Week 4 forests

World forest regions

  • Boreal

  • Temperate

  • Subtropical

  • Tropical

Origins of trees

  • Trees first began appearing on Earth 350M years ago

  • Hominids first appeared ~6m years ago

Oldest living things

  • Bristlecone pine Pinus longaeva, Pinus aristata

  • White Mountains, California

  • 5,000 years old

  • i.e. seeded when Egyptian pyramids were constructed

  • The oldest bristlecone is kept secret by California authorities

Ontario’s Ancient Ones

  • Eastern cedar trees found by uGuelph scientist D. Larson on Flower Pot Island to be >1600 years old

  • 1600 years ago = collapse of Roman Empire

How do we know how old a tree is?

  • Dendrochronology = science of dating trees by counting growth rings

  • Many tree species (e.g. oak) display very clear annual growth rings

  • The distance between rings reflects the environmental conditions of that particular year

  • (e.g. hot/dry years = small distance between rings)

Largest living single organism

  • Giant Sequoia (Sequoiadendron giganteum)

  • 2,200 years old

  • General Sherman

What is a forest?

  • Forest = where trees are the dominant form of land cover

Characteristics of forest biomes

  • Higher levels of precipitation than other biomes

  • High levels of production of organic material

  • High levels of biodiversity

  • Low levels of soil erosion

Mongolian Taiga or boreal

  • China

  • Russia

  • Finland

  • Sweden

  • Norway

  • USA

  • Canada

  • Relatively low biodiversity

  • Boreal Forest

  • Needles are difficult to digest

Mixed forest Ontario

  • Higher biodiversity than taiga

Eastern broad-leaf deciduous forest

  • Biodiversity increases even more

  • Forest extends to Carolinas

Pacific Coast temperate rainforest

  • Higher levels of biodiversity than taiga

  • Green year-round

Tropical rainforest

  • Tremendous biodiversity

Tropical rainforest biodiversity

  • A single tree in Peru was found to contain 43 different species of ants (only ~100 ant species in all of Canada)

  • A single hectare of forest in Ecuador was found to contain 473 tree species

  • Is estimated that >½ of all species on Earth live in tropical rainforests (which cover only 6% of the planet’s land surface)

Tropical deciduous forests

  • Characteristic of monsoonal climates (i.e. = climates with distinct rainy and dry seasons)

  • Vegetation goes dormant, and loses its leaves during the dry season

  • These forests are found in parts of Central/South America, India, Africa

Types of trees

  • Coniferous trees = have cones

  • Broadleaf trees = have leaves

  • Deciduous trees = trees that go dormant for part of the year, lose their leaves or needles

  • Evergreen = tree that does not go dormant, may be a tree with leaves or needles

  • Yellow tamarack trees in foreground shed their needles in winter

  • Cones (contain seeds)

  • Arbutus = an evergreen broadleaf tree native to British Columbia

Forest statistics

  • Roughly 1/3 of Earth’s land surface is forested

  • A temperate forest contains 60% of the biomass of a tropical forest

  • Humans have removed approximately ½ of world forest cover

  • Current forest clearance rates are highest in tropical regions

  • Deforestation results when forests are not allowed to regenerate after harvesting

Forest disturbance

  • Disturbance = any events that stimulate changes in the size, structure or composition of a forest

  • Disturbance can be natural or anthropogenic

  • In some instances, periodic disturbance is required to maintain the health of the forest

  • Forestry & deforestation are types of disturbance

Disturbance by insects

  • Bark-burrowing beetles are a common pest in Canadian forests

  • Cold winter temperatures are the main limiting factor for these beetles

  • Warming temperatures allow beetles to multiply, spread

  • Huge areas of western forest are now dying as a result

Disturbance by invasive species

  • Week 2 mentioned Canadian tree species affected by invasive insect species and imported diseases

  • Ash trees in Ontario and elsewhere are currently being decimated by emerald ash borers

  • If this persists, ash trees will vanish and the forest composition will change permanently

Fire disturbance & forests

  • Forest fires are a common, natural phenomenon in mountains of western North American & the boreal forest

  • Fire creates a heterogeneous mix of species, age classes of trees

  • Tree & plant species have adapted to fire

Impacts of fire-fighting

  • Humans have actively suppressed fire in the west for the last century

  • Why? To save timber for future harvesting; protect homes, property

  • Doing so interferes with ecosystem dynamics and elevates risk of catastrophic fire, tree die-off due to pests, disease

Forest fires in Canada, 2023

  • Wildfires in summer of 2023 burned across huge areas

  • Area burned = ~500% the 10-year average

Forestry industry in Canada

  • Net exporters of forest products

  • Net importers of forest products

  • Forest products industry generated C$24.6 billion in revenue in 2018

  • Forest sector employs >200,000 Canadians

  • Canada = world’s biggest exporter of forest products by $ value

  • Most of our exports go to USA

Three key sectors within Canada's forest economy

  • Logging operations

  • Processing wood for building material

  • Pulp and paper

Non-timber forest products

  • Economically valuable forest products other than wood

  • Examples include: Foods (e.g. maple syrup, mushrooms), Medicinal compounds (e.g. Taxol®, a chemotherapy drug extracted from yew trees in Canada), Ornamental products (e.g. wreaths, Christmas trees)

  • Are likely worth >C$350 million/year in Canada

Forest management in Canada

  • Over 90% of Canadian forests are on publicly owned (“Crown”) land

  • Under the constitution, provincial governments are responsible for managing natural resources on Crown land (including forests)

Three categories of forests from an economic perspective:


    • Primary forests: have not been logged, contain native species mix, and have regenerated on their own (36% of world's forest cover)

    • Production forests: have been logged at least once or are being actively logged (57% world forest cover)

