change and sustainability 1. importance of soil soil: the layer of material that covers the land...

Change and SustainabilityChange and Sustainability

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Importance of SoilImportance of Soil

• Soil: the layer of material that Soil: the layer of material that covers the land covers the land – Where plants anchor and growWhere plants anchor and grow– Made of weathered rock, decomposing Made of weathered rock, decomposing

plant and animal matterplant and animal matter– Has spaces for air and water movementHas spaces for air and water movement

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Layers of compositionLayers of composition

• 3 major types of soil3 major types of soil– Horizon A: Horizon A: – Horizon B:Horizon B:– Horizon CHorizon C

• Each layer has Each layer has different different characteristics characteristics depending on where depending on where it is found.it is found.

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GrasslandsGrasslands

• Horizon A is deep Horizon A is deep and supports root and supports root growthgrowth

• Horizon B is the Horizon B is the subsoil (mix of dirt subsoil (mix of dirt and rock)and rock)

• Horizon C is mostly Horizon C is mostly rock formationrock formation

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Forest Forest

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DesertsDeserts

• Horizon A: limited Horizon A: limited plant growth so plant growth so little little decomposition, so decomposition, so thin top soil or thin top soil or none at all.none at all.

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Biological CommunityBiological Community

• Interactions Interactions between plants between plants and animalsand animals

• Includes food Includes food chains and life chains and life cycles within the cycles within the soil.soil.

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Nitrogen Cycle ExplainedNitrogen Cycle Explained

• Nitrogen is critically important to life, as it is a Nitrogen is critically important to life, as it is a basic building block for amino acids and proteins.basic building block for amino acids and proteins.

• The chief reservoir of nitrogen is the atmosphere, The chief reservoir of nitrogen is the atmosphere, which is about 78% nitrogen.which is about 78% nitrogen.

• Nitrogen gas in the atmosphere is composed of Nitrogen gas in the atmosphere is composed of two nitrogen atoms bound to each other. two nitrogen atoms bound to each other. Nitrogen is a fairly non-reactive gas; it takes a lot Nitrogen is a fairly non-reactive gas; it takes a lot of energy to get nitrogen gas to break up and of energy to get nitrogen gas to break up and combine with other elements, such as carbon or combine with other elements, such as carbon or oxygen. oxygen.

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Nitrogen gas can be taken from the atmosphere Nitrogen gas can be taken from the atmosphere (fixed - reacted) in two basic ways. (fixed - reacted) in two basic ways.

• 1. Lightning provides enough energy to "burn" 1. Lightning provides enough energy to "burn" the nitrogen and fix it in the form of nitrate, the nitrogen and fix it in the form of nitrate, NONO33

--. This process is duplicated in fertilizer . This process is duplicated in fertilizer factories to produce nitrogen fertilizers.factories to produce nitrogen fertilizers.

• 2. Nitrogen fixing bacteria use special enzymes 2. Nitrogen fixing bacteria use special enzymes to fix nitrogen (react the nitrogen with oxygen to fix nitrogen (react the nitrogen with oxygen or hydrogen). The NHor hydrogen). The NH44

++ produced is converted produced is converted to NOto NO33

-- by nitrifying bacteria found in the soil. by nitrifying bacteria found in the soil.

Nitrogen Fixation

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The Cycle BeginsThe Cycle Begins• 1. Most plants can take up nitrates and 1. Most plants can take up nitrates and

convert it to amino acids and then possibly convert it to amino acids and then possibly proteins. proteins.

• 2. Animals acquire all of their amino acids 2. Animals acquire all of their amino acids when they eat plants (or other animals). when they eat plants (or other animals).

• 3. When plants or animals die (or release 3. When plants or animals die (or release waste) the nitrogen is returned to the soil. waste) the nitrogen is returned to the soil.

• 4. The nitrogen that is usually returned to the 4. The nitrogen that is usually returned to the soil in animal wastes or in the output of the soil in animal wastes or in the output of the decomposers, is ammonia. Ammonia is rather decomposers, is ammonia. Ammonia is rather toxic.toxic.

