Energy Systems
Nutrient Cycles
Nutrients are elements, chemical components, and ions that all organisms need for growth, cellular maintenance and all
other life processes. Nutrients are accumulated for short or long periods of time in the atmosphere, lithosphere,
hydrosphere, and biosphere. These accumulations are referred to as stores (sinks). Biotic processes such as
decomposition and abiotic processes such as river run-off can cause nutrients to flow in and out of stores. Therefore
there is a continuous flow of nutrients in and out of stores call nutrient cycles.
Over the long history of Earth, nutrient cycles have functioned in an overall state of balance. The concentrations of
nutrients flowing into the stores have been essential the same as the concentrations flowing out of the stores.
Human activities such as land clearing, agriculture, urban expansion, mining, motorized transportation, etc. can affect a
nutrient cycle by increasing the amounts or concentrations of nutrients in the cycle faster than natural biotic and abiotic
processes can move them back to the stores. Over periods of time, increased concentration of nutrients can accumulate
in the atmosphere, in bodies of water, an on land as a result of these activities. This accumulation can have significant
environmental effects.
There are 6 substances that limit the amount and types of life possible, because they are components of key organic
molecules. These substances are water, carbon, hydrogen, oxygen, nitrogen and phosphorus.
Earth’s Life Support System
Earth’s Spheres
Natural processes move matter in continuous cycles from the biotic to abiotic parts of the environment and back again.
At any time, matter occupies one of four “spheres” that make up the earth.
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Atmosphere – the gaseous part of earth, which is located mainly within 10km of the surface but also, extends
hundreds of kilometers higher.
o A thin spherical envelope of gases surrounding the earth’s surface.
o Troposphere – inner layer that contains the majority of the air we breathe
 All of the earth’s weather occurs here
 Greenhouse gases
o Stratosphere – next layer
 Holds ozone (O3) which filters out most of the harmful UV rays
Lithosphere (Geosphere) – the solid, mainly rocky component of earth
o rock, soil, and sediments
o Consists of the earth’s core, mantle and crust
Hydrosphere – all of the water that exists on and within the geosphere.
o It is found as liquid water, ice or water vapor
Biosphere – all of the areas on and under the lithosphere, in the atmosphere, and in the hydrosphere that are
inhabited by and support life.
3 Factors to Sustain Life
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Energy
o One way flow of energy from the sun through living organism and finally back to space in the form of
heat
Cycling of Nutrient
o Law of conservation of energy means that we have a fixed about and it moves and recycles to support
life
Gravity
o Allows the planet to hold onto its atmosphere and enables the movement of nutrients and chemicals
Components of an Ecosystem
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2 types of components make up ecosystems – Biotic and Abiotic
Biotic and Abiotic Components of the Environment
The environment of an organism includes biotic (living) and abiotic (non-living) components. Organisms affect and are
affected by these components as they interact with one another and with the components. Individuals are part of a
population – any group of individuals of the same species living in the same geographical area at the same time.
Populations of different species are part of a community of organism in a particular habitat.
Biotic Components
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Ecologists assign every type of organism in an ecosystem to a feeding level – trophic level
Producers
o Make their own nutrients from the environment (photosynthesis)
Carbon Dioxide + water + energy (sun)  Glucose + Oxygen
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Consumers
o Feed on other organism to obtain nutrients
o Herbivores – eat producers
o Carnivores – eat other animals
o Omnivores – eat plants and animals
o Decomposers – consume nutrients from dead plants or animals
o Detritivores – feed on wastes or dead bodies of other organisms
Glucose + Oxygen  Carbon Dioxide + water + energy
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Energy flows through food webs and chains
Abiotic Component
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Interacts with biotic components in cycling of matter
Biogeochemical cycles – life-earth-chemical cycles (nutrient cycles)
The Water Cycle
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The water cycle collects, purifies and distributes the supply of water
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3 major processes occur in the water cycle
o Evaporation
 Change of state of water from liquid to vapor
o Precipitation
 Water back to earth’s surface in the form of (rain, sleet, snow, hail, dew)
 Once precipitated - Surface run off is how some the water moves on the terrestrial surface – to
streams and lakes or to groundwater. Other water is frozen to ice in glaciers. And the rest
(which is very little) is consumed by biotic components (plants, animals, and microorganism)
o Transpiration
 Evaporation of water from plants and soil
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The Carbon Cycle
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Carbon (C) – is the major building block of biotic components. Carbon make up carbohydrates (sugars,
starches, cell walls), fats (lipid membranes), Proteins (enzymes), DNA and many others
The major linkage between biotic and abiotic components in the carbon cycle is photosynthesis and the
opposite reaction (respiration)
Many other processes alter and affect the carbon cycle – transportation, deforestation, burning of fossil
fuels, decomposition, etc.
