Lecture 18 Bio 113L (Physical enviorment)

Ecology

The study of distribution and abudance of organisms and thier interaction with the enviorment

Components of the enviorment

Physical

• conditions

• resources

Biological

• inter and intra species interactions

Climate

Average course of weather conditions (temp, precip, wind)

How does the temperature change with increased latitude?

Mean temperature decreases with latitude

Seasonal variation increases with latitude

Seasonal variation greater in North Hemisphere

How does seasonal variation of temperature change on land vs sea?

Seasonal variation is greater on land than sea

Solstice vs Equinox

Solstice: points in the year where the Earth’s tilt is the highest or lowest point toward the sun

Equinox: points in the year when day and night are of equal length. (tilt is aligned)

Thermal niche breadth…with latitude

Increases with latitude for terrestrial organisms (little change for aquatic)

3 types of wind cells and their behavior

Hadley Cell - between these is the equator with mass precipitation (location of intertropical convergence zone

Ferrel Cell - intermediate cell. Between these and Hadley cells are subtropical jets (Horse latitudes) with little precipitation→ subtropical high-pressure zone

Polar Cell - northern or southernmost cells →between theses and ferrel cells lie the polar jets (polar fronts) (60*N) with much precipitation.

3 types of winds

Tradewinds(Hadley), Prevailing westerlies (west to east), Polar easterlies (east to west)

Coriolis effect

the apparent curvature of path for long-distance moving objects (like air currents, ocean water, or planes) caused by the Earth’s rotation

Adiabatic cooling

• Warm, moist air is forced upwards

• cooling occurs

• dew point reached→rainfalls

The reason why mountain tops are cooler, and one side of the mountain is usually lush while the other side is barren.

Also driven by cell behavior.

Ocean Currents are driven by…

Tradewinds and prevailing westerlies

El Nino vs La Nina

El Nino- Increased convection, increased precip in certain areas

La Nina - normal convective loop.

Pathway for Climatic variation

Orbit around the sun→seasonal variation→Lattitudinal temperature gradient→Atomspheric circulation patterns →leads to ocean currents →Local temperature and rainfall patterns.

Plate tectonics →Mountains/topography→Atomspheric circulation patterns

Greenhouse effect and desertification

Rainforrest common features

Plants with buttressed roots, large amounts of rain

Tropical deciduous forest features

Drop leaves in dry season, not when it is cold (10-25 lat)

Subtropical deserts

Sonoran- Mild wet winters, summer monsoons, many plant growth forms

Mohave - Winter rains, few trees

Cold deserts

Freezing temps

Low precip.

Chaparrel conditions

Mediterranean climate → evergreens, hot dry summers, rapid regrowth after wildfires.

Temperate rainforest

High rainfall, moderate temperatures

Temperature deciduous forest

Drops leaves in winter

1) less transpirational demand

2. lower risk of freeze induced embolism

Boreal forest

Small leaved plants heat up less

Small diameter tracheids less prone to embolism then vessel elements of angiosperms

Tundra

Very short growing season, Dwarf shrubs and trees.

Mountains and Rainshadows

Adiabatic cooling causes these → Himalays vs Gobi desert is an example

Biogeographic realm vs Biome vs Ecoregion

Biogeographic realm - geographically isolated barriers to gene flow (servers essentially)

Biome types - shared among bio geographic realms → determined by climate and soil

Ecoregions - subdivisions of biogeographic realms; not isolated by barriers to dispersal.