Unit 2 Test Review. Biogeochemical cycles Biogeochemical Cycles, or Nutrient cycles, is how elements, chemical compounds, and other forms of matter are.

Unit 2 Test Review

Biogeochemical cycles

• Biogeochemical Cycles, or Nutrient cycles, is how elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another.

• Types of Biogeochemical Cycles:– Hydrologic- ex water cycle– Atmospheric- ex carbon cycle and nitrogen cycle– Sedimentary – ex phosphorus cycle

Evaporation and Transpiration

Condensation and Precipitation

Runoff, Seepage, and Root Uptake

• Organisms need nitrogen to build proteins.

• Different forms of nitrogen cycle through the biosphere.

• Nitrogen gas is the most abundant form of nitrogen on Earth.

• It cannot be directly used by organisms.• Nitrogen must be converted into

compounds that can enter food webs by the process of “Nitrogen Fixation”

• Homeostasis requires a conatant energy imput and is maintained in ecosystems by the cycling of matter through biotic and abiotic portions of the ecosystem

• Biogeochemical cycles demonstrate the Law of Conservation of Matter– a fundamental principle of classical physics that

matter cannot be created or destroyed in an isolated system

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What is Ecology??

• The study of interactions that take place between organisms and their environment.

• It explains how living organisms affect each other and the world they live in.

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Habitat & Niche• Habitat is the place a plant or animal lives

• Niche is an organism’s total way of life


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The Nonliving Environment

• Abiotic factors- the nonliving parts of an organism’s environment.

• Examples include air currents, temperature, moisture, light, and soil.

• Abiotic factors affect an organism’s life.


http://upload.wikimedia.org/wikipedia/en/6/69/Lightning_in_Arlington.jpg

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The Living Environment

• Biotic factors- all the living organisms that inhabit an environment.

• All organisms depend on others directly or indirectly for food, shelter, reproduction, or protection.


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1st Level of Organization• Organism:

An individual living thing that is made of cells, uses energy, reproduces, responds, grows, and develops


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2nd Level of Organization• Population:

A group of organisms, all of the same species, which interbreed and live in the same place at the same time.


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3rd Level of Organization• Community:

All the populations of different species that live in the same place at the same time.


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4th Level of Organization• Ecosystem:

Populations of plants and animals that interact with each other in a given area with the abiotic components of that area. (terrestrial or aquatic)


5th Level of Organization

• Biome: A group of ecosystems that share similar climates and typical organisms

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6th Level of Organization

• Biosphere:The portion of Earth that supports life.


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The Biosphere

• Life is found in air, on land, and in fresh and salt water.

• The BIOSPHERE is the portion of Earth that supports living things.



Producers• Autotrophs

– store energy in forms that make it available to other organisms

– They are known as primary producers

• First producers• Essential to flow of

energy

Life Without Light

• Chemosynthesis:– Chemical energy is

used to produce sugars

• Chemosynthetic organisms are found in the deepest, darkest oceans, hot springs, and tidal marshes.


Heterotrophs

• Many organisms cannot directly use energy from the environment.

• They must acquire energy from other organisms – They are known as heterotrophs


Consumers

• Organisms that rely on other organisms for energy and nutrients are called consumers

• There are different classes of consumers


Consumers

• Decomposers:– “feed” by chemically

breaking down organic matter

– Ex: fungi, bacteria

• Detritivores:– Feed on detritus

particles (waste, trash)– Ex: earthworms,

beetles


Consumers

• Omnivores:– Diet naturally includes

a variety of different foods.

– Both plants and animals

– Ex: humans, bears, pigs

• Scavengers:– Consume the

carcasses of other animals

– Ex: vultures,


Consumers

• Herbivores– Eat plants, roots,

seeds, or fruits– Ex: cows, caterpillars,

and deer

• Carnivores– Kill and eat other

organisms– Ex: snakes, cats,

dogs, etc


Population Dynamics

• Three Key Features of Populations– Size– Density– Dispersion

Three Key Features of Populations

• Growth Rate: – Birth Rate (natality) - Death Rate (mortality)– How many individuals are born vs. how many die– Birth rate (b) − death rate (d) = rate of natural

increase (r)

Density: measurement of population per unit area or unit volume

Pop. Density = # of individuals ÷ unit of space

Three Key Features of Populations

1. Immigration: movement of individuals into a population

2. Emigration: movement of individuals out of a population

3. Density-dependent factors: Biotic factors in the environment that have an increasing effect as population size increases (disease, competition, parasites)

4. Density-independent factors: Abiotic factors in the environment that affect populations regardless of their density (temperature, weather)

How Do You Affect Density?

