ENVIRONMENTAL SCIENCE

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ENVIRONMENTAL SCIENCE

• EXAM II POWER POINT

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• ECOLOGY

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Population Ecology

• Population a group of individuals of the same
  species living in a given area
• Limiting factors are essential resources that are
  in short supply. They influence the size (N) of
  a population

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Population is increased by

• Births
• Immigration
• Indirectly by technology, medicine, green
  revolution et.

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Population is decreased by

• Deaths
• Emigration
• Indirectly by diseases, catastrophes etc.

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Exponential growth

• N doubles each generation
• Produces a J shaped curve
• IS NOT REALISTIC over the long term

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Logistic growth

• N increases exponentially until the carrying
  capacity (K) is reached
• Produces an S shaped curve (theoretical) with
  oscillations around K (realistic)
• With oscillations around K, realistic for many
  species

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K selected species

• Produce few, relatively large offspring
• Lots of parental care
• Reproduce at relatively later ages

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R selected species

• Produce many, relatively small offspring
• Little to no parental care
• Reproduce at relatively young age

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• Community a group of individuals of different
  species living in a given area
• Limiting factors are essential resources that are
  in short supply. They also influence
  communities.

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Community Ecology

• Structure influenced by
• Abiotic factors
• History of the area
• Random events
• Predator-prey interactions
• Interspecific interactions

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Abiotic factors
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Abiotic factors
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History of area
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Random occurrences
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Predator-prey interactions

• predation, parasitism, herbivory where one
  species feeds on members from other species.
  Predators do the eating and are almost always
  animals, but prey may be animals, plants, fungi,
  protists, or bacteria.

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Robert Paynes Keystone predator experiment

• The experiment had two treatments, enclosures
  with Pisaster and enclosures without Pisaster.
  The findings were that species diversity went
  down without Pisaster and was high with Pisaster.
  This is mostly because mussels become the
  dominant species and out compete other organisms.

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Robert Payne, Pisaster ochraceus, and Mytilus
californianus
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Other Interspecific interactions

• Interspecific competition is competition for
  limiting resources between individuals of
  different species (on the contrary intraspecific
  competition is competition for limiting resources
  between individuals of the same species).

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Interspecific interactions

• Commensalism is a type of symbiosis where the
  members of one species benefit from the
  association while the members of the other
  species are neither benefited nor harmed.

Cattle Egret eating insects disturbed by the
buffalo
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Another one

• Mutualism is a type of symbiosis where the
  members of both of the species benefit from the
  interaction.

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• Each species that is present in the community has
  a niche that is the role that that species plays
  in the community. The niche of each species is
  multidimensional and three of these dimensions
  are most commonly studied place, time and
  resource.

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• Two species cannot occupy the same niche in a
  given area without one of the species going
  extinct (which is what happens when humans and
  the species that are associated with us occupy
  new areas- we drive the other species that need
  the same resources to extinction

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Plethodon shenandoah and talus
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Plethodon cinereus and habitat
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More Interspecific competition

• Robert MacArthurs warblers

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Connells barnacles
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Biomes
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Tundra
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Tiaga or Coniferous forest biome
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Temperate deciduous forest
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Tropical Dry forest
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Temperate Grassland
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Savanna
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Chaparral
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Desert
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Tropical Rain Forest
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Taken from the UNEP site, where the map was
found The tropical lowland and highland forests
of Borneo, including vast expanses of rainforest,
have decreased rapidly after the end of the
second world war. Forests are burned, logged and
clear, and commonly replaced with agricultural
land, built-up areas or palm oil plantations.
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Temperate rainforest
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Environmental Ethics

• Ethics is a subdiscipline of philosophy dealing
  with right and wrong, good and bad.
  Environmental ethics is a relatively recent field
  of study.

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• The frontier or developmentalist ethic involves
  placing the wants and needs of humans ahead of
  the environment and nature. This type of ethic is
  also called anthropocentrism, human-centeredness,
  or biocentrism.

• John Locke, writing in the seventeenth century
• "land that is left wholly to nature, that hath no
  improvement of pasturage, tillage, or planting,
  is called, as indeed it is, waste and we shall
  find the benefit of it amount to little more than
  nothing". For land to have value, it must be made
  to serve human needs and ends.

