EEcological systems, cological systems, biogeochemical cycling of biogeochemical cycling of

mather and energy in naturemather and energy in nature

Ecological systems Ecological systems represent recurring represent recurring groups of biological groups of biological communities that arecommunities that are found in similar found in similar physical environments physical environments and are influenced byand are influenced by similar dynamicsimilar dynamic ecological processes,ecological processes, such as fire or flooding.such as fire or flooding.

Ecological systems (ecosystems) Ecological systems (ecosystems) consist of all the living organisms in consist of all the living organisms in an area and their physical an area and their physical environment (soil, water, air).  environment (soil, water, air).  Ecosystems are influenced over time Ecosystems are influenced over time by the local climate, variations in the by the local climate, variations in the local landscape, disturbances such as local landscape, disturbances such as fire and floods, and the organisms fire and floods, and the organisms that inhabit them. that inhabit them.

Components of GrasslandsComponents of Grasslands

Grassland ecosystems have both Grassland ecosystems have both bioticbiotic abiotic components.  abiotic components. 

Classification of Classification of biotic components biotic components

producers producers ((grasses,grasses, shrubs and trees shrubs and trees )) cconsumersonsumers ( (grazinggrazing ungulates, birdsungulates, birds and insects) and insects) ddecomposersecomposers ((fungi, insectsfungi, insects and bacteria and bacteria ))

Classification of plantsClassification of plants

trees trees shrubs shrubs grasses grasses grass-like plants (sedges and rushes) grass-like plants (sedges and rushes) forbs (broad-leaved herbaceous forbs (broad-leaved herbaceous

plants) plants) cryptogams (mosses and lichens) cryptogams (mosses and lichens)

TreesTrees Trees can be either Trees can be either

coniferous or deciduous. coniferous or deciduous. Coniferous trees, including Coniferous trees, including

Douglas fir and ponderosa Douglas fir and ponderosa pine, have needle-like leaves pine, have needle-like leaves and seeds borne in cones.  and seeds borne in cones. 

Deciduous trees, such as Deciduous trees, such as trembling aspen, generally trembling aspen, generally have broad, net-veined have broad, net-veined leaves and seeds that are leaves and seeds that are produced from flowers.produced from flowers.

GrassesGrasses

Grasses are herbaceous plants, which Grasses are herbaceous plants, which mean that they die back to ground level mean that they die back to ground level each year. each year.

The flowers and seeds of grasses can vary The flowers and seeds of grasses can vary greatly and are used to distinguish greatly and are used to distinguish between different grass species. between different grass species. 

Grass-like plantsGrass-like plants

Sedges and rushes are similar to Sedges and rushes are similar to grasses in that they have slender, grasses in that they have slender, parallel-veined leaves, but their parallel-veined leaves, but their stems are unjointed and solid.  stems are unjointed and solid. 

Forbs Forbs

Forbs are generally small plants that Forbs are generally small plants that produce flowers.  They flower at different produce flowers.  They flower at different times throughout the growing season times throughout the growing season

Hazardous Plants Hazardous Plants and and CryptogamsCryptogams

Plants that are either poisonous or Plants that are either poisonous or injurious to livestock naturally exist injurious to livestock naturally exist in BC’s grasslands. in BC’s grasslands. 

Cryptogams are rather complex and Cryptogams are rather complex and have both visible and microscopic have both visible and microscopic components that grow over the components that grow over the surface of soils.  surface of soils. 

CryptogamsCryptogams The visible partThe visible part

includes lichens,includes lichens, mosses andmosses and liverworts, whileliverworts, while the the microscopicmicroscopic component iscomponent is made made up ofup of algae,algae, fungi and fungi and bacteria.bacteria.   

SystemsSystems

Ecological systems (ecosystems) Ecological systems (ecosystems) have many biogeochemical cycles have many biogeochemical cycles operating as a part of the system, for operating as a part of the system, for example the water cycle, the carbon example the water cycle, the carbon cycle, the nitrogen cyclecycle, the nitrogen cycle..

