Ecology Exam 1

Chapters 1,2,3

Ecology

the scientific study of how organisms affect, and are affected by, other organisms and their environment

scientific endeavor not environmental activism

species connections

even species that do not interact directly can be connected by shared environmental features

Ecologists ask questions about

the natural world in order to understand these connections

controlled experiment

experimental groups are compared with a control group that lacks the factor being tested

environmental science

incorporates concepts from the natural sciences (including ecology) and the social sciences and focuses on how people affect the environment and how to address environmental problems

balance of nature

early ecological view in which natural systems are stable and tend to return to an original state after disturbance

each species plays a distinct role in that balance

ecologists now recognize

natural systems do not necessarily return to their original state after disturbance

random perturbations can play an important role

different communities can form in the same area under similar environmental conditions

ecological interactions are much more complex than previously thought

Events in nature are always

interconnected,

a change in one part of an ecological system can alter other parts of that system

scale

the spatial or temporal dimension at which ecological observations are collected

spatial scales: small scale- soil microorganisms/large scale- atmospheric pollutants

temporal scales: short scale- leaf response to sunlight/ long scale- species change over geologic time

population

a group of individuals of a single species that live in a particular area and interact with one another

community

an association of populations of different species living in the same area at the same time

biotic

of or referring to the living components of an environment

abiotic

of or referring to the physical or nonliving environment

earth’s many communities

biosphere, ecosystem, community, population, organism

ecosystem

a community of organisms plus their physical environment

landscapes

areas with substantial differences, typically including multiple ecosystems

biosphere

all the world’s ecosystems comprise the biosphere

all living organisms on Earth plus the environments in which they live

evolution

all living systems change over time

1. change in genetic characteristics of a population over time

2. descent with modification- organisms gradually accumulate differences from their ancestors

adaptation

a characteristic that improves survival or reproduction

natural selection

an evolutionary process in which individuals that possess particular characteristics survive or reproduce at a higher rate than other individuals because of those characteristics

individuals with particular characteristics tend to survive and reproduce at a higher rate than other individuals because of those characteristics

then the offspring of individuals favored by natural selection will tend to have the same characteristics that gave their parents an advantage

if adaptation is heritable the frequency of the characteristic may increase in a population over time, the population will have evolved

producers

(autotrophs) use energy from an external source (the sun) to produce their own food. Also called primary producers

net primary production (NPP)

the amount of energy (per unit of time) that producers fix by photosynthesis or olost as heat in cellular respiration

consumers

(heterotrophs) get energy by eating other organisms or their remains

metabolic heat

energy captured by producers is eventually lost from the ecosystem as

how does energy move through ecosystems

energy moved through ecosystems in one direction only- it can’t be recycled

Nutrient Cycle

nutrients are continuously recycled from the physical environment to organisms and back again (food chains)

adaptation

a feature of an organism that improves its ability to survive or reproduce in its environment

How do ecologists answer ecological questions?

no single approach works in all situations, so ecologists use a variety of methods.

• observational studies in the field

• controlled experiments in the laboratory

• experiments in the field

• quantitative models

observational field study

research and surveying in the ecosystems like ponds

controlled experiment

in the laboratory

Field experiment

entire ecosystems, such as lakes or forests are manipulated

replication

performing each treatment more than once; reduces the possibility that results are due to a variable that was not measured or controlled in the study

experimental design

replication

assign treatments at random- also limits the effects of unmeasured variables

analyze results using statistical methods: standardized ways to determine whether observed differences are significant (great enough to be of biological importance)

scientific method

1. make observations and ask questions

2. use previous knowledge or intuition to develop hypotheses

3. evaluate by experimentation, observational studies, or quantitative models

4. use the results to modify the hypotheses, pose new questions, or draw conclusions about the natural world

the process is iterative and self-correcting

why is understanding the physical environment key to understanding all ecological phenomena?

physical environment is the ultimate determinant of where organisms can live, the resources available, and the rate at which populations can grow

weather

current conditions - temperature, precipitation, humidity, cloud cover

climate

long term description of weather, based on averages and variation measured over decades

• includes daily and seasonal cycles, as well as yearly and decadal cycles.

greenhouse effect

increased CO2 and other gases in the atmosphere due to human activities, these gases absorb energy and radiate it back to the surface, like a blanket trapping hot air and raising temperature

what does climate determine?

climate determines the geographic distribution of organisms

climate is characterized by average conditions but extreme conditions are also important to organisms because they can contribute to mortality

climate change effects on weather and environmental

frequency and severity of extreme temperature climate events have increased in association with global climate change

in a Mediterranean-type climate most precipitation is in winter, and summers are dry which promotes fire

the rate at which climate is fluctuating is concerning, not happening in a common ecological order

