Warm-Up: (1/06/15) Have you ever observed a vacant lot or an untended garden over a period of time?What changes did you see? Ecological Succession
The shrubs, moss or grasses you see when walking along a sidewalk could be the beginnings of new, natural communities. Given enough time, each area would become a complex and stable community. Succession and its Causes
Ecological succession the gradual rebuilding of an ecosystem after a drastic change. Natural, gradual, predictable changes in the types of species that live in an area; can be primary or secondary The gradual replacement of one plant community by another through natural processes over time Succession and its Causes
The diversity of organisms living in each community today is not the same as it was in the past. Biotic and abiotic factors have changed over time. What Causes Ecological Succession?
During succession, organisms alter their physical surroundings in a way that makes those surroundings more suitable for other kinds of organisms and less suitable for themselves. As a result, new organisms invade and the old organisms move out. Primary Succession Primary Succession: begins in areas where when starting out, there is no life, no topsoil and no ecosystem. Examples: Volcano, Sand dunes or Glacial Retreat This stage begins with very tough organisms - those that can grow under adverse conditions. Life after a Volcano (May 1980-Present)
Primary Succession: Life after a Volcano (May 1980-Present) Mt. St. Helens Primary Succession: How a Sand Dune becomes a Forest
Dune grassescottonwoods+shrubsevergreensoaksbeeches maples Primary Succession bare rocklichensmossesgrassesshrubstrees 1. 2.
3. 4. 5. Primary Succession The first species to populate an area is called the pioneer species. Pioneer species are often LICHENS and moses carried by wind or water, and can grow on bare rocks with little or no soil. Primary Succession Lichens - Its not a plant. It is one living thing made up of two organisms - algae and fungi. They work together, and weathers (definition?) rocks into topsoils. This often takes a long time. Lichens often grow in places where plants can't like bare rock.They still use photosynthesis for energy! Lichens Primary Succession Secondary Succession Succession often begins as a result of natural destruction, such as a fire, farm abandonment, deforestation, flooding, drought or by some human interference. If the land is left untended, secondary succession occurs. This happens more quickly than primary succession, soil is already present/formed and seeds may be present. Two photos of the same place, picture on the left taken one year and picture on the right two years after a fire. Secondary Succession Succession often begins as a result of natural destruction, such as fire, farm abandonment, deforestation, flooding, or by some human interference. Example: Hurricane Two photos of the same place, picture on the left taken before and after a hurricane. Secondary Succession Secondary Succession Farm Abandonment 1993 In 1993 the land here was cleared purposefully and then treated with Roundup to clear the site of all plants. The purpose was to observe the natural succession. 1998 As you can see, during Secondary Ecological Succession the PIONEER SPECIES are typically weeds and grass (since soil is already in place). 2002 2004 Climax Community climax community :The stable/final stage in the development of a community Because it is stable and complex, a climax community tends to remain the same over a long period of time without further succession.It could take centuries to reach this level. Equilibrium: When the numbers and species of organisms do not change suddenly in a community (aka a stable state of balance) . Climax community Climax Community Astable group of plants and animals that is the end result of the succession process Does not always mean big trees Grasses in prairies Cacti in deserts Primary vs. Secondary START: No soil FIRST: Pioneer species
Weathering & decomposition Humus (soil) and sand increase over time END =Climax ommunity START:Soil already exists FIRST: Seeds have suitable soil conditions. Occurs much faster END = Climax community. Pond Succession Pondmarshdry land/grassesshrubsforest Pond Succession Pond Succession If left unattended, ponds will fill in with dirt and debris until they completely fill in. It often takes hundreds of years for a pond to be transformed from a body of water into soil. Question 1: What type of change or disaster to an ecosystem might cause ecological succession? Flood, fire, windstorm, drought, lava flow, glacial retreat ,etc.
Answer 1: Flood, fire, windstorm, drought, lava flow, glacial retreat ,etc. Question 2: What type of change or disaster to an ecosystem might cause ecological succession? Humans often clear land for farming or ranching.
Answer 2: Humans often clear land for farming or ranching. When used, land is abandoned.Over time, the land may begin the process of secondary succession to rebuild itself. Question 3: If land is destroyed, how are seeds available to produce new plant life? Answer 3: Many seeds remain dormant in the soil until the environment is ale to support plant life.Others are carried by wind, water, or animals. How is primary succession different from secondary succession?
Question 4: How is primary succession different from secondary succession? Primary vs. Secondary No soil Pioneer species
Weathering & decomposition Humus and sand increase over time End =climax community Soil already exists Seeds have suitable soil conditions. Occurs much faster Climax community. Question 5: A field is destroyed by decades of agriculture, and then abandoned.When ecological succession begins, what is the first plant life to grow? A. trees B. bushes C. grasses D.vines Answer 5: A field is destroyed by decades of agriculture, and then abandoned.When ecological succession begins, what is the first plant life to grow? A. trees B. bushes C. grasses D.vines Question 6: When primary succession begins, what is the first species to populate an area called? Give an example. Answer 6 The first species to populate an area is called the pioneer species. Pioneer species are often lichens and moses carried by wind or water, and can grow on bare rocks with little or no soil.