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• The preservation ethic or ecocentrism involves
  placing nature and its needs above the needs of
  humans. It instills a reverence for Nature
  itself.

• Aldo Leopolds land ethic changes the role of
  Homo sapiens from conqueror of the land-community
  to plain member and citizen of it. The land
  ethic implies respect for his fellow-members
  including soil, plants, and animals of all kinds

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• The conservationist ethic, sustainable ethic, or
  biocentrism takes into account the needs of all
  organisms and the environment. The goal is to
  create sustainable solutions to our needs for
  resources that do not cause irreparable harm to
  the environment and leave a mess for future
  generations.
• This would also incorporate environmental justice
  (fairness for all people despite socioeconomic
  factors) and intergenerational ethics
  (consideration of future generations)

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Developing and Implementing Sustainable
Environmental Ethics.

• Promoting sustainable solutions to the various
  environmental problems.
• Education
• Obstacles include technical optimism, apathy and
  despair, emphasis on short-term gain, and an
  unwillingness to believe that humans could cause
  so much damage.

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• HUMAN POPULATION GROWTH

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• Currently there are approximately 6.8 billion
  people worldwide, with possible doubling times
  ranging from 24 to 500 years depending on the
  region.

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Rate of current growth

• http//www.census.gov/main/www/popclock.html

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• The early humans were hunter/gatherers. They
  were primarily nomadic, used very primitive tools
  fashioned from sticks, stones, and bones, and
  were relatively healthy Their lifestyles were
  sustainable in regards to the environment.
  Throughout this period the human population
  remained relatively stable.

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• About 10,000 -6,000 B.C. humans began the
  widespread practice of agriculture. First is was
  basically subsistence, but after the plow became
  more common, there was a move to mass production
  of food. increasing survival rates and allowing
  people to move into urban areas. A negative
  effect of mass production was that it severed the
  tie between people and nature. Poor farming
  practices and overgrazing resulted in a great
  deal of habitat alteration.

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• As technology advanced and after the discovery of
  coal, the industrial revolution began. There was
  a shift from small-scale production of goods to
  large-scale production (then the Green
  Revolution) facilitating a higher standard of
  living, lower death rates, and ultimately
  exponential population growth.

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• Each 60 seconds the human population grows by _at_
  150 people.
• Africa is the fastest growing area (doubling time
  predicted about 23 years), followed by Latin
  America, and Asia despite some decreases in birth
  rates in these regions.
• Although most scientists and many others believe
  that human population growth is a problem, some
  think that the world can hold an infinite number
  of people (Julian Simon), or that any methods
  used in population growth are implemented to
  decrease certain ethic or religious groups, or
  that for religious reasons, humans should produce
  as many children as possible.

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• Demographics

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GROWTH RATE

• Growth rate is calculated by using the formula
  Growth Rate (Crude birth rate - crude death
  rate). Crude birth rate is the number of
  births/1,000 people and crude death rate is the
  number of deaths/1,000 people.
• Depends on the age at which people get married,
  the amount of education, career vs. stay at home
  women, contraceptive use, the number of children
  that are desired by the couple, cultural values,
  and religious beliefs.

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DOUBLING TIME

• The doubling time or the time it takes for a
  population to double is calculated as follows
• Doubling time 70/Growth Rate ().
• Developed countries in general have longer
  doubling times than developing and third-world
  nations.

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TOTAL FERTILITY RATE

• Total Fertility Rate (TFR) is the number of
  children that women are expected to have in their
  lifetimes.
• In developed countries replacement level
  fertility (in some it is even below) has been
  achieved (in the U.S. replacement level fertility
  was 2.1 in 2000).

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ZERO POPULATION GROWTH

• A country reaches zero population growth when
  birth rates death rates and immigration
  emigration.

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• After a country reaches replacement level
  fertility, population growth can still occur. In
  fact worldwide the population will still continue
  to grow even if all nations reach replacement
  level fertility. Note that 50 out of 200 have
  achieved this.

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AGE STRUCTURE

• The age structure of a population (see figure
  8.10) also affects population growth. The
  different profiles include expansive (like
  Mexico), Constrictive (like the U.S.) and
  Stationary or nearly stationary (like Sweden).
  Note that worldwide 33 of the people are under
  age 15 and this could cause a great increase in
  the population as they begin to reproduce.

