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.
p = ET + r + S
Photosynthesis:
6CO2 + 6H2O + sunlight  C6H12O6 + 6O2
Respiration:
C6H12O6 + 6O2  6CO2 + 6H2O + energy
Photosynthesis (mol C m-2 s-1)
24
Maximum photosynthetic capacity
20
16
12
8
Light compensation point
Varies with QUE, R
4
Respiration rate, R
0
-4
0
500
1000
1500
2000
PAR (mol m-2 s-1)
2500
Leaf-level net photosynthesis modelling
  PAR  Pmax
Pn 

  PAR  Pmax
Thornley and Johnson (1990)
•20 de Julio Field Station,
1000m
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
· Popayán
·Pasto
CEAT - CENTRO DE ESTUDIOS
AMBIENTALES TAMBITO
·
100 km
1 kilometre
Leticia
mol m-2 s-1
•
“Cerro Perro”
Average Daily
Maximum
Temperature
• Bosque station
23°C (1100m) 11°C (3000m)
• Rio station
X
TEMPERATURE
(°C)
•
Campo station
100
90
80
Relative
Humidity
(Per-cent)
60
50
40
Ave ra ge
30
Ma ximum
20
STOREY
8
70
Minimum
10
DEFORESTED
0
20
22
0
2
4
6
8
10
12
Solar Hour
14
16
18
20
22
1000
CEAT (1450 m)
20 de Julio, PNM (2100 m)
Rainfall
(mm)
800
600
400
200
0
Jan
Mar
May
Jul
Month
Sept
Nov
12
rain
0 .7
s o il mo is ture
0 .6 5
10
0 .6
Hourly
Rainfall
(mm)
8
Hourly
Saturation
0 .55 Ratio
6
0 .5
0 .4 5
4
0 .4
2
0
20-Sep
0 .3 5
4-Oct
16-Oct
Date (2000)
28-Oct
0 .3
9-Nov
1.2
15000
40
NITROGEN
POTASSIUM
PHOSPHORUS
30
0.8
10000
1st/late 2nd.
Early 2nd.
Deforested
m.eq.
p.p.m.
p.p.m.
20
0.4
5000
10
0.0
0
0
0
40
80
0
Depth (cm)
8
40
Depth (cm)
0
60
20
40
60
Depth (cm)
5
12
CALCIUM
m.eq.
20
BORON
ALUMINIUM
4
m.eq.
p.p.m.
8
3
4
2
4
1
0
0
0
20
Depth (cm)
Figure 5.14
40
60
0
0
20
40
Depth (cm)
60
0
10
20
30
Depth (cm)
40
Average soil potassium, nitrogen, phosphorus, calcium, boron and aluminium levels at Centro de Estudios Ambientales
50
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
Habitat:
Mosses, lichen, insects, squirrels, birds
Temperature regulation
New nutrient rich material (dead biomass)
Fungi and insect habitat
Prevention of erosion
*** Biodiversity ***
Carbon uptake?
Myanmar
Source:atlas.gc.ca
Central Ontario
Photo: L. Kissau
•Forestry products are largest contributor to
Canada’s trade surplus (energy sector next)
•Almost 0.5% of Canada’s productive forest
is harvested every year
•A 1m x 1m stack of one year’s wood harvest
would circle the globe more than 4 times
(twice for B.C. alone)
•BC’s share is falling, New Brunswick’s share
is rising (private ownership – no U.S. penalty)
•Provincial governments have opened public
lands to multinationals (for pulp and paper
mills, sawmills, plywood plants etc.)
•Nearly 100% of Canada’s most productive
boreal forest, including several provincial
parks and wildlife reserves… is available for
logging
•Timber harvesting conflicts with indigenous
people’s traditional uses of forest land
•Total forested area expanding in the US,
but not yet in Canada
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
(Patch clearcutting)
Source: NRCAN
Done in even-aged
forests
Cutting priority given
to sick and injured trees
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
Methods of logging
Figure 16.11
•Toxic organochlorides
•Mercury in mill effluent
•Contamination of fish and shellfish
•Sulphur dioxide emissions kill forests
- various sources
•Especially problematic in Russia/Europe
•Fluorine emissions from aluminium
smelters
Luang Nam Tha, Laos
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.
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 people’s homes are located in or near
forested areas.