Ecology: Biology 1 Honors

Ecology

the study of interactions of organisms with each other and their physical surroundings

Biosphere

part of the Earth where life exists

Ecosystem

given physical arrest (abiotic) and the living organisms that inhabit that area (biotic factors)

What are some examples of ecosystems

pond that has water, algae, fish, soil/sand, microorganisms, etc.

Communities

collective terms for all organisms living in one ecosystem

Weather

the day to day conditions of the Earth’s atmosphere in a given area

Climate

refers to the average year to year conditions of temperature and precipitation

Climate is influenced by

shape and elevation of land, latitude, wind, ocean currents, and amount of precipitation

Greenhouse Effect

The Earth retains heat due to a layer of gases in the atmosphere

What are the gases in the atmosphere that create Greenhouse effect?

Carbon dioxide (CO2), methane (CH4), water vapor (H2O)

What does greenhouse effect allow solar radiation in to Earth as?

Sunlight

What is much of sunlight converted to when it hits Earth?

Heat

Gases do not allow __ energy out as readily as __: much __ is trapped

heat, light, heat

Energy flows but it _ recycled

is not

Nutrients _ be recycled but energy _

can, cannot

Where do plants trap some of their small amount of sun’s energy that they use to live?

tissues

Producers

capture energy from the sun (such as photosynthetic algae or phytoplankton) or other another inorganic source like chemosynthetic bacteria

What are the consumers?

primary consumers, secondary consumers, tertiary consumers

Primary consumers

feed on the producers

Secondary consumers

feed on the primary consumers

Tertiary consumers

feed on the secondary, etc.

Decomposers

break down dead organisms (bacteria & fungi)

Is there a limit to the number of trophic levels in an ecosystem?

no, but there is less energy at each higher level

Herbivores

eat plants

Carnivores

eat animals

Omnivores

eat both plants and animals

Detrivores

eat dead organic matter; detritus such as crabs, mites, earthworms

Decomposers

organism that breaks down dead organic material and live on it

Food webs

are a system of interdependent food chains

Keystone species

an organism that helps define an entire ecosystem

What happens if there are no keystone species?

an ecosystem would be dramatically different or cease to exist altogether

Can there be more than one keystone species?

Yes, but usually there is only one or few per ecosystem

Usually biodiverse ecosystems are likely to have more keystone species

Biomass

The total mass of organisms at one trophic level

_ of plant life to support _ consumers

Lots, a few

Pyramid of biomass shows that there is _ in higher trophic levels

less

10% Rule of Energy Transfer

When energy is passed from one trophic level to the next, only 10% (on average) of the energy will be passed on

Why only 10%?

• Can only feed on what was stored by another organism, not all of that will be stored

• That organism uses energy to grow, maintain cellular balance, or perhaps keep warm, etc.

• Not all organisms in one trophic level are eaten by another

• Always some energy lost during an energy transfer

Biomagnification

refers to the increase in concentration of a substance (such as a pesticide) in the tissues of organisms at successively higher levels in a food chain

In biomagnification energy…

may be lost at higher trophic levels but toxins are not

Ecological succession

start of a new community

How many types of ecological succession is there?

2

Primary succession

no life before

ex) volcanic islands like Galapagos

Secondary succession

one community replaces another

ex) pond begins to fill with organic matter and becomes a marsh land, then becomes solid over time

Pioneer species

organisms that begin to colonize areas that did not have living things before

they begin primary succession

LICHENS are an example of a pioneer species

lichens can grow on rock; they break it down and soil can form, moss can grow, then other plants, then animals come to live

Climax Community

a stable collection of organisms in an area

Primary productivity

of an ecosystem is the rate at which organic matter is created by producers

Limiting nutrients

are substances that limit the primary productivity

What are the often limiting nutrients?

Nitrogen or phosphorus

Nitrogen often limiting nutrient in ocean ecosystems, excess of these introduced nutrients can cause algal blooms

Tundra

• Northernmost

• Almost treeless

• Lichens, moss, grass

• Permafrost layer stunts plant growth from year to year

• Ground thaws a bit in summer; marsh-like

• reindeer and caribou typical animals

• Many species migrate south in winter (-94 degrees F)

Chaparral

• vegetation adapted to periodic fires, most often caused by lightning

• some plant species produce seeds that will germinate only after exposure to a hot fire

Taiga or Boreal Forest

• South of tundra

• Forest like conifers, pines, furs, spruce

• Mild summers, cold winters

• Many animals hibernate or travel to warmer regions in winter (-70 degrees F)

• Black bears, wolves, moose, elks

Temperate Deciduous Forest

• Eastern coast of US and most of Europe

• Forests of oak, maple

• Major seasonal changes; winter halts most plant regrowth

• Soil enriched with hummus - decaying layer of twigs/leaves

• Deer, foxes, birds, raccoons, squirrels

Temperate Grasslands

• Interior of most continents

• Grasses and small leafy plants

• Most rain falls in one season - hot summers and cold winters

• Midwest US

• not much succession because of grazing

Savanna — tropical gasslands

• Much less variation in temperature than grasslands

• more variation of wet/dry seasons

• periodic fires and lots of grazing; preventing succession

• Zebra, wildebeest, gazelles, elephants, lions

Tropical Rain Forests

• warm temps (25 degree C = 77 degree F) and consistent rainfall year round

• large diversity in organisms; but nutrient poor soils

• canopy of trees, where most organisms live

• many amphibians, lizards, birds, insects, larger cats

• humans destroying rainforest

Deserts

• Less than 25 cm of rain per year

• Sahara largest desert in the world

• Colder deserts higher elevation

• Cacti, lizards, birds

Which biome receives the least amount of rain?

