Fundamentals of Enviornmental Biology: Exam 3

Human Population Growth

Growth rate is slowing down, but the other graph shows it’s still continuing to grow

• World population reached 6 billion. in October. 1999 and is more than 8 billion. now

What type of growth is the human population experiencing?

Exponential Growth

Issues of Population Growth

• Easier spread of diseases

• Run out of resources

• Space problems

• Getting rid of waste

Benefits of Population Growth

Diversity

Population Doubling Time

• 70 years/growth percent = doubling time in years

• Current world growth rate is 0.85% (was 1.0%)- world doubling time: 82 years

• Current US growth rate is 0.54% (was 0.57%)- US doubling time: 130 years

Limits of Population Growth in Human History

• War

• Genecide

• Natural Disasters

• Diseases

Demographics

The study of the human population

What did an increase in women’s rights lead to?

Decrease in birth rates

• Children in lower birth rate societies face a smaller pool for reproduction, fewer working class, impact family’s name

  • Benefits: More resources, financial stability, more attention

Thailand- Successful family planning

• Increased availability of contraceptives

• Increased contraceptive use from 15 to 70% among married couples, now 80%

• Population growth rate dropped from 6.1 to 1.6%, currently listed at 0.3%

• Egalitarian relationship between men and women

• Buddhism “many children make you poor”

• Economic development

Thailand- Unintended Consequences

Currently working to reverse the declining birthrate through improved welfare structure and social supports, including increased parental leave, more childcare options, and other considerations. 

India- Off to a bad start

• Pushed sterilization instead of contraception in the 70’s

  • Not reversible

  • Expensive

• Improved the situation in the
  90’s

• Education and contraception

• Improved the situation of women

India- Changing Attitudes

• Now considering replacement level population growth as a positive thing

• Looking to turn population growth into economic growth, moving toward smaller cities and increased job opportunities in technology

• Continued pressure on employment, resources, and environment
  

China- The One Child Policy

• Initiated in 1979, ended 2016

• May have two if first is female or disabled

• Birth spacing of 3-4 years

• Fines for more children

• Denial of promotions, etc.

• Increased tuition for schooling

• Subject to discrimination for some ethnic groups

• Now can have 3

China- Results of the One Child Policy

• Distorted sex ratio

• Resisted by rural families

• Unreported children vs. infanticide

• Increased death rate for females

China- Demographic Challenges

• Birthrate dropped to 1.3 births per woman in 2020

• Population dropped for the 1st time in 2022

• India surpassed China in 2023

• Aging population affects workforce, and social programs

Global Citizen

Is aware of the wider world and has a sense of their own role as a world citizen

• Respects and values diversity

• Is willing to act to make the world a more equitable and sustainable place

• Takes responsibility for their actions

Worldview

The way a person sees and understand the world

Anthrocentric

(Human), makes human needs and wants the primary focus for decision-making

Biocentric

(Living), all living things (plants and animals) are considered

Ecocentric

(Ecosystem), both living and non-living aspects are included in any decisions being made about the region

Ecological Footprint Calculation

Approximates the amount of ecologically productive land and sea area required to sustain a population, manufacture a product, or undertake certain activities, by accounting for the use of energy, food, water, building material, and other consumables.

Ecological Footprint Averages

• US- 7.8 gha per person

• Canadians- 8.4 gha

• Italians- 4.5 gha

• Pakistanis- .8 gha

• Qataris- 15 gha

  • Global average is 2.6 gha per person

Soil

Is more than dirt; made up of worms, rocks, moisture, organic material, decomposing material, bacteria, nitrogen

What role does soil play in an ecosystem?

