CHAPTER 2 SCIENCE LITERACY AND THE PROCESS OF SCIENCE SCIENCE AND THE SKY Solving the mystery of disappearing ozone

CHAPTER 7 ECOSYSTEMS AND NUTRIENT CYCLINGENGINEERING EARTHA desert experiment gone awryENGINEERING EARTHA desert experiment gone awry7At the end of this chapter you will know:Environmental factors that affect the makeup and distribution of biomesTolerance limits and organization structure in ecosystemsNutrient cycling and the organisms responsible for these functions

Learning Outcomes

27Main ConceptENGINEERING EARTHA desert experiment gone awryEcosystems are complex assemblages of living and non-living components. Many of the roles played by the living organisms in a system are irreplaceable.

Case study: Eight scientists spent two years in an artificial environment known as Biosphere 2.

In addition to wanting to prove that survival in an artificial, self-sustaining habitat was possible, the purpose of this study was to gain a better understanding of the complex interactions on Earth, so we can make better decisions. 37TERMS TO KNOW:SustainableEconomicsEcosystem servicesENGINEERING EARTHA desert experiment gone awry

We learn from mistakes.

More than one-third of the flora and fauna became extinct.

Morning glory vines took over agriculture.

Cockroaches and crazy ants were thriving.

Trees failed to develop stress wood since there was no wind.

A heavy diet of sweet potatoes left the scientists orange.

Oxygen supplies became dangerously low.4Organisms and their habitats form complex systems7TERMS TO KNOW:BiospheresEcosystemHabitatSpeciesNiche

The scale of interactions between organisms aids human classification of natural systems.5Organisms and their habitats form complex systems7

TERMS TO KNOW:BiospheresEcosystemHabitatSpeciesNicheThe scale of interactions between organisms aids human classification of natural systems.

6Organisms and their habitats form complex systems7

TERMS TO KNOW:BiospheresEcosystemHabitatSpeciesNicheThe scale of interactions between organisms aids human classification of natural systems.7Organisms and their habitats form complex systems7

TERMS TO KNOW:BiospheresEcosystemHabitatSpeciesNicheThe scale of interactions between organisms aids human classification of natural systems.

8Organisms and their habitats form complex systems7

All ecosystems are based on nutrient cycling and energy flowTERMS TO KNOW:BiospheresEcosystemHabitatSpeciesNicheThe scale of interactions between organisms aids human classification of natural systems.

9Organisms and their habitats form complex systems7TERMS TO KNOW:Energy flowNutrient cyclesBiomassBiome

Biosphere 1 (The Earth) is materially closed but energetically open. This means that energy enters and leaves the system but biomassthe plants and animalsdo not.

Biomes fall into three broad categories based on climate and determined by predominant plants.Marine, freshwater, and terrestrial biomes are further distinguished as ecosystems based on interactions between specific biotic and abiotic components.

To conduct field research in biological systems is difficult due to our lack of control over the interactions. In the Biosphere 2, scientists were able to control and measure environmental variables like oxygen and CO2 balances periodically throughout their stay.10Organisms and their habitats form complex systems7TERMS TO KNOW:Energy flowNutrient cyclesBiomassBiome

Biosphere 1 (The Earth) is materially closed but energetically open. This means that energy enters and leaves the system but biomassthe plants and animalsdo not.

Biomes fall into three broad categories based on climate and determined by predominant plants.Marine, freshwater, and terrestrial biomes are further distinguished as ecosystems based on interactions between specific biotic and abiotic components.

To conduct field research in biological systems is difficult due to our lack of control over the interactions. In Biosphere 2, scientists were able to manipulate and measure environmental variables like oxygen and CO2 balances periodically throughout their stay.11Organisms and their habitats form complex systems7

12Organisms and their habitats form complex systems7

13Organisms and their habitats form complex systems7

14Organisms and their habitats form complex systems7

Biomes are specific types of terrestrial ecosystems with characteristic temperature and precipitation conditions.

