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Ecosystem Changes. Primary and Secondary Succession. Natural Changes in Ecosystems. There are 3 main ways in which change occurs in our ecosystems: Natural Selection – species change (adapt) to their environment Adaptive Radiation – new species arise
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Ecosystem Changes Primary and Secondary Succession
Natural Changes in Ecosystems • There are 3 main ways in which change occurs in our ecosystems: • Natural Selection – species change (adapt) to their environment • Adaptive Radiation – new species arise • Ecological Succession – changes in the types of organisms that live in an ecosystem
Ecological Succession • Ecological Succession refers to the change that takes place over time in the types of organisms that live in an area • There are 2 types of succession: • Primary Succession • Secondary Succession
Primary Succession • Primary succession occurs in an area where no soil exists, such as bare rock • Natural events such as retreating glaciers can scrape existing rock bare, or new rock can form when lava cools after a volcanic eruption
Primary Succession DO in-class activity! You need: • Different coloured pencil crayons or markers (green, blue, brown, black, grey, etc.) • Big piece of paper, folded into 6 sections (or just draw lines, creating 6 sections) • Listen to Ms. Tompkins tell a story!
Primary Succession Process • Spores of organisms (lichen) are carried to the rocks and begin to grow • Chemical and physical weathering of the rocks develops soil • Decaying lichen adds organic matter (nutrients) to the soil • Spores of plants (mosses) are carried to the new soil and begin to grow • These pioneer species provides food for organisms that move in to the area • Accumulation of soil from weathering and decay develop the soil • Seeds of trees are transported in by animals or wind, etc. to the soil and begin to grow • More niches are created, and more organism diversity occurs • As biotic and abiotic factors continue to change, more and new types of plant and animal species fill up the area • Eventually a mature community develops
Example: Primary Succession time Example: Colonization following a large scale disturbance (volcanic eruption)
Lichen • Lichens are a mutualistic symbiotic relationship between 2 organisms: a fungus and an algae • Lichens secrete (release) chemicals that break down rock • This chemical weathering (plus wind, rain and freezing) helps produce soil
Pioneer Species • Pioneer Species: organisms, such as lichen, that are the first to survive and reproduce in an area • First plants to colonize an area: mosses, lichens & herbs • Rapid growth (opportunistic) • Rapid colonizers • Relatively poor competitors in established environments • Due to symbiotic relationships they can survive in low nutrient environments
Mature Communities • Mature communities (also called climax communities) is a biological community of plants and animals which has reached a steady (stable) state. • The biotic and abiotic factors still change naturally over time, but not as dramatically • These take thousands of years to develop
Secondary Succession • Occurs as a result of a disturbance to an area that already has soil and was once the home of living organisms • Since the soil is already there and has been exposed to living organisms, worms, insects, etc. other seeds may blow in or be carried by animals returning to these areas and begin to grow immediately • Secondary succession only takes several decades
Natural Events that Affect Ecosystems • Natural events can cause disturbances in ecosystems and have an impact on mature communities and result in secondary succession • Example of these natural events include: • Flooding • Drought • Tsunamis • Forrest Fires • Insect infestations
Flooding • Flooding is when the volume of water exceeds the ability of the water body to contain it • Flooding occurs in coastal areas, rivers and lakes • Flooding can result in soil erosion, soil pollution, and widespread diseases • Flooding is attributed with global warming
Tsunamis • Tsunamis are huge, rapidly moving ocean waves • Tsunamis are usually caused by large earthquakes or underwater volcanic eruptions • The force of the wave carries away or destroys plants and animals • The large volume of salt water that is carried onto the shore can also change the composition of the soil, and as a result, plants that cannot survive in a salty environment are unable to grow
Drought • Drought usually occurs when there is a below-average amount of precipitation (rain) in an area over a period of many months or years • Most often ecosystems recover once normal precipitation patters are re-established • Prolonged drought can result in crop failures and livestock deaths
Insect Infestations • Insects play a major role in the natural process of a forest • However due to global warming and human interventions, insect populations are not being kept in check • These large populations of insects are having devastating effects on forests • With large losses to the forest canopy, many bird and mammal nests have been lost.
Homework • Complete Mountain Pine Beetle assignment – this is DUE FOR MONDAY!!