• Offers nutrients, air, water to protect roots, recycles carbon + nutrients, buffers temperature, regulates flow of rainwater

Soil Horizons

O- litter layer high in organic matter with no minerals or rock particles
A- topsoil layer rich in humus and finely decomposed rock with little or no clay
E- contains decomposed minerals, but little clay or organic matter
B- decomposed minerals and clay
C- slightly decomposed rock
R- bedrock

Erosion

The weathering away of natural materials which are then moved away 

• Caused By: wind, rain, compacting material, agriculture, acid rain, deforestation

Terracing

A sloped hillside that has been cut into a series of successively receding flat surfaces which resemble steps

Strip Cropping

Cultivating a field partitioned into long, narrow strips which are alternated in different crops

Crop Rotation

Growing a series of different types of crops in the same area across a sequence of growing seasons

Contour Planting

The farming practice of plowing and/or planting across a slope following its elevation contour lines

No-till-farming

A technique for growing crops or pasture without disturbing the soil

Windbreak/Hedgerow

One or more rows of trees or shrubs planted in such a manner as to provide shelter from the wind

Deposition/Sedimentation

The other side of erosion where all the sediment is washed in

Desertification

When land that is not a desert becomes a desert

• Caused By: lack of water, overgrazing, extremes in weather

Soil Degradation

Prevention: Being mindful of pollution, planting techniques, doing no ill planting, and being aware of drainage systems

Improve: Add fertilizers, composting

Fertilizers

If it runs out, it causes eutrificaion for aquatic ecosystems. causing fish to die

• Can have too many nutrients

Pest

An animal or bug interfering with what’s trying to grow

Weed

A plant that interferes with what’s trying to grow

• We regulate with chemicals

Integrated Pest Management (IPM)

We try to use a variety of means to control these pests; bottom uses biological control, middle is other tools, top is pesticides

• Reduce chemical use as much as possible

Pesticides and Resistance

Natural selection and survivial of the fittest can cause resistance

Biocontrol

Uses natural pests, those that feed off of what’s harming your garden; does not use chemicals (natural predators, parasites, fungi, and natural chemicals such as pheromones)

Mechanical/Physical Control

Crop rotation, mowing; not able to spread to other materials

Biotechnology can include:

• Genetically modified organisms

• Breeding programs

• Biopesticides

• Biofertilizers

What are some common toxins found in the environment?

Oil, waste, fossil fuels, carbon dioxide, acid migraine

Natural Toxins

Naturally occurring chemical components of fruits and vegetables serve as defense mechanisms against herbivorous animals, insects, bacteria, and fungi

• EX) venom, pesticides

Synthetic Toxins

Posions we’ve created by chemical processes rather than being derived from natural sources

• Chemicals we’ve produced

Carcinogens

Chemicals that cause cancer

• EX) Benzene, asbestos, many smoke compounds, formaldehyde, radication, vinyl chloride, dioxin, mercury

Mutagens

Chemicals that cause mutations of DNA in organisms

• EX) Nitrous oxide, UV radiation, alpha and gamma radiation, bromine, and some viruses

Teratogens

Chemicals that cause harm to unborn organisms

• EX) Aflatoxin, alcohol, atrazine, benzene, caffeine, cannabis, DES, lead, thalidomide, mercury

Allergens

Substances that trigger the immune system to respond unnecessarily

• EX) Pollen, dust, animal dander, poison ivy, mold, and foods

Neurotoxins

Chemicals that affect the function of the nervous system

• EX) Snake, spider, pufferfish, and scorpion venoms, carbon monoxide, red tides, molds, bacteria, bees, and red pepper

Endocrine Disruptors

Chemicals that interfere with or mimic hormones

• EX) DES, DDT, dioxin, PCBs and many pesticides and plasticizers

Which ecosystems have a high level of toxins?

Aquatic

Bioacculmation

Occurs when levels of toxin build up in a single organism over time

Biomagnification

Occurs when toxins increase in concentration as they move up the food chain

Is there a higher level of mercury in colder or hotter water?

Colder

Chemical Hazards

Enters the environment as a chemical and causes harm to what’s there

• EX) Oil spills, pesticides, fertilizers, acid mine, drainage, and DDT 

Physical Hazards

Events such as natural disasters

• EX) Hurricane Katrina, flooding, earthquakes, volcanic eruptions, diseases

Biological Hazards

Damage caused by the interaction between organisms

• EX) Diseases

Socioeconomic Hazards

Cultural or lifestyle-based effetcs on the ecosystem

• EX) Pollution

Additional Natural and Man-Made Health Threats

• Visible lights produce electromagnetic radiation

• Radiation occurs from nuclear power sources and weapons

• Indoor health threats such as radon and lead posiniong pose environmental risks