What Is An Ecosystem What Is An Ecosystem An ecosystem is a natural unit An ecosystem is a natural unit

consisting of all plants, animals and consisting of all plants, animals and micro-organisms (biotic factors) in an micro-organisms (biotic factors) in an area functioning together with all of the area functioning together with all of the non-living physical (abiotic) factors of non-living physical (abiotic) factors of the environment.the environment.

Aquatic systems are those that contain Aquatic systems are those that contain plants and animals that predominantly plants and animals that predominantly depend on a significant amount of depend on a significant amount of water to be present for at least part of water to be present for at least part of the year.the year.

Examples Of Ecosystem Examples Of Ecosystem Include:Include:

CHAPARRALCHAPARRAL• A dense, impenetrable thicket of A dense, impenetrable thicket of

shrubs or dwarf trees. A vegetation shrubs or dwarf trees. A vegetation type dominated by shrubs and small type dominated by shrubs and small trees, especially evergreen trees with trees, especially evergreen trees with thick, small leaves. thick, small leaves.

CORAL REEFCORAL REEFA large underwater formation A large underwater formation

created from the calcium created from the calcium carbonate skeletons of coral carbonate skeletons of coral animals; can also refer to the animals; can also refer to the animals living on and near the animals living on and near the coral reef.coral reef.

DESERTDESERTA desert is a landscape form or region A desert is a landscape form or region

that receives very little precipitation. that receives very little precipitation. Deserts can be defined as areas that Deserts can be defined as areas that receive an average annual precipitation receive an average annual precipitation of less than 250 mm (10 in), or as areas of less than 250 mm (10 in), or as areas in which more water is lost than falls as in which more water is lost than falls as precipitation.In the Köppen climate precipitation.In the Köppen climate classification system, deserts are classification system, deserts are classed as classed as BWhBWh (hot desert) or (hot desert) or BWkBWk (temperate desert).(temperate desert).

GREATER YELLOWSTONE GREATER YELLOWSTONE ECOSYSTEMECOSYSTEM

Greater Yellowstone is the last remaining large, Greater Yellowstone is the last remaining large, nearly intact ecosystem in the northern nearly intact ecosystem in the northern temperate zone of the Earth and is partly temperate zone of the Earth and is partly located in Yellowstone National Park. Conflict located in Yellowstone National Park. Conflict over management has been controversial, and over management has been controversial, and the area is a flagship site among conservation the area is a flagship site among conservation groups that promote ecosystem management. groups that promote ecosystem management. The Greater Yellow Ecosystem (GYE) is one of The Greater Yellow Ecosystem (GYE) is one of the world's foremost natural laboratories in the world's foremost natural laboratories in landscape ecology and geology and is a world-landscape ecology and geology and is a world-renowned recreational site. It is also home to renowned recreational site. It is also home to the animals of Yellowstone.the animals of Yellowstone.

HUMAN ECOSYSTEMHUMAN ECOSYSTEM Human ecosystems are complex cybernetic Human ecosystems are complex cybernetic

systems that are increasingly being used by systems that are increasingly being used by ecological anthropologists and other ecological anthropologists and other scholars to examine the ecological aspects scholars to examine the ecological aspects of human communities in a way that of human communities in a way that integrates multiple factors as economics, integrates multiple factors as economics, socio-political organization, psychological socio-political organization, psychological factors, and physical factors related to the factors, and physical factors related to the environment.environment.

LARGE MARINE ECOSYSTEMLARGE MARINE ECOSYSTEMAny marine environment, from pond to Any marine environment, from pond to

ocean, in which plants and animals ocean, in which plants and animals interact with the chemical and physical interact with the chemical and physical features on the environment.features on the environment.

LITTORAL ZONELITTORAL ZONEThe region of the shore of a lake or sea The region of the shore of a lake or sea

or ocean / the shore of a sea or ocean.or ocean / the shore of a sea or ocean.

MARINE ECOSYSTEMMARINE ECOSYSTEMAny marine environment, from pond to Any marine environment, from pond to

ocean, in which plants and animals ocean, in which plants and animals interact with the chemical and physical interact with the chemical and physical features of the environment.features of the environment.

