Untitled Flashcards Set

Prithish Srinivasan

Unit 1

Lecture 1 - Introduction

• Dept of Env Sci at Rutgers

  • There was a psychoda fly problem at Plainfield sewage plant

  • City approached agricultural college in New Brunswick (now known as SEBS) for help

  • Prof. Thomas J Headlee (State Entomologist) recommended a team of biologists, microbiologists, etc. to solve the problem

  • 1920 - Act of the NJ State Legislature created the Sewage Substation of the Agricultural Experiment Station

  • Later, it was called Department of Sanitation

  • 1960s - changed name to Environmental science

  • Environmental science is about problem solving through bringing people from different fields together

• Pollution

  • Contamination of the environment by a chemical or other agent that is harmful to organisms

    • Air pollution, water pollution, soil pollution

  • All matter is made up of chemicals

    • Some are naturally occuring, some are synthetic

    • Both can be harmless or deadly

    • Depends on chemical properties and concentration

• Concentration

  • How much of a component there is within a mixture

    • Measured by mass or volume

      • Mass per volume (mg/L) - water, air

      • Mass per mass (mg/kg) - water, solids

      • Volume per volume (mL/m^3) - air

      • Different units used to express the same concept

      • Most important measurement of pollution 

  • Depending on concentration, may be harmless, helpful or toxic (need to quantify)

• Units and measures

  • M = meter (length)

  • L = liter (volume)

  • G = gram (mass)

• Expressions of Concentration

  • % = 1 part per 100 parts

  • Parts per million, parts per billion

• What is 1 ppm?

  • 1 mg/kg in solids

  • 1 mg/L in water

  • 1 mL/m^3 (in air)

Lecture 2 - Environment/Sustainability

• Environment = everything around us

• Environmental science = interdisciplinary science connecting information and ideas from

  • Natural sciences - biology, chemistry

  • Social sciences - economics, politics

  • Humanities - philosophy

• Sustainability

  • Capacity of Earth’s natural systems and human cultural systems to survive in the long term future

  • Nature has sustained itself for billions of years by using solar energy, biodiversity, etc

• Three principles of sustainability from Natural sciences

  • Solar energy - Energy that comes from the sun. Provides warmth and fuels photosynthesis.

  • Biodiversity - Variety of natural systems provides stability.

  • Chemical cycling - Cycling of elements from the environment to organisms and then back to the environment. Allows life to survive indefinitely on finite resources.

• Natural capital

  • Our lives depend on energy from the sun and on natural services provided by the Earth

  • Everything that helps to keep a species alive

  • Natural resources - Useful materials and energy in nature

  • Natural services - Important nature processes such as renewal of air, water and soil

    • These services are provided by healthy ecosystems, not a degraded ecosystem

• Resources

  • Anything we obtain from the environment to meet our needs

    • Inexhaustible - solar and wind energy (no matter how much you use, it’ll always be there instantly)

    • Renewable resources - forests, fishes, air (It’ll be there, but it’ll take time to renew itself)

      • Maximum Sustainable Yield - highest rate at which we can use a renewable resource without reducing available supply

    • Nonrenewable - Oil, coal, natural gas

• Human activities can degrade natural capital

  • Using renewable resources faster than at the rate they’re replaced

  • Interfering ecosystems with pollution and loss of biodiversity

• Solutions to avoid degradation

  • Scientific, economic and political ways

• Other principles of sustainability come from social sciences

  • Full cost pricing: Include harmful health and environmental costs of goods and services in market prices

  • Win win solutions - Find solutions that benefit both people and the environment

  • A responsibility to future generations - we want to preserve the world for our posterity

• Ecological footprint - a way to measure how much land and water is needed to support a person

• As our ecological footprint grows, we are degrading more of the Earth’s natural capital

  • Human activities directly affect 83% of earth’s land surface

  • Species are becoming extinct at least 100 times faster than prehuman times

  • We are remaking the world to fit humans better, but not in a way that can be sustainable

• Ecological deficit - footprint is larger than the world’s ability to support

  • Total natural capital is going down

• IPAT - Environmental impact model

  • I = P x A x T

    • Impact = Population x Affluence x Technology

    • Some tech is beneficial, some tech is harmful

• Tragedy of the commons

  • Individuals, with access to a shared resource, act in their own self-interest through overusing the resource, leading to its depletion

  • Solution - use resource at a rate well below its sustainable yield

• Why do we have environmental problems?

