Ecological Succession http://www.youtube.com/watch?v=V49IovRSJDs&list=PL7A750281106CD067&index=60&feature=plpp_video

Ecological Succession Ecological Succession = the series of predictable changes that occur in a community over time Succession can occur because of slow changes in the physical environment or sudden disturbances, like a natural disaster or human activity.

Ecological Succession Ecosystems are constantly changing in response to natural and human disturbances. As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community. The organisms change the ecosystem over time.

Primary Succession Primary Succession – establishment of plant communities on newly formed habitats previously lacking plants Due to a disturbance that leaves no soil behind: volcanic eruptions or glaciers receding Begins with bare rock Rock  lichen  moss  grass  shrub  oak/hickory forest

What are lichen you say?

What Are Lichen? It is not just one organism, but two organisms living in a symbiotic relationship (fungi and algae) Lichen is a PIONEER SPECIES, which means it is the first species to populate an area. Lichen can grow on bare rock. They help break up the rock as they grow. When they die, they help form the soil so that plants can begin to grow.

Primary Succession Can take 1000 years

Secondary Succession Begins with soil on which the previous ecosystem has been removed (by fire, agriculture, flooding, etc.) First species are small plants (grasses) instead of lichen, because soil is already present and doesn’t have to be formed before things can grow. Soil  Grass  shrub  oak/hickory forest

Secondary Succession Faster than primary succession May only take a few hundred years

Climax Community A stable group of plants and animals that is the end result of the succession process EX. Deciduous Forest = many large deciduous trees, a few coniferous trees, and lots of biodiversity Does not always mean big trees Grasses in prairies Cacti in deserts