RAINFORESTRAINFORESTMixed rainforest or mixed forest) is a Mixed rainforest or mixed forest) is a

rainforest classification where eucalypt rainforest classification where eucalypt forest grows in combination with Cool forest grows in combination with Cool Temperate rainforest species.Temperate rainforest species.

SAVANNASAVANNA A tropical or subtropical grassland A tropical or subtropical grassland

containing scattered trees and drought-containing scattered trees and drought-resistant undergrowth.resistant undergrowth.

SUBSURFACE LITHOAUTOTROPHIC SUBSURFACE LITHOAUTOTROPHIC MICROBIAL ECOSYSTEMMICROBIAL ECOSYSTEM

A minute life form; a microorganism, A minute life form; a microorganism, especially a bacterium that causes especially a bacterium that causes disease.disease.

TAIGATAIGA A moist sub arctic coniferous forest A moist sub arctic coniferous forest

that begins where the tundra ends and that begins where the tundra ends and is dominated by spruces and firs.is dominated by spruces and firs.

TUNDRA TUNDRA • A type of ecosystem dominated by A type of ecosystem dominated by

lichens, mosses, grasses, and woody lichens, mosses, grasses, and woody plants. Tundra is found at high plants. Tundra is found at high latitudes (arctic tundra) and high latitudes (arctic tundra) and high altitudes altitudes

A treeless plain characteristic of the A treeless plain characteristic of the arctic and sub arctic regions.arctic and sub arctic regions.

URBAN ECOSYSTEMURBAN ECOSYSTEM Is the subfield of ecology which deals with the Is the subfield of ecology which deals with the

interaction of plants, animals and humans with interaction of plants, animals and humans with each other and with their environment in urban or each other and with their environment in urban or urbanizing settings. Analysis of urban settings in urbanizing settings. Analysis of urban settings in the context of ecosystem ecology (looking at the the context of ecosystem ecology (looking at the cycling of matter and the flow of energy through cycling of matter and the flow of energy through the ecosystem) can result in healthier, better the ecosystem) can result in healthier, better managed communities. Studying the factors which managed communities. Studying the factors which allow wild plants and animals to survive (and allow wild plants and animals to survive (and sometimes thrive) in built environments can also sometimes thrive) in built environments can also create more livable spaces. It allows people to create more livable spaces. It allows people to adapt to the changing environment while adapt to the changing environment while preserving the resources.preserving the resources.

The dark arrows represent the movement The dark arrows represent the movement of this energyof this energy .The movement of the inorganic nutrients is represented by the open arrows.

Energy Flow Through the Energy Flow Through the EcosystemEcosystem

• The diagram The diagram above shows above shows how both how both energy and energy and inorganic inorganic nutrients flow nutrients flow through the through the ecosystem. ecosystem.

To summarize: In the flow of energy and To summarize: In the flow of energy and inorganic nutrients through the ecosystem, a inorganic nutrients through the ecosystem, a few generalizations can be made:few generalizations can be made:

1.1. The ultimate source of energy (for most The ultimate source of energy (for most ecosystems) is the sunecosystems) is the sun

2.2. The ultimate fate of energy in ecosystems is The ultimate fate of energy in ecosystems is for it to be lost as heat.for it to be lost as heat.

3.3. Energy and nutrients are passed from Energy and nutrients are passed from organism to organism through the food chain organism to organism through the food chain as one organism eats another.as one organism eats another.

4.4. Decomposers remove the last energy from Decomposers remove the last energy from the remains of organisms.the remains of organisms.

5.5. Inorganic nutrients are cycled, energy is not.Inorganic nutrients are cycled, energy is not.

Food Chains and Webs:Food Chains and Webs:• A food chain is the path of food from a given final A food chain is the path of food from a given final

consumer back to a producer. For instance, a typical consumer back to a producer. For instance, a typical food chain in a field ecosystem might be:food chain in a field ecosystem might be:

grassgrass grasshoppergrasshopper mousemouse snakesnake hawk

The real world, of course, is more complicated The real world, of course, is more complicated than a simple food chain. While many organisms than a simple food chain. While many organisms do specialize in their diets (anteaters come to do specialize in their diets (anteaters come to mind as a specialist), other organisms do not. mind as a specialist), other organisms do not. Hawks don't limit their diets to snakes; snakes Hawks don't limit their diets to snakes; snakes eat things other than mice. Mouse eats grass as eat things other than mice. Mouse eats grass as well as grasshoppers, and so on.well as grasshoppers, and so on.

