Ecology

Communities and Biomes

Limiting Factors

environmental factors that affect an organism’s ability to survive

Two typesDensity-dependentDensity-independent

Limiting Factors Density-dependent factors has increasing effect as the population increases Examples:

Food & Water supply

Predators

Parasitism Disease

Shelter & Space

Predator-Prey Relationships

Limiting Factors Density-independent factors- affects all populations

regardless of density Most abiotic factors

earthquake

storm

temperature

flood

fire

What would a football field look like in thirty years if it was not cared for or played on?

?

Succession orderly, natural changes and species replacements

that take place in the communities of an ecosystem

Lake Succession

Succession Begins with: Pioneer plants- first

organisms to inhabit an area

Ex. Moss and lichen

Ends with: Climax community-

tends to remain stable or long periods of time with little or no change

Primary Succession colonization of a new site from rock

Secondary Succession sequences of changes that

take place after a community is disrupted by natural or human actions.

Ex.- abandoned building, fire, hurricane

Trends in SuccessionSmall plants with short life cycles are

replaced with large plants with long life cycles

diversity increases

less energy is wasted

food webs become more complex

populations stabilize

Biomes of the World Biome- a large group of ecosystems that share the

same type of climax community Aquatic biomes- approximately 75% of the earth’s

surfaceOceans, lakes, rivers

Terrestrial biomes- land

Terrestrial Biomes

Taiga 19%

17%

Terrestrial Biomes3 factors that influence type of biome

Latitude

Altitude

precipitation

}Influences temperature

Sample Climatograph

Terrestrial BiomesTundraTaigaTemperate forestTropical RainforestGrasslandsDesert

Tundra

12 cm precipitation per year usually snow

long winters and darkness Permafrost -soil remains

permanently frozen Long winters and darkness,

Short summers Russia, Iceland, Greenland Low temperatures Plants have fast life cycles Animals-Snowshoe hare, caribou,

reindeer, voles, ducks, geese

Taiga largest biome wet climate, foggy acidic soil Most of Canada, Alaska, Eurasia 35 to 40 cm precipitation yearly Plants- large coniferous forest

(firs, pines) Animals- Moose, elk, wolves,

porcupines, caribou, black bear,

crossbills

south of Taiga has definite seasons most of US, N & S America, Europe

and Asia ~ 100 cm precipitation yearly mixture of trees

(pines and hardwoods-deciduous trees) plants shed leaves in winter, Animals- Deer, opossum, black bear,

fox, squirrel, many bird species

and insects

Temperate Forest

Tropical Rainforest equatorial almost constant temperature of 25 oC > 250 cm of rain fall or more yearly very humid greatest diversity Central and South America   Plants- large variety, tree branches

form canopy, vines Animals-Toucans, monkeys, gorilla,

tree frogs, snakes, lizards, parrots

Grasslands steppe, plains, or prairie West of Mississippi Uneven rainfall 25-75 cm Plants- Scattered trees,

grass varies in length Animals-Bison, antelope, gophers, jackrabbits, sheep

Desert less than 25 cm of rainfall yearly long droughts Can have high or low temperature W US, Africa, India, Asia, S America sparse vegetation Plant adaptations for survival

shallow root systems– absorb little rainfall quickly

stems can photosynthesize, leaves modified to needles waxy cuticle Cacti

 Small animals- lizards, kangaroo rat, scorpions, snakes