Chapter 2 - ECOLOGY INTRODUCTION NOTES

Ecology – from the Greek work “oikos” which means house. It is the study of interrelationships between organism and their environment.
Ecosystem – self sustaining unit of organisms and their environments.

1.Divisions

1.Biosphere – earth including water, air, land and living organisms. Extends 8 km above and below the surface.

2.Biome – subdivision of biosphere.

Land – characterized by dominant vegetation and type of climate
Aquatic – characterized by type of water and location

3.Community – group of interacting species that co-exist in an ecosystem. Forms a system of producer, consumers and decomposers.

4.Population – division of a community made of individual species which share a common area.

2.Environmental factors

1.Abiotic factors – non-living factors i.e. temperature, sunlight, soil type, water, minerals, pollution

2.Biotic factors – living factors i.e. plants, animals, bacteria, fungi, etc.

Forces of a Community
Competition – competition for a limited resource can inhibit the growth of both population or even eliminate one of the populations. Pg. 38
Predation – one species eats the other – includes both plants and animals – Pg. 38

1.Coevolution – a series of reciprocal adaptations in two species which effect the survival of both – ex. Butterfly and leaves - pg. 439

2.Camouflage – common defense of prey – pg. 428

3.Batesian Mimicry – one species mimics another undesirable species – pg. 429

4.Mullerian mimicry – two unpalatable species in the same community mimic each other – pg. 429

Symbiotic Relationships – pg. 39 - 40

1.Parasitism – one organism derives food at the expense of another organism

2.Commensalism – one partner benefits without significantly harming the other

3.Mutualism – both partners benefit

Energy Flow –
Food Chains and Webs - Sun ------producer ------consumer

Producer = autotroph – always base level in chain , web or pyramid

1.Consumer = heterotroph – makes us the levels after the first one

2.Decomposer = Breaks down dead organisms. Detritivores eat fragments of dead matter

3.Food Chain – path of energy flow from producer to consumer. Only 10% of energy is transferred to next level. Each feeding level is called a trophic level. Arrows point in the direction of the energy flow – not who eats what.

4.Food Web – interconnected food chains

Pyramids

1. Pyramid of Energy –pg. 44 – Each level represents the amt. of energy available to trophic level. Remember – 90% of energy is lost between each level

2.Pyramid of Biomass – pg. 44 – Each level represents the amt. of biomass consumed – Usually the available amt. of biomass decreases with each level

3.Pyramid of Numbers – pg. 44 – Each level represents the number of individual organisms consumed – Usually the population size decreases with each level

Biogeochemical Cycles – Exchange of matter through the biosphere which includes the living organisms, chemical processes and geological processes
Hydrologic Cycle – needed for life

1. Water evaporates from soil, organisms and bodies of water into atmosphere

2.Water vapor rises and cools in the atmosphere forming clouds.

3.Water returns to earth thru rain, sleet and snow

Carbon Cycle – necessary to make organic compounds

1.Carbon dioxide and water are used during photosynthesis to produce glucose

2.Glucose is broken down during cellular respiration to produce carbon dioxide, water and ATP

3.Carbon dioxide buried in fossil fuels is released when those fuels are burned

4.Carbon is also stored in calcium carbonate shells and released when the shells decompose.

Nitrogen Cycle – Nitrogen needed to make proteins

1. Largest concentration is in atmosphere but plants and animals cannot use the nitrogen gas.

2.Bacteria in the soil, water and on the roots of plants absorb the nitrogen gas and modify it to a form usable by plants and animals. (Nitrogen fixation)

3.Nitrogen is transferred between trophic levels and is recycled into needed amino acids.

4.Nitrogen released from organisms during urination, decomposition and conversion of ammonia.

Phosphorous Cycle – is necessary for nucleic acids

1.Stored in rocks and absorbed by producers for transfer to upper trophic levels

2.Returns to soil during decomposition and the weathering and erosion of rocks

Chapter 3 – Communities and Ecosystems

Community – all the populations of organisms living together and potentially interacting in a particular area
Properties of a Community
Diversity – variety of different kinds of organisms that make up a community – has two parts
species richness – total number of different species in the community
relative abundance – how many of each species exists
Prevalent Form of Vegetation –
which plants are dominant
how are plants arranged – example: large trees at top of forest, shrubs below to catch filtered light
Stability –
Ability to resist change and return to its original species composition after being disturbed
Trophic structure –
the feeding relationships among the species making up the community
determines the passage of energy and nutrients from plant to herbivores to carnivores
Limiting Factors – abiotic or biotic factors that restrict the numbers, reproduction or distribution of organisms
Abiotic limiting factors – sunlight, climate, temperature, water, nutrients, fire, soil chemistry and space
Biotic limiting factors – other plant and animal species
Range of Tolerance – the upper and lower limits that define the conditions the organism can survive in.

