Ecology Communities and Biomes

Limiting Factors  environmental factors that affect an organism’s ability to survive  Two types  Density-dependent  Density-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 Succession  Small 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 surface  Oceans, lakes, rivers  Terrestrial biomes- land

Terrestrial Biomes

 3 factors that influence type of biome  Latitude  Altitude  precipitation } Influences temperature Sample Climatograph

Terrestrial Biomes  Tundra  Taiga  Temperate forest  Tropical Rainforest  Grasslands  Desert

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 o C  > 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 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