  • Population growth

  • Wasteful and unsustainable resource use

  • Failure to include harmful environmental cost of goods in market

  • Increasing isolation from nature - Lack of contact with nature

  • Competing environmental worldviews

    • Human centered worldview - humans are the most important

    • Life centered worldview - all species have value

    • Earth centered worldview - natural capital exists for all species

  • Poverty - short term survival more important than environmental concerns

• Three big ideas

  • A more sustainable future will require that we

    • Rely more on energy from the sun and other renewable resources

    • Protect biodiversity through the preservation of natural capital

    • Avoid disrupting the earth’s vitally important chemical cycles

  • We will benefit ourselves and future generations if we commit ourselves to

    • Finding win win win solutions to our problems

Lecture 3 - Science, Matter and Energy

• Hubbard Brook Experimental Forest in New Hampshire

  • Compared the loss of water and nutrients from an uncut forest (control site) with one that had been stripped (experimental site)

  • Stripped site

    • 30-40% more runoff

    • More dissolved nutrients

    • More soil erosion

• General steps in the scientific method

  • Identify a problem/make observations

  • Propose a scientific hypothesis to explain observations

  • Use the hypothesis to make predictions that can be tested

  • Test the predictions with further experiments or observations

  • If result is positive, “accept” hypothesis

• Hypothesis

  • Educated guess to describe what is happening

    • Based on previous information

    • Provides testable predictions

  • Developing a model

    • Physical/mathematical representation

    • Used to study complex systems like climate

    • Tested against new data to evaluate how well it “fits” the real world

• Scientific knowledge advances through

  • Scientists publishing details of methods and results

  • Peer review

• New data and analysis can lead to revised hypotheses

• Scientific theory

  • Well tested and widely accepted hypothesis

  • Rarely overturned unless new evidence discredits them

• Scientific law and the law of nature

  • A well tested and widely accepted description of what we find happening repeatedly and in the same way of nature

• Reliable science

  • Widely accepted by experts

• Tentative science/frontier science

  • Not yet considered reliable by the scientific community

• Unreliable science

  • Has not been through peer review or has been discredited

• Important features of the scientific process

  • Curiosity

  • Skepticism

    • Evaluate evidence and hypotheses using inputs from a variety of reliable sources

    • Identify and evaluate personal assumptions, biases and beliefs to distinguish facts and opinions before coming to a conclusion

  • Reproducibility

  • Peer review

  • Imagination

• Scientists cannot prove or disprove anything completely (metaphysics)

  • Science establishes high probability 

• Scientists are not free of their own bias about their own hypotheses

• The world is extremely complex

• Matter has mass and takes up space

• Matter - consists of elements and compounds that are made up of atoms, ions, etc

• Elements

  • Has unique properties that’s determined by their atomic structure

  • Cannot be broken down into other substances chemically

• Law of conservation of matter - matter is not created or destroyed, can undergo physical/chemical changes

• Atomic theory

  • All elements are made up of atoms

• Subatomic particles

  • Nucleus of the atom

    • Protons - positive

    • Neutrons - none

    • Electrons - negative

• Atomic number = amount of protons

• Not all atoms in an element have the same number of neutrons

  • This results in atoms with the same atomic number but different weights

  • These are known as isotopes

  • Each element has several isotopes

    • Has tiny differences

• Ions

  • Atom or group of atoms with net positive or negative electrical charge

  • Formed when electrons are gained or lost

• Molecules

  • Two or more atoms held together by a chemical bond is a molecule

• Compounds

  • Two or more different elements bonded together

• Chemical formula

  • Shows number of each type of atom or ion in a compound

• Ionic compounds

  • Atoms with a net positive and negative charge attract each other to form ionic compounds (NaCl, also known as salt)

  • Tend to dissolve in water

• Covalent compounds

  • Atoms share electron pairs in order to become more stable and form molecules (H2O)