All chemical elements occurring in All chemical elements occurring in organisms are part of organisms are part of biogeochemical cycles. biogeochemical cycles.

Biogeochemical cycleBiogeochemical cycle

IIs a pathway by which a s a pathway by which a chemicalchemical elementelement or or moleculemolecule moves through moves through both biotic (both biotic (biospherebiosphere) and abiotic () and abiotic (lithospherelithosphere, , atmosphereatmosphere, and , and hydrospherehydrosphere) compartments of ) compartments of EarthEarth..

Classification of sClassification of systemsystems

closed systemclosed system open systemopen system

carboncarbon, , nitrogennitrogen, , oxygenoxygen, , phosphorusphosphorus, , and and sulfursulfur—used in ecosystems by —used in ecosystems by living organisms are a part of a living organisms are a part of a closed systemclosed system;;

flow of energy in an ecosystem is an flow of energy in an ecosystem is an open systemopen system

ReservoirsReservoirs

CChemicals are sometimes held for hemicals are sometimes held for long periods of time in one place. long periods of time in one place.

This place is called a This place is called a reservoirreservoir.. example, as example, as coalcoal deposits that are deposits that are

storing storing carboncarbon for a long period of for a long period of time. time.

CCarbon cycle arbon cycle

Carbon cycle: Carbon cycle: Carbon is one of the Carbon is one of the most important elements that sustain most important elements that sustain life on earth. Carbon dioxide and life on earth. Carbon dioxide and methane gases (compounds of methane gases (compounds of carbon) in the earth's atmosphere has carbon) in the earth's atmosphere has a substantial effect on earth's heat a substantial effect on earth's heat balance. It absorbs infrared radiation balance. It absorbs infrared radiation and hence may contribute to global and hence may contribute to global warming and climate change.warming and climate change.

Nitrogen Nitrogen cyclecycle

The The nitrogen cyclenitrogen cycle represents one represents one of the most important nutrient cycles of the most important nutrient cycles found in ecosystems.Nitrogen is a found in ecosystems.Nitrogen is a required nutrient for all living required nutrient for all living organisms to produce a number of organisms to produce a number of complex organic molecules like complex organic molecules like amino acids, the building blocks of amino acids, the building blocks of proteinsproteins..

Water cycle   Water cycle  

Hydrological cycleHydrological cycle: This is some : This is some times called the water cycle. Water is times called the water cycle. Water is the most important chemical of life the most important chemical of life for all living organisms on earth. for all living organisms on earth. Water in the atmosphere is usually in Water in the atmosphere is usually in form of vapor but condenses to liquid form of vapor but condenses to liquid water and can solidify when water and can solidify when temperatures are 0temperatures are 000C to form ice. C to form ice.

Oxygen cycle   Oxygen cycle  

Oxygen cycle:Oxygen cycle:

The oxygen cycle describes the movement The oxygen cycle describes the movement of oxygen within and between its three of oxygen within and between its three main reservoirs: the atmosphere, the main reservoirs: the atmosphere, the biosphere, and the lithosphere. The main biosphere, and the lithosphere. The main driving factor of the oxygen cycle is driving factor of the oxygen cycle is photosynthesis and because of this, photosynthesis and because of this, oxygen and carbon cycles are usually oxygen and carbon cycles are usually linked and the two cycles are collectively linked and the two cycles are collectively called oxygen-carbon cycle. called oxygen-carbon cycle.