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• Factors involved in this increase include but are
  not limited to
• Expansion into new habitats.
• Increased carrying capacities
• Side-stepping limiting factors
• Social and Religious influences

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THE FUTURE

• Future projections vary

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• Strategies
• for
• Stabilization

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Family Planning involves the use of birth control
in order to allow couples to determine the number
and spacing of their children.

• 1. Voluntary programs involve the dissemination
  of information about birth control and methods
  of birth control are made available to people at
  a low cost. Thus, people are given the chose of
  using or not using family planning.
• 2. Extended voluntary programs involve
  governmental agencies. For example, in Egypt a
  song promoting birth control was played on a
  government-sponsored commercial. Sometimes
  incentives are given to people who practice birth
  control.
• 3. Forced family planning programs are rare and
  involve limits arising from the government on the
  number of children that a couple can have with
  punishments for exceeding these limits. This is
  the program utilized in China and it is very
  controversial.

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• On July 11, USAID will join the global community
  in celebration of World Population Days 20th
  anniversary to highlight the importance of family
  planning in the lives of women, communities, and
  the world.
• This years theme Investing in women is a smart
  choice. The objective is to highlight the
  importance of investing in the education of women
  to address a host of development issues,
  including poverty, human rights, and gender
  equality.

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• Health Minister Hatem el-Gabali announced an 80
  million family-planning campaign Tuesday, with
  the slogan "Two children per family -- a chance
  for a better life."

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• Thirty states in the United States passed
  eugenics laws between 1907 and 1931, and these
  laws were upheld by the U.S. Supreme Court in
  1916 and 1927. By the end of the World War II, it
  was estimated that 40,000 sterilizations had
  taken place, mostly on poor white women. Because
  of racial segregation, it was not deemed
  necessary to sterilize black people at this time.
  This situation was to change, however
• The Native American population has also been
  subjected to forced sterilization. From 1973 to
  1976, for example, 3,406 American Indian women
  were sterilized, many of whom were under
  twenty-one years old

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• In the United States, individuals are expected to
  be self-reliant and to not expect social support,
  even when social conditions are not conducive for
  them to be self-reliant. Social assistance is
  available for sterilization purposes, however.
  Under these circumstances, those who suffer from
  poverty and destitution may be forced to
  choosesterilization to control their
  reproduction. People in this situation, who are
  mostly women of color, have been denied economic
  support but encouraged to use government
  subsidies to use sterilization or pharmaceutical
  methods such as Norplant for birth control

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• Other strategies include improving the standard
  of living for people in developing countries by
  providing jobs and education for women and thus
  empowering women.

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WHY CONTROL POPULATION GROWTH?

• One of the most
• important reasons
• Also, environmental
• issues are impacted
• By the number of
• humans

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• There are three primary barriers to stabilizing
  the human population.
• Psychological barriers. In developing countries
  many children are seen as an asset (e.g., as
  helpers and security for old age) and as a kind
  of status symbol.
• Education barriers. There is an inverse
  relationship between the amount of education a
  person has and the number of children that person
  will have. Education takes a long time and often
  leads to a career that results in a delay of
  childbearing.
• Religious barriers. Many religions support large
  families (e.g., Catholicism).

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A shanty town in Manila
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For Population control

• We should
• continue to strive to reduce suffering by
  combating disease and poverty around the world
• continue to improve resource efficiency and
  pollution control so that standards of living can
  rise without negative impact and
• keep human population to numbers that are
  sustainable.

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Solutions continued

• On the population front, that means
• making sure people around the world have access
  to family planning services
• empowering women in developing countries
  economically, socially, and legally in a manner
  that results in them having an equal say (with
  their husbands) in reproductive decisions
• modifying school curricula to include information
  on population levels and implications for the
  future
• reforming tax laws in a way that encourages
  couples to have no more than two children. (They
  would still be able to have as many kids as they
  want, but the tax code would no longer subsidize
  more than two.)
• People are a good thing, but population growth
  without limit is not. The US and all developed
  countries should reinvigorate their international
  efforts to slow population growth. The future of
  the world depends on it!