• Physical changes

  • Changing from a solid to a liquid to a gas

  • Energy is used or released

  • No change in chemical composition

• Chemical change

  • Change in chemical composition

  • Ionic or covalent bonds broken and formed

  • Energy is used or released

• Bonds between atoms contain a certain amount of energy

  • Energy is released when a bond is broken

  • Energy is used to make new bonds

• Nuclear change

  • Radioactive decay - important for generating geothermal energy

  • Nuclear fusion - source of solar energy

  • Nuclear fission

• Big ideas

  • Law of conservation of matter - you cannot throw anything away

  • We cannot do anything with matter, we can only change it from one physical state or chemical form to another

Lecture 4 - Matter, Energy and Systems

• Organic compounds

  • Contain carbon atoms with carbon-carbon or carbon-hydrogen bonds

  • Covalent bonds

  • Types

    • Hydrocarbons

    • Plastics

    • Pesticides

    • Pharmaceuticals

• Hydrocarbons

  • Contain only carbon and hydrogen atoms

  • May be straight, branched or rings

  • Physical properties depend on size and shape

    • 1-4 carbon atoms are gases

    • 5-20 carbon atoms are liquids

• Organic compounds

  • Many types of organic molecules make up our cells

    • Fatty acids

    • Simple carbohydrates

    • Amino acids

    • Nucleotides

  • Organized into macromolecules

    • Polymers

    • Lipids, complex carbohydrates, proteins

• Fatty acids

  • Contain carbon, hydrogen, and oxygen

  • Long hydrocarbon chain with an acidic carboxyl head

  • Properties depend on length of carbon chain and the presence of any double bonds

    • Saturated = no double bonds

    • Unsaturated = at least one double bond

    • Polyunsaturated = multiple double bonds

• Lipids

  • Three fatty acids bonded to a glycerol molecule

  • Properties determined by fatty acids

• Carbohydrates (sugars)

  • Contain carbon, hydrogen and oxygen

  • 1:2:1 ratio

  • Properties depend on number of carbons and arrangement of -OH groups

• Complex carbohydrates

  • Long chains of sugars

  • Properties determined by type and arrangement of bonds between units

• Amino acids

  • Contain carbon, hydrogen, oxygen, nitrogen (and sometimes sulfur)

  • Each contains

    • An amino group

    • A carboxyl group

    • A side group

  • Properties are determined by the side group

• Proteins

  • Long chain of amino acids bonded together by peptide bonds

  • Properties determined by the order of amino acids in the chain

  • Peptide chain folds into complex shapes which give the protein its function

  • Many proteins function as enzymes (biological catalysts that carry out reactions in the cell)

• Nucleotides

  • Comprised of

    • A phosphate ion

    • A five carbon sugar

    • A nitrogenous base

  • The nitrogenous base determines what other nucleotide it will pair with

• Nucleic acids (DNA and RNA)

  • Long chain of nucleic acids bonded together by phosphate-sugar bonds

  • Strands are paired in DNA

    • Held together by bonds between bases

    • A bonds to T

    • G bonds to C

    • Strands coil around each other

  • Information is stored in the order of bases along the strand

• Cells

  • Fundamental units of life

  • All organisms have one or more cells

• Genes

  • Sequences of nucleotides within DNA

  • Creates inheritable traits

  • Instructions for proteins

• Protein enzymes carry out metabolic processes

• Energy is the ability do work or transfer heat

  • Change the position of matter

  • Change the physical state of matter

  • Change the temperature of matter

  • Break or form chemical bonds

• Whenever energy is converted from one form to another in a physical or chemical change, two rules always apply:

  • No energy is created or destroyed (first law of thermodynamics)

  • We end up with lower quality or less usable energy than we started with (second law of thermodynamics)

• Kinetic energy

  • Energy of movement

  • Heat

  • Electromagnetic radiation

• Potential energy

  • Can be changed into kinetic energy

• Stored energy

• Chemical energy

• Bonds between atoms contain a certain amount of energy

  • Energy is released when a bond is broken

  • Energy is used to make new bonds

• Renewable energy

  • Gained from resources that are replenished by natural processes in a relatively short time

• Nonrenewable energy

  • Gained from resources that can be depleted and are not replenished by natural processes within human timescale