Energy flow in ecosystemsEnergy flow in ecosystems

What is an ecosystem?What is an ecosystem? SystemSystem = regularly interacting and = regularly interacting and

interdependent components forming interdependent components forming a unified wholea unified whole

EcosystemEcosystem = an ecological system; = an ecological system;

= a community and its physical = a community and its physical environment treated together as a environment treated together as a functional systemfunctional system

OR, MORE SIMPLYOR, MORE SIMPLY an ecosystem is composed of the organisms an ecosystem is composed of the organisms

and physical environment of a specified area.and physical environment of a specified area.SIZE: micro to MACROSIZE: micro to MACRO

THE RULES OF ECOLOGYTHE RULES OF ECOLOGY F. A. BAZZAZ:F. A. BAZZAZ:

1. Everything is connected to everything 1. Everything is connected to everything else.else.

2. Everything must go somewhere.2. Everything must go somewhere.

3. There is no such thing as a free lunch.3. There is no such thing as a free lunch.

Attributes of EcosystemsAttributes of Ecosystems OrderOrder DevelopmentDevelopment Metabolism (energy flow)Metabolism (energy flow) Material cyclesMaterial cycles Response to the Response to the environmentenvironment

Porous boundariesPorous boundaries

ENERGY FLOW IN ECOSYSTEMSENERGY FLOW IN ECOSYSTEMS

All organisms require energyAll organisms require energy,,for growth, maintenance, for growth, maintenance, reproduction, locomotion, etc.reproduction, locomotion, etc.

Hence, for all organisms thereHence, for all organisms there mustmust be: be: A A sourcesource of energy of energy

Types of energyTypes of energy

heat energyheat energy

mechanical energymechanical energy (+ gravitational (+ gravitational energy,etc.)energy,etc.)

chemical energy chemical energy = energy stored in = energy stored in

molecular bondsmolecular bonds

Transformations of energyTransformations of energy

How is solar energy converted to How is solar energy converted to chemical energy?chemical energy?

How does this process influence life as How does this process influence life as we see it on earth?we see it on earth?

The transformations of energy from solar The transformations of energy from solar radiation to chemical energyradiation to chemical energy

An ecosystem has abiotic and An ecosystem has abiotic and biotic components:biotic components:

ABIOTIC componentsABIOTIC components::SolarSolar energyenergy provides practically all provides practically all

the energy for ecosystems.the energy for ecosystems.Inorganic substancesInorganic substances, e.g., sulfur, , e.g., sulfur,

boron, tend to cycle through boron, tend to cycle through ecosystems.ecosystems.

Organic compoundsOrganic compounds, such as , such as proteins, carbohydrates, lipids.proteins, carbohydrates, lipids.

AutotrophsAutotrophs Autotrophs (=self-nourishing) are called Autotrophs (=self-nourishing) are called

primary producersprimary producers.. PhotoautotrophsPhotoautotrophs fix energy from the sun fix energy from the sun

and store it in complex organic compoundsand store it in complex organic compounds (= green plants, algae, some bacteria)(= green plants, algae, some bacteria)

photoautotrophssimpleinorganiccompounds

complexorganic compounds

light

ChemoautotrophsChemoautotrophs (chemosynthesizers) are (chemosynthesizers) are bacteriabacteria that oxidize reduced inorganic that oxidize reduced inorganic substances substances (typically sulfur and ammonia (typically sulfur and ammonia compounds)compounds) and produce complex and produce complex organic compounds.organic compounds.

chemoautotrophsreducedinorganiccompounds

complexorganic compounds

oxygen

Chemosynthesis near Chemosynthesis near hydrothermal ventshydrothermal vents

Other chemoautotrophs:

Nitrifying bacteria in the soil under our feet!

HeterotrophsHeterotrophs Heterotrophs (=other-nourishing) Heterotrophs (=other-nourishing) cannot cannot

produce their own food directly from produce their own food directly from sunlight+ inorganic compounds. sunlight+ inorganic compounds. They They require energy previously stored in require energy previously stored in complex molecules.complex molecules.

heterotrophssimpleinorganiccompounds

complexorganic compounds

(this may include several steps, with

several different types of organisms)

heat

Heterotrophs can be grouped as:Heterotrophs can be grouped as: consumersconsumers

decomposersdecomposers

Consumers feed on organisms or particulate Consumers feed on organisms or particulate organic matter.organic matter.

