and South America , many human-caused
disturbances , such as the introduction of exotic plants and animals and
the introduction of fire, have had a much greater effect in South America
than in North America . Grazing , subsistence agriculture , and anthropogenic fire have had the greatest impact in South America , whereas
loggingfor pulpwood export has had the greatest impact in North America .
Meserve describes the mammals and reptiles of the seasonal rainforests
of North America and the perhumid rainforests of Chile. Different
families dominate in each hemisphere. Lizards dominate in the south ,
while snakes dominate in the north. Fewer than half the number of
mammal species in northern rainforests occur in Chilean rainforests.
As with rainforest plant species, Chilean mammals have a much higher
degree of uniqueness and have evolved in much greater isolation than
their counterparts in North America . Logging, poaching, and resource
development activities have resulted in much greater declines in mammal
species diversity in Chile than in North America .
Willson and her collaborators examine the community structure of
birds inhabiting rainforests in the perhumid zone of both southern Chile
and coastal Alaska. They find that the rainforests of sourthern Chile
support similar numbers of regularly breeding bird species as their counterparts in coastal Alaska , but relative abundances of birds tend to be
higher in Chile. The structures of bird communities are significantly
different in both regions as well, with a greater representation of upper-
Introduction
America are extremely isolated from other moist forest types yet have
developed and maintained a high level of species diversity. These forests
evolved under very different conditions than in North America , since
they were once a part of a large, cool rainforest type that was continuous
with tropical rainforests and they were subject to much less climatic
variation than North American rainforests . Chilean rainforests have a
much greater richness of unique specialized species than in analogous
forests in North America. Woody genera also dominate southern rainforests to a much greater degree than in North America. Chilean rainforests are likely to be more sensitive to environmental stresses caused by
climatic change and human activities than North American rainforests.
Veblen and Alaback study the role of natural disturbance in determining
forest structure and composition in temperate forests in both hemispheres.
Infrequent large-scale catastrophic disturbances as well as small-scale
localized disturbances play key roles in structuring rainforests in both
hemispheres. Windstorms are pervasive as chaotic disturbance agents in
both hemispheres, but stem breakage is the dominant mechanism for tree
mortality in North America , whereas rootthrow dominates in South
America. Some disturbances, such as earthquakes and landslides, are of
greater significance in South America, but others, such as wildfires and
snow avalanches, are more important in North America . While a large
degree of similarity exists between the material disturbance regimes of
rainforests in North America and South America , many human-caused
disturbances , such as the introduction of exotic plants and animals and
the introduction of fire, have had a much greater effect in South America
than in North America . Grazing , subsistence agriculture , and anthropogenic fire have had the greatest impact in South America , whereas
loggingfor pulpwood export has had the greatest impact in North America .
Meserve describes the mammals and reptiles of the seasonal rainforests
of North America and the perhumid rainforests of Chile. Different
families dominate in each hemisphere. Lizards dominate in the south ,
while snakes dominate in the north. Fewer than half the number of
mammal species in northern rainforests occur in Chilean rainforests.
As with rainforest plant species, Chilean mammals have a much higher
degree of uniqueness and have evolved in much greater isolation than
their counterparts in North America . Logging, poaching, and resource
development activities have resulted in much greater declines in mammal
species diversity in Chile than in North America .
Willson and her collaborators examine the community structure of
birds inhabiting rainforests in the perhumid zone of both southern Chile
and coastal Alaska. They find that the rainforests of sourthern Chile
support similar numbers of regularly breeding bird species as their counterparts in coastal Alaska , but relative abundances of birds tend to be
higher in Chile. The structures of bird communities are significantly
different in both regions as well, with a greater representation of upper-