• Solar energy

  • 99% of the energy that keeps us warm and supports plans

• Commercial energy

  • Energy sold in the marketplace

  • Supplements the sun’s energy

  • 80% of it comes from fossil fuels

    • Oil, coal, natural gas

• High-quality energy

  • High capacity to do work

  • Concentrated

  • Examples

    • High temperature heat, strong winds and fossil fuels

• Low quality energy

  • Low capacity to do work

  • Dispersed (spread out)

    • Low temperature moving molecules

    • Heat in the ocean

• Energy efficiency

  • Measure of how much work results from a unit of energy put into a system

  • Improving efficiency reduces waste

• Estimate: 84% of energy used in the United States is wasted

  • Unavoidably because of second law of thermodynamics (41%)

  • Unnecessarily (43%)

• First law of thermodynamics

  • Law of conservation of energy

    • Energy is neither created nor destroyed in physical and chemical changes

  • Second law of thermodynamics

    • Energy always goes from a more useful to a less useful form when it changes from one form to another

• Systems are complex networks of relationships between components

  • Set of components that interact in a regular way

• Systems have inputs, flows and outputs of matter and energy, and feedback can affect their behavior

• Feedback

  • Any process that increases or decreases a change in a system

  • Based on outputs coming back to a system as inputs

• Positive feedback loop (usually bad)

  • Causes system to change further in the same direction

  • Can cause major environmental problems

• Negative feedback loop (usually good)

  • Causes system to change in opposite direction

Lecture 5 - Ecosystems and Cycles

• Life is sustained by the flow of energy from the sun through the biosphere, and the cycling of nutrients within the biosphere

• One way flow of high quality energy

  • Sun to plants to living things to environment as heat to radiation to space

• Cycling of nutrients through parts of the biosphere

• Ecology

  • Science of organisms’ interactions with each other and their nonliving environment

• Feeding level (trophic level)

  • Organisms classified as producers or consumers based on source of energy

    • Some organisms can take energy from their environment to produce the food they need (producers) (usually comes from sunlight)

    • Others get their energy by consuming other organisms (consumers)

    • Some recycle nutrients back to producers by decomposing the wastes and remains of organisms (decomposers)

• Producers (autotrophs)

  • Photosynthesis

    • Co2 + H20 + sunlight to glucose + oxygen

    • Converts kinetic (electromagnetic) into potential (chemical) energy

• Consumers (heterotrophs) cannot produce the nutrients they need

  • Primary consumers (herbivores) eat plants

  • Carnivores feed on flesh of other animals

    • Secondary and tertiary (or higher) consumers

  • Omnivores eat both plants and animals (most animals)

• Detritivores

  • Feed on dead bodies of other organisms

• Decomposers

  • Consumers that release nutrients from wastes or remains of plants or animals

  • Nutrients return to soil, water and air for reuse

  • Bacteria, fungi

• Consumers and decomposers (heterotrophs)

  • Respiration

    • Glucose + oxygen changes to CO2 + H20 + energy

    • Converts potential (chemical) energy into kinetic (work/heat) energy

• Producers (autotrophs)

  • Also carry out respiration in order to release energy from the glucose they produce

• • Inorganic compounds (Carbon dioxide, oxygen) is taken up by plants

    • Solar energy is used to make them plants

    • Heat is lost

  • Those producers (plants) can be eaten by consumers

    • When these consumers die, the decomposers re release those nutrients

    • More energy is lost

  • Energy is put back by solar energy

• All organisms use the chemical energy stored in glucose by photosynthesis

  • Using oxygen to turn glucose back into CO2 and water through respiration

• Energy flows through ecosystems in food chains and webs

• The amount of chemical energy available to organisms decreases at each new level

• Gross Primary Productivity (GPP)

  • Rate that producers convert solar energy into chemical energy

• Net Primary Productivity (NPP)

  • Rate that producers produce biomass that can be used by consumers

• Biomass 

  • Dry weight of all organic matter of a given trophic level in a food chain or food web

• Food chain

  • Movement of energy and nutrients from one trophic level to the next

    • Photosynthesis to feeding to decomposition

• Food web

  • Network of interconnected food chains

• Biomass is a measure of available energy

  • Decreases at each higher trophic level due to heat loss

• Pyramid of energy flow

  • 90% of energy lost with each transfer

  • Less chemical energy for higher trophic levels

• Matter, in the form of nutrients, cycles within and among ecosystems and the biosphere

