Bio Chapter 4

Front 1

Engineered ecosystems

Back 1

• Humans spend little time in natural ecosystems. Most of our environments have been designed by humans (for example, buildings and parks). • We can manipulate our environment because we have tools and concentrated energy sources (e.g. fossil fuels). • Engineered ecosystems cover a large part of Earth’s land area.

Front 2

Modern agriculture

Back 2

• There are close to 7 billion people on Earth. Producing food is critical to our survival and must continue on a large scale. Most of our food is produced on large agricultural farms. • Most of the major foods we produce in Canada wereintroducedfrom other parts of the world. They are non-native species. • Plants and animals used for food have beendomesticatedby humans over thousands of years, so they areproductive,nutritious, andeasy to producein large quantities.

Front 3

Agro ecosystems vs. Natural ecosystems

Back 3

• Agroecosystemsare different from natural ecosystems in several ways: – Mostagroecosystemscontain non-native species. – Agroecosystemshave more uniformabioticfeatures, have lower biodiversity, and are more intensively used by humans. – Agroecosystemsrequire humans to maintain them. Innatural ecosystems, many species interact, participating in and maintaining naturalcycles. In agriculturalecosystems, a very limited number of species interact, and most cycles are directly altered by human activity.

Front 4

Managing soil

Back 4

• Soils are some of our most important resources.• Fertile soil is essential to grow crops. Plants depend on the soil forphysical supportand to provide water, nutrients, and oxygen to their roots.• Soil is a complex mixture ofminerals,water,dissolvednutrients,air spaces, anddecomposing organic matter.• The most important nutrients in soil arenitrogen,phosphorus, andpotassium.• Nutrients are cycled through ecosystems as plants grow and are consumed by animals and mirco-organisms as the produce wastes, die, and decompose.

Front 5

Natural and synthetic fertilizers

Back 5

• Fertilizers are the most common way to replace lost nutrients on farmland. • Throughout history, farmers depended on natural fertilizersmade from plant and animal wastes. Examples include:manure,compost,bone meal, andwood ashes. • Today,synthetic fertilizersmanufactured by humans are most common. Examples includeammonia,synthetic urea,potash, and commercial fertilizers.

Front 6

Environmental imapcts of fertilizer use

Back 6

Fertilizers Impact the Environment: • They may enter the soil rapidly and alter soil organisms. This causes: – Less natural organic matter – Stressed organisms • Soil can lose their supply of naturally occurring nutrients. This causes: – A dependency on synthetic fertilizers – Soil to be more susceptible to erosion • May get into groundwater. This causes: – Leeching:where nutrients become dissolved in water and seep out of the soil. • Contamination of drinking water • Run-off which can enter aquatic ecosystems • “algal blooms” where algae grow and then die and decompose which causes a decrease of oxygen in the water = dead fish!

Front 7

Controlling the flow of water in soil

Back 7

• Farmers need a reliable supply of water. • They can obtain water from many different surface sources (lakes, rivers, groundwater) and can add water to fields using: – Irrigation • Can damage aquatic ecosystem and cause water shortages – Drainage technologies • Used to convert natural wetlands into fertile farmland • Results in loss of wetlands and associated species

Front 8

Soil air spaces and compaction

Back 8

• Air spaces serve 2 functions o Allow water and nutrients to pass through the soil to reach roots o Provide oxygen to plant roots and soil organisms • Air spaces are influenced by the physical characteristics of soil particles (soil with smaller particles = less air space). o Compaction= when pressure squeezes soil particles closer together

Front 9

Pests and pesticides

Back 9

• To maximize crop yield, farmers try to eliminate pests. By controlling pests, farmers grow crops in an environment with hardly any consumers or competitors.• Pests are organisms that compete with or damage cropspecies. Examples include weeds, caterpillars, and mice.• In nature, there are no such things as pests. All organisms are producers or consumers within food webs.

• When farmers plant monocultures, they create ideal environments for pests. If not controlled, pest populations would increase enough to devastate the entire crop.• Pesticidesare poisons that kill pests. Types of pesticide includeherbicides(kill plants),insecticides(kill insects), androdenticides(kill rodents, such as rats).• Pesticides work by causing biological or physical harm to organisms.