Sustainable forest management in a changing climate

1
Sustainable forest management in a changing
climate

• Jay R. Malcolm
• Faculty of Forestry
• University of Toronto
• April 2003

2
Background

• causal connection between increasing greenhouse
  gas concentrations and recent warming
• magnitude of potential warming in the coming
  century is enormous from an ecological viewpoint

• hundreds of species are showing responses
  already
• very high confidence that anthropogenic
  climate change is already affecting living
  systems

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Using coupled GCMs and GVMs to investigate
potential ecological changes
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Current Climate (GVM MAPSS)
Doubled-CO2 Climate (Hadley Centre, with
sulphate aerosol cooling) (GVM MAPSS)
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Biome change for
14 combinations of GCMs and GVMs
Percent of Models
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Ecosystem change, but also the outright loss of
certain ecosystem types
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Implications of habitat loss for species
diversity
Current area (ab) vs. future area (bc)
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Global estimate of species loss based on 14
CGMs/GVMs
Area Percent area under 2xCO2 Percent species loss
Tundra 8.5 50.0 -9.9
Taiga/Tundra 7.0 43.9 -11.6
Boreal Conifer Forest 12.9 102.8
Temperate Evergreen Forest 7.8 106.6
Temperate Mixed Forest 9.3 147.9
Tropical Broadleaf Forest 14.8 120.8
Savanna/Woodland 28.2 103.6
Shrub/Woodland 7.4 78.3 -3.6
Grassland 22.7 114.4
Arid Lands 14.2 80.3 -3.2
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• Implications for forested ecosystems
• Regional disappearances of certain forest
  types/working groups (e.g., Spruce-fir forests
  disappeared and maple-beech-birch forests showed
  near extirpation in eastern U.S. under doubled
  CO2 Iverson Prasad 1998, 2001, 2002)
• Shifts of species ranges by 100-500 km,
  including commercially important species
  
  (e.g., Sugar maple, balsam fir,
  trembling aspen, and red pine reduced by more
  than 90 in eastern U.S. under doubled CO2
  Iverson Prasad 1998, 2001, 2002)
• Increasing stress as climate conditions change,
  with increased vulnerability to diseases and
  pests
• Increased probability of fire
• Potential for increased growth provided that
  enough water is available
  
  (if insufficient water is
  available, potential to exacerbate drought
  conditions)
• Increased emphasis on forests as carbon sinks
  (increase sequestration and decrease losses from
  soil)

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• Economic implications
• little or net positive impacts on timber markets
  in the United States (e.g., between -1 and 11
  Perez-Garcia et al. 1997, Sohngen Mendelsohn
  1998).
• however, assumed appropriate adaptive responses
• -e.g., Sohngen Mendelsohn (1998) practices on
  intensive lands would rapidly establishing
  appropriate species lags on low-intensity lands
  only 10-30 years.
• -understanding of likely tree responses is key
  because changes in forest growth and productivity
  will constrain the choices of adaptation
  strategies
• -promotion of appropriate regeneration through
  planting (shortens period of stand establishment
  when C accumulation is low and soil C losses are
  relatively high)
• -planting of genetically modified species or
  specific ecotypes
• -development of silvicultural systems that
  maintain forest vigour
• -important among these strategies are those that
  facilitate species migration, either through
  artificial or natural means

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Potential importance of migration

• planting has not been successful in many cases
  even in the absence of climate change

• if migration fails to make up for
  warming-induced local losses of species, a net
  decline in forest biomass and local diversity can
  be expected (e.g., 7-11 increase in global
  forest carbon under perfect migration 3-4
  decline under zero migration Solomon Kirilenko
  1997)
• natural migration is especially important in
  situations where natural regeneration is used as
  a management tool
• artificial migration (e.g., planting) not useful
  for great majority of forest species (In this
  sense, the conservation of biological diversity
  as a goal in sustainable forest management could
  be threatened by climate change)

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Implications of habitat loss for species
diversity no migration scenario
Current area (ab) vs. future area (b only)
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Implications of habitat loss for species
diversity no migration scenario
Area Percent area under 2xCO2 Percent species loss
Tundra 8.5 45.0 -11.3
Taiga/Tundra 7.0 14.7 -25.0
Boreal Conifer Forest 12.9 54.1 -8.8
Temperate Evergreen Forest 7.8 47.8 -10.5
Temperate Mixed Forest 9.3 73.4 -4.5
Tropical Broadleaf Forest 14.8 92.0 -1.2
Savanna/Woodland 28.2 74.2 -4.4
Shrub/Woodland 7.4 51.2 -9.6
Grassland 22.7 79.1 -3.4
Arid Lands 14.2 69.7 -5.3
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How do future rates compare with past rates?
Migration rate distance time period
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How do future rates compare with past rates?
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Percent of 14 models showing high rates
(gt1,000 m/yr)
Finland (1st place) 59.9 Canada (8th)
33.1 U.K. (13th) 29.8
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Future rates compared with Spruce post-glacial
rates
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Making future rates agree with post-glacial rates
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Making future rates agree with post-glacial rates
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Barriers to migration
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Barriers to migration
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Barriers to migration
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Southern Red Oak
Current range (black line) and potential future
range (CCC)
Colonized future range assuming post-glacial
capabilities
Iverson, Schwartz, and Prasad (in prep.)
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Percentage of new suitable habitat colonized in
100 yrs assuming postglacial migration rates
Climate Scenario Prob. Coloniz. S. Red Oak Sourwood Sweetgum Persimmon Loblolly
CCC gt2 7.6 12.7 11.6 2.7 8.4
CCC gt20 2.0 2.4 2.2 0.8 1.5
CCC gt50 1.2 1.0 1.2 0.6 0.6
HAD gt2 11.5 8.2 14.7 3.8 9.9
HAD gt20 4.1 2.2 5.1 1.3 3.2
HAD gt50 2.5 0.9 3.0 0.9 1.6
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• Conclusions
• Potential migration rates appear to be
  unprecedented by historical standards
• Less vigorous, lower biomass weedy forests,
  with lower diversity
• Most important strategy is to reduce emissions
  not clear that adaptation per se is viable
  (clearly not in the arctic)
• Potentially greater economic impacts where
  reliance on natural regeneration is higher and
  adaptive responses are more limited (e.g., Canada
  vs. United States)
• Focus on facilitating migration (which is
  intrinsically limited) by maintaining and
  restoring functional connectivity in landscapes

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Central Labrador
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Sugar Maple facilitating natural migration
Potential migration contribution of current
populations to new distribution (average distance
to new distribution)
Current (1961-1990) and future (2040-2069)
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i j SS pij
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• Conclusions
• Potential migration rates appear to be
  unprecedented by historical standards
• Less vigorous, lower biomass weedy forests,
  with lower diversity
• Most important strategy is to reduce emissions
  not clear that adaptation per se is viable
  (clearly not in the arctic)
• Potentially greater economic impacts where
  reliance on natural regeneration is higher and
  adaptive responses are more limited (e.g., Canada
  vs. United States)
• Focus on facilitating migration (which is
  intrinsically limited) by maintaining and
  restoring functional connectivity in landscapes
• Research focus on more than just carbon
  (regional climate models, comprehensive
  information on tree and other species
  distributions, correlative and process-based
  approaches)
• Wake-up call for the forest industry, which is
  geared towards harvesting of primary forests