Ecosystems and Their Interactions Chapter 6 Lesson 6.2

PA Academic Standards for Environment & Ecology Standard B Explain how cycles affect the balance in an ecosystem.Explain how cycles affect the balance in an ecosystem. Describe an element cycle and its role in an ecosystem.Describe an element cycle and its role in an ecosystem. Explain the consequences of interrupting natural cycles.Explain the consequences of interrupting natural cycles.

Learning Objectives Students will describe an element cycle and its role in an ecosystem.Students will describe an element cycle and its role in an ecosystem. Students will explain the consequences of interrupting natural cycles.Students will explain the consequences of interrupting natural cycles.

Theme Outline Lesson 6.2 Cycles in an EcosystemCycles in an Ecosystem The Water CycleThe Water Cycle The Carbon CycleThe Carbon Cycle The Nitrogen CycleThe Nitrogen Cycle

Cycles in an Ecosystem Earth is a closed system Matter continuously cycles throughout different parts of an ecosystem

Major Cycles Three major cycles Water Cycle Carbon Cycle Nitrogen Cycle

Major Cycles Three major cycles Water Cycle Carbon Cycle Nitrogen Cycle

The Water Cycle

Worldwide Water Supply

Water water everywhere but… Covers 70% of the Earth’s surface.Covers 70% of the Earth’s surface. Most living things are primarily water.Most living things are primarily water. Humans are ~65% water.Humans are ~65% water. … the Earth’s water supply is finite – Finite – a fixed amount. Which means … The same amount of water that was on Earth when the dinosaurs were around, still exists today!!!

The Water Cycle

Processes at work… Evaporation Liquid water to water vapor Condensation Water vapor cools and condenses into clouds as water droplets Precipitation Water droplets fall to the Earth as rain, sleet, hail, or snowWater droplets fall to the Earth as rain, sleet, hail, or snow Runoff Water runs off into nearby streams, rivers, lakes, or enters the groundwaterWater runs off into nearby streams, rivers, lakes, or enters the groundwater Infiltration/Percolation

Why is water such an important substance? There is less than 1% of freshwater available on the surface of the Earth for drinking, bathing, and cooking. Human activities have greatly impacted quality of freshwater supplies. Example: pollution from chemical spills, poor wastewater treatment, agricultural runoff, and septic tank failure

Water Quality Concerns Agricultural runoff contains a host of potentially harmful chemicals and sediments that can easily enter waterways. In Pennsylvania, access to potable drinking water is not an issue for most. However, in other parts of the world, limited access to safe potable water is a major concern for populations living along many waterways.

Major Cycles Three major cycles Water CycleWater Cycle Carbon CycleCarbon Cycle NitrogenNitrogen

The Carbon Cycle

Why is carbon important anyway? Carbon is the building block for life. Carbon is the basis for all organic life. Carbon is essential for making … DNA DNA Proteins Proteins Fats Fats Carbohydrates Carbohydrates

Where else is carbon found? Carbon Dioxide (CO 2 ) This greenhouse gas helps maintain heat in the Earth’s upper atmosphere.This greenhouse gas helps maintain heat in the Earth’s upper atmosphere. Carbon reservoirs Oceans Atmosphere Rocks

The Carbon Cycle… simplified

The Carbon Cycle: Rock and Fossil Fuel Formation Organic matter Marine shells Rocks Minerals pressure Wetland Material Organic Matter Fossil Fuels pressure

Major Cycles Three major cycles Water CycleWater Cycle Carbon CycleCarbon Cycle NitrogenNitrogen

The Nitrogen Cycle

Nitrogen Composes ~79% of the atmosphereComposes ~79% of the atmosphere The atmosphere is a major nitrogen reservoir.The atmosphere is a major nitrogen reservoir. However, most of the nitrogen in the atmosphere is not in a usable form so it can not be used by plants and animals.However, most of the nitrogen in the atmosphere is not in a usable form so it can not be used by plants and animals.

Nitrogen is necessary for making… DNADNA ProteinsProteins Amino AcidsAmino Acids ChlorophyllChlorophyll

The Big 3… N 2 Atmosphere NO 3 Nitrates NO 2 Nitrites

Four major processes… 1) 1)Nitrogen fixation 2) 2)Decay 3) 3)Nitrification 4) 4)Denitrification

Types of Nitrogen Fixation Atmospheric fixation Lightning in the atmosphere breaks up nitrogen molecules and when combine with oxygen they form nitrates. N 2  NO 3 N 2  NO 3 Atmospheric Nitrogen  Nitrates

Industrial fixation Combines nitrogen in the atmosphere with hydrogen to form ammonia Occurs under pressure and high temperatures (~600 o C) Product used as fertilizer in agriculture N 2  NH 3 Atmospheric Nitrogen  Ammonia

Fertilizer Labels

Biological fixation Plants and bacteria convert atmospheric nitrogen into ammonia N 2  NH 3 Atmospheric Nitrogen  Ammonia Soybeans/Legumes - Nitrogen fixing bacteria

Decay Nitrogen cycles through food chains like other elements. Nitrogen is found in excreted wastes from animals. Microorganisms break down excretions and dead animals to form ammonia.

Nitrification A process that converts nitrogen, in various forms, into more usable forms of nitrogen that can be taken up through the roots of plants. Convert organic nitrogen into nitrites and nitrates. NH 3  NO 3 Ammonia  Nitrates

Denitrification A process preformed by bacteria that live deep in soils and aquatic sediments under anaerobic conditions. What does it mean when we say anaerobic? NO 3  N 2 Nitrates  Atmospheric Nitrogen

The Nitrogen Cycle

Changes to Ecosystems Occur more frequently in some ecosystems than othersOccur more frequently in some ecosystems than others Cycles and processes continue to cycle materials through ecosystems, even after disturbancesCycles and processes continue to cycle materials through ecosystems, even after disturbances Ecosystems change in order to meet the conditions presentEcosystems change in order to meet the conditions present Example: regrowth of a forest after forest fires destroy forest floor (organic matter)