3.2/3.3 How Humans and Introduced Species Influence Ecosystems

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

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

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 - 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 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

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)

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

Endangered in China Due mainly to deforestation Main food source is bamboo

Soil compaction – occurs when soil particles are squeezed together and the air spaces between the particles is reduced Biggest contributors are: Farm vehicles Grazing animals

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

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 – 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

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

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.

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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

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

1.High reproduction rates 2.Aggressive competitors 3.Lack natural predators in new habitats They can affect native species through: Competition Predation Disease Parasitism Habitat Alteration

Invasive species compete with natural species for resources such as food, and habitat Invaders disturb natural sharing of resources Eg: Carpet Burweed

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

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

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

Invasive Species to BC Eurasian Millfoil Norway Rat American Bullfrog European Starling

About Garry Oak Ecosystem on Vancouver Island Work on Chapter 3 Review Page # 1-24 Chapter 3 Test on Monday STUDY!!!!!!!!!!!! STUDY!!!!!!!!!!!!!!!!!!! STUDY!!!!!!!!!!!!!!!!!