Succession of a Community - -
Stability – most communities, when left alone, tend to remain in a more or less constant balance due to interactions between the organisms.
Disturbances – are forces that alter a biological community and usually remove organisms from it. These can be positive – new species can move into an area or be favored by the change
Ecological Succession – when a community changes resulting from a disturbance – pgs. 62 - 64
Primary Succession – community arises in a virtually lifeless area with no soil is present

Ex: new volcanic islands

Autotrophic microorganisms
Lichens and mosses
Soil begins to develop from their breakdown
Grasses, shrubs and trees
Dominant plant form takes over

Secondary Succession – community arises after a disturbance has destroyed an existing community but soil is intact. 0ccurs faster than primary because soil is present

Ex: Abandoned farmland

grasses and other non-woody plant species
woody shrubs and trees

Climax Community – permanent, final plant stage for that climate and soil type – Seldom reached as factors are constantly affecting the communities.

Biomes –
Land Biomes – classified according to the climax plant population. Characterized by temp and precipitation

1. Tundra - Permafrost – layer of permanently frozen subsoil, less than 15 cm/yr rainfail

a. Upper topsoil thaws ruing the summer, but the deeper soil (permafrost) remains permanently frozen

b. Location – south of the polar ice cap in northern hemisphere – northernmost biome

c. Plants – mosses, lichens, grasses, few stunted trees

d. Animals – birds, wolves, foxes, mosquitoes, caribou, reindeer, salmon, trout

Taiga – Boreal/Coniferous Forest – fir, pine and spruce – ex. Redwood forest

a. Precipitation in form of snow; Cold winters and mild summers

b. Covers much of N. America, Asia and a narrow band in Norway and Sweden

c. Animals – birds, black bears, grizzly bears, wolves, moose, elk, deer, mountain lions

Temperate Deciduous Forest - trees lose leaves in winter; an adaptation to short, cold days and poor growing conditions

a. Covers the eastern coast of the U.S., southern coast of Canada, most of Europe, parts of Japan, China and Australia

b. Abundant organic matter and nutrients stored in humus (decaying twigs and leaves)

c. Good Farmland

d. Warm summers, cold winters, moderate precipitation

e. Plants – oak, maple, beech, birch

f. Animals – birds, deer, moose, foxes, chipmunks, raccoons, squirrels

Temperate Grasslands – less water and lower temperatures than savannah, treeless

a. Covers the pampas in Argentina and Uruguay, steppes in Asia and the prairies in Central North America

Plant growth is dependent on rainfall. Areas of greater rainfall have higher grasses while drier areas have short grass. Sagebrush may also be found in drier areas.
Animals – bison, pronghorn, gazelles, zebras, wild horses, sheep

Desert – less than 25 cm of rainfall/year
Hot, dry climate
Growth of annual plants limited to time of rainfall – sagebrush, grasses, shrubs
Plant adaptations to hostile conditions such as leathery leaves and spines (reduced leaves)
Animals – thick skins, decreased urine production, restriction of daytime activities – mainly active at night

Savanna – grassland dotted with trees
Location – cover wide areas of the tropics in central South America, central and South Africa and parts of Australia.
Temperature –fairly constant temperature
Climate - rainfall is within one season for the most part – usually summer
Plant –small trees and flowering grasses
Animals – giraffes, zebras, baboons, lions, cheetahs, elephants, insects, birds.

