Sc 7 notes (p. 69-85)

6.0 Human Activities Can Change Ecosystems

Ecosystems can be changed by both abiotic factors (i.e. floods, fires, erosion, high winds, etc.) and biotic factors (i.e. human activities such as clear-cutting forests, hunting, construction, using herbicides to kill weeds/pesticides to kill insects, etc.).

First Nations and Métis people of Saskatchewan do not view human beings as being at the top of the food chain, but rather the bottom. This is because humans depend on everything else on Earth for their survival.

6.1 The Impact of Technology

Human beings have a bigger impact on ecosystems than any other living things, because:

1. We exist in every biome on the planet (our species is very widespread)
2. We invent and use technology to alter our ecosystems
3. There are nearly 7 billion of us in the world

6.2 The Impact of Human Activities

Because the human population on Earth is so large (and continuously growing), we need to adapt to our growing population by altering our ecosystems.

Human beings need:

1. Space to live. We require more land for growing food and for buildings (schools, houses, businesses, etc.).
2. Energy sources to fuel our technologies.
3. Materials to build our homes, vehicles, etc.

Human beings regularly pollute the environment (air, soil, water). Because humans depend on all other living things for survival, essentially we are poisoning our own food chains when we pollute our planet.

Humans can also harm themselves by polluting ecosystems with chemicals. See pg. 74 for a diagrammatic example (spraying cockroaches, etc.).

7.0 Technologies have been developed to manage wastes that humans generate

Many years ago, all of the wastes that humans generated were biodegradable (could be broken down by scavengers and decomposers). However, now we produce many types of waste that are not able to be broken down to return nutrients to the soil.


7.1 Human Generated Waste: Dealing With Our Garbage

Garbage dumps used to be the most common places in which our waste was disposed. However, these dumps were unattractive and potentially dangerous (rainwater washing bacteria from garbage into the water systems, etc.) and so we developed technologies to improve our garbage disposal practices.

Examples of garbage disposal methods:

1. Recycling depot
2. Composting
3. Household hazardous waste operation
4. Sanitary landfill
5. Incineration

Landfills waste a great amount of energy. Reusing and recycling wastes is much more environmentally efficient than cutting down more trees for paper or drilling/mining new sources of oils and minerals, for example.

7.2 Have We Learned From Our Past?

Humans use a tremendous amount of energy and materials, while also creating a great amount of waste. In the past, we didn’t worry much about the impact that we had on ecosystems. Fortunately, with the “go green” movement of today’s society, we are paying more attention to our actions with regards to the environment.