Temperature decreases when moving away from the equator and with increased elevation. 15

Organisms and their habitats form complex systems7

TundraTropical rainforestBoreal forestMediterranean scrubDesertSavanna

16

Organisms and their habitats form complex systems7Biosphere technology was developed in the 1960s and 1970s as preparation for space exploration. Biosphere 2 remains the largest enclosed ecosystem ever created.Biosphere 2 houses several biomes under one roof, each contributing to overall function.17Organisms and their habitats form complex systems7

Each biome required consideration of the interactions between plant and animal species as well as careful assessment of nutrient requirements for each organism.Biosphere 2 houses several biomes under one roof, each contributing to overall function.18Living things survive within a specific range of environmental conditions7TERMS TO KNOW:Limiting factorRange of tolerance

Each biome required consideration of the interactions between plant and animal species as well as careful assessment of nutrient requirements.

Most desert biomes fluctuate from extreme cold at night to high temperatures during the day. By comparison, rainforests need consistently warm temperatures.

Each organism must maintain homeostasis within a narrow range. In Biosphere 2, tolerances needed to be maintained within a closed system.

19Living things survive within a specific range of environmental conditions7Populations have a range of tolerance for each environmental factorlight, water, salinity, nitrogen.

Each species has an upper and lower limit of tolerances beyond which the organism cannot survive.

On the lower end of the spectrum is the absolute minimum for survival of a factor. This is where limiting factors determine survival.

The optimal level is somewhere in the middle and will vary somewhat among individuals within a population.

20

Living things survive within a specific range of environmental conditions7Populations have a range of tolerance for each environmental factorlight, water, salinity, nitrogen.

Each species has an upper and lower limit of tolerances beyond which the organism cannot survive.

On the lower end of the spectrum is the absolute minimum for survival of a factor. This is where limiting factors determine survival.

The optimal level is somewhere in the middle and will vary somewhat among individuals within a population.

21

Living things survive within a specific range of environmental conditions7Populations have a range of tolerance for each environmental factorlight, water, salinity, nitrogen.

Each species has an upper and lower limit of tolerances beyond which the organism cannot survive.

On the lower end of the spectrum is the absolute minimum for survival of a factor. This is where limiting factors determine survival.

The optimal level is somewhere in the middle and will vary somewhat among individuals within a population.

22

Living things survive within a specific range of environmental conditions7TERMS TO KNOW:Limiting factorRange of toleranceThe Biosphere ocean is still used for marine research.In the beginning, things went smoothlycarrots, broccoli, spinach, kale, and other vegetables had been planted next to the human habitat, and a few domestic animals provided milk and meat. The scientist got healthier at first. Less light than anticipated led to lower productivity than needed.

Pests and disease began to cut production, too.23Nutrients such as carbon cycle through ecosystems7TERMS TO KNOW:BioticAbioticReservoirs (or sinks)ProducerConsumerCellular respiration

Nutrients cycle through and are stored in both biotic (living) and abiotic (non-living) components of a system.

Reservoirs for CO2 include plants, oceans, and soil.

The producers use the stored CO2 from the atmosphere to produce sugar while releasing oxygen.The sugar molecule represents stored chemical energy that the producer can use.

The consumer eats the plant and, in so doing, releases the energy from the sugar molecules through cellular respiration.24Nutrients such as carbon cycle through ecosystems7

Carbon cycles in and out of living things during photosynthesis and cellular respiration.

Carbon is transferred as consumers and decomposers eat other organisms.

Some carbon is stored in the bodies of organisms and in oceans, soil, and the atmosphere.

Overall, the carbon cycle is balanced between respiration and photosynthesis.

25Nutrients such as carbon cycle through ecosystems7

Carbon cycles in and out of living things during photosynthesis and cellular respiration.

Carbon is transferred as consumers and decomposers eat other organisms.

Some carbon is stored in the bodies of organisms and in oceans, soil, and the atmosphere.

Overall, the carbon cycle is balanced between respiration and photosynthesis.

26Nutrients such as carbon cycle through ecosystems7

Carbon cycles in and out of living things during photosynthesis and cellular respiration.

