Ecology Chapter 2: The Physical Environment

Climate

•the most fundamental component of the physical environment.

Climate Parameters

•all possible combinations of (Cold/Hot/Wet/Dry)

Weather

short term and highly variable conditions

Climate

long term and less variable conditions

Climatic Variation can include

Seasonal cycles, yearly, and decadal cycles.

Long term climate change results from

changes in the intensity adn distribution of solar radiation

Some scientists think current climate change is possibly due to increased

CO2 and other gases in the atmosphere due in part to human activities

Climate largely determines the geographic distribution of organisms -

firstly primary producers and secondly everything else

Climate effects are characterized by __________ conditions, but ___________ conditions are also important (Piñon Pines example in book) to organisms because they can contribute to mortality.

average, extreme

The physical environment must be characterized by -

its variability over time, as well as average conditions

The timing of variation is also important, such as __________________ of rainfall. For example: In a Mediterranean-type climate, most precipitation is in winter; summers are dry. Dry summers promote fire. Grasslands may receive the same amount of annual precipitation, but it is spread evenly throughout the year. Grasslands may receive the same amount of annual precipitation, but it is spread evenly throughout the year.

seasonality

Climate also affects __________________, such as the rate of rock weathering, which releases nutrients, which in turn influence organisms.

abiotic processes

Periodic disturbances such as fires, rockslides, and avalanches kill organisms and disrupt communities, but also create ___________________________________________________ of new organisms and communities.

opportunities for growth

Energy gains from ___________________________ must be offset by energy losses if Earth's temperature is to remain the same.

solar radiation

Much of the solar radiation absorbed by Earth's surface is emitted to the atmosphere

as __________________ radiation (a.k.a. terrestrial radiation).

infrared

When water at/on the surface evaporates it absorbs energy resulting in a latent heat flux. The stored energy is imparted into the atmosphere via:

conduction and convection

Kinetic energy transferred via molecule to molecule

conduction

Energy transfer by movements of air or water currents

convection

The atmosphere contains greenhouse gases that absorb and reradiate the infrared radiation emitted by Earth =

the greenhouse effect

This greenhouse effect is a natural and necessary process for the normal functioning of the Earth and atmosphere (without the greenhouse effect, Earth's climate would be ~ 33°C _______________).

cooler

Heating of our atmosphere is a direct result of the energy originating from the sun (radiation) interacting with the mixture of gases and suspended materials in the Earth’s atmosphere

(N2, O2)the bulk of the physical components comprising the atmosphere are fairly steady but are essentially invisible to short wave radiation while other less abundant materials –

(ozone, aerosols, water vapor) are much more variable over time and are better absorbers of long wave radiation

In general the intensity of the Sun’s energy varies but in 4 predictable patterns:

Angle, length, thickness, amount

1. ____________ - of incoming radiation changes with latitude and seasonal patterns

Angle

2. ____________________ - of daylight changes with seasonal changes. In Northern hemisphere Summer solstice = longest/ Winter solstice = shortest/ and Fall

& Spring Equinox =12/12 day night)

Length

3. _____________ - of atmosphere radiation travels through to a given point on Earth changes with seasonal pattern

Thickness

4. _______________ - of material sun encounters changes with thickness of atmosphere. Sunset less intense radiation compared to noon day.

Amount

Winds and ocean currents result from differences in solar radiation on Earth’s surface.

• Near the equator, the sun’s rays strike Earth ~ _____________________.

perpendicularly

Toward the poles, the sun's rays are spread over a _________________ area and take a longer path through the atmosphere.

Larger

___________________________________ - heats Earth's surface, which emits infrared radiation (long wave radiation) to the atmosphere, warming the air above it.

Solar radiation

___________________ air is ________ dense than cool air, and it rises (uplifts), air pressure decreases and the air expands and cools (______________________ cooling).

warm, less, adiabatic

___________________ air - holds _________ water vapor than warm air (principles of relative humidity) so as the rising air expands and cools, water vapor _______________________ to form clouds

cool, less, condenses

_________________________ is a warming process (energy from Sun coming back). The pocket of air stays warmer than the surrounding atmosphere and enhances its uplift.

Condensation

__________________ clouds form rain clouds when there is heating at Earth's surface = uplift, and progressively cooler atmosphere above to the boundary between the ________________________________________________ (the two lowest atmospheric layers, respectively).

