ecological succession ecosystems are constantly changing in response to natural and human...
TRANSCRIPT
Ecological Succession
Ecosystems are constantly changing in response to natural and human disturbances.
ecological succession: series of predictable changes that occur over time in an ecosystem
Primary Succession• Succession that occurs on surfaces where no soil exists:
•Sides of volcanoes•Rock after glaciers retreat
• Starts with the arrival of living things such as lichens that do not need soil to survive, called PIONEER SPECIES
Lichens: formed symbiotic relationship between fungus and algae and can grow on bare rock
Primary Succession
Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces
When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil
Simple plants like mosses and ferns can grow in the new soil
Glacial RetreatGlacial Retreat
Mount St. Helen’s Case study
1978 1980
1 year later
5 years after
15 years after
25 years after
Secondary Successionsuccession that occurs following a disturbance that changes an existing community without removing the soil
wildfires, clearing of land for agriculture or development, wind storms, lakes that dry up, etc.
On-going processPre-existing seeds will germinate to establish new plants.
Yellowstone Fire 1988
Immediately after fire
2 months after fire
1 year later
20 years later
Station Fire 2009: Chaparral Succession
Decomposition of a fallen log
Primary or Secondary Succession?
Old- field Succession
Occurs in farmland that has been abandoned
Grasses and weeds grow quickly, and procede many seeds that cover large areas
Maintenance of Prairie Ecosystems
Before: high fuel load During controlled burn Just 2 months later
Climax Community
A stable group of plants and animals that is the end result of the succession process
Does not always mean big treesGrasses in prairiesCacti in deserts
4-1 The Role of Climate
What Is Climate?
Weather is the day-to-day condition of Earth's atmosphere at a particular time and place.
Climate refers to the average year-after-year conditions of temperature and precipitation in a particular region.
Climate is caused by:
trapping of heat by the atmospherelatitudetransport of heat by winds and ocean currents
amount of precipitationshape and elevation of landmasses
The Greenhouse Effect
Atmospheric gases that trap the heat energy of sunlight and maintain Earth's temperature range include: carbon dioxide (CO2)
Methane (CH4)
water vapor (H2O)
The Greenhouse Effect
The natural situation in which heat is retained in Earth’s atmosphere by this layer of gases is called the greenhouse effect.
Sunlight
Earth’s Surface
Atmosphere
Some heat escapes into space
Greenhouse gases trap some heat
Greenhouse Effect in a Car
The Effect of Latitude on Climate
Solar radiation strikes different parts of Earth’s surface at an angle that varies throughout the year.
At the equator, energy from the sun strikes Earth almost directly.
At the North and South Poles, the sun’s rays strike Earth’s surface at a lower angle.
Making Climate Graphs
Climate graphs show us the two factors in a climate:
Temperature and Precipitation
Making Climate Graphs
Let’s look at two climate graphs
The line graph is temperature
The bar graph is precipitation
Making Climate Graphs
Let’s look at two climate graphs
The y-axis on the left is for temperature
The y-axis on the right is for precipitation
Making Climate Graphs
What trends can we see on these graphs?
1. Cold winters, hot summers
1. Even precipitation (no rainy season)
1. Moose Factory, Ontario gets much colder in the winter than Chicago,IL