Chapparal –dense, spiny everygreen shrubs found near offshore areas
Found in the Mediterranean, coastal areas of Chile, California, southwester Africa and southwestern Asia
Climate – mild rainy winters, hot dry summers
Periodic fires caused by lightning. Some plants need this for seeds to germinate
Plant life varies according to location and rainfall
Animal – browsers such as deer, fruit-eating birds, seed-eating rodents, lizards, snakes

Tropical Rain Forests –
Location – equatorial areas of South America, Southeast Asia, Africa and Central America.
Temperature - temperature is warm @ 25 degrees Celsius and days are 11 – 12 hours long year-round.
Climate – abundant rainfall (greater than 250 cm per year) reduced rainfall only during a few months. Nutrient poor soil, warm temperatures
Plant – trees grow up to 70 meters in height; form a dense canopy so that little light reaches soil level. Other plants grow on trees, such as large woody vines (lianas), orchids, etc. Epiphytes (live commensally with other plants) are numerous and absorb their water and nutrients from the air
Animals – monkeys, birds, insects, snakes, bats, frogs. More varied than any other biome.
Importance – ecological pulse of biosphere – shows great change because of large numbers of disappearing species here. Also, most medicines are originally found thru plants, many of which exist only here.

Aquatic Biomes –
Freshwater Biomes – rivers, lakes and streams
Rivers and Streams – extend from headwater (point of origin) to a larger body of water (usually characterized by a mouth)
Usually originates from underground springs or snowmelt
Speed and direction of flow determined by slope of land
Sediment , material picked up by wind, water and glaciers, is carried with water and deposited as the speed slows in the form of sand, silt and mud at the mouth.
Lakes and Ponds – inland body of standing water; divided into zones based on sunlight penetration
Photic Zones – where light penetrates

a. Littoral Zone – area closest to shore, shallow sunlight reaches the bottom. Lots of algae and plants in this area. Consumers – frogs, crustaceans, insect larvae, fish

b. Limnetic Zone – open water that is well lit and characterized by plankton, both phyto and zoo. Lots of fish

Aphotic Zone – where light does not reach

a. Profundal Zone – deepest area of lake, little light so cold and low in oxygen. Few species live here, nutrients sink from above, winds mix photic and aphotic zones

c. Lake Types –

1. Oligotrophic – deep, nutrient poor, blue in color, young lake

2. Eutrophic – shallow, nutrient rich, greenish in color, mature lake – Hypereutrophic – really

green, too much phytoplankton choking the environment

Transitional Aquatic Ecosystems – boundary between water and land or fresh and salt water
Wetlands – marshes, swamps and bogs – saturated with water and support aquatic plants

1. Characterized by high species diversity

2. Plants – duckweed, pond lilies, cattails, cypress, mangroves, decomposing vegetation

3. Animals – amphibians, reptiles, ducks, herons, raccoons, mink

Estuaries – boundary between fresh and salt water
Salt marshes, mangrove swamps, lagoons, mouths of rivers
Shallow, photosynthesis occurs at all levels
Vulnerable to pollution and development from humans
Diversity of plants and animals rivaled only by tropical rainforest and coral reefs

Marine Biomes – ocean/salt water – divided by water depth
Intertidal – covered by water during high tide but uncovered during low tide. Exposed to wave action, temperature changes, varying exposure to air and sunlight.
Divided into spray zone, high tide zone, mid tide zone, low tide zone
Neritic – from low tide line to open sea (around continental shelf); completely in photic zone -

Characterized by seaweed, algae (kelp), crustaceans, fish and turtles

Pelagic Zone – occurs after the continental shelf; extends from surface to the abyssal depth
Photic Zone – area of pelagic which received light, A.K.A. open sea

a. Phytoplankton responsible for 80% to 90% of photosynthetic activity

b. Food chain - phytoplankton ----- zooplankton ------sm. fish ------dolphins, etc.

c. Phytoplankton grows slowly which keeps number of animals lower than neritic

2. Aphotic zone – area of pelagic zone that doesn’t receive light, A.K.A. deep sea

a. cold, total darkness, no phytoplankton so animals depend on material that drift from

above

b. Abyssal Zone – coldest regions of aphotic zone, does contain hydrothermal vents which increase localized temperatures and provide hydrogen sulfide for chemosynthetic bacteria

d. Benthic Zone – area long the ocean floor consisting of sand, silt and detritus. Exists in both photic and

aphotic zones so diversity of life decreases with depth.

****** Coral Reefs – exist in warm shallow marine waters to form natural barriers along continents. They

protect the shoreline and are one of the most diverse environments in the world. Extremely sensitive to ecological changes