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: 6CO 2 + 6H 2 O + sunlight  C 6 H 12 O 6 + 6O 2 Respiration: C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + energy

PAR (  mol m -2 s -1 ) Photosynthesis (  mol C m -2 s -1 ) Light compensation point Varies with QUE, R Respiration rate, R Maximum photosynthetic capacity

Leaf-level net photosynthesis modelling Thornley and Johnson (1990)

100 km CAUCA COLOMBIA CEAT - CENTRO DE ESTUDIOS AMBIENTALES TAMBITO 1000m 3000m 2000m 1500m 2500m · Popayán · Cali · Bogotá · Medellin · Cartagena · Leticia Cúcuta · · Buenaventura · Pasto El Tambo Campo Station Home 20 de Julio Field Station, Parque Nacional Munchique Bosque Station PALO VERDE CATCHMENT TAMBITO CATCHMENT 1 kilometre

 mol m -2 s -1

Average Daily Maximum Temperature 23°C (1100m) - 11°C (3000m)

Relative Humidity (Per-cent) Solar Hour

At night: - canopy to atmosphere - respiration from leaves, plant roots, soil Daytime:- CO 2 assimilation exceeds respiration Seasonal Variation in Temperate Environments Spring: Uptake increases with leaf area index and solar radiation availability/day length Midsummer: F c 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 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

Source: NRCAN (Patch clearcutting)

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.