SUCCESSION Natural Change Over Time

Organization in Ecology Ecosystem Community Population Organism

Ecology also studies how ecosystems change over time and how communities recover from a disturbance. This is called SUCCESSION.

What Is Succession? The orderly, natural progression of stages that communities of an ecosystem go through

Two kinds of SUCCESSION. There are two kinds of succession, depending on how the ecosystem starts out or how an ecosystem is disturbed

PRIMARY SUCCESSION The colonization of barren land by communities of organisms Primary Succession happens when a disturbance destroys the entire community so that there is not even any soil left behind For example a glacier could melt away to expose bare rock.

PRIMARY SUCCESSION Another way to think of primary succession is that it occurs when life enters an area for the first time. In this case the land is completely devoid of soil and vegetation

SECONDARY SECESSION Sequence of changes that takes place after an existing community is severely disrupted in some way However, the disturbance was not big enough to remove the soil. Secondary succession might occur after land is cleared for farming, or after a forest fire.

SECONDARY SECESSION In secondary succession, the dominant plants in the community are removed, allowing new plants to colonize.

PIONEER SPECIES The first species that move into a barren or disturbed area Pioneer Species are tough and can live in conditions that other organisms cannot Many PIONEER SPECIES create soil. For example, lichen attaches to rocks and breaks them down into soil. Mosses and grasses can also be pioneer species. Pioneer Species often colonize a new area by seeds being blown by the wind.

PIONEER SPECIES Please answer the following questions on your own: Why are mosses and lichens pioneer species, but pine trees and deer are not?

CLIMAX COMMUNITY A stable, mature community that undergoes little or no change in species A CLIMAX COMMUNITY is what the community would be like if no disturbances ever occurred. Some ecosystems contain a climax community for hundreds or thousands of years. In other ecosystems, as soon as a climax community is reached a disturbance becomes much more likely. For example, some climax communities use up the nutrients in the soil or increase the likelihood of a fire

CLIMAX COMMUNITY Another way to think of a climax community is an ecosystem that has a steady amount of TOTAL BIOMASS.

Climax community – a mature, stable community - what the community would be like if no disturbances ever occurred. Pioneer species – the first species to populate an area. These species start making the soil  Lichens and mosses are an important pioneer species  #1.6 Aim: How do ecosystems change over time? Agenda QOD (10) Lesson: succession (15) Activity: courtyard scavenger hunt (15) Summary Share (5) HW #5

Typical forest succession Lichens and mosses Flowers and weeds Non-woody plants and grasses Woody shrubs, grasses, tree saplings Young forest Mature trees As the ecosystem changes, the animals change to accommodate the available food and shelter.

Forests In the east, the climax community may be different than the northwest.

What does this graph tell us about succession?

Primary or Secondary? Volcanic Eruption Clear Cutting Tornadoes, clear-cutting, and fires all cause secondary succession. Volcanic eruptions destroy the soil base, so succession is primary– first build soil.

Primary or Secondary? Tornados Mudslide

Exit Ticket 1) What is the difference between PRIMARY and SECONDARY succession? 2) How do PIONEER SPECIES help speed up the process of ecological succession?