forest management forests provide us timber, and this has helped our society achieve the standard of...

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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Light compensation pointVaries with QUE, R

Respiration rate, R

Maximum photosynthetic capacity

max

max

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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DEFORESTEDUNDERSTOREY

RelativeHumidity(Per-cent)

Solar Hour

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CEAT (1450 m)

20 de Julio, PNM (2100 m)

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Hourly Rainfall(mm)

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POTASSIUM NITROGEN PHOSPHORUS

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Depth (cm) Depth (cm) Depth (cm)

Depth (cm) Depth (cm) Depth (cm)

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?

Myanmar

Source:atlas.gc.ca

Photo: L. Kissau

Central Ontario

•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.