Ecology

Ecology• study of the interactions

of organisms with their environments– Biotic factors

• Organisms• Populations• Communities

– Abiotic factors

Abiotic factors• Non-living components

– atmosphere is the gaseous earth

• Nitrogen 78%, oxygen 21%, & other gases, including carbon dioxide (at 0.03%)

– hydrosphere is the aqueous earth

• Surface water (rivers, lakes, oceans, etc.), Water vapor, Ice, Subterranean water stores (aquifers)

– lithosphere is the rocky earth • Rock, Soil, Sediment, Dust,

etc.– Energy in its many forms

• Solar, Chemical, Mechanical– In combination: temp., wind,

climate, etc

• Ecosystem– Interactions of

living (biotic) communities and nonliving (abiotic) physical and chemical factors

• Biosphere– Global ecosystem

• All of Earth’s ecosystems

Limits of the biosphere

• Every interaction, at any level, has consequences– E.g. everything we do

affects the people that we interact with and vice versa

– E.g. DDT a popular & very effective pesticide of the 1950s

• Indirectly affected birds, insects, waterways, milk, etc

• Perhaps no part of the biosphere is untouched Rachel Carson, Silent Spring

Marine Ecosystems (oceans & seas)

Freshwater ecosystems

• Lentic systems– Lakes & ponds

• Lotic systems– Flowing water as in

rivers and streams

• Influenced by nutrient levels and productivity

Estuarine systems• Estuaries -- coastal areas

where saline and fresh water mix

– Salinity highly variable– among the most productive

of all ecosystems– rapidly dwindling--primarily

due to development.– prone to eutrophication from

river flow contaminated with fertilizer run-off and livestock manure

Wetlands

• Highly variable• Transitional

– Btwn aquatic & land• Examples

– Perpetually wet mossy bogs and tropical swamps

– Seasonally wet vernal pools

– Estuaries

Terrestrial ecosystems or Biomes• Named for the dominant vegetation

– not necessarily the most common species, but most important to the ecosystem

• Influenced by certain limiting abiotic factors– Temperature– Water availability– Soil type– General climate

• Distribution affected by latitude & altitude

• Described by amount of productivity

– (total biomass)

Deciduous forests -- broadleaf forest, drop leaves in winter; summers hot and humid; winters cold; soil excellent; diversity moderate

Coniferous forests -- evergreen forest, summers more temperate; winters cold (except for some coastal examples); soil poor; diversity low to moderate; broad forests called Taiga, some are fire adapted

Chaparral -- “scrub forest”; typical of Southern Cal; summers hot and dry; winters moderate and wetter; soil poor; diversity low to moderate, tend to be fire adapted

Temperate grasslands -- summers hot and humid; winters cold; soil excellent; diversity moderate to high; these are the croplands of the world, are fire adapted

Tropical grasslands -- hotter than temperate grasslands, droughts more severe; sometimes called Savannah, are fire adapted

Desert – very hot, very dry, poor soil, low diversity

Tundra -- cold windy winters; short windy summers; may have permafrost; plants very low to ground, minimal root system due to permafrost or minimal soil; soil poor; diversity low

Tropical rain forest -- hot & humid; massive rainfall; diversity high; soil poor (erodes quickly, and nutrients tied up in biomass)