Biological Succession SPI 3210.2.7

Bell Ringer Which of the following is MOST LIKELY to lead to secondary succession? A- a forest fire C- the retreat of a glacier B- a volcanic eruption D- strip mining (vegetation and soil removed) Which term refers to the oldest stage of a forest’s development? A- pioneer forest C- climax forest B- secondary forest D- conifer forest Which of the following organisms are MOST LIKELY to be found on a small island that was recently formed by a volcanic eruption? A- climbing vines C- grasses B- hardwood trees D- lichens

Ecological succession Primary succession: follows a disturbance that destroys all the living things and soil in an area. Ex). Happens close to a volcanic eruption where red-hot lava has flowed over the land and fiery ash has rained down on it Ex). After glaciers have recede from an area, leaving behind piles of rocks and boulders on barren land Secondary succession: follows a disturbance that has wiped out most living things in an area but has not destroyed, covered, or removed the soil. Ex).When people clear-cut a forest, they remove all the trees and most other plants, leaving only the fertile soil behind. Ex). Hurricane can blow down large stands of trees and shrubs leaving behind the soil of an open forest floor. The soil contains seeds of the plants that had grown there before the disturbance.

Pioneer Species Pioneer Species: The first organisms to return to an area after a disturbance Organisms such as: lichens (combination of algae and fungi) and mosses -----break down rocks, which is the first step in the production of soil. Animal population in an ecosystem depends on the plant populations. Insects, birds, and small rodents are some of the animals that enter a young ecosystem to feed on and seek shelter among the small plants WHY DO TREES OFTEN REPLACE GRASSES DURING ECOLOGICAL SUCCESSION? A- trees grow better in warm climates B- animals carry tree seeds from long distances C- grasses cannot grow in the shade D- Animals eat all the grass of trees

Climax Community When an ecosystem reaches a stage in which it does not change The make up of the climax community depends on the climate Ex). Warmer areas: conifers will often be replaced by deciduous forest. STABLE FOR A LONG TIME BEFORE EXPERIENCING A NEW DISTURBANCE!

Questions 1). Which of the following organisms are MOST LIKELY to be found on a small island that was recently formed by volcanic eruption? A- climbing vines C. grasses B- hardwood trees D. lichens 2). Which of the following is MOST LIKELY to be followed by secondary succession? A- filling of a wetland to build C. clear-cutting of a mountainside a shopping mall B- retreat of a glacier D. introduction of a new species