• 5. Nitrifying bacteria in soil or water convert 5. Nitrifying bacteria in soil or water convert ammonia to nitrates, which are taken up by ammonia to nitrates, which are taken up by plants to continue the cycle.plants to continue the cycle.

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Cycle CompletedCycle Completed

Soil also contains bacteria the uses Soil also contains bacteria the uses NONO33

-- as a fuel source. These as a fuel source. These Denitrifying Bacteria release NDenitrifying Bacteria release N22 back back to the atmosphere. to the atmosphere.

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Disturbing soilsDisturbing soils

• Soils change over Soils change over time naturallytime naturally

• Human impact: Human impact: deforestation leads deforestation leads to increased to increased erosion of topsoil erosion of topsoil (no roots to hold (no roots to hold soil in place)soil in place)

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Feeding the Human Feeding the Human Population!Population!

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Productivity of EcosystemsProductivity of Ecosystems

• Ecosystems have different Ecosystems have different productivities, based on light productivities, based on light availability, soil types, precipitation, availability, soil types, precipitation, temperature, nutrients.temperature, nutrients.

• Productivity: the quantity of biomass Productivity: the quantity of biomass of plants produced each year on a of plants produced each year on a given area (g/mgiven area (g/m22))

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Productivity of different Productivity of different ecosystems:ecosystems:

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Sustaining lifeSustaining life

• Biotic: living part Biotic: living part of the of the environment. Ex: environment. Ex: plants and animalsplants and animals

• Abiotic: non-living Abiotic: non-living part of the part of the environment. Ex: environment. Ex: elements, air, and elements, air, and water.water.

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The key events - respiration and photosynthesisThe key events - respiration and photosynthesis

• Respiration takes Respiration takes carbohydrates and carbohydrates and oxygen, combines oxygen, combines them to produce them to produce carbon dioxide, carbon dioxide, water, and energy.water, and energy.

•Photosynthesis takes carbon dioxide, water and energy to produce carbohydrates and oxygen.

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COCO22 + H + H22O O CC66HH1212OO66 + O + O22

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• Photosynthesis starts with Photosynthesis starts with water present in the soil and water present in the soil and carbon dioxide from the carbon dioxide from the atmosphere (the product of atmosphere (the product of respiration, combustion).respiration, combustion).

• Chlorophyll is the green Chlorophyll is the green

pigment in plants (gives them pigment in plants (gives them their color). This uses the light their color). This uses the light from the sun as the energy from the sun as the energy needed to transform carbon needed to transform carbon dioxide and water into sugar dioxide and water into sugar (made into starch, cellulose (made into starch, cellulose and lignin – woody fiber).and lignin – woody fiber).

• Photosynthesis also produces Photosynthesis also produces

oxygen which the plant oxygen which the plant releases into the atmosphere.releases into the atmosphere.

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The cell works constantly to stay alive.The cell works constantly to stay alive.• It constructs macromolecules It constructs macromolecules • It transports substances into and out of the cell It transports substances into and out of the cell • It moves (some cells)It moves (some cells)• It growsIt grows• It reproduces It reproduces To accomplish these tasks and many others, the To accomplish these tasks and many others, the

cell needs energy that it must get from it’s cell needs energy that it must get from it’s environment. We know that the sun is the environment. We know that the sun is the energy for plants and other photosynthetic energy for plants and other photosynthetic organisms, but what about the consumers?organisms, but what about the consumers?

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What happens to the Carbon?What happens to the Carbon?• Plants take up carbon dioxide and convert it Plants take up carbon dioxide and convert it

into carbohydrates through photosynthesis.into carbohydrates through photosynthesis.• This carbon in the plants now has 3 This carbon in the plants now has 3

possible fates: possible fates: (i) it can be liberated to the atmosphere by (i) it can be liberated to the atmosphere by the plant through respiration; the plant through respiration; (ii) it can be eaten by an animal, (ii) it can be eaten by an animal, (iii) it can be present in the plant when the (iii) it can be present in the plant when the plant diesplant dies

• Animals obtain all their carbon from their Animals obtain all their carbon from their food, and, thus, all carbon in biological food, and, thus, all carbon in biological systems ultimately comes from plants systems ultimately comes from plants (autotrophs). (autotrophs). In the animal, the carbon has the same 3 In the animal, the carbon has the same 3 possible fates as in plants. possible fates as in plants.