Desert

What biome has the most diversity of organisms?

Tropical rainforest

What types of vegetation can you find in the taiga?

Coniferous forest

Deciduous trees

Leaves fall off seasonally

Coniferous trees

Leaves do not fall off seasonally

What biome would deciduous trees be found in?

Temperate deciduous forest

What biome would coniferous trees be found in?

Taiga

What biome is found in much of South America?

Tropical Rainforest

Which biome is the northernmost?

Tundra

What biome would you find lions lving in?

Savanna

What biome would you find tigers living in?

Tropical rainforest

Which biome lacks tree growth entirely?

Tundra

Where can you find a desert biome with a cold temperature?

Tundra

Freshwater

• 3% of all surface water

• rivers, streams, lakes

• provide much of our drinking water and food

• trout, and other fish

• many organisms much anchor themselves due to the flow of current

• wind/currents recycle nutrients as they fall to the bottom and bring them back up

Marine

• covers most of the Earth’s surface

• can be divided into vertical and horizontal zones

• vertical zones divided based upon how far light penetrates

Vertical Zones

• photic zone is where light can penetrate

• allows phytoplankton and algae to grow

• depth varies from 30-200 meters

• aphotic zone - no light penetrates

Intertidal Zones

• radical daily changes in environment as tide moves in and out

• many organisms cling to rocks to withstand waves like barnacles

• some burrow in sand to keep from being swept out to sea

Neritic Zone

• extends from low tide line to open sea

• falls in photic zone, so lots of algae, seaweed, and fish

• lots of nutrients

• lobsters/crabs crawl along ocean floor

Open Sea

• phytoplankton responsible for most photosynthesis

• many fish and mammals

• nutrients scarce and limits number of organisms that can grow

Deep Sea Zone or Benthic Zone

• Attached or near the bottom

• High pressure, cold temperatures

• no sunlight

• Strange creatures live like tube worms or gulper eels

• Many detritivores

• Some chemosynthesis by deep sea vents

Coral Reefs

• warm, shallow, tropical waters

• tiny animals that secrete hard calcium rich exterior

• their small tentacles capture food

• have symbiosis with algae

• need warm, salty water

Estuaries

• Boundaries of fresh and salt water; wetlands

• shallow - much photosynthesis

• Allows much plant life and variety of animals

• many give birth here and then move to open sea

• Lots of available nutrients (mouths of rivers that flow into oceans

Salt Marshes

temperate zone and dominated by salt tolerant grasses above water level and sea grass underwater

Mangrove Swamps

tropical and dominated by salt tolerant trees called mangrove

Biogeochemical cycle

the movement of nutrients through the biosphere in a series of physical or biological processes (abiotic and biotic elements)

it is unlike the one way flow of energy in an ecosystem

Examples of biochemical cycles

water cycle, nitrogen, carbon, oxygen

Water Cycle

• water is recycled within the environment

• water evaporates into the atmosphere, or is lost from plants through transpiration

• it will condense and fall back down to the Earth in the form of rain or snow

• Water may runoff into lakes and streams, be soaked up by plants or soak down further into the ground

• groundwater contained in rock beds beneath soil

Nitrogen Cycle

• all living things need nitrogen for assembly of molecules like amino acids and nucleotides

• some bacteria can “fix” nitrogen (N2) into a usable form through nitrogen fixation

• these bacteria often live in symbiosis with plants, but can be free-living as well

• nitrogen fixation creates an excess of NH3 which then becomes available to other organisms

• most soil is acidic, so the NH2 picks up a H+ ion to become ammonium, or NH4+

• Plants can take up the NH4+ directly, not often

• or soil bacteria use it to create NO2 and NO3 through a process called nitrification

• NO3 is more often taken in by plants

• Animals eat plants and each other to obtain their nitrogen

• However, must recycle the nitrogen at some point

• If nitrogen balance is thrown off, growth of organisms is thrown off

  • ex: algal bloom

How many percent of our air is nitrogen?

80%

Most nitrogen in the form of _ in the air

N2

Biological processes

photosynthesis, respiration, decomposition

Human Activities

mining, cutting and burning forests (deforestation), combustion of fossil fuels

Mutualism

Both species involved benefit

Commensalism

One is helped and the other species is not affected

Parasitism

one species benefits and the other is harmed

Population density

the number of individuals per unity area

What are the 3 major factors that influence population growth?

Number of births, number of deaths, how many either enter or leave the population

Exponential growth

if a population is abundant in space and food, etc. and also in ideal conditions, it has the potential to grow exponentially

Logistic Population Growth

if a population is limited by the environment, logistic growth occurs

Carrying Capacity

the number of individuals that the environment can support

Density-dependent Factors

limits on population size that are based on the size of the population

What are some examples of density-dependent factors?

competition, predation, parasitism, disease

Are density-dependent factors a positive or negative feedback?

negative feedback