ECOLOGICAL SUCCESSION ByDr P B Sirsat Assist Professor

ECOLOGICAL SUCCESSION By-Dr. P. B. Sirsat Assist. Professor in Zoology, B. SC. T. Y.

ECOLOGICAL SUCCESSION Ecosystems tend to change with time until a stable system is formed. The stable system that will form depends on climatic limitations.

Definition: Natural, gradual changes in the types of species that live in an area; can be primary or secondary The gradual replacement of one plant community by another through natural processes over time

Ecological Succession The replacement of one community by another until a stable stage is reached is called ecological succession.

Primary Succession` Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil

Primary Succession These plants die, and they add more nutrients to the soil Shrubs and trees can survive now The simple plants die, adding more organic material The soil layer thickens, and grasses, wildflowers, and other plants begin to take over

Primary Succession Simple plants like mosses and ferns can grow in the new soil

Secondary Succession Begins in a place that already has soil and was once the home of living organisms Occurs faster and has different pioneer species than primary succession Example: after forest fires When a community is disrupted and succession occurs again, it is called secondary succession. Disruption may be from fire, farming, wind, foresting

Ecological Succession The replacement of one community by another until a stable stage is reached is called ecological succession.

Climax Community The final stage of succession is called the climax community. The climax community in New York State is an oakhickory forest or a maple-beech forest.

Primary Succession Primary succession occurs where there was no previous community, such as on bare rock or sand. Primary succession begins with pioneer organisms.

Pioneer Organisms Pioneer organisms can tolerate extreme conditions: hot and cold; dry and wet. Moss, dune grass, and lichens are pioneer organisms.

Lichens are algae and fungus growing together in a mutualistic relationship. Algae make the food; fungus anchor and capture water.

Pioneer organisms Soil is produced over hundreds of years by pioneer organisms. These organisms break apart rock, add humus as they die and decompose, and hold water This allows other organisms to grow there.

Succession occurs BECAUSE Each community changes the conditions so that they are more favorable to other organisms that replace them. For example, some types of trees need a lot of sun and their saplings cannot grow under the shade of their own species. They will be replaced by the types of trees whose saplings can grow in shade of other trees.

A community is still undergoing succession As long as the species keep changing: Here, the plants growing under the pine trees are NOT small pine trees, so the species will be changing as the old pine trees fall.

Climax Community The same climax community will develop unless the abiotic conditions have changed.

We can tell it’s a climax community A climax community replaces itself with more of itself: Under sugar maple trees, we will see sugar maple saplingsthat shows that it is a climax community

Climax Community The climax community will be part of the BIOME of that area. Our climax communityoak/hickory forest-is part of the temperate deciduous forest biome

A stable group of plants and animals that is the end result of the succession process Does not always mean big trees Grasses in prairies Cacti in deserts

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