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• heterotrophes. heterotrophes. use organic use organic molecules in molecules in their food to their food to get the energy get the energy they need. they need.

• Respiration Respiration uses the sugar uses the sugar in food to make in food to make energy. The energy. The byproducts of byproducts of respiration are respiration are water and water and carbon dioxide.carbon dioxide.

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Water is one of the components needed for photosynthesis and a very important component in living things. How is water cycled around the earth?

Ecological FootprintsEcological Footprints

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What impact do humans have on the earth?What impact do humans have on the earth?

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The Ecological Footprint of a The Ecological Footprint of a population is equal to:population is equal to:

Area of land and water occupied by the Area of land and water occupied by the populationpopulation

++Land and water used to produce Land and water used to produce

resources for the populationresources for the population++

Land and water used to dispose of Land and water used to dispose of wastes for the populationwastes for the population

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-1000m2

The Food we EatThe Food we Eat

The food we eat contributes 11 percent The food we eat contributes 11 percent of the total household output of of the total household output of greenhouse gases which cause global greenhouse gases which cause global warming; warming;

21 percent of common and 13 percent of 21 percent of common and 13 percent of toxic air pollution; toxic air pollution;

47 percent of common and 26 percent of 47 percent of common and 26 percent of toxic water pollution; toxic water pollution;

and 78 percent of aquatic and 54 and 78 percent of aquatic and 54 percent of terrestrial habitat alteration percent of terrestrial habitat alteration

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• Most of the world's fresh water and land is Most of the world's fresh water and land is used in agriculture. used in agriculture.

• Our North American diets are particularly Our North American diets are particularly water intensive. water intensive. It takes 5,020 liters of water It takes 5,020 liters of water per person per day to produce what we eat.per person per day to produce what we eat. Compare this to 2,810 liters per person per Compare this to 2,810 liters per person per day in Latin America, 2,530 liters in China, day in Latin America, 2,530 liters in China, and 1,760 liters in Africa. and 1,760 liters in Africa.

• Much of this difference is accounted for in Much of this difference is accounted for in the quantities of meat (production and the quantities of meat (production and processing of meat takes a lot of water) and processing of meat takes a lot of water) and irrigated crops we eat. irrigated crops we eat.

• Meat production and processing contributes Meat production and processing contributes four timesfour times more water pollution than fruits, more water pollution than fruits, veggies and grainsveggies and grains. .

• Pesticide contaminants to water are roughly Pesticide contaminants to water are roughly the same in both categories. the same in both categories.

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• Livestock production in Canada over the past five Livestock production in Canada over the past five years has increased, in some cases dramatically years has increased, in some cases dramatically (cattle 4.4%, pigs 26,4%, chickens 23.4% and sheep (cattle 4.4%, pigs 26,4%, chickens 23.4% and sheep 46%), and the per capita demand for meat 46%), and the per capita demand for meat worldwide is growing. This has led to the worldwide is growing. This has led to the development of giant feedlots or mega-barns where development of giant feedlots or mega-barns where animal husbandry is replaced by mechanized animal husbandry is replaced by mechanized production. Unlike the traditional mixed farms production. Unlike the traditional mixed farms where livestock raised was well-matched with crops where livestock raised was well-matched with crops that could use the manure, these feedlots generate that could use the manure, these feedlots generate huge amounts of liquid manure that must be stored huge amounts of liquid manure that must be stored and disposed of. Most often, the volumes of manure and disposed of. Most often, the volumes of manure overwhelm the ability of local cropland to absorb it overwhelm the ability of local cropland to absorb it all safely. Gigantic liquid manure lagoons can leak all safely. Gigantic liquid manure lagoons can leak or rupture, contaminating groundwater, streams, or rupture, contaminating groundwater, streams, rivers and estuaries with nitrates, phosphates, rivers and estuaries with nitrates, phosphates, antibiotics and other drugs, and disease vectors like antibiotics and other drugs, and disease vectors like bacteria and viruses. Factory farms are also a bacteria and viruses. Factory farms are also a source of toxic air pollution and noxious odours. source of toxic air pollution and noxious odours.

