Ecosystems

What they are?Ecosystems1Plum Island

21) What are Ecosystems? Ecosystems are the biotic and abiotic factors in a specified area that interact with one another.

Understanding the interaction of the biotic and abiotic factors in an ecosystem can help us to see why particular human activities may be a problem for human survival.

Example: The loss of ozone in the stratosphere increases the quantity of UV radiation on the surface of the planet. In the same way that humans experience sunburn from too much sun exposure, so do plants. Excessive UV may damage or destroy plant protein and DNA, killing the plant.

3Important ecological termsEcology: Study of ecosystems and the interactions that occur among organisms and between organisms and their environment

Ecologist: The investigators who conduct ecological studies

4Important ecological termsSpecies: All the members of a specific kind of plant, animal or microbe; a kind given by similarity of appearance or capacity for interbreeding and producing fertile offspring

Biotic communities: All the populations of different plants, animals and microbes occupying a given area.

Abiotic factors: All the factors of the physical environment: moisture, temperature, light, wind, pH, type of soil, salinity, etc.

5Important ecological termsPopulations: All the members of a particular species occupying a given area.

Associations: A plant community with a definite composition, uniform habitat characteristics, and uniform plant growth.

6Important ecological termsEcotone: transitional region that shares many of the species and characteristics of two ecosystems. It also includes unique conditions

Fig. An ecotone may create a unique habitat with specialized species not found in either of the ecosystems bordering it.

7Important ecological termsLandscapes: group of interacting ecosystems in a particular area. A barrier island, a saltwater bay, constitute a landscape

Fig. Ecosystems are not isolated from one another. One ecosystem blends into the next through a transitional region, an ecotone, which contains many species common to the two adjacent systems.

8Important ecological termsBiomes: grouping of all the ecosystems of a similar type. I.e. tropical rain forests, grasslands, deserts, etc.

Biosphere: All the species on Earth, along with all the environments, make up one vast ecosystem, the Biosphere.

92) The structure of EcosystemsFeeding relationships

Trophic structure10Trophic structure

Producers

Primary consumers

Secondary consumers

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Trophic structure

Producers: capture energy from the Sun or chemical reactions to convert carbon dioxide, an inorganic molecule into organic matter.

What is the difference between organic and inorganic molecules?

Producers are also known as autotrophs. What is an autotroph?12Trophic structure2) Consumers: Primary consumers: feed directly on producers (herbivores)Secondary consumers: feed on primary consumers (carnivores)Omnivores: feed on both plants and animals

Consumers are also known as heterotrophs. What is an heterotroph?

13The Structure of EcosystemsFeeding relationships among consumers

Predator/prey relationships: any relationship in which one organism feeds on another.

Parasites: plants or animals that become intimately associated with their prey and feed on in over an extended period of time without killing it. The organism that is fed upon is called host.

Pathogens: bacteria and viruses that cause disease

14Trophic structure3) Detritus feeders and decomposers: Organisms that feed on death plants or animals, feaces, etc.

Primary detritus feeders: organisms that feed directly on detritus Decomposers: secrete digestive enzymes that break down dead matter. I.e. bacteria and fungi.

Secondary detritus feeders: feed on primary detritus feeders. I.e. protozoans, mites, insects, and worms.

Are detritus feeders autotrophs or heterotrophs?

15Trophic categories

AUTOTROPHSHETEROTROPHSPRODUCERSCONSUMERSDETRITUS FEEDERS AND DECOMPOSERSPhotosynthetic green plantsPrimary consumers (herbivores)Decomposers (fungi and bacteria)Photosynthetic bacteriaOmnivoresPrimary detritus feedersChemiosynthetic bacteriaSecondary consumers (carnivores)Secondary and higher orders of detritus feedersHigher orders of consumers (carnivores)Parasites: plants or animals 162) The structure of EcosystemsFeeding relationships

Trophic relationships17Trophic relationshipsa. Food chains: feeding pathways

Food chains are a description of who eats whom.Predator-prey and host-parasite describe specific feeding relationships.

b. Food webs: complexes of feeding relationships.

c. Trophic Levels or Feeding Levels

All producers belong to the first trophic level.All herbivores (primary consumers) are on the second trophic level.All primary carnivores (secondary consumers) are on the third trophic level.

18Trophic RelationshipsFood chainFood web

192) The structure of EcosystemsFeeding relationships

Biomass and biomass pyramids20Biomass and biomass pyramidAll organic matter can be defined as biomass

All biomass can be arranged into a feeding relationship with the producers on the first trophic level.