Immigration

Emigration

Natality MortalityPopulation+

+

-

-

Factors That Affect Future Population Growth

Carrying Capacity

• Carrying Capacity (k): – The maximum population size that can be

supported by the available resources– There can only be as many organisms as the

environmental resources can support

• Idealized models describe two kinds of population growth:

1. Exponential Growth

2. Logistic Growth

How Do Populations Grow?

• Doubled three times in the last three centuries• About 6.1 billion and may reach 9.3 billion by

the year 2050• Improved health and technology have lowered

death rates

The Human Population

Energy

• Energy flows in a one-way stream from primary producers to various consumers through the food chain

Food Chains

• Food chains are series of steps in which organisms transfer energy by eating and being eaten

• Producer Herbivore Carnivore

Food Webs

• Feeding relationships are usually more complex than just a simple chain

• Many animals eat more than one kind of food

• Complex networks of feeding relationships are called food webs.

Trophic Levels

• Each step in a food chain or food web is called a trophic level

• “nourishment level”

autotrophs

herbivores

Carnivores/omnivores

Carnivores/omnivores

Energy Pyramid

• Shows the amount of energy available at each trophic level of a food chain or food web.

• Only a small portion of energy in each trophic level makes it to the next level– 10% rule Between each trophic level 90% of energy is lost to the

atmosphere as heat. Only 10% of energy is transferred from one level to the next.

Ecological Pyramids

Pyramid of NumbersBiomass Pyramid

Shows the individual number of organismsat each trophic level.

Measures the total dry mass of organisms at each trophic level.

What is Ecological Succession?

• Natural, gradual changes in the types of species that live in an area

• Can be primary or secondary • The gradual replacement of

one plant community by another through natural processes over time

Primary Succession

• Begins in a place without any soil:

»Sides of volcanoes»Landslides»Flooding

• First, lichens that do not need soil to survive grow on rocks

• Next, mosses grow to hold newly made soil

• Known as PIONEER SPECIES

Secondary Succession

• Begins in a place that already has soil and was once the home of living organisms

• Occurs faster and has different pioneer species than primary succession

• Example: after forest fires

Climax Community

• A stable group of plants and animals that is the end result of the succession process

• Does not always mean big trees–Grasses in prairies–Cacti in deserts

Aquatic Ecosystems• The types of

organisms that live in an aquatic ecosystem is determined by the water’s salinity

• Salinity is the amount of dissolved salts the water contains.– Freshwater= <0.5

ppt– Saltwater= 30-50

ppt• Aquatic

Ecosystems are divided into Freshwater and Saltwater or Marine

Freshwater vs Saltwater Freshwater

Lakes and Ponds-Slow Rivers and Streams-Fast Wetlands-water logged land Marshes and Swamps

Saltwater or Marine Marshes and Swamps-

Coastal Coral Reefs Deep Oceans

Characteristics of Aquatic Ecosystems Aquatic Ecosystems are characterized by

Temperature Sunlight Depth Oxygen Concentration Available Nutrients

Aquatic Organisms are grouped by their location at water depths and adaptations Plankton-Surface, provide most of food, producers

Zooplankton-microscopic animalsPhytoplankton-microscopic plants

Nekton-Free swimming organisms Fish, Turtles, Whales

Benthos-Bottom dwelling organism, lived attached to hard surfaces Mussles, worms and Barnacles

Lakes and Ponds• Form naturally where

ground water reaches the Earth’s surface

• Humans and animals like beavers create lakes and ponds by interrupting water flow

• Lake structure-2 zones– Littoral Zone-Surface,

Sunlight• Aquatic Plants and Animal

– Benthic Zone-Bottom, Dark• Bacteria, Decomposers,

Bottom Feeding Fish

• Animal Adaptations-Whiskers on Catfish to find food on the bottom, Amphibians burrow into the mud in winter to avoid freezing

Wetlands Areas of land covered by water for

part of the year 2 Types of Wetlands

Marshes-contain nonwoody plants such as cattails, low, flat lands, characterized by salinity-ex. Florida Everglades

Swamps-dominated by woody plants such as cypress trees, low, poorly drained land, good habitat for amphibians- ex. Louisiana bayou

2 Purposes of Wetlands Filter and absorb water-prevents

pollutants from entering ground water Control Flooding-absorb river overflow Homes and nesting area for migratory

birds Cranberry, crawfish production

Wetlands are protected in many states

Rivers

• Originate from snow melt in the mountains of Minnesota 1475 ft above sea level

• 2320 miles long, flows southward in meanders, terminating 95 miles below New Orleans at sea level or O ft.

• 4th longest river in the world

• Changes with the land and climate through which it travels– Higher altitudes-cold,

narrow, fast, oxygen rich-Head Waters

• Trout, Minnows, Moss – Lower altitudes-warmer,

wider, slower and decreased dissolved oxygen-Ends in a fan shape called the Delta

• Plankton, Carp, Catfish• Arrowhead, Crowfoot

Threats to River Systems• Industries use river water in

manufacturing processes and release waste into the waters.

