POB 2 - Exam 2: Week 10

Ecology

the scientific study of the:

* Patterns and causes of the abundance and distribution of organisms 
* Relationships among organisms and their interaction with the environment
* Interactions between organisms and their environments

What greek words does Ecology come from?

Comes from the Greek words *logos* “study of” and *Oikos* “house”

Ecosystem

the biotic community and its abiotic components functioning as a system

Abiotic factors

nonliving attributes (ex: temperature, water, oxygen, salinity, sunlight, soil, nutrients)

Biotic factors

*living* organisms that are part of an individual’s environment

What are the Subfields of Ecology?

Organismal → Population Ecology → Community Ecology → Ecosystem Ecology and Landscape Ecology → Biomes → The Biosphere

Organismal ecology

how individuals adaptations and choices affect their reproduction and survival

Population ecology

how populations grow and interact with other organisms 

Community ecology

factors that influence a number of species in an area

Ecosystem ecology

energy flow and chemical cycling between organisms 

Landscape ecology

factors controlling exchanges of energy, materials, and organisms across multiple ecosystems

Climate

the long-term prevailing weather conditions in a given area

Seasons result from..?

Seasons result from the Earth’s permanent tilt on its axis as the planet orbits the Sun

At what degree is Earth constantly tilted at?

23\.5 degrees

June solstice

Northern Hemisphere tilts towards sun and has longest day and shortest night; Southern Hemisphere tilts away from sun and has shortest day and longest night

March equinox

Equator faces sun directly; neither pole tilts towards sun; all regions on Earth experience 12 hours of daylight and 12 hours of darkness

December solstice

Northern Hemisphere tilts away from sun and has shortest day and longest night; Southern Hemisphere tilts toward sun and has longest day and shortest night

September equinox

the length of day and night is nearly equal all over the world because the Earth's axis is tilted neither toward nor away from the sun, causing the sun's rays to shine directly on the equator.

Summer solstice (June 20)

solar radiation falls directly on Tropic of Cancer

Vernal and autumnal equinoxes

solar radiation falls directly on equator

Winter solstice (December 21)

solar radiation falls directly on the Tropic of Capricorn

What area experiences the least amount of seasonal variation?

The area around the equator

What affects the amount of heat the Earth receives?

The angle at which sunlight hits Earth affects its intensity

What experiences the least seasonal variation and greatest annual input in solar radiation?

The tropics

Arid

having little or no rain; too dry to support vegetation

How does the air at the surface respond to intense radiation?

\
By: descending dry air absorbs moisture; ascending moist air releases moisture (Trade Winds)

Why does warm air rise?

it is less dense

Trade Winds

the wind that flows towards the equator from the north-east in the Northern Hemisphere or from the south-east in the Southern Hemisphere

Why does air cool as it rises?

because less molecules are around to retain heat, causing precipitation

What direction do cooling trade winds blow?

east to west

What direction do Westerlies blow?

west to east; they blow in middle latitudes

Intertropical Convergence Zone (ITCZ)

where northeasterly and southeasterly trade winds meet; high precipitation

Coriolis effect

air is deflected because of the rotation of the Earth

Is ITCZ stationary?

ITCZ is not stationary, it migrates towards the region with the warmest surface temperature

Ocean currents

They are created by winds, the planet’s rotation, unequal heating of surface waters, and the locations and shapes of continents

Gyres

formed as the warm water moves away from the equator

Is specific heat higher or lower on land?

Specific heat (amount of energy it takes to raise 1 gram of substance 1 degree) is lower on land

During the day, does land warm faster or slower than the ocean?

It warms faster

Topography

study of the forms and features of land surfaces

What does Topography influence?

rainfall

Windward

side that faces towards the prevailing, or trade, winds

Leeward

side faces away from the wind, sheltered from prevailing winds by hills and mountains

Forests *_____ solar energy*, but this is offset by…

absorb, transpiration; *more* vegetation absorbs *more* solar radiation = *more* photosynthesis *and* transpiration (cools plants down)

Forests _____ *Earth’s temperature* and _____ *precipitation rates*

reduce, increase; More water returns to the atmosphere, the surface cools (through moist air released by plants) 

Deforested land surface causes:

Higher temperatures, less precipitation

Why do deforested land surface areas cause high temps and less precipitation?

* Less vegetation means reduced photosynthesis and transpiration rates
* Less water returns to the atmosphere; the surface warms

Biomes

major life zones characterized by vegetation type in terrestrial habitats and physical environment in aquatic habitats

What are the six biomes?

1. Desert
2. Temperate Grassland
3. Temperate Broadleaf Forest
4. Tundra
5. Tropical Forest
6. Northern Coniferous Forest

Biomes are _____ → constantly responding to disturbances, such as storms, hurricanes, and human activities

dynamic

* Warm Temperature and Moist Air
* Nutrient-poor soils
* Plants with drip tips towards ends of leaves

Tropical Rain Forest

What is a threat to a Tropical Forest biome?

deforestation

* Succulents, deeply rooted shrubs and herbs are main vegetation
* Reduction of leaves to protect from water loss via transpiration (adaptation)
* Trichomes (protect from evaporative water loss)
* Camels

Desert

What is a threat to Desert Biomes?

urbanization

* Warm year round
* Plants adapted to fire and tolerant to drought
* Thorny trees and small leaves
* Trees create microenvironment→ higher soil nutrients and moisture can be found underneath them 
* Herbivores, insects, carnivores, scavengers

Savanna

Threats to Savanna Biomes?

