Moderate climate

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FORESTS
-Moderate climate
-Improve air quality
-Regulate water flow
-Protect aquatic
ecosystems
-Promote biodiversity
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Timber for construction
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Pulp and Paper Mill
Vancouver Island
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Forest management

• Forests provide us timber, and this has helped
  our society achieve the standard of living we
  enjoy today.
• Forests are also natural ecosystems that are
  severely altered by timber harvesting.
• The practice of forestry has had to balance these
  two identities in trying to manage forest
  resources.

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Soil-plant-atmosphere system
p ET r ?S Photosynthesis 6CO2
6H2O sunlight ? C6H12O6 6O2 Respiration C6H1
2O6 6O2 ? 6CO2 6H2O energy
Regulation of moisture regime
Photosynthesis and Evaporation
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Leaf Photosynthesis
Maximum photosynthetic capacity
Photosynthesis (?mol C m-2 s-1)
Light compensation point Varies with QUE, R
Respiration rate, R
PAR (?mol m-2 s-1)
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Leaf-level net photosynthesis modelling
Thornley and Johnson (1990)
(Just one example)
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NEE and Net Canopy Photosynthesis
Determined by
Photosynthetically active radiation
Temperature
Vapour pressure deficit
Light extinction and canopy structure
Leaf area distribution
Canopy vs. understorey photosynthetic capacity
Soil Moisture
Soil and leaf nutrient status
Interspecies competition
Ultraviolet radiation
Diffuse vs. spectral radiation
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Matt's Cloud Forest Site

1000m
20 de Julio Field Station, Parque Nacional
Munchique
CAUCA
 
 
1500m
  El Tambo
PALO VERDE CATCHMENT

2000m

Bosque Station
Home

2500m

Campo Station
TAMBITO CATCHMENT
3000m

Cartagena


Cúcuta

Medellin

Bogotá
Buenaventura


Cali
COLOMBIA
1 kilometre

Popayán

Pasto
CEAT - CENTRO DE ESTUDIOS AMBIENTALES TAMBITO

100 km
Leticia
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Photosynthetically active radiation
?mol m-2 s-1
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Temperature
Average Daily Maximum Temperature 23C
(1100m) - 11C (3000m)
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Humidity Vapour Pressure Deficit
Relative Humidity (Per-cent)
Solar Hour
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Precipitation
Rainfall in mm
Month
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Soil Moisture
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Soil nutrient concentration
Spatial distribution is also important
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Plant Canopies and Carbon Dioxide Flux
in the middle latitudes
At night - canopy to atmosphere -
respiration from leaves, plant roots,
soil Daytime - CO2 assimilation exceeds
respiration Seasonal Variation in Temperate
Environments Spring Uptake increases with
leaf area index and solar radiation
availability/day length Midsummer Fc drops
despite sun, due to soil moisture depletion
flux higher in morning Winter Small,
negative flux in temperate climates
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Internal Carbon Allocation
Foliage
Rooting networks
Woody biomass
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High
Biodiversity
Old-growth
Forest
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LOW BIODIVERSITY
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Importance of Old Growth Forest
Habitat Mosses, lichen, insects, squirrels,
birds Temperature regulation New nutrient rich
material (dead biomass) Fungi and insect
habitat Prevention of erosion Biodiversity
Carbon uptake?
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Agroforestry
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Monocultural
Rubber
Plantation
Myanmar
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Rubber - tea agroforestry
in China
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Silvopasture
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'Reforestation' of Degraded Land
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Main Forest Types
Tropical Forests
Temperate Forests
Boreal Forests
40 of the Earth's land surface in forested biomes
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Tropical Forests
1.7 billion ha
-15 million ha/y
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Clearing Tropical Forest for Agriculture
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Cocoa
Banana
Sugar
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Timber extraction
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Fuelwood
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Mahogany
Teak
Sandalwood
Rosewood
Balsa
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REVIEW
Temperate Forests
1.7 billion ha
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Temperate Rain Forest
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Tall Coniferous Species of
Canada's Temperate Rainforest
Western Red Cedar
Sitka Spruce
Douglas Fir
Western Hemlock
Yellow Cedar
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Temperate
Broadleaf
Forest
Sourceatlas.gc.ca
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Temperate
Mixed Forest
Central Ontario
Photo L. Kissau
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Boreal Forest
Spruce, Fir, Pine, Larch, Aspen, Willow
920 million ha
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Canadian Forestry Facts

• Forestry products are largest contributor to
• Canadas trade surplus (energy sector next)
• Almost 0.5 of Canadas productive forest
• is harvested every year
• A 1m x 1m stack of one years wood harvest
• would circle the globe more than 4 times
• (twice for B.C. alone)
• BCs share is falling, New Brunswicks share
• is rising (private ownership no U.S. penalty)

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• Provincial governments have opened public
• lands to multinationals (for pulp and paper
• mills, sawmills, plywood plants etc.)
• Nearly 100 of Canadas most productive
• boreal forest, including several provincial
• parks and wildlife reserves is available for
• logging
• Timber harvesting conflicts with indigenous
• peoples traditional uses of forest land
• Total forested area expanding in the US,
• but not yet in Canada

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Forests and Deforestation

• Demand for wood products, and for open land for
  agriculture, has led to deforestation, the
  clearing and loss of forests, throughout the
  world.

• Africa and Latin America are losing their forests
  most quickly.
• Forests are starting to grow back in North
  America and Europe after centuries of
  deforestation.

Figure 16.7
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CLEARCUTTING
Most cost-effective and
environmentally-deleterious method
85 of Canadian logging operations
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Gilford Island, Johnstone Strait
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St. Maurice, PQ
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Coniferous Forest Clearcutting
Whitecourt, AB
(Patch clearcutting)
Visible imagery
Radar imagery
Source NRCAN
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Shelterwood
Cutting
Done in even-aged forests
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Selective
Cutting
Cutting priority given to sick and injured trees
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Other Silvicultural Systems
Seed Tree Cutting A few large trees left for
regeneration Patch Clear Cutting Small-scale
clear-cuts Strip Cutting Narrow rows of forest
cut Whole Tree Harvesting Deprives soil
of plant nutrients
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Methods of logging
Figure 16.11
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Environmental Effects of Pulp Paper Industry

• Toxic organochlorides
• Mercury in mill effluent
• Contamination of fish and shellfish

Air Pollution Effects on Forests

• Sulphur dioxide emissions kill forests
• - various sources
• Especially problematic in Russia/Europe
• Fluorine emissions from aluminium
• smelters

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Slash and Burn Agriculture
Luang Nam Tha, Laos
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Peten, Guatemala
1986
1997
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1975
Rhondonia, Brazil
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1986
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1992
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1975-1992
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Management of Forest Fires

• Fire policy a challenge
• for forest management.
• Fire is a natural phenomenon that can renew
  forests.
• Decades of human fire suppression allowed lots
  of combustible debris to accumulate in forests.
• When fires occur, they often are
• damaging rather than renewing.

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• Foresters and others
• have used controlled burning and
• have cleared brush and understory trees
• to reduce fuel loads and restore ecosystems.
• However, fire suppression continues, because so
  many peoples homes are located in or near
  forested areas.