Changes in Ecosystems: Ecological Succession 1.5

Changes by Fire Naturally occurring catastrophic events can change the planet we live on. Earth is constantly changing. Sometimes these changes take millions of years, but sometimes they happen in just minutes…

MOST DEADLY AND DESTRUCTIVE VOLCANO IN THE UNITED STATES: MOUNT ST. HELENS

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

Primary Succession Begins in a place without any soil Sides of volcanoes Land uncovered by retreating glacier After flooding when soil was washed away Starts with the arrival of living things such as lichens that do not need soil to survive Called PIONEER SPECIES

Lichen: A combination of algae and fungus that can survive on bare rock, tree bark, and other surfaces. Lichen is a “pioneer species”

Other early species include mosses and ferns Other early species include mosses and ferns. They begin the breakdown of rocks into soil These rocks are slowly becoming the soil!

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 tiny amounts of soil

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

Primary Succession The simple plants die, adding more organic material The soil layer thickens, and grasses, wildflowers, and other plants begin to take over

Primary Succession These plants die, and they add more nutrients to the soil Shrubs and trees can survive now

Primary Succession Insects, small birds, and mammals have begun to move in What was once bare rock now supports a variety of life I’m cute!

Primary Succession: Starts on Bare Rock! No SOIL yet.

Secondary Succession Begins in a place that already has soil & was once the home of living organisms Occurs faster than primary succession Examples after forest fires after agriculture/cultivation

Secondary Succession: Soil already in place

Climax Community A stable group of plants and animals that is the end result of the succession process AFTER SUCCESSION THE POPULATION AND NUMBER OF SPECIES INCREASES!! Nature is all about a balance (equilibrium).

Today’s Reading/Questions 1. What is ecological succession? A. The gradual change of an ecosystem over time; the gradual change of the types of species that live in an area

Today’s Reading/Questions 2. Explain the difference between primary and secondary succession. A. Primary succession begins on bare rock/rocky surface with no existing soil, plants, etc. (“new” land) Secondary succession begins with soil already in place (nature takes over)

Ecological Succession Create a Venn Diagram comparing primary and secondary succession and underneath write a Notes Summary! Summary of the notes and information learned