Mind Stretcher After one species disappears, the other species in the ecosystem Die Benefit ARE affected Are NOT affected Removing top predators from a food web is always beneficial to the other species. True False

How does an ecosystem get started? Look at the sticks on your desk. Do you notice the light green “stuff”? What is it and what is its purpose.

Succession in Ecosystems

Crash Course - Succession

Succession- a series of changes where new populations in a community gradually appear. There are two types Primary Secondary

Primary succession- Takes place where no life currently exists-like a rock. Much like Zerbia.

Primary Succession- Rock

New bare rock comes from two sources: Primary succession- volcanic lava flow cools and forms rock. Primary succession-

New bare rock comes from two sources: Primary succession- Glaciers retreat and expose rock Primary succession-

Pioneer organisms- The first organisms to colonize a new site in primary succession Ex: lichens are the first to colonize lava rocks

What are lichens? Lichens are two different organisms, algae and fungus, which live together in a mutually beneficial relationship (symbiosis). The fungus protects the algae from the harsh world outside, and provides it with water and mineral nutrients. The algae makes its own food by photosynthesis, and leaks some of this food, which is then absorbed by the fungus (which cannot make its own food).

What makes lichen so special? This partnership is so tough and self-reliant that lichens can grow in places like bare rock in deserts, where nothing else can survive. When it is too dry, too hot, or too cold, lichens go into a state of dormancy until conditions improve. Their only weakness? They must absorb their mineral nutrients from the rain.

An example of primary succession: vegetation recovery on the mudflows of Mount St. Helens At 8:32 Sunday morning, May 18, 1980, Mount St. Helens erupted. The eruption latest 9 hours, but changed 200 square miles of forest into a lifeless, ash covered moonscape. Thousands of game animals died, 12 million salmon, and uncounted millions of birds and small mammals. 57 people were killed.

Forest, before Same spot, after

Fireweed, seen just weeks after eruption, is an example of a “pioneer species”.

Primary succession-

Secondary succession-

Secondary succession- Takes place when Life that had previously existed was disrupted, so some life and nutrient rich soil exists.

Secondary succession- Ex: A fire levels portions of a forest Secondary succession-

An example of secondary succession: The Yellowstone fire of 1988. The fire burnt 1.4 million acres (36% of the park) during a summer that was the driest in the Park's recorded history. $120 million was spent and 25,000 people participated in saving people and property. The fire itself was finally stopped by rain and snow in September.

Secondary succession- Ex: A farmer plows his field

Secondary succession-

Climax community- a stable, mature community that undergoes little or no succession