Ecosystem ChangesPrimary 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

Primary Succession

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

Primary Succession Process

Primary Succession

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

Mature Communities

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

Secondary Succession

Secondary Succession

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

Natural Events that Affect Ecosystems

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

Flooding

Flooding

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

Tsunamis

Tsunamis

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

Drought

Drought

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.

Insect Infestation

Insect Infestations