How does climate affect abiotic processes and periodic disturbances

affects rate of weathering, which releases nutrients that are released back into the system

also influences rate of periodic disturbances such as fires rockslides and avalanches which kill organisms and disrupt communities but also create opportunities for growth of new organisms and communities

climate is changing so fast that organisms can’t recover quick enough

Sun and climate

the sun must lose the same amount of energy that it is gaining, if not the Earth will over heat

Solar Radiation must be offset by energy losses if earth’s temperature is to remain the same

much of the radiation absorbed by Earth’s Surface is emitted to the atmosphere as infrared (longwave) radiation

Earth’s Surface is also cooled when water at the surface evaporates and absorbs energy

latent heat flux

heat loss by evaporation

our oceans have high latent heat flux

conduction

kinetic energy is transferred by molecules in direct contact with one another (friction)

convection

energy transfer by movements of air or water currents

energy is produced with conduction then transferred with convection

sensible heat influx

energy transfer from warm air immediately above the surface to the cooler atmosphere by convection and conduction

heat transferred back to cooler parts of the atmosphere

greenhouse gases effects on the atmosphere

the atmosphere absorbs and reradiates the infrared radiation emitted by Earth

H2O CO2 CH4 and N2O

some gases are produced through biological activity, linking the biosphere to the climate system

earth without greenhouse gases

climate would be 33 degrees Celsius cooler

climate fluctuations

increased concentrations of greenhouse gases due to human activities altering Earth’s energy balance, changing the climate system and causing global warming

the disturbance of convection winter may be cooler than usual

sun rays on earth

sun strikes the equator directly

north and south poles are more shadowed and take the longer path through the atmosphere

establishes latitudinal gradients in temperature and is the driving force for climate dynamics

subsidence

air descends when it cools and forms a high-pressure zone at about 30 degrees N and 30 degrees S

Major deserts of the world are at these latitudes

uplift

heating leads to uplift and low pressure in a large band

hadley cells

large scale circulation patterns resulting from uplift in the tropics

polar cells

at the north and south poles- cold air descends, creating high-pressure zones with little precipitation (polar deserts)

ferrell cells

exist at mid-latitudes

Circulation cells result in

major climatic zones in each hemisphere - tropical, temperate, and polar zones

create surface wind patterns

prevailing winds

air flows from areas of high pressure to areas of low pressure, resulting in consistent patterns of air movements

Coriolis Effect

winds are deflected due to the rotation of the Earth

water

higher heat capacity than land - it absorbs and stores more energy with less temperature change

vertical ocean circulation

surface waters are warmer and less saline (less dense) than deep waters, so the two layers generally do not mix

top layer of ocean has less salt and is warmer, more evaporation, the deeper they get less sun and denser and cooler water

downwelling

warm currents cool and turn into ice in the polar regions, water becomes more saline, and dense and sinks

this water then moves back toward the equator carrying cold polar water

upwelling

prevailing winds blow parallel to a coastline

upwellings influence coastal climates

surface water flows away and deeper colder water rises to replace it

nutrients that are deep down are brought up to the top otherwise they would never receive those nutrients

phytoplankton and upwelling

brought to the photic zone light penetrates the nutrients and helps phytoplankton grow, gives food to zooplankton and their consumers, and are the most productive in open oceans

Ocean Currents

influence regional climate

“heat pumps” or “thermal conveyers”

great ocean conveyer belt is an interconnected system of ocean currents that link all the oceans and transfers heat from the tropics to the poles

maritime climate

little daily and seasonal variation in temperature, and high humidity

coastal areas

continental climates

much greater variation in daily and seasonal temperatures, especially in temperate zones

center of large continents

how do mountains influence regional climate?

temperature decreases and precipitation and wind speed increase with elevation, vegetation types change as you move upslope. When air masses meet mountain ranges, they are forced upward, cooling and releasing precipitation.

rain shadow effect

the windward mountain slope facing the prevailing winds has high precipitation and lush vegetation; the leeward slope gets little precipitation

albedo

amount of solar radiation a surface reflects; light-colored the surfaces have highest albedo

ex: a dark coniferous forest has a lower albedo than bare dormant grassland and absorbs more solar energy

how can vegetation cool the atmosphere?

through transpiration (evaporation of water from inside a plant via its leaves)

