Unit B: Sustainable Ecosystems
4.1: Engineered Ecosystems and Modern Agriculture
pg. 119
Key Concepts:
1. Some ecosystems, such as; farms and cities, are designed, created, and
maintained by humans.
Agroecosystem: an agricultural ecosystem.
- Humans spend very little time in natural ecosystems, including out doors.
- Natural vegetation can be removed and replaced with other plants or
artificial surfaces.
- Biogeochemical and water cycles have been changed. Biodiversity has
been threatened and climate patterns are changing.
- Humans are able to alter their environment, yet for us to survive we can not
disrupt the biotic and abiotic conditions.
Modern Agriculture – Food for Thought
- All living things must take in energy by feeding we get nutrients which
supply energy to our bodies through cellular respiration.
- There are over 7 billion people in the world, producing food is critical for
survival.
- Our food is produced through large scale agricultural farms and livestock.
Canadian Agriculture Is Based on Imported Species
- Most of our food is grown in Canada, but the species of plant is not native
to Canada.
- Most plants and animals are exotic species, domesticated by humans.
Table 2: Selected Native and Non-native Crops and Livestock Species
Grown and Raised in Canada
Plant
Crops
Livestock
Species
Non-native Species
Corn, wheat, potatoes, beans,
barely, rye, oats, soybeans,
canola, tomatoes, apples,
squash, peanuts, carrots.
Cattle, pigs, chickens, sheep,
goats.
Native Species
Strawberries, maple sap,
wild rice, blueberries.
Turkeys
Agroecosystems Differ from Natural Ecosystems
Monoculture: the cultivation of a single crop in an area.
Pest: any plant, animal, or other organism that causes illness, harm, or
annoyance to humans.
- Farms are not natural ecosystems since they grow exotic species, the
uniform growth pattern, low biodiversity, and use fertilizers.
- Farmers grow crops in monocultures, only one species are grown per field.
- Ecological cycles are disturbed, and biodiversity is reduced.
- Sustainability comes into question, management practices must be
developed to sustain productivity.
- Farmers try to create ideal and uniform growing conditions.
- Elimination of competitors, disease, and pest is a must for monocultures to
be successful.
Figure 3: In a) natural ecosystems, many species interact, participating in
and maintaining natural cycles, whereas in b) agricultural ecosystems, a very
limited number of species interact, and most cycles are directly altered by
human activity.
Evidence of Learning: Students can …
- explain the impact of human activity in human-designed ecosystems.
- describe how agriculture can impact the sustainability of an ecosystem.
- identify the major differences between natural ecosystems and
agroecosystems.
Check Your Learning
Questions 1 – 11, page 122
Summary:
- Engineered ecosystems, such as; farmland and cities, make up a large
portion of Earth’s land area.
- Most of Canada’s crop and livestock species are introduced, non-native
species.
- Engineered ecosystems have uniform abiotic features and low biodiversity.
- Most monoculture crops consist of plants of uniform age and size.
- Farmers attempt to create ideal abiotic and biotic growing conditions for
crops.