A more realistic depiction of who eats whom is A more realistic depiction of who eats whom is called a food, web; an example is shown called a food, web; an example is shown below:below:

It is when we have a picture of a food web in front of It is when we have a picture of a food web in front of us that the definition of food chain makes more sense. us that the definition of food chain makes more sense. We can now see that a food web consists of We can now see that a food web consists of interlocking food chains, and that the only way to interlocking food chains, and that the only way to untangle the chains is to trace untangle the chains is to trace backback along a given food along a given food chain to its source.chain to its source.

• The food webs you see here are grazing food chains since at their base are producers which the herbivores then graze on. While grazing food chains are important, in nature they are outnumbered by detritus-based food chains. In detritus-based food chains, decomposers are at the base of the food chain, and sustain the carnivores which feed on them. In terms of the weight (or biomass) of animals in many ecosystems, more of their body mass can be traced back to detritus than to living producers.

PYRAMIDS

• The concept of The concept of biomass is biomass is important.important.

It is a general principle that the further It is a general principle that the further removed a trophic level is from its source removed a trophic level is from its source (detritus or producer), the less biomass it will (detritus or producer), the less biomass it will contain (biomass here would refer to the contain (biomass here would refer to the combined weight of all the organisms in the combined weight of all the organisms in the trophic level).trophic level).

This Reduction In Biomass Occurs This Reduction In Biomass Occurs For Several Reasons:For Several Reasons:

1. Not everything in the lower levels gets eaten.

2. Not everything that is eaten is digested.

3. energy is always being lost as heat.

• It is important to remember that the decrease It is important to remember that the decrease in number is best detected in terms or in number is best detected in terms or biomass. Numbers of organisms are biomass. Numbers of organisms are unreliable in this case because of the great unreliable in this case because of the great variation in the biomass of variation in the biomass of individualindividual organisms. organisms.

• A generalization exists among ecologists that A generalization exists among ecologists that on average, about 10% of the energy on average, about 10% of the energy available in one trophic level will be passed available in one trophic level will be passed on to the next; this is primarily due to the 3 on to the next; this is primarily due to the 3 reasons given above. Therefore, it is also reasons given above. Therefore, it is also reasonable to assume that in terms of reasonable to assume that in terms of biomass, each trophic level will weigh only biomass, each trophic level will weigh only about 10% of the level below it, and 10x as about 10% of the level below it, and 10x as much as the level above it.much as the level above it.

Roles Of Organisms In An Ecosystem

• Organisms can be either Organisms can be either producersproducers or or consumersconsumers in in terms of energy flow through an ecosystem.terms of energy flow through an ecosystem.

• Producers convert energy from the environment into Producers convert energy from the environment into carbon bonds, such as those found in the sugar carbon bonds, such as those found in the sugar glucose. glucose. PlantsPlants are the most obvious examples of are the most obvious examples of producers; plants take energy from sunlight and use it producers; plants take energy from sunlight and use it to convert carbon dioxide into glucose (or other sugars). to convert carbon dioxide into glucose (or other sugars). Algae and cyanobacteria are also Algae and cyanobacteria are also photosyntheticphotosynthetic producers, like plants. Other producers include bacteria producers, like plants. Other producers include bacteria living around deep-sea vents. These bacteria take living around deep-sea vents. These bacteria take energy from chemicals coming from the Earth's interior energy from chemicals coming from the Earth's interior and use it to make sugars. Other bacteria living deep and use it to make sugars. Other bacteria living deep underground can also produce sugars from such underground can also produce sugars from such inorganic sources. Another word for producers is inorganic sources. Another word for producers is autotrophsautotrophs..

Consumers get their energy from the carbon bonds made by Consumers get their energy from the carbon bonds made by the producers. Another word for a consumer is a the producers. Another word for a consumer is a heterotrophheterotroph. Based on what they eat, we can distinguish . Based on what they eat, we can distinguish between 4 types of heterotrophs:between 4 types of heterotrophs:

• A A trophic level trophic level refers to the organisms refers to the organisms position in the food chain.position in the food chain.