Cumulus, troposphere and stratosphere

Tropical regions (23.5o N & S) receive the most solar _____________ and the most ___________________.

radiation, precipitation

______________________: (1 of 3 pairs of global convection cells) = the large scale circulation cell ranging from 0-30o N/S of equator resulting from uplift in the tropics

Hadley cells

Uplift of air in the tropics results in an ______________________________________________________________. When air masses

reach the troposphere-stratosphere boundary, air flows towards the poles. Subsidence

occurs as the air descends when it cools and forms a sub tropical high pressure zone at

about 30° N and S.

equatorial low pressure zone

________________________ - of the world are at these latitudes because air in this region is arid and as it descends adiabatically warms.

Major deserts

_____________ __________________- located between 60 to 90o N/S. At the North and South Poles cold air descends, creating high pressure zones with little precipitation—"polar deserts."

Polar cells

__________________ ___________-- located between 30 to 60o N/S, the mid-latitudes.

Ferrell cells

•These three cells result in the three major climatic zones in each hemisphere—______________, ____________________, and ____________

tropical, temperate, and polar zones.

Major ocean surface currents are driven by surface winds, so patterns are similar.

Speed of ocean currents is about _________________of the wind speed

2%-3%

Atmospheric processes influence vertical ocean circulation

•Surface waters of the tropical ocean are warmer and less _______________ (less dense) than deep waters due to influence of Sun’s radiation.

saline

Tropical surface currents move ______________=___________ (via the global winds) where water cools, ice forms, and the water becomes more saline & dense and sinks (downwelling). The sinking water moves along the ocean floor, carrying cold polar water toward the equator.

pole-ward

____________________ (deep ocean water rising to surface) occurs where prevailing winds blow parallel to a coastline. Surface water flows away from the coast and deeper, colder ocean water rises up to replace it.

Upwelling

•Upwelling processes influence coastal climates, bring nutrients from the deep to the _________________________ (provides food for primary producers). Upwelling zones are the most productive in the open oceans.

photic zone

•Ocean currents transfer heat from the tropics to the poles via "________________________________________________________" amongst interconnected Pacific, Indian, and Atlantic Oceans.

great ocean conveyer belt

Large-scale atmospheric and oceanic circulation patterns establish global patterns of temperature and precipitation.

•Average annual temperatures become progressively ______________ from the equator toward the poles. This pattern is influenced by ocean currents, continental topography, and relative distribution of land masses.

cooler

•Air temperatures over land show greater seasonal _____________________ than those over the oceans.

variation

•High elevations have colder climates. Air pressure and

density decreases with elevation—__________________________________________________________________.

fewer air molecules to absorb infrared radiation.

•Lapse rate describes the rate at which temperatures decrease with __________________ __________________ above the surface (1oC/100 m rise in unsaturated air 0.5oC/100 m rise in saturated air).

increasing height

Precipitation patterns associated with atmospheric ____________________ cells are modified by mountain ranges and semi-permanent high- and low-pressure zones.

circulation

Regional climates reflect the influence of the distribution of oceans and continents, mountains, and vegetation.

Coastal areas have a maritime climate with less ____________________ variation and higher ________________________ while continental area have greater temperature variation.

temperature, humidity

On mountain slopes, vegetation shifts reflect climate changes as temperature _______________________, and precipitation and wind speed increase with elevation.

decreases

Mountain ranges also create a rain shadow - the slope facing prevailing winds (windward) has ___________ precipitation, while the leeward slope gets _________________ precipitation

high, little

___________________ - capacity of Earth to reflect solar radiation is influenced by cloud cover, vegetation type, soils, and topography (a coniferous forest has a darker color and lower albedo than bare soil or a dormant grassland.

Albedo

____________________________- •water loss through transpiration by plants, plus evaporation from the soil also influences the climate as it results in a transfer of energy (as latent heat) and water into the atmosphere.

evapotranspiration

Loss of change in _______________ can affect climate

vegetation

_____________________ for example increases albedo and decreases evapotranspiration

deforestation

Seasonal and long-term _________________ variations are associated with changes in Earth’s position relative to the sun.

•Climate has varied over hundreds and thousands of years and has influenced the evolutionary history of organisms and the development of ecosystems.

climatic

•Since Earth is tilted at an angle of ___________° relative to the sun's

direct rays, the angle and intensity of the sun's rays striking

any point on Earth vary as Earth orbits the sun (seasons).

23.5

Temperature & polar zones have pronounced seasonal variation in solar radiation and temperature which influences _______________ activity and __________________of organisms

biological, distributions

Temperate & ________________ zones have pronounced seasonal variation in solar radiation and temperature which influences biological activity and distributions of organisms.

polar

Oceans and lakes become __________________ over time

•In temperate-zone lakes, stratification changes with the seasons. Stratification results in warm surface waters overlaying a colder, denser water layer with little mixing between the two.

stratified

Stratification determines the movement of ____________________________________________;

both are important to organisms.

nutrients and oxygen

In summer, the warm _______________________over lies colder hypolimnion, separated by the ______________________ (zone of transition). Complete mixing (turnover) occurs in spring and fall when water temperature and density become uniform with depth.

epilimnion, thermocline

El Niño and La Niña are temporal processes

•El Niño events occur ~ every _____________________ years and last about 18 months due to changes in high- / low-pressure systems over Pacific.