Evapotranspiration

water loss by transpiration, plus evaporation from the soil

transfer water and energy (as latent heat) into the atmosphere, thereby affecting air temperature and moisture

deforestation effects on climate

increases albedo = less absorption of solar radiation and less heating; offset by less cooling by evapotranspiration, this results in less moisture in the atmosphere and less precipitation

in the tropics this can lead to a warmer, dryer regional climate

seasonality

earth is tilted at 23 degrees

angle and intensity of the sun’s rays change as Earth orbits the sun, resulting in seasonal changes, especially in temperate and polar zones

influences biological activity and distributions of organisms, especially in temperate and polar zones

intertropical convergence zone (ITCZ)

zone of maximum solar radiation and atmospheric uplift

seasonal changes in precipitation result from movement of the ITCZ

stratified

warm surface water on top of colder, denser water results in layers that do not mix

influences the movement of nutrients and oxygen which are important to organisms

in temperate zone lakes stratification changes with seasons

thermocline

zone of transition between the upper epilimnion and hypolimnion

turnover happens in spring and fall when temperature and density in the water become uniform with depth

El Nino Southern Oscillation ENSO

a switch in the positions of high and low pressure cells over the equatorial Pacific leads to a weakening of the trade winds that normally push warm water toward Southeast Asia

La Nina

stronger phases of the normal pattern; usually follow el nino but are less frequent

comes back with forces and resets the currents in the right direction usually associated with unusual climate change and extreme storms

salinisalty

concentration of dissolved salts in water

salts are highest near equator and come from gases emitted by volcanic eruptions early in earth’s history and the gradual break down of earth’s crust

salinization

soils in arid regions become saline when water is brought to the surface by plant roots or irrigation and high rates of evapotranspiration result in salt build up

acidity

ability of a solution to act as an acid - a compound that gives up protons to a solution

alkalinity

ability of a solution to act as a base - a compound that takes up H+ or gives hydroxide ions

measured as ph

biosphere

lies between the lithosphere (earth’s surface crust and upper mantle) and the troposphere (lowest layer of the atmosphere)

biomes

large scale terrestrial communities shaped by the physical environment, categorized by dominant plant growth forms and characteristics such as leaf deciduousness or succulence

convergence

evolution of similar growth forms in response to similar selection pressures

What influences biome distribution?

determined by Earth’s climate zones

topography, ocean currents, and other factors

human impact

land use change

conversion of land for agriculture, logging, resource extraction, urban development

potential and actual distributions of biomes are very different

climate diagram

a graph of average monthly temperature and precipitation at a location, showing the characteristic seasonal climate pattern

Tropical Rainforests

very rare, found in sparce parts of Africa, Southeast Asia and South America

20% of landmass

abundant rainfall, high biomass and diversity about 50% of earth’s species

Layers of vegetation, each different and dependent on light exposure

Issues with Tropical Rainforests today

about half has been deforested due to logging and conversion to pastures and croplands

recovery is slim, soils are nutrient-poor and recovery takes a very long time

Loss of forest means less biosphere to take up carbon that is being released from soils and decaying vegetation

Tropical Seasonal forests and savannas

north and south of the wet tropics

shorter trees, deciduous in dry seasons, more grasses and shrubs, includes tropical dry forests, thorn woodlands, and tropical savannas

fires promote establishment of savannas- grasses mixed with intermixed trees and shrubs

deserts

at high-pressure zones

high temperatures, low moisture, sparse vegetation, and animal populations

low water availability constrains plant abundance, but diversity can be high, many plants have succulent stems that store water

desertification

long-term droughts and unsustainable grazing

loss of plant cover and soil erosion

temperate grasslands

between 30 and 50 latitude

warm, moist summers and cold dry winters

grasses dominate, maintained by frequent fires and large herbivores such as bison

high soil fertility

North American and Eurasian grasslands

much has been converted to agriculture

grazing can exceed capacity for regrowth leading to grassland degradation and desertification

temperate shrublands and woodlands

between 30 and 40 latitude

evergreen shrubs and trees

mediterranean type climate- cool wet winters and hot dry climates

plants can keep leaves during cool wet winters and not make new ones every year

without the 30 to 40 year intervals of fires shrublands would turn into forests

temperate deciduous forests

30 to 50 latitude

continental edges for tree growth, leaves are deciduous in winter

oaks, maples, and beeches occur everywhere, species diversity is lower than tropical rainforests

4 seasons, becoming less common due to climate change, southern animals are beginning to move north

fertile soils and climate make this biome good for agriculture

temperate evergreen forests

30 to 50 N or S latitude

coastal, continental and maritime zones

high rainfall and mild winters, located on west coasts

lower diversity, leaves tend to be acidic and soils nutrient poor

used for paper pulp, logged extensively

issues impacting evergreen forests today

density of forests has increased which results in more intense fires and increases the spread of pathogens and insect pests

air pollution has damaged some temperate evergreen forests