Ecological Succession
Transcript of Ecological Succession
Ecological Succession
Ch. 4 continued
How do ecosystems change over time?
• Always changing in response to natural and human disturbances– Older inhabitants die out, new organisms
move in
• Ecological succession – predictable changes in a community over time– Caused by slow changes in physical
environment– Caused by sudden natural disturbance
What is primary succession?
• Succession on land where no soil previously existed– Hardened volcanic lava
or ash– Rocks exposed from
glacier melt
• Pioneer species – 1st to populate an area– i.e. Lichens– Creates soil
c. Steps of Primary Succession
1. Formation of Soil- rocks broken down by
lichen- pioneer species (1st in area)
weathering- wind, rain, frost
2. Colonization- of plants and animals
Grasses & small plants
Shrubs
Pine trees
Deciduous trees- oak, hickory, maple, elm
3. As plants move in, they create shade. This causes smaller plants to die off. As they die, their bodies decompose and create more soil. This allows larger plants to take over.
4. As plants become established, animals will move in. Herbivores first followed by their predators.
5. This process can take 100’s of years.
*** A final stable complex community will form- CLIMAX COMMUNITY.
What is secondary succession?
• Follows a community changing disturbance– Wild fires, humans clearing land
• Climax Communities – ending point of succession – mature stable community– Still goes through change over time
Secondary Succession after a fire
Secondary Succession of
a
Lake
Succession in Marine Ecosystems
• Begins with the death a large animal like a whale• Carcass sinks to barren ocean floor• Scavengers and decomposers feast on dead meat• Meat is gone now and population of scavengers is
smaller• Decomposed nutrients in sediment attract many
sediment dwellers like worms• Lastly, heterotrophic bacteria decompose oil in
remaining bones• This releases chemical compounds which serve as
energy for chemosynthetic bacteria which serve as food for a diverse marine community
Biomes
• particular physical environment with unique set of abiotic factors, especially climate, and a characteristic ecological community
• Major biomes: tropical rainforest, tropical dry forest, tropical savanna, desert, temperate forest, temperate grassland, temperate woodland and shrubland, NW coniferous forest, boreal forest, and tundra
Other land areas
• Don’t fit neatly within a biome
• Mountain ranges – abiotic and biotic factors vary with elevation
• Polar Ice Caps -
Describe some aquatic ecosystems.
• Determined by depth, flow, temperature, and chemistry of overlying water
• Inhabitants specially adapted to each ecosystem
• Freshwater ecosystems– Flowing water – rivers,
streams, creeks– Standing water – lakes,
ponds
More aquatic ecosystems
• Estuaries – wetlands where rivers meet the sea, fresh and salt water – made of mostly detritivores– Salt marshes – east
coast– Mangrove swamps –
everglades in Fla.
– Both of these are valuable nurseries for fish, shellfish, and vegetation
Marine Ecosystems• Light zones
– Photic – well lit upper layer where organisms are able to carry out photosynthesis
– Aphotic – permanently dark zone beneath the photic zone, chemosynthetic autotrophs live here
• Zones based on depth and distance from shore– Intertidal zone– Coastal ocean– Open ocean– Benthic zone – ocean floor– Coral reefs – unique, diverse and
productive environment