• Autotrophs are at the base. Organisms that Autotrophs are at the base. Organisms that eat autotrophs are called eat autotrophs are called herbivores herbivores or or primary consumersprimary consumers..

consumer consumer trophic level trophic level food source food source Herbivores Herbivores primary primary plants plants Carnivores Carnivores secondary or higher secondary or higher animals animals Omnivores Omnivores all levels all levels plants & plants &

animals animals Detritivores Detritivores - - - - - - - - - - -- - - - - - - - - - - detritus detritus

• An organism that eats herbivores is a An organism that eats herbivores is a carnivorecarnivore and a and a secondary consumersecondary consumer..

• A carnivore which eats a carnivore which eats a A carnivore which eats a carnivore which eats a herbivore is a herbivore is a tertiary consumertertiary consumer, and so on., and so on.

• It is important to note that many animals do not It is important to note that many animals do not specialize in their diets.specialize in their diets.

• OmnivoresOmnivores (such as humans) eat both animals and (such as humans) eat both animals and plants. Further, except for some specialists, most plants. Further, except for some specialists, most carnivores don't limit their diet to organisms of carnivores don't limit their diet to organisms of only one trophic level. Frogs, for instance, don't only one trophic level. Frogs, for instance, don't discriminate between herbivorous and discriminate between herbivorous and carnivorous bugs in their diet. If it's the right size, carnivorous bugs in their diet. If it's the right size, and moving at the right distance, chances are the and moving at the right distance, chances are the frog will eat it. It's not as if the frog has brain cells frog will eat it. It's not as if the frog has brain cells to waste wondering if it's going to mess up the to waste wondering if it's going to mess up the food chain by being a secondary consumer one food chain by being a secondary consumer one minute and a quaternary consumer the next.minute and a quaternary consumer the next.

Components of an Ecosystem ABIOTIC COMPONENTS BIOTIC COMPONENTSSunlight Primary producersTemperature HerbivoresPrecipitation CarnivoresWater or moisture OmnivoresSoil or water chemistry (e.g.,

P, NH4+) Detritivores

etc. etc.All of these vary over space/time

Processes of EcosystemsProcesses of Ecosystems• This figure with the plants, zebra, lion, This figure with the plants, zebra, lion,

and so forth illustrates the two main and so forth illustrates the two main ideas about how ecosystems ideas about how ecosystems function: function: ecosystems have energy ecosystems have energy flowsflows and and ecosystems cycle ecosystems cycle materialsmaterials. These two processes are . These two processes are linked, but they are not quite the linked, but they are not quite the same (see Figure 1).same (see Figure 1).

• Figure 1. Energy flows and material cycles.Figure 1. Energy flows and material cycles.• Energy enters the biological system as light energy, Energy enters the biological system as light energy,

or photons, is transformed into chemical energy in or photons, is transformed into chemical energy in organic molecules by cellular processes including organic molecules by cellular processes including photosynthesis and respiration, and ultimately is photosynthesis and respiration, and ultimately is converted to heat energy. This energy is dissipated, converted to heat energy. This energy is dissipated, meaning it is lost to the system as heat; once it is lost meaning it is lost to the system as heat; once it is lost it cannot be recycled.  Without the continued input of it cannot be recycled.  Without the continued input of solar energy, biological systems would quickly shut solar energy, biological systems would quickly shut down. Thus the earth is an down. Thus the earth is an open systemopen system with respect with respect to energy.28to energy.28

• During decomposition these materials are not destroyed or lost, so the earth is a closed system with respect to elements (with the exception of a meteorite entering the system now and then). The elements are cycled endlessly between their biotic and abiotic states within ecosystems. Those elements whose supply tends to limit biological activity are called nutrients.

The Transformation of The Transformation of EnergyEnergy

• The transformations of energy in an ecosystem begin first with the input of energy from the sun. Energy from the sun is captured by the process of photosynthesis. Carbon dioxide is combined with hydrogen (derived from the splitting of water molecules) to produce carbohydrates (CHO). Energy is stored in the high energy bonds of adenosine triphosphate, or ATP (see lecture on photosynthesis).