  • Cycles driven by incoming solar energy and gravity

• Cycles are made up reservoirs and the processes that move nutrients between them

• Nutrient cycles

  • Carbon cycle - major component of all macromolecules

  • Nitrogen - important component of proteins and nucleic acids

• Hydrologic cycle collects, purifies and distributes earth’s fixed supply of water

• Incoming solar energy causes evaporation

• Gravity draws water back as precipitation

  • Surface runoff evaporates to complete the cycle

  • Some precipitation is stored as groundwater

• Major processes

  • Evaporation

  • Condensation and Precipitation

  • Infiltration and runoff

• Alteration of the hydrologic cycle by humans

  • Withdrawal of large amounts of freshwater at rates faster than nature can replace it

  • Clearing vegetation

  • Increased flooding when wetlands are drained

• Processes based on CO2

  • Producers remove CO2 from the atmosphere through photosynthesis

  • Consumers produce CO2 through respiration

• Some carbon takes a long time to recycle

• Humans have added large amounts of carbon dioxide to the atmosphere

  • Faster rate than natural processes can remove

    • Levels have been increasingly sharply since we started measuring them directly in about 1960

    • Result: climate change

  • Clearing vegetation reduces ability to remove excess carbon dioxide from the atmosphere

• Useful forms of nitrogen

  • Created by specialized bacteria in topsoil and sediment of aquatic systems, and by lightning

  • Used by plants to produce proteins, nucleic acids and vitamins

• Bacteria convert nitrogen compounds back into nitrogen gas

• Life is sustained by

  • The flow of energy from the sun through the biosphere

  • The cycling of nutrients within the biosphere

• Organisms fill different roles in ecosystems

  • Some organisms produce the food they need

  • Some organisms consume others

  • Some organisms live on wastes and recycle nutrients

• Ecosystem functions relies on the flow of matter (nutrients) from one reservoir to another

Lecture 6 - Economics, Environment and Sustainability

• Case study - Germany using economics to spur a shift to renewable energy

  • Phase out dependence on fossil fuels and nuclear energy

    • Goal: 80% of electricity from renewable sources by 2050

  • Government legislation

    • Feed in tariff system for solar and wind energy

  • Offshore wind farms

  • New, state of the art electrical grid

• Ecological economists and most sustainability experts regard human economic systems as subsystems of the biosphere

• Economic systems

  • Social institutions meant to distribute goods and services

• Economics

  • Science of production, distribution and consumption of goods and services

• Natural capital

  • Resources provided by earth’s natural processes

• Human capital

  • People’s physical and mental capabilities

• Manufactured capital

  • Tools

• Externalities

  • When external costs aren’t available in the price of a product/service

    • Pollution

• Regulations and subsidies

  • Pass laws to control air and water pollution

  • Other tools: subsidies and taxes

• Subsidies

  • Government payments to help a business grow and thrive

• Neoclassical economists

  • View the earth’s natural capital as a part of a human economic system

  • Assumes growth can go on without limits

• Ecological economists

  • View human economic systems as subsystems of the biosphere

  • Believes that conventional economic growth is unsustainable

• Economists have developed several ways to estimate:

  • Present and future values of a resource or ecosystem service

  • Optimum levels of pollution control and resource use

• Comparing likely costs and benefits of an environmental action is useful but has uncertainties

• Valuing natural capital

  • Estimating values of earth’s natural capital

    • Monetary worth of ecosystems

  • Estimate nonuse values

    • Existence value

    • Aesthetic value

    • Bequest value

      • Willingness to pay to protect natural capital for future generations

• Discount rate

  • Estimate of a resource’s future economic value compared to its present value

• Proponents of a high (5-10%) discount rate

  • Inflation can reduce future earning’s value

  • Opportunity cost

• Critics of a high discount rate

  • Encourages rapid exploitation of resources

• Cost-benefit analysis

• Incentive based regulation example

  • Tradeable pollution or resource-use permits governed by caps

• Cap and trade approach used in US to reduce SO2

• Making a transition to more sustainable economies will require finding ways to estimate and include harmful health costs for producing these goods services in the market price