Decomposers utilize complex compounds in dead Decomposers utilize complex compounds in dead protoplasm.protoplasm.

BacteriaBacteria and and fungifungi are the main groups of are the main groups of decomposers.decomposers.

Bacteria Bacteria are the main feeders on are the main feeders on animal animal material.material. FungiFungi feed primarily on feed primarily on plantsplants, although bacteria , although bacteria

also are important in some plant decomposition also are important in some plant decomposition processes.processes.

The Laws of ThermodynamicsThe Laws of ThermodynamicsEnergy flow is a one-directional process. Energy flow is a one-directional process. sunsun---> ---> heatheat (longer wavelengths) (longer wavelengths)FIRST LAW of THERMODYNAMICS:FIRST LAW of THERMODYNAMICS:Energy can be converted from one form to another, but Energy can be converted from one form to another, but

cannot be created or destroyed.cannot be created or destroyed.

SECOND LAW of THERMODYNAMICSSECOND LAW of THERMODYNAMICS Transformations of energy always result in some loss or dissipation of energyTransformations of energy always result in some loss or dissipation of energy oror In energy exchanges in a closed system, the potential energy of the final state In energy exchanges in a closed system, the potential energy of the final state

will be less than that of the initial statewill be less than that of the initial state oror Entropy tends to increase (entropy = amount of unavailable energy in a system)Entropy tends to increase (entropy = amount of unavailable energy in a system) oror Systems will tend to go from ordered states to disordered states (to maintain Systems will tend to go from ordered states to disordered states (to maintain

order, energy must be added to the system, to compensate for the loss of energy)order, energy must be added to the system, to compensate for the loss of energy)

ExamplesExamplesInternal combustion engines in cars Internal combustion engines in cars

are 25% efficient in converting are 25% efficient in converting chemical energy to kinetic energy; chemical energy to kinetic energy; the rest is not used or is lost as heat.the rest is not used or is lost as heat.

My house, particularly my girls' My house, particularly my girls' rooms, goes from a complex, ordered rooms, goes from a complex, ordered state to a simpler, disordered state.state to a simpler, disordered state.

Energy flowEnergy flow

Simplistically:Simplistically:

heat

Producers Consumers

Decomposers

heat

It is useful to distinguishIt is useful to distinguish different different types of organisms within these types of organisms within these major groups, major groups, particularly within the particularly within the consumer group.consumer group.

Consumers

Terminology of trophic Terminology of trophic levelslevels

We can further separate the We can further separate the TROPHIC LEVELS, particularly the TROPHIC LEVELS, particularly the Consumers:Consumers:

Producers (Plants, algae, Producers (Plants, algae, cyanobacteria; some cyanobacteria; some chemotrophs)--capture energy, chemotrophs)--capture energy, produce complex organic produce complex organic compoundscompounds

More trophic levels:More trophic levels:

DetritivoresDetritivores--invertebrates that --invertebrates that feed on organic wastes and feed on organic wastes and dead organisms (detritus) from dead organisms (detritus) from all trophic levelsall trophic levels

DecomposersDecomposers----bacteria and bacteria and fungi that break down dead fungi that break down dead material into inorganic material into inorganic materialsmaterials

Alternate TerminologyAlternate TerminologyProducers = plants etc. that Producers = plants etc. that

capture energy from the suncapture energy from the sunHerbivores = plant-eatersHerbivores = plant-eatersCarnivores = animal-eatersCarnivores = animal-eaters

Omnivores--eat both Omnivores--eat both animals and plantsanimals and plants

Together, these groups make Together, these groups make up aup a FOODFOOD CHAINCHAIN

E.g., grass, rabbit, eagleE.g., grass, rabbit, eagle

Carnivore Herbivore Producer

CarnivoresCarnivores Carnivores can be further Carnivores can be further

divided into groups:divided into groups:

quaternary carnivore (top)quaternary carnivore (top) tertiary carnivoretertiary carnivore secondary carnivoresecondary carnivore primary carnivoreprimary carnivore

The last carnivore in a chain, The last carnivore in a chain, which is not usually eaten by which is not usually eaten by any other carnivore, is often any other carnivore, is often referred to as the referred to as the top carnivore.top carnivore.

