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CHAPTER 5 HOW ECOSYSTEMS WORK. Chapter 5 - section 3 How Ecosystems Change. ECOSYSTEMS ARE CONSTANTLY CHANGING!!! . Ecological Succession - a regular pattern of changes in a community that occur over time . * the process may take hundreds or thousands of years.
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Chapter 5 - section 3 How Ecosystems Change ECOSYSTEMS ARE CONSTANTLY CHANGING!!!
Ecological Succession - a regular pattern of changes in a community that occur over time * the process may take hundreds or thousands of years
ECOLOGICAL SUCCESSION occurs when 1. a new land area is exposed or when 2. an existing land area is disturbed
Primary Succession occurs on new land areas or where no soil exists What are some examples of primary succession?
Secondary Succession occurs when an existing community had been disturbed What are some examples of secondary succession? due to humans or natural causes ?
How are fires a necessary part of secondary succession? • Some trees only release seeds after exposure to the intense heat of a fire • Minor fires remove brush and dead wood that accumulates • Some animals depend on vegetation that sprout s after a fire has cleared the land
FIRES IN YELLOWSTONE Since 1972 National Park Service policy on fires has been to ….. - allows fires caused by lightning to burn unless they threaten lives, property or unique scenic areas - put out all human-caused fires Fires of 1988 – conditions were unusual • little rain during the summer • summer turned out to be driest on record • the previous winters were dry
Pioneer Species – the first species to inhabit an area Pioneer Community – the first community of living things to inhabit an area Lichens Mosses Small Plants
LICHEN What is a lichen? a mutualisticrelationship between a fungus and alga Alga – produces food (by photosynthesis) Fungi – absorbs nutrients from rocks and makes the environment hospitable for the alga Why are lichens important? the action of lichens begins to break down rock which begins the formation of soil so that succession can occur
Succession CULMINATES when… a final, stable community is established – the final community is called a CLIMAX COMMUNITY climax community in Baja, California is a DESERT
SERAL COMMUNITY = a transitional community or communities that occur before a climax community is established PIONEER COMMUNTIY to SERAL COMMUNITY(IES) to CLIMAX COMMUNITY
What would be the climax community in the eastern US? Deciduous Forest