• Making this economic transition will also mean phasing out environmentally harmful subsidies and tax breaks, and replacing them with environmentally beneficial subsidies and tax breaks

• Another way would be to tax pollution and wastes instead of wages and profits and to use the revenue to promote environmental sustainability and reduce poverty

Lecture 7 - Policy, Ethics and Worldview

• Through its policies, a government can protect environmental interests

• Needs to be a balance between government and free enterprise

• Policy life cycle

  • Recognition

  • Formulation

  • Implementation

  • Adjustment

• Special interest groups pressure the government

  • Profit making organizations, nongovernmental organizations, labor unions, and trade unions

• Politicians focus on short-term problems

• Principles can guide us in making environmental policy

  • Reversibility principle - avoid making decisions that cannot be reversed

  • Precautionary principle - Take measures to prevent harm if the risk is unknown

  • Prevention principle - Preventing a problem from happening or becoming worse is easier than cleaning it up

  • Net energy principle - Avoid energy technologies with low or net negative energy yields

    • If you have to put a lot of energy into the process to get out energy, it’s inefficient

  • The polluter pays principle - Make policies that ensure polluters bear the cost of the damage caused by pollution

  • The environmental justice principle - No group should have unfair share of burden caused by pollution

  • The holistic principle - Problems are interconnected so solutions need to consider whole ecosystem

  • The triple bottom line principle - Balance economic and environmental needs when rules are made

  • The humility principle - Knowing that we do not know everything about how the natural world works

• Ideal: Every person is entitled to protection from environmental hazards

• Studies show large share of polluting factories in the US are in minority communities

• Policy making involves enacting laws, funding programs and writing/enforcing rules

  • Complex process affected by political processes

• Individuals can work together to become part of political processes that influence environmental policies

• Developing environmental policy is a controversial process

  • Funding is needed

  • Regulation and rules needed to implement the law

  • Environmental regulation agencies play an important role

    • Regulated businesses try to have their members appointed to regulatory agency

• Most environmental lawsuits are civil suits

  • Injunction - court order to stop action

  • Class action suit - civil suit filed by group

• Why it’s hard to win these cases

  • Legal standing - has the plaintiff suffered health/financial problems?

  • Very expensive

  • Public interest law firms

  • Plaintiffs must establish that harm has been done

  • Statutes of limitation

  • Appeals can take years

  • Strategic lawsuits against public participation (SLAPPs)

    • Defamation lawsuits

• Types of legislation

  • Set standards for pollution levels

  • Encourage resource conservation

• Environmental legislation has been effective

• Since the 80s, well organized forces have been against existing environmental laws

  • They’re strongly opposed to these regulations

• Modern environmental problems are complex

• Major environmental worldviews differ on what’s more important

  • Human needs vs overall health of ecosystems

• Environmental worldviews

  • Beliefs about how the natural world works and how people should interact with it

• Environmental ethics

  • Beliefs about what is right and wrong in our behavior towards the environment

• Two human centered worldviews

  • Planetary management worldview

    • We can and should manage the earth for our own benefit

    • No problem school

    • Free-market school

  • Stewardship worldview

    • We have an ethical responsibility to be caring stewards

• Criticisms of the human centered worldview

  • Assumes we can be good stewards

  • Humility principle

• Life centered worldview

  • Humans have ethical responsibility to avoid hastening extinction of other species

• Earth centered worldview

  • Responsibility to preserve earth’s biodiversity

• The first step to living more sustainably is to become more environmentally literate

  • Three foundations of environmental literacy

    • Natural capital matters

    • Our ecological footprints are immense and growing rapidly

    • Ecological and climate tipping points are irreversible and should never be crossed

• Formal environmental education

  • Is it enough

• In addition to nature’s economic value

  • Appreciate ecological, aesthetic and spiritual aspects of nature

• Experiencing nature is necessary for healthy living

  • Nature deficit disorder (increasing isolation from nature)

• Three big ideas

  • An important outcome of the political process is environmental policy

  • Our environmental worldviews plays a key role in how we treat the earth that sustains us, and thus, in how we treat ourselves