• Water runoff from land carries pesticides, fertilizers and manufacturing chemicals into the river coating sediment with toxic waste

• Pollutants enter ground water and human drinking water resources in rural areas.

Biodiversity encompasses several levels

• Humans are reducing Earth’s diversity of life

• Biodiversity – sum total of all organisms in an area– Split into three specific levels:

• Species diversity• Genetic diversity• Ecosystem diversity

Species diversity• Species Diversity = the number or variety of

species in the world or in a particular region– Richness = the number of species– Evenness or relative abundance = extent to

which numbers of individuals of different species are equal or skewed

– Speciation generates new species and adds to species richness

– Extinction reduces species richness

Genetic diversity• Encompasses the differences in DNA among individuals within species and populations

• The raw material for adaptation to local conditions

• Populations with higher genetic diversity can survive– They can cope with environmental change

• Populations with low genetic diversity are vulnerable– To environmental change– Disease– Inbreeding depression = genetically similar parents

mate and produce inferior offspring

Ecosystem diversity

• Ecosystem diversity = the number and variety of ecosystems

• Also encompasses differing communities and habitats

• Rapid vegetation change and varying landscapes within an ecosystem promote higher levels of biodiversity

Biodiversity losses and species extinction

• Extinction = occurs when the last member of a species dies and the species ceases to exist

• Extirpation = the disappearance of a particular population from a given area, but not the entire species globally– Can lead to extinction

Earth has experienced five mass extinctions

• In the past 440 million years, mass extinctions have eliminated at least 50% of all species

• After every mass extinction the biodiversity returned to or exceeded its original state

Current extinction rates are higher than normal

• The Red List = an updated list of species facing high risks of extinctions– 23% of mammal species – 12% of bird species– 31 - 86% of all other species

• Since 1970, 58 fish species, 9 bird species, and 1 mammal species has gone extinct– In the U.S., in the last 500 years, 236 animal and 17

plant species are confirmed extinct– Actual numbers are undoubtedly higher

Biodiversity loss has many causes

• Reasons for biodiversity losses are multifaceted, complex, and hard to determine– Factors may interact synergistically

• Four primary causes of population decline are:– Habitat alteration– Invasive species– Pollution– Overharvesting

• Global climate change now is the fifth cause

Invasive species cause biodiversity loss

• Introduction of non-native species to new environments– Accidental: zebra mussels– Deliberate: food crops

• Island species are especially vulnerable• Invaders have no natural predators, competitors, or parasites• Cost billions of dollars in economic damage

Biodiversity provides free ecosystem services

• Provides food, shelter, fuel• Purifies air and water, and detoxifies wastes• Stabilizes climate, moderates floods, droughts, wind,

temperature• Generates and renews soil fertility and cycles nutrients• Pollinates plants and controls pests and disease• Maintains genetic resources• Provides cultural and aesthetic benefits• Allows us to adapt to change

The annual value of just 17 ecosystem services = $16 - 54 trillion per year

Conservation biology responds to biodiversity loss

• Conservation biology = devoted to understanding the factors that influence the loss, protection, and restoration of biodiversity– Arose as scientists

became alarmed at the degradation of natural systems

– An applied and goal-oriented science

Should conservation focus on endangered species?

• Endangered Species Act (1973) (ESA) = forbids the government and private citizens from taking actions that destroy endangered species or their habitats– To prevent extinction– Stabilize declining populations– Enable populations to recover

• As of 2007, the U.S. had 1,312 species listed as endangered or threatened

Protecting biodiversity

• Captive breeding – individuals are bred and raised with the intent of reintroducing them into the wild– Zoos and botanical gardens

• Some reintroductions are controversial– Ranchers opposed the reintroduction of wolves to

Yellowstone National Park– Some habitat is so fragmented, a species cannot

survive

Umbrella species

• Conservation biologists use particular species as tools to conserve communities and ecosystems– Protecting the habitat of these umbrella species helps protect less-

charismatic animals that would not have generated public interest

• Flagship species – large and charismatic species used as spearheads for biodiversity conservation– The World Wildlife Fund’s panda bear

• Some organizations are moving beyond the single species approach to focus on whole landscapes

Biodiversity hotspots

• Biodiversity hotspots – prioritizes regions most important globally for biodiversity– Support a great number of endemic

species = species found nowhere else in the world

– The area must have at least 1.500 endemic plant species (0.5% of the world total)

– It must have lost 70% of its habitat due to human impact

Unit 2 Test Review. Biogeochemical cycles Biogeochemical Cycles, or Nutrient cycles, is how elements, chemical compounds, and other forms of matter are.

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living organisms

organisms life

organisms environment

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group of organisms

energy life

nitrogen gas

level of organizationorganism