Primary and Secondary Succession

 Succession refers to the change that take place over time in the types of organisms that live in an area  Primary succession occurs in an area where no soil exists, such as bare rock  Natural events such as retreating glaciers can scrape existing rock bare, or new rock can form when lava cools after a volcanic eruption

 Spores of organisms (lichen) are carried to the rocks and begin to grow  Chemical and physical weathering of the rocks develops soil  Decaying lichen adds organic matter (nutrients) to the soil  Spores of plants (mosses) are carried to the new soil and begin to grow  These pioneer species provides food for organisms that move in to the area  Accumulation of soil from weathering and decay develop the soil  Seeds of trees are transported in by animals or wind, etc. to the soil and begin to grow  More niches are created, and more organism diversity occurs  As biotic and abiotic factors continue to change, more and new types of plant and animal species fill up the area  Eventually a mature community develops

 Mature communities (also called climax communities) is a biological community of plants and animals which, through the process of ecological succession, has reached a steady state.  The biotic and abiotic factors naturally change over time, but not as dramatically  These take thousands of years to develop

 Occurs as a result of a disturbance to an area that already has soil and was once the home of living organisms  Since the soil is already there and has been exposed to living organisms, worms, insects, etc. other seeds may blow in or be carried by animals returning to these areas and begin to grow  Secondary succession only takes several decades

 Natural events can cause disturbances in ecosystems and have an impact on mature communities and result in secondary succession  Example of these natural events include: ◦ Flooding ◦ Drought ◦ Tsunamis ◦ Insect infestations

 Flooding is when the volume of water exceeds the ability of the water body to contain it  Flooding occurs in coastal areas, rivers and lakes  Flooding can result in soil erosion and soil pollution and widespread diseases  Flooding is attributed with global warming

 Tsunamis are huge, rapidly moving ocean waves  Tsunamis are usually caused by large earthquakes or underwater volcanic eruptions  The force of the wave carries away or destroys plants and animals  The large volume of salt water that is carried onto the shore can also change the composition of the soil, and as a result, plants that cannot survive in a salty environment are unable to grow

 Drought usually occurs when there is a below-average amount of precipitation (rain) in an area over a period of many months or years  Most often ecosystems recover once normal precipitation patters are re-established  Prolonged drought can cause result in crop failures and livestock deaths

 Insects play a major role in the natural process of a forest  However due to global warming and human interventions, insect populations are not being kept in check  These large populations of insects are having devastating effects on forests  With large losses to the forest canopy, many bird and mammal nests have been lost.