    • Plantation forests: forests consisting primarily of commercial varieties that have been deliberately planted/seeded (7% world forest cover)

Global Primary Forest stock

  • Forests that have not been harvested yet

    • Half are in developed countries, half in less-developed countries

    • Only 20% is in protected areas

    • Much of it is fragmented

    • Rate of net loss is about 0.5% per decade

    • There is no international convention, protocol, etc to protect primary forests

Forestry vs deforestation


    • Forestry: practice of harvesting trees to make use of the wood

      • When done skillfully, forestry does not result in long-term net loss of forest or forest diversity, and can facilitate afforestation

    • Deforestation: cutting down trees and not allowing them to grow back

      • Typically results in land being put to some other use

      • May occur for a variety of reasons

    • Afforestation: process of increasing the amount of net forest cover in a given area/region

Drivers of Deforestation

  • Drivers of deforestation:

    • Drivers differ by region

    • In North America, Europe & much of Asia, wildfires + commercial forestry are main drivers

    • In Africa, deforestation is driven by small-scale, subsistence agriculture

    • In Latin America and Southeast Asia, forests are cleared to make way for commercial agriculture (i.e. "commodity-based" deforestation)

What happens when it rains

  • What happens when it rains?

    • Soil erosion

    • No erosion:

      • Water falls on canopy

      • Trickles down to ground

      • Tree roots hold soil in place

North American deforestation

  • North American deforestation:

    • European settlers cleared forests for timber for export

    • And for establishing farms

    • Governments used to encourage settlers to clear forests

Canadian forest conservation

  • Canadian environmental management started with forests:

    • Sir John A. MacDonald expressed concern about reckless destruction of Canadian timber

    • 1882 Canada-US forest conference held in Montreal

    • Quebec created the first national forest in 1883

    • Banff made the first national park in 1887 to encourage CPR tourism

    • Algonquin Park created in 1893 as a forest preserve for harvesting

Pinchot’s 3 principles of conservation

  1. Natural resources should be used for the benefit of people who live here now

  2. Do not waste natural resources; efficient use is critical

  3. Natural resources must be developed for the benefit of all people, not just a few

Page 58:

  • "Conservation" goes out of fashion:

    • In 1920, PM Arthur Meighen declared conservation to be outdated

    • Said it simply locked up the country's resources from "proper development and use"

    • Laurier's Commission for Conservation was disbanded

    • Period of rapid forest exploitation ensued during the 1920s

Ecosystem services provided by forests:


    • Trees prevent soil erosion

    • Forests protect rivers

    • Forests have high biodiversity

    • Trees provide fuel, building material

    • Trees take carbon from the atmosphere

    • Forests generate rain

    • Trees cool cities

    • Forests heal people

Trees take carbon dioxide out of the air

  • Trees take carbon dioxide out of the air:

    • A return flight Waterloo-Calgary generates approximately 1/2 tonne of CO2 per passenger

    • 10-15 trees can remove 1 tonne of CO2 from the air over their lifetimes

    • Amazon rainforest accounts for 25% of all CO2 absorbed by forests globally (total storage =~90,000,000,000t)

How forests generate rain

  • How forests generate rain:

    • Transpiration (50%)

    • Evaporation (25%)

    • Run-off (25%)

    • Trees draw water out of the soil

Trees cool cities and heal ppl

  • Trees heal people:

    • Trees are aesthetically pleasing

    • People become more relaxed around trees

  • Trees cool urban areas

Getting back to nature: how forest bathing can make us feel better

  • Spending time under the green canopy is critical in fighting diseases and conditions.

  • Forest bathing, also known as shinrin-yoku, has psychological benefits and boosts the immune system.

  • Forest bathing is a popular activity in Japan.

Deforestation is dumb

  • Deforestation happens due to short-term economic gain.

  • The long-term value of ecosystem services provided by forests outweighs the short-term gain from clear-cutting trees.

  • Palm oil plantations in Indonesia contribute to deforestation.

Sustainable forestry

  • Sustainable forestry is increasingly practiced in Ontario.

  • Ontario's Crown forests are organized into management units with ongoing planning processes for harvesting and regeneration.

  • Mazinaw-Lanark forest management unit is an example of forest management in Ontario.

Forest management in Mazinaw-Lanark

  • Mazinaw-Lanark has a mixed forest with most forestry conducted by family-owned and operated businesses.

  • Hardwood trees are used for building material and firewood, pines for flooring, and softwood for pulp and paper.

  • Clear-cutting and selective cutting methods are used for harvesting.

Natural regeneration and sustainability

  • Natural regeneration occurs after clear-cutting, with remaining trees holding soil and providing seeds.

  • Oak trees regenerate naturally along logging roads, and pine seedlings are planted after harvest.

  • Sustainable forestry supports livelihoods and maintains a healthy ecosystem.

Maple syrup harvesting and sustainable practices

  • Efficient pipeline systems collect sap from thousands of spiles, causing minimal disturbance to the forest.

  • Maple syrup harvesting maintains high levels of biodiversity while producing a valuable product.

What sustainability looks like in forest management

  1. Protecting forests with unique ecological characteristics and setting aside areas of untouched primary forests to preserve biodiversity.

  2. Careful management of production forests to provide livelihoods, economic opportunities, and preserve biodiversity.

  3. Avoiding forestry practices that damage soil, water, and prevent forest regeneration.

Government and individual actions for sustainable forestry

  • Governments should insist on sustainable forest management practices, monitor timber companies, enforce existing laws, require labeling for consumer awareness, and enshrine environmental protection rules in free trade agreements.

  • Individuals can reduce, reuse, recycle, choose wood over plastic, avoid tropical wood products, purchase certified building products from sustainable forests, buy rainforest certified food products, avoid processed foods containing palm oil, and go for walks in the woods often.