Succession

• Succession – the orderly natural changes and species replacements that take place in the communities of an ecosystem

• Takes a long time, not easily observable

• Occurs in stages

Primary Succession

• From a disturbance, such as rocks moving to expose new soil starts Primary succession.

• Pioneer species set up such as mosses and lichens

• As these species die, they create soil for further species

• Shrubs, ferns, grasses come next

• Pines, beeches and maples colonize after that

• When the community stabilizes, a climax community is established– How can you tell?

Secondary Succession

• Occurs when interrupted by natural disasters or human actions

• Occurs in areas that previously contained life and soil.

• Pioneer species maybe different since the soil is already present

• Occurs by the same process as primary succession.

• Takes less time– Why?

Biomes

• Ecosystems that have similar kinds of climax communities are called Biomes.

• Biomes are limited by temperature and precipitation (terrestrial types)

• There are two major types of biomes– Aquatic (those in the water, sea) (3/4 of the

Earth)– Terrestrial (those on land)

Marine Biomes

• Estuary – coastal body of water, in part surrounded by land where freshwater and saltwater mix.

• Scientists separate marine biomes into two parts:– Photic Zone : portion of the

biome shallow enough to allow light through

• Plankton, juvenile marine organisms

– Aphotic zone : deeper water where light cannot penetrate

• Adapted to life in the dark.

Terrestrial Biomes - Tundra

• Tundra – Circles the poles, treeless with long summer days and short periods of winter sunlight

• Under the topsoil is a frozen part called permafrost.

• Soil is nutrient poor and can’t hold larger plants & trees

• Small mammals live there like owls and lemmings

Taiga

• Taiga – just south of the tundra

• Warmer than the Tundra, land of fir & spruce trees

• Canada, Northern Europe & Asia

• Contains larger species like Caribou, snowshoe hare

Desert

• Desert – driest biome with sparse plant life

• Less than 25 cm of precipitation

• Organisms have adapted to conserve water (mice, scorpions, snakes, owls, etc)

Grassland

• Grasslands – covered by grasses and similarly small plants

• 25 – 75 cm of precipitation

• Occupies more area than any other land biome

• Good for growing crops• Dominated by grazing

animals (bison)

Temperate Forest

• Temperate Forest – above and below the equator

• Nutrient rich soil with Hardwood trees

• 70 to 150 cm of precipitation

• Home to many forest animals (bears, squirrels, salamanders)

Tropical Rain Forest

• Tropical Rain Forest – located at the equator

• Warm and wet with lush plant growth

• Average 25C, with 200-600 cm of rain

• Home to the most amount of species on the planet

• Has many niches due to the layers of the rainforest (forest floor, trees, canopy, etc)