Chapter 5 Population Ecology POPULATION 5 1 How

Chapter 5: Population Ecology POPULATION

5. 1 How Populations Grow 4 Things Ecologists Study about Populations: A) Geographic Distribution/ Range – area inhabited by a population ex: humans range include all continents! B) Density and Distribution – number of individuals per unit area AND how they are spaced out across the range RANDOM UNIFORM CLUMPED

How Ecologists Study Populations Growth Rate – determines whether population will increase, decrease or stay the same (zero) Age Structure – number of males and females of each age within a population C) D) ¡ ¡ Reproduction doesn’t occur until a certain age Only females can reproduce… or can they?

Factors Affecting Population Growth 3 Factors that affect population growth: A) Birth and Death rates ¡ BR > DR Growth Migration -Immigration (entering) and emigration (leaving) B) ¡ Immigration > emigration Growth

Types of Population Growth Exponential Growth – unlimited growth of a population – J Shaped Curve A) ¡ ¡ ¡ Occurs when population has food, space, protection from predation/disease, removal of waste products (unlimited resources) Each future generation will grow faster than the last Ex: bacteria - cell reproduces every 20 minutes. How many after 20 min. ? How many after another 20 min? How many after one day?

Types of Population Growth Logistic Growth – population grows, slows, and eventually reaches carrying capacity S Shaped Curve B) ¡ ¡ n ¡ Phase 1 – exponential growth Phase 2 – slows down Due to: BR decreases, DR increases, immigration decrease, emigration increases Phase 3 – population stabilizes, reaches carrying capacity • Carrying Capacity – (k) maximum number of individuals than a particular environment can support

5. 2 – Limits to Growth Limiting Factors – factors that control the growth of a population B) Include: Competition, Predation, Parasitism/Disease, Extreme Climates, and Human Disturbances Classified as: ¡ Density Dependent Factors – factors that depend on the density of the population; control the populations and keep numbers in check n Non-native species have a tendency to elude this and grow uncontrollably due to lack of natural predators, etc. ¡ Density Independent Factors – factors that do NOT depend on the density of the population; will affect all populations equally, regardless of their size A)

Density Dependent Factors Competition A) ¡ ¡ ¡ Fighting for space, food, water, sunlight, mates, etc. Can be within the same or different species Some will survive and reproduce, some will survive but NOT reproduce, some will die : 0( Herbivory B) ¡ ¡ Predators to plant species Large loss of plant species may affect other primary consumers

Density Dependent Factors Predation C) ¡ Cyclic relationship (rise of one may induce the fall of the other; trend of rises and falls continues)

Density Dependent Factors Parasitism – feed at the expense of their hosts D) ¡ E) Ticks feeding on blood of dogs Disease – can cause a dramatic drop in a population due to infestation of a disease; decrease in one population may trigger a rise in another!

Density Dependent Factors Stress from Overcrowding – species fighting amongst themselves may lead to high levels of stress which may affect an organism’s ability to fight disease! F) ¡ Hmmmm…. might explain why students get sick right before tests…. maybe? ?

Density Independent Factors Weather A) ¡ Hurricanes, droughts, floods Natural Disasters B) Wildfires ¡ Volcanic eruptions HUMANS! ¡ 2004 Sri Lanka Tsunami

5. 3 - Human Population Growth Historical Overview • For a long time, human growth rate was low due to a high death rate • Harsh conditions • Lack of food • Predation • Disease Industrial Revolution • Human population begins to grow more rapidly due to reduced death rates • Improved nutrition • Improved sanitation • High birth rates remain

Malthus Prediction Human population cannot continue to grow exponentially forever Human population growth can be limited by n n q q q Competition (war) Limiting Resources (famine) Parasitism (disease )

The Effect of Age on Population n United States q Equal numbers of people in each age group q Slow but steady growth in the future Guatemala q Much higher numbers of young people q Prediction is that population size will double within 30 years Current Predictions for Our World: 9 billion people by 2050!

