Properties of Communities & Succession

Communities & Species Diversity• Remember… a community is a group of

populations living together is a defined area.• Species Diversity is the number species living in a

community (The more species living in an area, the higher species diversity it will have)

Community Stability• Ecosystems & Communities are constantly changing

in response to natural and human disturbances

• As ecosystems change, older inhabitants gradually die out, while new organisms move in, causing additional changes to the community.

• Succession is a series of the gradual, sequential re-growth of a community over time

• There are 2 types of succession1. Primary succession2. Secondary succession

Primary Succession Primary Succession - the development of a community in an area where NO life has previously lived and no soil is

presentEx: The surfaces of land covered by lava or volcanic ash after a volcano eruptsEx. The bare rock exposed when glaciers melt.Ex. An abandoned parking lotEx. Sand dune

This process proceeds very slowly Minerals necessary for plant growth are unavailable

Pioneer Species- the first species to populate the area such as lichen (small, fast growing/reproducing)•Lichen is made up of a fungus and an alga and can grow on bare rock. When lichen die, they add organic materials to help form soil allowing plants to grow

Primary Succession

Secondary SuccessionSecondary succession takes place when some

disturbance changes an existing community, WITHOUT removing the soil.

Ex: Land that has been cleared and plowed for farming and then is abandoned

Ex. Wildfires • Through the process of succession, after

hundreds of years a more stable community may result. This community is referred to as the climax community.– This community remains constant for along period

of time but can still undergo change