Chapter 3 Ecosystems continually change over time

3.2/3.3 How Humans and Introduced Species Influence Ecosystems

Importance of wetlands bogs

• Wetlands – soil is waterlogged for all or part of year• Referred to as “kidney” of earth because

bogs are able to filter out wastes• Can reduce concentration of nitrate by

more than 80% and help climate by retaining carbon• Bogs like sponges, can hold large

amounts of water = flood prevention• In lower mainland, many peat bogs

Human use of bogs

• Wild blueberries and cranberries thrive in the bog, eaten by aboriginal people• Peat bogs often burnt so no larger trees

could grow• Peat was sold for use in gardens

(retains water and lowers ph)• Currently commercial farms for

cranberry and blueberry are in bogs in Richmond and Langley

Negative impact of humans on bogs• Transformed to parking lots, subdivisions, dumps,

malls, etc.• In Vancouver and on the island between 50-70% of

wetland habitat has disappeared• S. Okanagan, as high as 85%

• Affects biodiversity reducing number of plant and animal species

• Also agricultural and industrial pollution• Introduction of invasive species• Drying out wetlands could release more carbon

dioxide and methane into atmoshpere = climate change

Sustainability

• Sustainability - The ability of an ecosystem to sustain ecological processes

• Another definition involving humans is - to use the resources of an ecosystem to meet our needs today without reducing the function and health of that ecosystem or the ability of future generations to meet their needs

Land and resource use

• Land Use – refers to the way we use the land around us for urban development, agriculture, industry, mining, and forestry

• Resource Use – the way we obtain and use things such as soil, wood, water, gas, oil and minerals

Effects of our land and resource use

Habitat Loss - through the destruction of habitats by human expansion, which causes the habitats to no longer be able to support species that lived there

• Habitat fragmentation – division of habitats into smaller isolated fragments

Go to Table 3.1 in text (Page 127)

Effects of deforestation• Deforestation – the practice in which forests are

logged or cleared for human use and never replanted

Deforestation can lead to...

• Soil degredation – occurs when water and wind erosion removes topsoil from bare land

• Most plants need large amounts of topsoil to grow

Giant panda• Endangered in China

• Due mainly to deforestation• Main food source is bamboo

Effects of agriculture• Soil compaction – occurs when soil particles are

squeezed together and the air spaces between the particles is reduced

• Biggest contributors are: Farm vehiclesGrazing animals

Effects of resource exploitation

• Resource exploitation – resource use

• Examples include: harvesting fish, timber, mining coal and minerals, and extracting oil and gas

• This exploitation leads to habitat loss and degredation

• Also affects by contamination – introduction of chemicals, toxins, wastes, or micro-organisms into environment in harmful quantities

Mine Reclamation• Required in BC after a mine closes• Restoration of land and development of water

treatment to remove heavy metals• Also uses plants to remove soil contaminants

Overexploitation

• Overexploitation – use or extraction of resources until they are depleted

• Example: Orcas used to feed on sperm whales

• They were overexploited, so Orcas moved onto seals, sea lions and otters

• Sea otters keep sea urchin populations under control

• Less sea otters means tons of sea urchins!• Sea urchins in turn destroy kelp forests

= affects whole ecosystem

How do we avoid all this??

Proper management of resources in order to have sustainability!!!

What is an ecological Footprint?• The Ecological Footprint has emerged as the

world’s premier measure of humanity’s demand on nature. It measures how much land and water area a human population requires to produce the resource it consumes and to absorb its carbon dioxide emissions, using prevailing technology.

Websites to calculate your own Ecological Footprint!!• http://www.footprintnetwork.org/en/index.php/GFN

/page/calculators/

• http://myfootprint.org/en/

3.3 How Introduced Species Affect Ecosystems• Native Species – plants and animals that

naturally inhabit an area

• Introduced or Foreign Species – Species that are transported by humans into regions where they did not previously exist

• Most are harmless but some can cause major problems in ecosystem

• Invasive Species – organisms that can take over the habitat of native species or invade their bodies, which weakens the immune system

European Leaf Feeding Beetle and Purple Loosestrife• Purple loosestrife was

introduced to N. America in 1800’s in ships ballasts and is now established in many wetland habitats• Chokes out other plants, and

local organisms avoid it• Scientists have tested the

European Leafing eating beetle for compatibility in our wetlands and they do not cause problems but instead they eat the loosestrife, allowing native plants to grow again

Why are invasive species so successful?

1. High reproduction rates2. Aggressive competitors3. Lack natural predators in new habitats

• They can affect native species through:• Competition• Predation• Disease• Parasitism• Habitat Alteration

Competition• Invasive species compete with natural species for

resources such as food, and habitat• Invaders disturb natural sharing of resources

• Eg: Carpet Burweed

Predation

• Have an advantage over natural predators because prey not be adapted to avoid the invasive predators

• Eg: Yellow crazy ants• Escaped from cargo from W. Africa into

Australia• Ants build supercolonies size of 500

football fields and will devour all plants and prey on young reptiles, birds, mammals and especially red crabs

• They have killed 20 million red crab which are keystone species in ecosystem

Disease and Parasites

• Invasion of parasites or disease causing viruses can weaken immune response of ecosystems plants, animals and even humans

• The weakening provides less dominant species opportunities to outcompete other species

• Eg: Parasitic sea lampreys made their way into great lakes by human made canals

• Lampreys attach to fish and suck the body fluids from their prey

Habitat Alteration

• Introduced species can make a habitat unsuitable for natural species by changing its structure or composition• Ex: they may change light

levels, soil chemistry, etc• Example of this is Wild Boar

• They damage the environment by rooting, wallowing, and spreading weeds that interfere

Know Table 3.3!!!• Invasive Species to BC

• Eurasian Millfoil• Norway Rat• American Bullfrog• European Starling

Homework• About Garry Oak Ecosystem on Vancouver Island• Work on Chapter 3 Review Page 148-149 # 1-24• Chapter 3 Test on Monday

STUDY!!!!!!!!!!!! STUDY!!!!!!!!!!!!!!!!!!!

STUDY!!!!!!!!!!!!!!!!!