3 to 8

During El Niño the trade winds which normally push warm surface water toward Southeast Asia reverse. ___________________________ of deep ocean water off the coast of South America ceases, resulting in climate changes. La Niña events usually follow El Niño and are stronger phases of the normal pattern.

Upwelling

Long-term climate change

•Over the past _____________ million years, Earth’s climate has

alternated between warm and cool cycles.

500

•Earth has alternated between ___________________________(glacial maxima) and warm periods (interglacial periods). These glacial–interglacial cycles occur at frequencies of about _________________________ years.

cool phases, 100,000

•We are currently in an interglacial period - The last glacial maximum was about ____________________ years ago.

18,000

The glacial-interglacial cycles have been explained by

regular changes in the shape of Earth's orbit, the tilt

of its axis, __________________________________ cycles, & the intensity of solar radiation reaching Earth.

Milankovitch

________, ______________, and _______________ concentrations are major determinants of the chemical environment.

Salinity, acidity, and oxygen

Salinity - concentration of _____________ _____________in water.

Salts affect the ability of organisms to absorb water and can serve as nutrients as well.

Salinity of the oceans varies between ______-_______ ppt as a result of evaporation, precipitation, and sea ice melting. Salinity is generally higher near the equator & decreases with latitude.

dissolved salts, 33-37

•Ocean salts consist mainly of sodium, chloride, magnesium, calcium, sulfate, bicarbonate, and potassium which come from gases emitted by _______________ __________________ past and present, and from the gradual breakdown of minerals in Earth's crust.

Volcanic Eruptions

Some inland lakes become more saline over time, reflecting a balance between _________________, ____________________, and ____________________ of salts.

precipitation, evaporation, and inputs

_____________________: Soils in arid regions become saline when water is brought to the surface by plant roots or irrigation, and high rates of evapotranspiration which all result in salt build-up.

Salinization

Acidity / Alkalinity measured as pH are important influences on _________________ functions, and the chemistry and availability of nutrients

Organisms have a limited range of pH tolerance. pH variation is more influential in freshwaters and terrestrial ecosystems. In the oceans, pH doesn’t vary much because ocean water acts as a buffer.

metabolic

Environmental pH changes over time

Soils may become acidic due to the selective breakdonw of rocks. Additionally, soils contain organic matter from the decomposition of dead plants and other organisms, which also adds acids to soils.

Acidic pollutants from ________________sources can also increase the acidity of soils and surface waters.

anthropogenic

Oxygen variability influences the environment

Oxygen levels influence chemical reactions that determine nutrient availability.

Availability of atmospheric oxygen decreases with elevation above sea level, as the overall density of air decreases.

Oxygen concentration can vary greatly in soils and water.

Oxygen diffuses slowly into water. Waves and currents help mix oxygen from the atmosphere into water.

A case study- climatic variation and salmon abundance

Salmon are anadromous—they return to streams from the ocean to spawn.

Salmon are important in the culture of Native Americans,

and are currently fished commercially.

Grizzly bears feed on spawning salmon.

Many threats to streams, such as damming, pollution, and overfishing, have decreased spawning and reproductive success of salmon. Additionally, the conditions of oceans, where salmon spend most time as adults, have also been implicated.

Researchers studied fish harvest records and

showed alternating periods of high and low production

associated with climatic variation in the North Pacific.

Periods of high salmon production in Alaska corresponded with periods of low production in Oregon and Washington.

There was also found a correlation between salmon production shifts and sea surface temperatures.

•Research on salmon production led to discovery of the Pacific Decadal Oscillation. The PDO is associated with 20- to 30-year cycles of warm and cool temperatures in the North Pacific.

•

•

•The PDO has been linked to changes in abundance and

distribution of many marine organisms (i.e., salmon).

•

•Through its climatic effects, it influences functioning of

terrestrial ecosystems in western North America, eastern

Asia, and Australia.

•Two aspects of the PDO are significant for ecology:

1.The relationship between climate and organism functioning, growth and reproduction, and population and community processes.

2. PDO phases may be longer than the life spans of most of the organisms

affected by it, limiting their ability to adapt to this climatic oscillation.

•The PDO represents a disturbance, an event that detrimentally affects some species’ populations. Although the causes are uncertain, the PDO has existed for at least the last 400 years. Understanding its effects will help us place other climatic phenomena in perspective.