Chapter 6: Human Environmental Impact n Humans: q q “Humans affect regional and global environments through agriculture, development, and industry in ways that have an impact on the quality of Earth’s natural resources, including soil, water, and the atmosphere. ” Rely on Earth’s life-support systems Affect our environment when we: n n n Obtain food Eliminate waste products Build places to live

The Effect of Human Activity n Agriculture - Supplies a dependable food source that can be stored for later use q q n Positives n Enabled human settlements that ultimately led to modern civilization Negatives n Impacts natural resources as >7 billion people!!! need q Food q Fresh water q Fertile soil q Fossil fuels (fertilizer & farm equipment) Development - Trend to move to suburbs & cities q q Positives n High standard of living Negatives n Produce lots of waste that affect air, water, & soil resources n Uses up farmland n Divides natural habitats into fragments

The Effect of Human Activity n Industrial Growth – Industry & scientific know-how q q Positives n Modern conveniences of life n Comfortable homes, clothes, electronic devices Negatives n Require energy and consume power n Need to burn fossil fuels (coal, oil, & natural gas) n Wastes discarded into air, water, & soil Sustainable Development n Ecosystem Goods & Services q q The goods and services produced by ecosystems that benefit the human economy n Goods – things that can be bought & sold n Services – processes or actions that produce goods Examples n n Breathable air Drinkable water – can be provided naturally, but if polluted we must spend $$ to provide it

Sustainable Development n Renewable and Nonrenewable Resources q Renewable – can be renewed or replaced by a healthy ecosystem n q A single southern white pine Nonrenewable – natural processes cannot replenish them in a reasonable amount of time n n Fossil fuels (formed from buried organic material over millions of years) A whole forest of white pines

Sustainable Development n Sustainable Resource Use q Sustainable development n n q Provides for human needs & wants Preserves the ecosystems that produce natural resources What does it look like? n n n Does not cause harm to the soil, water, and climate Consumes as little energy and material as possible Flexible to survive environmental stress/disasters Takes into account human economic systems as well as ecosystem goods and services SURVIVE AND IMPROVE

Soil Resources n n n Why is it needed? q When healthy, supports agriculture and forestry q Topsoil – absorbs/retains moisture but allows water to drain What are we doing to destroy it? q Allowing soil erosion – nutrients are washed away with rain n Desertification – over-plowing, overgrazing, allowing land to be barren between plantings n Deforestation – loss of forests q Forests help to hold soil in place, absorb CO 2, absorb freshwater How can we protect it? q Leaving stems and roots in place between plantings q Crop-rotation q Contour Plowing and Terracing – creating steps to prevent water and soil from flowing downward q Creating tree farms (makes trees a renewable resource)

Freshwater Resources n n Why is it needed? q Drinking water q Industry q Transportation q Energy q Waste Disposal What are we doing to destroy it? q Overuse (Ogallala aquifer – took 1 million years to collect…non-renewable!!) q Pollution n Point (factories, oil spills) n Non-point (Grease and oil washed by rain off streets, chemicals released into air) n Industrial/Agricultural Chemicals q n Biomagnification – pollutants (like DDT, PCBs, heavy metals) magnify as they move through the food chain from primary producers to primary consumers, etc. Residential Sewage ( )

Freshwater Resources n How can we protect it? q Protection of natural resources involved in water cycle n Plants can filter out pollutants q Watershed conservation – protecting all inter-connected bodies of water q Pollution control n Sewage treatment n Decrease pesticide use q Use biological controls instead of poisonous sprays n Water conservation q Drip irrigation

Atmospheric Resources n Why is it needed? q Oxygen Absorption of UV radiation Regulation of global temperature q Pollution (Industry, Burning Fossil Fuels) q q n What are we doing to destroy it? n n n Smog - Ground Level Ozone q Causes respiratory diseases Acid Rain – nitrogen and sulfur oxides mixing with precipitation q Damages plants, releases toxic elements from soil Greenhouse Gases – burning of fossil fuels releases CO 2, CH 4 and H 2 O q Releases carbon dioxide into the air, contributes to global warming and climate change Particulates – microscopic particles of ash and dust released by industry q Can be inhaled and cause respiratory problems How can we protect it? q q q Emission standards Clean-air regulations Unleaded gasoline

