forest management forests provide us timber, and this has helped our society achieve the standard of...
Post on 19-Dec-2015
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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.
p = ET + r + S
Photosynthesis:6CO2 + 6H2O + sunlight C6H12O6 + 6O2
Respiration:C6H12O6 + 6O2 6CO2 + 6H2O + energy
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otos
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Light compensation pointVaries with QUE, R
Respiration rate, R
Maximum photosynthetic capacity
max
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PPAR
PPARPn
Leaf-level net photosynthesis modelling
Thornley and Johnson (1990)
100 km
CAUCA
COLOMBIA
CEAT - CENTRO DE ESTUDIOS AMBIENTALES TAMBITO
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· Popayán
·Cali
·Bogotá·Medellin
·Cartagena
·Leticia
Cúcuta·
·Buenaventura
·Pasto
El Tambo
Campo StationHome
•20 de Julio Field Station,Parque Nacional Munchique
• Bosque Station
PALO VERDECATCHMENT
TAMBITOCATCHMENT
1 kilometre
mol m-2 s-1
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Campo station
Bosque station
• “Cerro Perro”
TEMPERATURE(°C)
• Rio station
Figure 5.8 Modelled air temperature distribution at noon on a clear, August day atCentro de Estudios Ambientales Tambito. Temperature decreases by 0.55°C with each 100 m elevation increase.
Average DailyMaximum Temperature
23°C (1100m) -11°C (3000m)
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Depth (cm) Depth (cm) Depth (cm)
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1st/late 2nd.Early 2nd.Deforested
Figure 5.14 Average soil potassium, nitrogen, phosphorus, calcium, boron and aluminium levels at Centro de Estudios Ambientales Tambito. Note the higher nutrient concentrations in primary/late secondary forest.
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?
Source:atlas.gc.ca
•Forestry products are largest contributor toCanada’s trade surplus (energy sector next)
•Almost 0.5% of Canada’s productive forestis harvested every year
•A 1m x 1m stack of one year’s wood harvestwould circle the globe more than 4 times(twice for B.C. alone)
•BC’s share is falling, New Brunswick’s shareis rising (private ownership – no U.S. penalty)
•Provincial governments have opened publiclands to multinationals (for pulp and papermills, sawmills, plywood plants etc.)
•Nearly 100% of Canada’s most productiveboreal forest, including several provincialparks and wildlife reserves… is available forlogging
•Timber harvesting conflicts with indigenouspeople’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
Source: NRCAN
(Patch clearcutting)
Done in even-agedforests
Cutting priority givento 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 ofplant 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.