  • We need to become more environmentally literate 

Lecture 8 - Biodiversity and Population Ecology

• The biodiversity found in genes, species, ecosystems and ecosystem processes is vital to sustaining life on the earth

• Biodiversity - variety in the earth’s species

• Species - set of individuals who can mate and produce fertile offspring

  • 8 million to 100 million

  • About 2 million identified

• Species biodiversity

  • Number and variety of species

• Genetic diversity

  • Variety of genes in a population

• Ecosystem diversity

  • Biomes: regions with distinct climates/species

• Functional diversity

  • Biological and chemical processes such as energy flow and matter recycling needed for the survival of of species, communities and ecosystems

  • High biodiversity increases sustainability of ecosystems

  • Produce more plant biomass to support greater number of consumer species

  • Contain species traits that enable them to adapt to changing environmental conditions

• Each species plays a specific ecological role called its niche

• Ecological niche

  • Everything that affects survival and reproduction

    • Water, space, sunlight, food

• Native species

  • Normally live and thrive in a particular environment

• Nonnative species

  • Migrate or are accidentally introduced into an ecosystem

  • Invasive species are harmful nonnative species

• Indicator species

  • Provide early warning of damage to a community

  • Can monitor environmental quality

• Keystone species

  • Have a large effect on the types and abundance of other species

  • Can play critical roles in helping sustain ecosystems

    • Top predators - consume the consumers, control what species live in the ecosystem

    • Pollinators - determine what types of plants will grow

    • Ecosystem architects - physically change the environment in a way that promotes the growth of other species

• The American alligator

  • Keystone species in subtropical wetland ecosystems

  • Digs gator holes that hold freshwater and serve as refuge for aquatic life

  • 1930s: hunted for sport, meat and skin

  • 1967: added to endangered species list

  • 1977: impressive comeback

• The way that species interact with others affect the resource use and population sizes of the species in an ecosystem

• Five basic types of interaction

  • Interspecific competition

    • Competing to use the same limited resources

    • Resource partitioning - Species may use only parts of resource at different times and in different ways

  • Predation

    • Predators feed directly on all or part of a living organism

  • Parasitism

    • Parasites are usually much smaller than the host

    • Parasites rarely kill the host

  • Mutualism

    • Both species benefit

      • Nutrition and productive relationship

      • Ex: Pollinators

  • Commensalism

    • Benefits one species and has little effect on the other

      • Epiphytes

      • Birds nesting in trees

• Ecological succession

  • Normally gradual change in structure and species composition of a given system

• Primary ecological succession

  • Involves gradual establishment of communities in lifeless areas

  • Needs to build up fertile soil or aquatic sediments to support a plant community

  • Starts with pioneer species such as lichens or mosses

• Secondary ecological succession

  • A series of terrestrial communities or ecosystems that develop in places that already have soil or sediment

  • Ex: abandoned farmland

  • Sometimes called old field succession

• Population 

  • Group of interbreeding individuals of the same species

• Population size governed by

  • Births, deaths, immigration and emigration

• Population change = (births + immigration) - (deaths + emigration)

• There are always limits to population growth

• Each population has a range of tolerance

  • Variation under physical/chemical environment under which it can survive

• Limiting factors

  • Precipitation

  • Water temperature

  • Population density

• Environmental resistance - The sum of the factors that limit population growth

• Carrying capacity 

  • Maximum population of a given species that a particular habitat can sustain indefinitely

  • Can change when limiting factors change

• Population crashes

  • Happens when a population greatly exceeds its carrying capacity

  • Reproductive time lag may lead to overshoot

    • Subsequent population crash

    • Tipping point

  • Damage may reduce area’s carrying capacity

• Species diversity is important

  • Major component of biodiversity

  • Tends to increase sustainability of ecosystems

• Human activity can decrease biodiversity

  • Causing extinction of species

  • Destroying/degrading habitats needed for the development of new species

• A species’ population size is determined by its limiting factors in its environment

Lecture 9 - Human Population

• From the evolution of Homo sapiens to a total population of two billion took 200,00 years