• Figure 2 portrays a simple food chain, in which energy from the Figure 2 portrays a simple food chain, in which energy from the sun, captured by plant photosynthesis, flows from sun, captured by plant photosynthesis, flows from trophic leveltrophic level to trophic level via the to trophic level via the food chainfood chain. A trophic level is composed . A trophic level is composed of organisms that make a living in the same way, that is they of organisms that make a living in the same way, that is they are all are all primary producersprimary producers (plants), (plants), primary consumersprimary consumers (herbivores) or (herbivores) or secondary consumerssecondary consumers (carnivores). Dead tissue (carnivores). Dead tissue and waste products are produced at all levels. Scavengers, and waste products are produced at all levels. Scavengers, detritivores, and decomposers collectively account for the use detritivores, and decomposers collectively account for the use of all such "waste" -- consumers of carcasses and fallen leaves of all such "waste" -- consumers of carcasses and fallen leaves may be other animals, such as crows and beetles, but may be other animals, such as crows and beetles, but ultimately it is the microbes that finish the job of decomposition. ultimately it is the microbes that finish the job of decomposition. Not surprisingly, the amount of primary production varies a Not surprisingly, the amount of primary production varies a great deal from place to place, due to differences in the amount great deal from place to place, due to differences in the amount of solar radiation and the availability of nutrients and water.of solar radiation and the availability of nutrients and water.

• For reasons that we will explore more fully in subsequent For reasons that we will explore more fully in subsequent lectures, lectures, energy transfer through the food chain is inefficient.energy transfer through the food chain is inefficient. This means that less energy is available at the herbivore level This means that less energy is available at the herbivore level than at the primary producer level, less yet at the carnivore than at the primary producer level, less yet at the carnivore level, and so on. The result is a pyramid of energy, with level, and so on. The result is a pyramid of energy, with important implications for understanding the quantity of life that important implications for understanding the quantity of life that can be supported.can be supported.

• Usually when we think of food chains we visualize green Usually when we think of food chains we visualize green plants, herbivores, and so on. These are referred to as plants, herbivores, and so on. These are referred to as grazer food chainsgrazer food chains, because living plants are directly , because living plants are directly consumed. In many circumstances the principal energy consumed. In many circumstances the principal energy input is not green plants but dead organic matter. These input is not green plants but dead organic matter. These are called are called detritus food chainsdetritus food chains. Examples include the . Examples include the forest floor or a woodland stream in a forested area, a salt forest floor or a woodland stream in a forested area, a salt marsh, and most obviously, the ocean floor in very deep marsh, and most obviously, the ocean floor in very deep areas where all sunlight is extinguished 1000's of meters areas where all sunlight is extinguished 1000's of meters above. In subsequent lectures we shall return to these above. In subsequent lectures we shall return to these important issues concerning energy flow.important issues concerning energy flow.

• Finally, although we have been talking about food chains, Finally, although we have been talking about food chains, in reality the organization of biological systems is much in reality the organization of biological systems is much more complicated than can be represented by a simple more complicated than can be represented by a simple "chain". There are many food links and chains in an "chain". There are many food links and chains in an ecosystem, and we refer to all of these linkages as a ecosystem, and we refer to all of these linkages as a food food webweb. Food webs can be very complicated, where it . Food webs can be very complicated, where it appears that appears that "everything is connected to everything else""everything is connected to everything else", , and it is important to understand what are the most and it is important to understand what are the most important linkages in any particular food web. important linkages in any particular food web.

Controls on Ecosystem Function• There are two dominant theories of the control of ecosystems. There are two dominant theories of the control of ecosystems.

The first, called bottom-up control, states that it is the nutrient The first, called bottom-up control, states that it is the nutrient supply to the primary producers that ultimately controls how supply to the primary producers that ultimately controls how ecosystems function. If the nutrient supply is increased, the ecosystems function. If the nutrient supply is increased, the resulting increase in production of autotrophs is propagated resulting increase in production of autotrophs is propagated through the food web and all of the other trophic levels will through the food web and all of the other trophic levels will respond to the increased availability of food (energy and respond to the increased availability of food (energy and materials will cycle faster).materials will cycle faster).

