xxii
Introduction
about the role of small-scale processes such as stand levelland conversions
that may depend on latitude, geomorphology , or regional climate controls.
Spittlehouse notes the need to look at forest ecosystems and species in
a broader sense, thereby eliminating the requirement to predict variability
at the site level. By identifying and analyzing the sensitivity of key
limiting factors , he assesses the impacts of future climatic change on
forests . In the seasonal rainforest zone of southern British Columbia , for
example, the key limiting factor to Douglas fir is available moisture .
Consequently, an increase in temperature due to global change mayor
may not affect survival and distribution of Douglas fir, depending on the
changes in precipitation that occur in conjunction with the warming.
Tasmania has a significant representation of both seasonal and perhumid
temperate rainforest but contrasts with Chile and North America in
history of human occupation and environmental management. These
rainforests have many structural features in common with the rainforests
of Chile, but they differ in disturbance history and degree of isolation.
Brown and Read show that in contrast with North America and Chile,
catastrophic disturbances play only a limited role in maintaining stand
structure in Tasmania . Anthropogenic fire has played a key role in
Tasmania for a much longer period than it has in rainforests in the
Americas. Tasmania has one of the most comprehensive protected areas
strategies of any rainforest region, with nearly 60% of the existing rainforest in established or proposed reserves and another 15% to 20% in
deferred status. However , management of human-caused fire remains one
of the most important challenges for the conservation of rainforests in
Tasmania , as it does in Chile.
The range of human-use effects on forests involves the effects of logging
on the wood, water , and air resources in the watershed . Hetherington
assesses the influence of logging in a small stream ecosystem in a coastal
temperate rainforest area over a 20-year period. In the logged areas ,
there was a reduction in evapotranspiration and increases in water yield
and ground-water levels. However, the magnitude and direction of changes
in peak flows , sediment transport, water quality, and fish populations
were variable over time. This finding suggests that the rate and areal
extent of logging is an important consideration in determining the overall
impacts of logging.
Boyle notes that the coastal rainforests of western Canada represent
some of that nation's most diverse and productive forests and account for
as much as 40% of Canada's wood exports. They also have great ecological
importance because of their high diversity of vertebrates in comparison to
other Canadian forests. In addition , lichen and moss diversity is exceptionally high in coastal forests. A higher proportion of species are habitat
or climate specialists in British Columbia rainforests than in forests of
other provinces, and fewer threatened species occur in this area . Boyle
observes that little protection exists for the most productive forests in
Introduction
about the role of small-scale processes such as stand levelland conversions
that may depend on latitude, geomorphology , or regional climate controls.
Spittlehouse notes the need to look at forest ecosystems and species in
a broader sense, thereby eliminating the requirement to predict variability
at the site level. By identifying and analyzing the sensitivity of key
limiting factors , he assesses the impacts of future climatic change on
forests . In the seasonal rainforest zone of southern British Columbia , for
example, the key limiting factor to Douglas fir is available moisture .
Consequently, an increase in temperature due to global change mayor
may not affect survival and distribution of Douglas fir, depending on the
changes in precipitation that occur in conjunction with the warming.
Tasmania has a significant representation of both seasonal and perhumid
temperate rainforest but contrasts with Chile and North America in
history of human occupation and environmental management. These
rainforests have many structural features in common with the rainforests
of Chile, but they differ in disturbance history and degree of isolation.
Brown and Read show that in contrast with North America and Chile,
catastrophic disturbances play only a limited role in maintaining stand
structure in Tasmania . Anthropogenic fire has played a key role in
Tasmania for a much longer period than it has in rainforests in the
Americas. Tasmania has one of the most comprehensive protected areas
strategies of any rainforest region, with nearly 60% of the existing rainforest in established or proposed reserves and another 15% to 20% in
deferred status. However , management of human-caused fire remains one
of the most important challenges for the conservation of rainforests in
Tasmania , as it does in Chile.
The range of human-use effects on forests involves the effects of logging
on the wood, water , and air resources in the watershed . Hetherington
assesses the influence of logging in a small stream ecosystem in a coastal
temperate rainforest area over a 20-year period. In the logged areas ,
there was a reduction in evapotranspiration and increases in water yield
and ground-water levels. However, the magnitude and direction of changes
in peak flows , sediment transport, water quality, and fish populations
were variable over time. This finding suggests that the rate and areal
extent of logging is an important consideration in determining the overall
impacts of logging.
Boyle notes that the coastal rainforests of western Canada represent
some of that nation's most diverse and productive forests and account for
as much as 40% of Canada's wood exports. They also have great ecological
importance because of their high diversity of vertebrates in comparison to
other Canadian forests. In addition , lichen and moss diversity is exceptionally high in coastal forests. A higher proportion of species are habitat
or climate specialists in British Columbia rainforests than in forests of
other provinces, and fewer threatened species occur in this area . Boyle
observes that little protection exists for the most productive forests in