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The Nitrogen Cycle
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The majority of nitrogen is held in the atmosphere (78%)
Nitrogen is a major component of proteins, DNA, Enzymes, vitamins, etc.
The problem is that we cannot use atmospheric nitrogen – it must be changed into a useable form. This
can be done by
 Lightning
 Bacteria
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The Phosphorus Cycle
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Phosphorus – is an important component for nucleic acids and energy molecules (ATP and ADP)
The phosphorus cycles moves through water, living organisms and land – but does not include the
atmosphere
Phosphorus buildup can lead to blooming of algae in water
This buildup can occur from runoff from fertilizers or sewage or mining wastes or erosion due to
deforestation
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The Sulfur Cycle
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A component in many proteins
It is taken up by soil, rocks and fossil fuels to use
However it is also a large contaminant – acid rain,
Sustaining Biodiversity
Biodiversity
Biodiversity is a general terms that encompasses all plants, animals, microorganisms, and ecosystem. Biodiversity is
often discussed at 3 levels. Genetic diversity refers to the variety of different versions of the same genes within
individual species. Species diversity describes the number of different kinds of organisms within communities.
Ecosystem (or ecological) diversity assesses the rich variety of ecosystems where organisms live.
Species Approach
Species approach is looking at sustainability through the eyes of protecting species and in the process protecting
individual habitats.
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Endangered species – has so few remaining individual that the species soon could be extinct
Threatened species – has declining numbers and therefore likely to become endangered
Cause of Extinctions
α HIPPCO – Habitat destruction, degradation, and fragmentation
o Invasive species
o Population and resource use growth
o Pollution
o Climate change
o Overexploitation
Prevention
α International Treaties and National Laws to protect species
 To protect elephants, crocodiles, chimpanzees, cheetahs
α U.S. Endangered species Act
α Protect endangered species in U.S. and abroad
o Laws and Treaties to help protect Marine Species
o Establish Wildlife Refuges and other protected areas
o Gene Banks, Botanical Gardens and Wildlife Farms
o Zoos and Aquariums
Ecosystem Approach
An ecosystem approach to sustainability is looking at protecting individual ecosystems and in turn hopefully protecting
species that live within those specific ecosystems.
Protecting Terrestrial Ecosystems
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Protecting biodiversity – protecting hotspots (rich in plant species that are only located in a specific area)
Rehabilitate and restore ecosystems that have been damaged
o Restore – returning and ecosystem to the condition of its natural state
o Rehabilitation – fixing an ecosystem to be functional or useful, but not to its natural state
o Replacement – replacing a degraded ecosystem with a different type of ecosystem
Biodiversity
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Biological diversity is the variety of the earth’s species, their genetic makeup, the diversity in the ecosystem and
the processes and cycles that sustain life
Diversity allows life to adapt and survive changes to the environment (Galapagos island and finches)
That diversity is required for animals as well as plants – therefore needing a variety of biomes (large areas of
distinct climates and species)
Biodiversity has occurred through the process of Evolution and Natural Selection
Natural Selection
o It is the idea that a individuals with certain traits will be more likely to survive and reproduce in a set
environment and conditions
Evolution
o We have changed and adapted over time to become different species
o These changes occur through mutations that gives a species an reproductive advantage over another
o Speciation – process of creating a new species
 Occurs through 2 process
 Geographic Isolation – migrate to different location, adapt and change to create 2
different species
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 Reproductive isolation – genetically different so they cannot create live offspring
Extinction – when an entire species ceases to exist
o Endemic species – species found only in one area
o Background Extinction – disappearing at a low rate due to environmental changes
o Mass extinction – global event
Interactions of Species
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There are 5 major ways that species interact with one another
o Interspecific Competition – competition between species
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Predation – one species feeds one another species
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Parasitism - one species feeds one another species – a living host
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Mutualism – when 2 species live together and benefit from one another (e.g. lichen)
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Commensalism – an interaction that benefits one, and the other is unaffected
Coevolution – when 2 species have an interaction with each other over a long period of time can evolve with
one another. Meaning that as one changes the other will follow a similar change to keep the relationship
Limits to Growth of Population – each population has a carrying capacity for a specific environment. When a
species gets close to the carrying capacity it fluctuates around it to maintain the species (p. 87 – turtle)
If a species fail to live within its constraints it can experience a population crash (resource dies out killing the
species that feed off of that resource)
Changing Environmental Conditions
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Ecological Succession – gradual change in species to get to a mature state
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Primary Succession – introduction of biotic species in which there was none before
Secondary Succession – begins in an area that has been disrupted, removed or destroyed
Stability of a living system – due to
o Persistence (Inertia) – ability to survive disturbances
o Resilience – ability to restore after a disturbance