  • It took less than 50 years to add another two billion

  • It took 25 years to add the third two billion

  • Nineteen years later, the earth had 7.6 billion people

  • It took 24 years to add the fourth two billion

• Factors impacting rapid rise of human population

  • Emergence of agriculture increased food production

  • Technologies helped humans expand into almost all the planet’s climates and habitats

  • Improved sanitation and healthcare led to drops in death rates

• The continuing rapid growth of the human population and its impacts on natural capital raise questions about how long the human population can keep growing

• IPAT Model

  • Impact = Population x Affluence x Technology

• Rate of population growth has slowed from more than 2% in 1960 to less than 1%

  • The world’s population is still growing

• Human population growth is unevenly distributed geographically

  • 2% added to more developed countries

  • 98% added to less developed countries

• People are moving from rural to urban areas

• Many differing views

  • We have already exceeded tipping points, or planetary boundaries

  • Technological ingenuity will help find substitutes to resources we are depleting

  • The main problem is the rapidly growing number of people in less-developed countries

  • The main problem is overconsumption in more-developed countries

• As the human population grows, so does the global total human ecological footprint

• Cultural carrying capacity

  • Total number of people who could live in reasonable freedom and comfort indefinitely without decreasing the ability of the earth to sustain future generations

• Human population size in 2050 was projected to be between 7.8 billion and 10.8 billion

• Factors influencing range of estimates

  • Reliability of current population estimates

  • Assumptions about trends in fertility

  • Different organizations that estimate populations use different methods and data

• Population size increases through births and immigration, and decreases through deaths and emigration

• The average number of children born to women in a population (total fertility rate) is the key factor used to predict population size in the future

• Population change = (births + immigration) - (deaths + emigration)

• Fertility rate - number of children born to a woman during her lifetime

• Replacement-level fertility rate

  • Average number of children a couple must have to replace themselves

  • Approximately 2.1 in developed countries

• Total fertility rate (TFR)

  • Average number of children born to women in a population

  • Between 1955 and 2012, the global TFR dropped from 5 to to 2.4 (2.24 by 2025)

  • However, to eventually halt population growth, global TFR must drop to 2.1

• Several factors affect birth rates and fertility rates

  • Children as part of the labor force

  • Cost of raising and educating children

  • Availability of private and public pension

  • Urbanization

  • Educational and employment opportunities for women

  • Average age of a woman at marriage

  • Availability of legal abortions 

  • Availability of reliable birth control methods

  • Religious beliefs, traditions, and cultural norms

• Several factors affect death rates

  • Life expectancy

  • Infant mortality rate

    • Number of live births that die in first year

  • High infant mortality rate indicates

    • Insufficient food

    • Poor nutrition

    • High incidence of infectious disease

• Migration

  • The movement of people into and out of specific geographic areas

• Causes of migration

  • Economic improvement

  • Religious and political freedom

  • Wars

• Environmental refugees

• Number of males and females in young, middle and older age groups determine how fast a population grows or declines

• Age structure categories

  • Pre-reproductive ages (0-14)

  • Reproductive ages (15-44)

  • Post-reproductive ages (45+)

• Country with large percentage of people younger than age 15 will experience rapid population growth

• Global population of seniors expected to triple between 2015 and 2050

• What factors lead to slower population growth?

  • Human population growth slows when poverty is reduced, the status of women is elevated and family planning is encouraged

• Economic development

  • Demographic transition

    • As countries become industrialized, first death rates decline, then birth rates decline 

  • Four stages

    • Preindustrial

    • Transitional

    • Industrial

    • Postindustrial

• Empowering women can slow population growth

  • Women have fewer children if

    • Educated

    • Able to earn an income

    • Society does not suppress their rights

  • Women

    • Do most of the domestic work and childcare

    • Provide unpaid healthcare

    • Have fewer rights and educational opportunities than men

• Family planning in less developed countries

  • Responsible for a 55% drop in TFRs

  • Financial benefits - money spent on family planning saves far more in health, education costs

• Three Big Ideas

  • The human population is increasing rapidly and may soon bump up against environmental limits

  • Increasing use of resources per person

    • Expanding the overall human ecological footprint and putting a strain on the earth’s resources

  • We can slow population growth by reducing poverty through economic development, elevating the status of women, and encouraging family planning