Ecological succession



Ecological succession

Ecosystem Stability

The interrelationships and interdependencies of organisms affect the development of stable ecosystems. The types of animal communities found in an ecosystem are dependent upon the kinds of plants and other producer organisms in that ecosystem.

Succession

|A Typical New York State Succession |

|[pic] |

The environment may be altered in substantial ways through the activities of humans, other living things, or when natural disasters occur, such as climate changes and volcanic eruptions. Although these changes are sometimes occur very quickly, in most cases species replace others gradually, resulting in long-term changes in ecosystems. These gradual long-term changes in altered ecosystems are called ecological successions. Ecosystems tend to change with time until a stable system is formed. The type of succession, which occurs in an ecosystem, depends upon climatic and other limitations of a given geographical area.

|A Pond Succession Sequence |

|[pic] |

Pioneer organisms are the first organisms to reoccupy an area, which has been disturbed by a disruption. Typical pioneers in a succession include grasses in a plowed field or lichens on rocks. These pioneer organisms modify their environment, ultimately creating conditions which are less favorable for themselves, but establishing conditions under which more advanced organisms can live. Over time, the succession occurs in a series of plant stages, which leads to a stable final community, which is very similar to the plant community, which originally existed in the ecosystem. This final stable plant community is called a climax community. This community may reach a point of stability that can last for hundreds or thousands of years.

It has been observed that when natural disasters occur, such as a floods or fires, the damaged ecosystem is likely to recover in a series of successional stages that eventually result in a stable system similar to the original one that occupied the area.

Material cycles

|The Water Cycle |

|[pic] |

The atoms and molecules on the Earth cycle among the living and nonliving components of the biosphere. Some of the water molecules, which are used in photosynthesis, are returned to the environment. The change of water from the liquid to the gas state is called evaporation, while the water lost to the atmosphere by the activities of plants is referred to as transpiration water loss. This water vapor eventually condenses to form clouds, and is returned to the earth as precipitation. This process is called the water cycle. The processes of cell respiration and excretion also release some water to the environment as well.

|The Carbon-Oxygen Cycle |

|[pic] |

Carbon dioxide molecules are used in the process of photosynthesis to form energy-rich organic sugar compounds. These carbon dioxide molecules are returned to the environment by the process of cell respiration, when the energy from these compounds is eventually released by cells. Some carbon is also returned to the environment by the decomposition of dead organisms.    

Oxygen is required by many living things to release the energy in their food in the process of aerobic cellular respiration. Oxygen is released to the environment as a waste product of the process of photosynthesis.

Other compounds, such as nitrogen, are cycled in the environment when organisms synthesize proteins from simpler compounds and then return these nitrogen compounds to the environment when they die and decompose.

Name: _______________________________________ Date: __________ Period: __________

Cycles and Succession Activity

|_______________________ |

|[pic] |

Define and explain:

1. Precipitation

2. Evaporation

3. Condensation

4. Infiltration

5. Runoff

6. Transpiration

|______________________ |

|[pic] |

Define and explain:

1. Photosynthesis

2. Respiration

3. Combustion

Define and Explain:

1. Nitrogen fixation

2. Why does nitrogen need to be “fixed” by bacteria?

Define and Explain:

1. Primary Species

2. Climax community

3. Is this picture primary or secondary succession?

4. Why? (provide facts and details)

5. What is the difference between primary and secondary succession?

-----------------------

[pic]

[pic]

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download