* Frequent fires
* Cattle ranching
* overhunting

* Mid-latitude coastal regions
* Highly seasonal precipitation
* Rainy winters and dry summers
* Shrubs, small trees, grasses, and herbs adapted to fire and drought
* Amphibians, birds, reptiles

Chaparral

* Seasonal precipitation
* Dry winters and wet summers
* Periodic drought in common
* Many converted to farmland

Temperate Grassland

* Largest terrestrial biome on Earth
* Dominant trees are coniferous (cone-bearing) trees
* Low diversity in lower shrub and herb layers

Northern Coniferous Forest

What is a threat to Northern Coniferous Forest biomes?

logging (a process of harvesting trees)

* Precipitation in all seasons
* Summers are hot and humid
* Deciduous trees (drop leaves before winter) in Northern Hem and Evergreen Eucalyptus in Australia'
* Vertical layering of canopy trees

Temperate Broadleaf Forest

Threats to Temperate Broadleaf Forest

* Logging
* Agriculture
* Urbanization

* Treesless
* Low precipitation
* Cold winters, cool summers
* Permafrost (permanent layer of soil that prevent water infiltration)
* Vegetation close together, low to the ground

Tundra

What is a threat to Tundra biomes?

oil extraction

How much of Earth’s surface do Aquatic biomes cover?

75%

How do Oceans greatly impact the biosphere?

* Evaporated water provides rain
* Photosynthetic organisms supply oxygen and take up carbon dioxide
* Ocean temp influences global climate and wind patterns

Pelagic zone

open water component of aquatic biomes

Photic zone

region where light penetrates and allows for photosynthesis

Aphotic zone

region below photic zone where light does not penetrate sufficiently for photosynthesis to occur

Benthic zone

the bottom surface of an aquatic environment; made of sand and organic/inorganic sediments

Abyssal zone

the part of the ocean's benthic zone 2,000 to 6,000 m deep

Littoral zone

shallow, well-lit waters close to shore

Limnetic zone

farther from shore where water is too deep to support rooted aquatic plants, inhabited by a variety of phytoplankton 

bioluminescence

chemical reaction used to produce light, capture prey and avoid predators

What shapes aquatic communities?

Light and availability of nutrients

How does the benthic zone support organisms?

based on water depth and light penetration

Water becomes _____ dense with _______ salinity

more, increasing

In areas where fresh and saltwater mix, freshwater will…

stay on top of the salt water

Stratification

the arrangement or classification of something into different groups; it leads to seasonal turnover in many temperature lakes

During turnovers, plankton are carried ______, nutrients from decomposition are carried ______.

downward, upward

Turnover

mixing of oxygenated water from the surface with nutrient rich water from the bottom

Thermocline

narrow layer of abrupt temperature change

* Coldest water in the lake (0 degrees C)
* Water becomes progressively warmer at deeper levels of the lake

Winter

* Surface water warms to 4 degrees and mixes with the layers below, eliminating thermal stratification
* Oxygen is brought to the bottom and nutrients to the surface

Spring

* Warm surface; cold bottom

Summer

* As surface water cools rapidly, it stinks beneath the underlying layers, remixing the water until the surface begins to freeze (reestablishing winter profile)

Autumn

Eutrophication

Enrichment of ecosystem with chemical nutrients (Nitrogen, Phosphorus, or both); can be accelerated by human activities

Lentic

non flowing water

Lotic

flowing water

Oligotrophic

low nutrient levels, low algal growth, good light penetration, high dissolved oxygen, deep water

Eutrophic

high nutrient levels, high algal growth, poor light penetration, low dissolved oxygen, shallow waters

* Oligotrophic
* Eutrophic

Lakes

Threats to Lakes

Nutrient runoff

* Headwater is cold, clear, swift and turbulent, rich in oxygen
* As you move down from headwater to downstream, it warms up, more suspended sediment, more turbid (cloudy), and slower moving
* Move from coarse organic matter to fine matter

Streams and Rivers

Threats to Streams and Rivers

* Dams prevent fish from migrating to reproduce and feed


* Invasive species alter trophic dynamics and filter photosynthetic organisms 
* Nutrients that runoff can degrade water quality 
* Climate change and urbanization

* “Earth’s kidneys” because they absorb waste
* Habitat that is inundated (overwhelmed) by water at least some of the time
* Water and soil low in dissolved oxygen
* Bogs
* Most productive ecosystem

Wetlands

Bogs

spongy peat and acidic water, mosses, nutrient-poor

Threats to Wetlands

draining for land conversion (agriculture), mining (ex. peat used for fuel, pollution, human development, lack of knowledge

* Brackish Biome
* Mangroves (plants adapted to conditions)


* Salt marsh plants (air filled spaces in stems allows oxygen to move from leaves to roots w/ out accumulation of CO2)

Estuaries (transition area between river and sea)

Threats to Estuaries

* Support high levels of nutrients carries to them by rivers→ growth of algae


* Coastal development, invasive species, overfishing, dams, upstream pollutants, climate change

* Brackish Biome
* Periodically submerged and exposed to tides twice a day
* Benthic zone can either be rocky or sandy based on exposure to wave action

Intertidal zones