2. Ecological Succession
Ecological Succession is a series of changes in a community in which new populations of organisms gradually replace existing ones
Ecosystems change over time, especially after disturbances
Over the course of succession, the number of different species present typically increases.
Increase in genetic diversity!!!!

3. Primary succession
Primary succession begins in an area with no remnants of an older community– takes place on bare rock or newly exposed surfaces

4. Primary succession New bare rock comes from 2 sources:
1. volcanic lava flow cools and forms rock
2. Glaciers retreat and expose rock

5. Pioneer organisms
Pioneer species- the first organisms to colonize a new site
Ex: lichens are the first to colonize lava rocks/bare rock
Lichens are composed of two different species (fungi + algae) living together in symbiosis

6. Lichens also secrete acids to break down rock to form soil
Over time, lichens convert, or fix, atmospheric nitrogen into useful forms for other organisms
Atmospheric Nitrogen (N2)  Ammonia (NH3)
Lichens also secrete acids to break down rock to form soil
Primary succession of a dry land environment:
Rock lichen moss grasses

7. Primary succession

8. Secondary Succession
Takes place when a developed community is disrupted by natural disaster or human actions – takes place on existing soil
Secondary succession proceeds faster than primary succession
But does not occur rapidly!
In part because soil survives the disturbance.
As a result, new and surviving vegetation can regrow rapidly.

9. Secondary Succession
Secondary succession often follows a wildfire, hurricane, or other natural disturbance.
We think of these events as disasters, but many species are adapted to them.
Some trees are spared, and fire can stimulate their seeds to germinate.
Ex: A fire levels portions of a forest

10. Secondary Succession
Ex:
A farmer plows his field

11. Secondary Succession

12. Why Succession Occurs
Every organism changes the environment it lives in.
For example: as lichens add organic matter and form soil, mosses and other plants can colonize and grow.
As organic matter continues to accumulate, other species move in and change the environment further.
Over time, more and more species can find suitable niches and survive.

13. Difference Between Primary & Secondary Succession
What is the MAIN difference between primary & secondary succession?
Primary succession= new exposed surfaces/rock
Secondary succession= existing soil

14. Ecosystem Stability Does succession ever end?
Succession in a given area always proceeds through the same stages to produce a specific and stable climax community
Secondary succession in healthy ecosystems following natural disturbances often reproduces the original climax community
Ecosystems may or may not recover from extensive human-caused disturbances
Stability- ability of an ecosystem to resist change when a disturbance occurs
Biodiversity tends to promote stability

15. Climax community
Climax community- a stable, mature community that undergoes little or no succession
Last step of
succession
contains
HARDWOOD TREES!

16. Ecosystem Stability
Keystone species- species that are crucial to the stability of an ecosystem
If members of a keystone species die, then the entire ecosystem can collapse
i.e. sea otters- keep sea urchins in check, which would take over the kelp beds without the otters

17. Ecosystem Stability
Invasive Species (Introduced Species) (Non-native species)- destroy ecosystems
They are species that are brought by humans accidentally or purposefully from other places and take hold
They multiply unchecked due to lack of predators in new place they are moved to
Ex: Asian longhorn beetle, Zebra mussels

18. Invasive Species

19. Invasive Species

20. Biomes
Tolerance- the ability of plants and animals to survive and reproduce under conditions that differ from their optimal conditions
Microclimate- the climate in a small area that differs from the climate around it
There are 10 different biomes including:
Tropical rain forest
Tropical dry forest
Tropical savanna
Desert
Temperate grassland
Temperate woodland and shrub land
Temperate forest
Northwestern coniferous forest
Boreal forest
Tundra

21. Savanna mid biodiversity -dry season/wet season, always warm, frequent fires in dry season, many herbivores

22. Desert low biodiversity -very dry, hot in day & cold at night, very few plants & only small animals: reptiles, insects, rodents, birds

23. Tropical Rainforest high biodiversity -lots of rain, lots of sunlight, always warm, many plants & animals

24. Temperate Grassland (midwest US) mid biodiversity -dry season/wet season, cold winters/hot summers, frequent fires in dry season, many herbivores

25. Temperate Deciduous Forest high biodiversity -4 seasons: warm summer with rains, cold winter with snow, deciduous trees, many mammals, insects, birds, etc.

26. Coniferous Forest (Taiga) mid biodiversity -northern forest, drier, cooler, evergreens, mammals, birds, insects, etc.

27. Tundra low biodiversity -cold year round, dry, permafrost, only lichens & mosses & mostly migrating animals

28. Aquatic Ecosystems
Aquatic ecosystems- are determined primarily by the depth, flow, temperature, and chemistry of the overlying water
Water depth strongly influences aquatic life because sunlight penetrates only a relatively short distance through water
The zone near the surface where photosynthesis can take place is the photic zone
Contains plankton- a free floating organism
2 main types of plankton
1. phytoplankton is a unicellular algae (producer)
2. zooplankton is an animal plankton (consumer of phytoplankton)
The zone below the photic zone that is dark is the aphotic zone where photosynthesis cannot occur

29. Aquatic Ecosystems Terminology
Wetland- is an ecosystem in which water either covers the soil or is present at or near the surface of the soil
Ex: Florida Everglades
Estuaries- are wetlands formed where rivers meet the sea
Salt marshes- are temperate-zone estuaries dominated by salt-tolerant grasses above the low- tide line, and sea grass under water
Mangrove swamps- are coastal wetlands that are widespread across tropical regions

30. Marine Ecosystems Terminology
Photic zone- the thin surface layer where algae producers can engage in photosynthesis as sunlight penetrates this area
Aphotic zone- is found below the photic zone and is permanently dark
Chemosynthetic autotrophs are the only producers capable of surviving here
Kelp forests- are named from the dominant organism- the kelp