Atmospheric Resources (continued) n What are we doing to destroy it? (continued) q Pollution (Industry, Burning Fossil Fuels) n n n Greenhouse Gases – burning of fossil fuels releases CO 2, CH 4 and H 2 O q Releases carbon dioxide into the air, contributes to global warming and climate change Particulates – microscopic particles of ash and dust released by industry q Can be inhaled and cause respiratory problems How can we protect it? q q q Emission standards Clean-air regulations Unleaded gasoline

Biodiversity: total of all the genetically-based variation in all organisms in the biosphere n Value of Biodiversity q q q n Ecosystem Diversity - variety of habitats, communities, and ecological processes in that biosphere n 1. 8 million species already identified! n 30 million more estimated yet to be discovered!! Species Diversity - number of different organisms in a particular area Genetic Diversity – sum total of all different forms of genetic information carried by a particular species Benefits of Biodiversity n n n Sources of medicines Genetic diversity used to increase pest resistance Keystone species (if removed) can change entire ecosystem

Biodiversity n Threats to Biodiversity q q q n Altering habitats Hunting Introducing Invasive Species Releasing Pollution Contributing to Climate Change Conserving Biodiversity q q q Protect Individual Species Preserve Habitats and Ecosystems Consider Local Interests

Invasive Species Pythons in Florida • Have few or no predators in new ecosystem • Use more resources or use resources more efficiently • May reduce the endemic (native) population via predation Invasive Species Disaster

Why is biodiversity important? n n The greater the VARIATION in an ecosystem, the more likely it is to RECOVER if there is a disruption. q Increased diversity = healthier environment. Biodiversity is a resource q Most pharmaceutical drugs from plants. q Future food sources, building materials, etc… q “Beauty, fascination, & wonder” q Recreation (ecotourism).

Threatened, Endangered, and Extinct Species n n n Threatened q Abundant in range, but decreasing in numbers. q At risk Endangered q Very few remaining in natural range q At risk for going extinct Extinct q Local extinction – gone from local range q Ecological extinction – gone from natural range (in zoos only) q Biological extinction – gone from Earth forever.

Meeting Ecological Challenges n Ecological Footprint – total area of functioning land water ecosystems needed both to provide the resources an individual or population uses and to make harmless the wastes that an individual or population generates n The average American has an ecological footprint that is: q 4 x larger than global average q 2 x that of England q >2 x that of England q 6 x that of China

Ozone Layer n n n Why is it needed? q Ozone Layer – molecules of O 3 q At ground level = danger; q Upper atmosphere = protection against harmful UV radiation which can cause cancer, eye damage and decreased immunity What are we doing to destroy it? q Primary problem is CFCs (Chloroflurocarbons) n Found in refrigerants, aerosol cans and plastic foams How can we protect it? q CFCs banned in the late 80’s (Montreal Protocol), however residual CFCs can remain in the atmosphere for more than 30 years!!

Fisheries n n What is the problem? q Despite increased efforts and new technology, seafood catch numbers continue to decline What are we doing to destroy it? q Fish thought to be a renewable resource q n Death rates (commercial fishing) surpassed the birth rates of the fish How can we protect it? q Regulations put in place to limit fish catches q Certain areas closed to fishing until populations recovered (Sustainable Fisheries Act) q Aquaculture – farming of aquatic animals

Climate Change n n What’s the Problem? q Global warming – increase in average temperature of our planet (0. 74ºC between 1906 and 2005) with 11 of the 12 warmest years occurring between 1995 -2006 q Melting sea ice q Rising seal levels What are we doing to destroy it? q “Enhanced Greenhouse Effect” not allowing solar heat to move back into outer space Burning fossil fuels n Automobile exhaust n Industrial pollution How can we protect it? q Alternative energy sources (water, wind, solar) q Decrease our ecological footprint n n

Greenhouse Gases n Methane, carbon dioxide, water vapor, ozone

HIPPCO – Factors Leading to Species Extinction 1. Habitat Loss q 2. 3. 4. 5. 6. “Hot spots” with greatest impact: tropical areas, coral reefs, wetlands, grasslands, water (fresh & salt) Invasive Species q Organisms not normally in habitat q Air, water, soil impacts q Arrival of humans and exponential population growth q Ocean Fisheries Pollution Population Climate Change Overexploitation

Terrestrial Biomes

Aquatic Biomes