ENVS 1100 Lecture Notes - Lecture 17: Forest Ecology, Ecosystem Services, Hectare
3 May 2018
School
Department
Course
Professor
Forest Ecosystems and Forestry
October 21, 2014
Forests cover about 33% of the Earth’s surface and create an important biome.
Agricultural land covers around 38%. Over 3 billion of hectares have been lost from
human impacts.
Deforestation – Net loss of trees in a forested area
Forest Biomes
• For forests to grow, climatic factors that are required include:
o Precipitation
o
• There are boreal, temperate and tropical rainforests
• Forests provide protective qualities including stopping mudslides and
preventing pollution to enter water systems
1. Boreal
• Largest terrestrial biome, high elevations, low latitudes, short growing
season, acidic soil
• Major trees are evergreen
• Includes coniferous trees
2. Temperate
• Distinct seasons, fertile soil, rich and diverse plant life
• Trees are predominantly evergreens and deciduous
• Trees usually loose their leaves in the autumn
3. Tropical
• Similar year-round temperatures – usually have a dry and wet season
• Soils are thin, acidic and low in nutrients (vegetation takes up nutrients
immediately or they are washed away by rainfall)
• Rapid decomposition supports dense vegetation
Canopy – Upper layer of forest formed where the crowns (tops) of the majority of
the tallest trees meet
Emergent Layer – region where a tree that is taller than the canopy rises above the
canopy layer
Understory Layer – smaller trees, shrubs and saplings that live in the shade of the
forest canopy
Primary Growth Forest – forest which has never been cut
Secondary Growth Forest – forest which has been cut and regrown
Old-Growth Forest – forest which has reached its climax community
find more resources at oneclass.com
find more resources at oneclass.com
Urban Forests:
• Produce oxygen and clean air
• Absorb noise, dust, pollution and CO2
• Reduce storm water runoff
• Provide habitat for wildlife
Ecological and Economic Value of Forests
1. Ecosystem Services
• Watershed services: water purification and provision
• Atmosphere and Climate effects: major sink for carbon dioxide;
increase rainfall in some areas; biggest contribute to oxygen in the
atmosphere
• Soil maintenance and protection: soil production and recycling of
nutrients; reduction of soil erosion
• Disturbance regulation: protection from storm damage, especially in
costal areas
• Biodiversity and genetic resources: food and habitat for
biodiversity; a rich storehouse of genes that might prove useful to
improve out crops or provide as yet undiscovered medicines
2. Economic value
• Goods: provides many of the basic good we depend on (food, fuel,
building materials, rubber, cork, medicines)
• Jobs: more than 10 million people make their living in and from
forests
• Recreational: provides ecotourism opportunities
3. Sociocultural Benefits
• Beauty of forests provides a place for spiritual renewal, artistic
inspiration and stress reduction.
• Ancient stands of trees provide a connection to the past; many
indigenous people are an important part of their forest ecosystem,
possessing ancestral knowledge of the forest and its inhabitants
**See $US from each Ecosystem Service on page 193.
Note: Nutrient Cycling is the highest valued ecosystem service.
Stormwater runoff – water from precipitation that flows over the surface of the
land
Carbon sinks – places like forests, ocean sediments, and soil, where accumulated
carbon does not readily reenter the carbon cycle
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Forests cover about 33% of the earth"s surface and create an important biome. Deforestation net loss of trees in a forested area. Over 3 billion of hectares have been lost from human impacts. Canopy upper layer of forest formed where the crowns (tops) of the majority of. Emergent layer region where a tree that is taller than the canopy rises above the. Understory layer smaller trees, shrubs and saplings that live in the shade of the. Primary growth forest forest which has never been cut. Secondary growth forest forest which has been cut and regrown. Old-growth forest forest which has reached its climax community forest canopy the tallest trees meet canopy layer. Urban forests: produce oxygen and clean air, absorb noise, dust, pollution and co2, reduce storm water runoff, provide habitat for wildlife. **see from each ecosystem service on page 193. Note: nutrient cycling is the highest valued ecosystem service.