Carbon is transferred as consumers and decomposers eat other organisms.

Some carbon is stored in the bodies of organisms and in oceans, soil, and the atmosphere.

Overall, the carbon cycle is balanced between respiration and photosynthesis.27Nutrients such as carbon cycle through ecosystems7

Carbon cycles in and out of living things during photosynthesis and cellular respiration.

Carbon is transferred as consumers and decomposers eat other organisms.

Some carbon is stored in the bodies of organisms and in oceans, soil, and the atmosphere.

Overall, the carbon cycle is balanced between respiration and photosynthesis.

28Nutrients such as carbon cycle through ecosystems7

In Biosphere 2, oxygen and carbon were off by such a great amount that the scientists found themselves constantly exhausted.

The reason was that oxygen levels had fallen to dangerously low levelslevels too low to extract energy from the food they were eating.The plants in Biosphere 2 were producing oxygen, but the excessive growth of soil microbes used oxygen faster than the plants could replace it.29

Nutrients such as carbon cycle through ecosystems

TERMS TO KNOW:Nitrogen fixationPhosphorus cycleNitrogen and phosphorus are two additional chemicals that are essential for life.7730

Nutrients such as carbon cycle through ecosystems7Nitrogen is the most abundant element in the Earths atmosphere and is needed to make proteins and nucleic acids.

Plants cannot use nitrogen directly from the atmosphere but, rather, must convert it into usable forms through the nitrogen cycle.

During nitrogen fixation, one form of nitrogen is converted by bacteria to another form that can be taken up by the roots of plants.Nitrogen is needed by all living things to make biological molecules like protein and DNA. It is continuously moved in and out of organisms and the atmosphere in a cycle dependent on soil bacteria.31Nutrients such as carbon cycle through ecosystems7Nitrogen is the most abundant element in the Earths atmosphere and is needed to make proteins and nucleic acids.

Plants cannot use nitrogen directly from the atmosphere but rather, must convert it into usable forms through the nitrogen cycle.

During nitrogen fixation, one form of nitrogen is converted by bacteria to another form that can be taken up by the roots of plants.Nitrogen is needed by all living things to make biological molecules like protein and DNA. It is continuously moved in and out of organisms and the atmosphere in a cycle dependent on soil bacteria.

32Nutrients such as carbon cycle through ecosystems7

TERMS TO KNOW:Nitrogen fixationPhosphorus cycleNitrogen and phosphorus are two additional chemicals that are essential for life.33Nutrients such as carbon cycle through ecosystems7

Phosphorus is needed by all organisms to make DNA. This is a very slow cycle. There is no atmospheric componentit is dependent only on the weathering of rock to release new supplies into the water and soil. Once dissolved in water, the phosphorus can be taken up by organisms.Phosphorus passes from inorganic to organic form through interaction with water and organisms.

In Biosphere 2, the phosphorus became trapped in water systems and polluted aquatic habitats. Algal mats absorbed much of the excess phosphorus.

Once dried, the minerals could be reclaimed from the algae.34

Nutrients such as carbon cycle through ecosystems7

Another Biosphere 2 project is experimentation to predict the effects of climate shifts on trees.

35Ecosystems are complicated, but learning how they function will help us restore degraded ones7Lessons from Biosphere 2The Earth is far more complicated than we imagined or could plan for.A small change can set off a sequence of events that can degrade a systems capacity to support life.Negative results can be just as informative as positive results.We gained a greater understanding of carbon cycling.Biosphere 2 is still used by scientists from around the world to study the effects of an atmosphere loaded with CO2.

36PERSONAL CHOICES THAT HELP

737UNDERSTANDING THE ISSUE7

38UNDERSTANDING THE ISSUE7

39ANALYZING THE SCIENCE7

40

EVALUATING NEW INFORMATION7

The Smithsonian: http://nationalzoo.si.edu/SCBI/MigratoryBirds/Coffee/default.cfm

41MAKING CONNECTIONS7

42