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• Aquaculture has developed along the same trajectory. Aquaculture has developed along the same trajectory. Over 20 years, small family fish farms including those Over 20 years, small family fish farms including those in the Bay of Fundy have become huge industrial-scale in the Bay of Fundy have become huge industrial-scale feedlots with control or ownership increasingly feedlots with control or ownership increasingly concentrated in a few large hands. Chemical inputs - concentrated in a few large hands. Chemical inputs - drugs, pesticides, feed contaminants, anti-foulants, drugs, pesticides, feed contaminants, anti-foulants, dyes - and fish excrement have become a huge source dyes - and fish excrement have become a huge source of pollution to coastal waters where aquaculture is of pollution to coastal waters where aquaculture is practised. Now even shellfish aquaculture is growing so practised. Now even shellfish aquaculture is growing so large that there are localized impacts on the seafloor. large that there are localized impacts on the seafloor.

• Industrial scale growing of monoculture crops also has Industrial scale growing of monoculture crops also has a huge environmental impact. Overworked soils cause a huge environmental impact. Overworked soils cause irreplaceable topsoil to erode and soil health to decline. irreplaceable topsoil to erode and soil health to decline. Chemical fertilizers used to compensate for degraded Chemical fertilizers used to compensate for degraded soil pollute groundwater and surface water. Toxic soil pollute groundwater and surface water. Toxic pesticides used to control insects and kill weeds inject pesticides used to control insects and kill weeds inject poisons into the air, water and food we eat. This poisons into the air, water and food we eat. This chemical-dependent crop production has become chemical-dependent crop production has become dominant over the past thirty years. dominant over the past thirty years.

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SuccessionSuccession

• One ecosystem is gradually replaced One ecosystem is gradually replaced by another over time.by another over time.

• Primary succession: Primary succession: – Sequence of changes that begins with Sequence of changes that begins with

bare landscape and ends with a climax bare landscape and ends with a climax communitycommunity

– Climax community is one at maximum Climax community is one at maximum productivity and supportproductivity and support

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Secondary SuccessionSecondary Succession

• Restores a community back.Restores a community back.

• Ex: fireEx: fire

• Fire will destroy a forest, but over a Fire will destroy a forest, but over a 10 year period that forest can return 10 year period that forest can return to its original state.to its original state.

• Quicker than primary successionQuicker than primary succession

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Irreversible ChangeIrreversible Change

• Frequent and Frequent and severe change can severe change can cause the cause the destruction of any destruction of any ecosystemecosystem

• Remediation: can Remediation: can be restored so it is be restored so it is suitable for wildlife suitable for wildlife and forestryand forestry

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Protecting landProtecting land

• Wetlands: Wetlands: – Believed by humans Believed by humans

to be worthless to be worthless because could not use because could not use for farming or building for farming or building home/businesshome/business

– Humans changed the Humans changed the land to be useful, so land to be useful, so they drained the they drained the water and filled in the water and filled in the landland

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• Would this affect Would this affect the environment? the environment? Yes!Yes!– Wetlands act like Wetlands act like

sponges, holding sponges, holding in lots of water, in lots of water, but slowly but slowly releasing it when releasing it when needed.needed.

– They improve They improve water quality by water quality by trapping (filtering) trapping (filtering) particles out.particles out.

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• Wetlands provide Wetlands provide peat (a valuable peat (a valuable source of nutrients)source of nutrients)– Can be used for soil Can be used for soil

improvementimprovement– Burned as a fuel Burned as a fuel

sourcesource

• Peat is sold for lots Peat is sold for lots of money ($100 of money ($100 million a year)million a year)

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Protecting WetlandsProtecting Wetlands

• Loss of an area leads Loss of an area leads to loss of the entire to loss of the entire ecosystem (plant ecosystem (plant and animal and animal biodiversity)biodiversity)

• Loss for the scientific Loss for the scientific communitycommunity

• Loss for cultural Loss for cultural groups that consider groups that consider the land sacred.the land sacred.

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