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Name: _____________________________________________ Ecosystem Balance Environmental Science E2 Ecological Sucession Organisms _______________ the environments in which they live • Some changes are ______________________ • ____________________ help form soil by breaking down rocks • Some changes are ________________________ • Species can alter environment so that a niche ______________________ • Replaced by new niches to which ________________________________ are better adapted • Cause their own _______________________ Other ___________________ can also change the environment • Forest _____________, volcanic eruptions, earthquakes, __________________ As environments change, the ______________________ living in that environment changes • In many cases, different communities follow one another in a definite __________________ Primary Succession The ____________________ of communities forming in an originally _______________ habitat • On ______________ after it has cooled and hardened • Bare ______________ exposed by a retreating glacier Primary Succession is an _________________ process First – _________________________ by new organisms & formation of _______ • Rocks are colonized by ______________________ – a fungus and an alga living in a _______________________ relationship • Lichens secrete ____________ that _______________________ the rock & form organic material • Rocks are also broken down by ___________________________ caused by wind, rain, and frost • The lichen and weather form _______________ Next – after soil has formed, __________________ and small _______________ begin to grow • Seeds are carried to the habitat by _____________ or ___________________ • Plant ______________ continue to break down rocks • Dead __________________ also help soil formation • In time, plants grow dense and tall enough to ______________ the sun from the lichens • The lichen community is ___________________ by the grass community Next – grass community survives for many ____________________________ • Makes the soil _________________ and more fertile • Allows for the growth of _____________________ plants and __________ with deeper roots • In time this foliage becomes tall and dense enough to form a ___________________ that blocks the sun from grasses Next – when the soil is deep enough, _____________ or other trees with _______________________ move in • As trees move in, the community _________________ again • Trees shade out the ______________ and grasses Finally – ___________________ and __________________ trees begin to grow and replace the pines • Hardwood forest is the ________________ stage of succession • It changes very ________________ over time • Climax community – A community that _________________ undergo further _______________ Ecosystem Balance _________________ community E2 _________________ community Secondary Succession Primary succession occurs _____________ on freshly exposed rock or places where _______ the organisms and soil have been removed or destroyed • However, most disturbances are _________ that drastic Secondary succession – occurs where a disturbance eliminates most _______________________ but does ___________ destroy the ______________ • Example: A forest fire will ______________ trees and plants, but leave the soil • Living things can _____________________________ areas created by these types of disturbances • Resembles the ______________ stages of primary succession • Usually begins at the _________________ or ______________ stage Incomplete Succession Many habitats never develop ____________________ communities • It takes several _________________________ years to complete the process of succession • If disturbances occur more _______________________ than that, the area ___________________ complete the succession • Example: A Grasslands Habitat • ____________________ or ___________________ disturbances kill seedling shrubs and trees • Succession _______________ progresses _____________ the grass community Aquatic Succession Succession also occurs in ___________________ habitats • Newly formed lake where water has ____________ nutrients • _____________ and other water plants grow near the _____________ • Organic matter begins to _________________ in the lake • Provides _____________________ for more plants • ____________________ accumulates on the bottom of the lake • More _____________________ can survive • Water plants cover the ___________________ of the lake • Lake fills with sediment and becomes a ________________ • _______________ plants colonize the marsh • Marsh becomes a ______________________ • Meadow ultimately turns into a _____________________ Ecosystem Balance E2 Section Review 1. How does primary succession differ from secondary succession? 2. What is a climax community? 3. Suppose humans put out all the fires in a large area of grassland over a period of 100 years. What would happen to the grassland community? 4. Would you expect primary succession or secondary succession to occur in an area after a tsunami destroyed a coastal community? Explain 5. List, in order, the 6 communities in primary succession from the pioneer community to the climax community 6. Primary succession can occur in which of the following habitats? a. old-growth forest b. new pond c. corn field d. cooled lava field 7. A defining characteristic of a climax community is that it is essentially a. grassy b. forested c. stable d. sedimented 8. The first organisms to colonize a newly formed lifeless habitat are part of a. mature communities b. primary succession c. secondary succession d. a shoreline ecosystem 9. Lichens are important to an ecosystem because they a. help form soil b. prevent trees from growing c. are unstable d. replace older communities 10 A mature, stable, and diverse ecosystem is called a. a habitat b. primary forest c. successful d. climax community 11. Through aquatic succession, a clear lake may eventually become a. an aquifer b. a meadow c. barren rock d. an ocean 12. Which type of disturbance would most likely result in secondary succession a. glacier retreats leaving barren rock b. a volcanic eruption c. rainfall creates a new lake at the top of a mountain d. an earthquake 13 Aquatic succession typically begins a. in the middle of a lake b. at the bottom of a lake c. at the shoreline of a lake d. on the surface of a lake