• The second theory, called top-down control, states that The second theory, called top-down control, states that predation and grazing by higher trophic levels on lower trophic predation and grazing by higher trophic levels on lower trophic levels ultimately controls ecosystem function. For example, if levels ultimately controls ecosystem function. For example, if you have an increase in predators, that increase will result in you have an increase in predators, that increase will result in fewer grazers, and that decrease in grazers will result in turn in fewer grazers, and that decrease in grazers will result in turn in more primary producers because fewer of them are being eaten more primary producers because fewer of them are being eaten by the grazers. Thus the control of population numbers and by the grazers. Thus the control of population numbers and overall productivity "cascades" from the top levels of the food overall productivity "cascades" from the top levels of the food chain down to the bottom trophic levels. chain down to the bottom trophic levels.

The Geography of EcosystemsThe Geography of Ecosystems• There are many different ecosystems: rain forests

and tundra, coral reefs and ponds, grasslands and deserts. Climate differences from place to place largely determine the types of ecosystems we see. How terrestrial ecosystems appear to us is influenced mainly by the dominant vegetation.

• The word "biome" is used to describe a major vegetation type such as tropical rain forest, grassland, tundra, etc., extending over a large geographic area. It is never used for aquatic systems, such as ponds or coral reefs. It always refers to a vegetation category that is dominant over a very large geographic scale, and so is somewhat broader than an ecosystem.

Figure 3: The distribution of biomesFigure 3: The distribution of biomes..A schematic view of the earth shows that, complicated though climate A schematic view of the earth shows that, complicated though climate may be, many aspects are predictable (Figure 4). High solar energy may be, many aspects are predictable (Figure 4). High solar energy striking near the equator ensures nearly constant high temperatures striking near the equator ensures nearly constant high temperatures and high rates of evaporation and plant transpiration. Warm air rises, and high rates of evaporation and plant transpiration. Warm air rises, cools, and sheds its moisture, creating just the conditions for a cools, and sheds its moisture, creating just the conditions for a tropical rain forest. Contrast the stable temperature but varying rainfall tropical rain forest. Contrast the stable temperature but varying rainfall of a site in Panama with the relatively constant precipitation but of a site in Panama with the relatively constant precipitation but seasonally changing temperature of a site in New York State. Every seasonally changing temperature of a site in New York State. Every location has a rainfall- temperature graph that is typical of a broader location has a rainfall- temperature graph that is typical of a broader region.region.

• Figure 4. Climate patterns Figure 4. Climate patterns affect biome distributions.affect biome distributions.

• We can draw upon plant We can draw upon plant physiology to know that physiology to know that certain plants are distinctive certain plants are distinctive of certain climates, creating of certain climates, creating the vegetation appearance the vegetation appearance that we call biomes. Note how that we call biomes. Note how well the distribution of biomes well the distribution of biomes plots on the distribution of plots on the distribution of climates (Figure 5). Note also climates (Figure 5). Note also that some climates are that some climates are impossible, at least on our impossible, at least on our planet. High precipitation is planet. High precipitation is not possible at low not possible at low temperatures -- there is not temperatures -- there is not enough solar energy to power enough solar energy to power the water cycle, and most the water cycle, and most water is frozen and thus water is frozen and thus biologically unavailable biologically unavailable throughout the year. The high throughout the year. The high tundra is as much a desert as tundra is as much a desert as is the Sahara. is the Sahara.

What are the 2 kinds of ecosystem?

• NATURAL ECOSYSTEM - ecosystem made naturally & occurred naturally with no influence by man ( ex. forest, backyard)

•MAN-MADE ECOSYSTEM - ecosystem with the influence of man, this is usually controlled ( ex. fishpond, zoo)

The Ten Global Threats to The Ten Global Threats to Ecosystem ViabilityEcosystem Viability

1)1) Loss of crop & grazing landLoss of crop & grazing land2)2) Depletion of world's tropical forestsDepletion of world's tropical forests3)3) Extinction of speciesExtinction of species4)4) Rapid population growth Rapid population growth 5)5) Shortage of fresh water resourcesShortage of fresh water resources6)6) Over fishing, habitat destruction, & pollution in the Over fishing, habitat destruction, & pollution in the

marine environment. marine environment. 7)7) Threats to human healthThreats to human health8)8) Climate change Climate change 9)9) Acid rain Acid rain 10)10) Pressures on energy resources Pressures on energy resources

Thank you!!!