FoodFoodchainschains

ProblemsProblems

Too simplisticToo simplistic

No detritivoresNo detritivores

Chains too longChains too long

Rarely are things as simple as grass, Rarely are things as simple as grass, rabbit, hawk, or indeed any simple rabbit, hawk, or indeed any simple linear sequence of organisms.linear sequence of organisms.

More typically, there are multiple More typically, there are multiple interactions, so that we end up with a interactions, so that we end up with a FOOD WEBFOOD WEB..

Energy transfers among trophic Energy transfers among trophic levelslevels

How much energy is passed How much energy is passed from one trophic level to the from one trophic level to the next?next?

How efficient are such How efficient are such transfers?transfers?

Biomass--the dry mass of organic Biomass--the dry mass of organic material in the organism(s).material in the organism(s).

(the mass of water is not usually (the mass of water is not usually included, since water content is included, since water content is variable and contains no usable variable and contains no usable energy)energy)

Standing cropStanding crop--the amount of --the amount of biomass present at any point in time.biomass present at any point in time.

Primary productivityPrimary productivity

Primary productivity is the rate of Primary productivity is the rate of energy capture by producers.energy capture by producers.

= the amount of new biomass of = the amount of new biomass of producers, per unit time and spaceproducers, per unit time and space

Gross primary production (GPP)Gross primary production (GPP) = total amount of energy = total amount of energy

capturedcapturedNet primary production (NPP)Net primary production (NPP) = GPP - respiration= GPP - respirationNet primary production is thus the Net primary production is thus the

amount of energy stored by the amount of energy stored by the producers and potentially available to producers and potentially available to consumers and decomposers.consumers and decomposers.

Secondary productivity is the rate of Secondary productivity is the rate of production of new biomass by production of new biomass by consumers, consumers, i.e., the rate at which i.e., the rate at which consumers convert organic material consumers convert organic material into new biomass of consumers.into new biomass of consumers.

Note that secondary production simply Note that secondary production simply involves the repackaging of energy involves the repackaging of energy previously captured by producers--no previously captured by producers--no additional energy is introduced into the additional energy is introduced into the food chain.food chain.

Ecological pyramidsEcological pyramidsThe standing crop, The standing crop,

productivity, number of productivity, number of organisms, etc. of an organisms, etc. of an ecosystem can be ecosystem can be conveniently depicted using conveniently depicted using “pyramids”, where the “pyramids”, where the size of size of each compartment represents each compartment represents the amountthe amount of the item in each of the item in each trophic level of a food chain.trophic level of a food chain.

producersherbivorescarnivores

Pyramid of energyPyramid of energyA pyramid of energy depicts the A pyramid of energy depicts the

energy flow, or productivity, of energy flow, or productivity, of each trophic level. each trophic level.

Due to the Laws of Due to the Laws of Thermodynamics, each higher Thermodynamics, each higher level level mustmust be smaller than lower be smaller than lower levels, due to loss of some energy levels, due to loss of some energy as heat (via respiration) within as heat (via respiration) within each level.each level.

Pyramid of numbersPyramid of numbersA pyramid of numbers indicates A pyramid of numbers indicates

the number of individuals in the number of individuals in each trophic level.each trophic level.

Since the size of individuals may Since the size of individuals may vary widely and may not indicate the vary widely and may not indicate the productivity of that individual, productivity of that individual, pyramids of numbers say little or pyramids of numbers say little or nothing about the amount of energy nothing about the amount of energy moving through the ecosystem.moving through the ecosystem.