On average, 10% of the energy from one trophic level moves to the next trophic level. (This is due partly to the First and Second Laws of thermodynamics.) At each trophic level most of the organisms are not consumed, portions of organisms consumed pass through the consumer undigested, and energy is released to the environment as high potential energy is converted to low potential energy.

21Biomass and biomass pyramidBecause so little energy can be transferred between trophic levels, it is necessary that the first trophic level contain the greatest number of organisms, and the subsequent trophic levels contain fewer and fewer organisms. Limitations on the transfer of energy between trophic levels creates the biomass pyramid.

If organisms (humans) eat high on the biomass pyramid (trophic levels 3, 4, 5, etc.), then fewer organisms can be supported than if organisms eat lower on the biomass pyramid.

22Biomass and biomass pyramid

232) The structure of EcosystemsNon-feeding relationships

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Non feeding relationshipsMutually Supportive Relationships: mutualism.

Competitive Relationships

How are competitive relationships reduced?HabitatNiche: resource partitioning

What happens when competition is not reduced?Competitive exclusion principle

25ABIOTIC FACTORSConditions: abiotic factors that vary in space and time, but are not used up or made unavailable to other species. i. e. temperature, wind, pH, salinity, fire

Resources: factors (biotic or abiotic) that are consumed by organisms. i.e. water, chemical nutrients, light, oxygen262) The Structure of EcosystemsLimiting Factors

Factors that limit growth, reproduction or even survival of a population. Biotic or abioticBasic items include temperature, light, oxygen, carbon dioxide, and precipitation. Only one limiting factor need be out of its optimum range to cause stress for an organism.

27Optimum, zones of stress and limits of toleranceOptimum: level at which an organisms do best. Range of tolerance: the entire span that allows any growth at all.Limits of tolerance: points at the high and low ends of the range of toleranceZones of stress: between the optimal range and the high or low limit of tolerance

Range of tolerance

28Limiting factorsLaw of Limiting Factors - Quantities of any single factor above or below optimum levels necessary for organism growth, reproduction, or survival will limit growth, reproduction, or survival.

Synergistic effects (synergism): two or more factors interacting in a way that causes an effect much greater than one would anticipate from the effects of each of the two acting separately. 293) Global biomes

The Role of Climate30

The role of climateClimate: describes the average temperature and precipitation of a given regionWeather the daily variations in temperature and precipitationVary widely in different parts of the world. A given climate supports only those species that find the temperature and precipitation levels optimal or within ranges of tolerance. Temperature and precipitation combine to create the world's biomes.

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Activity: Describe how ecosystems change as temperature and precipitation change:

a. Vary temperature while precipitation is held constant (Moderate rainfall: cold = cool tundra, warmer = grassland)

b. Vary precipitation while temperature is held constant (Cold temperature: little rain = tundra, more rain = cool taiga).

32Activity: Describe the effects of altitude and latitude

333) Global biomes

Microclimate

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MicroclimateMicroclimateSpecific sites with temperature and moisture conditions significantly different from the overall or average climate of the region in which it is located.

Microclimates. Abiotic factors such as terrain, wind, and type of soil create different microclimates by influencing temperature and moisture in localized areas354) Implications for humansThe three revolutions:Neolithic Revolutiona. Development of agricultureb. Required permanent or long term settlements and specialized skillsc. Allowed for the initial increase in human population reliable food.

Industrial Revolutiona. Created the modern worldb. Energized by fossil fuels (initially timber). resulted in the concentration of waste productsd. Created even greater increase in human population size because of the specialization of the workforce and the replacement of animal/human power with fossil fuels.Environmental Revolutiona. Need to create sustainable human systemsb. Need to create systems in which waste products are not concentrated (pollution), and wastes are resources.

36http://www.harmonartillustrations.com/store/murals.phphttp://emilyyyyyyyyyy.glogster.com/food-web-/http://drake.marin.k12.ca.us/stuwork/rockwater/PLANKTON/Food%20Chain.htmhttp://cumuseum.colorado.edu/Research/Objects/sep04_lichens.htmlhttp://www.colorado.edu/geography/courses/geog_1001_lab/http://apesnature.homestead.com/chapter2.htmlhttp://www.exploringnature.org/db/detail.php?dbID=45&detID=2589http://gohealed.com/http://pediaview.com/openpedia/Detritivore

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