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 in response to natural and human disturbances.

Primary Succession• Succession that occurs on surfaces where no soil exists:

•Sides of volcanoes•Rock after glaciers melts

Glacial RetreatGlacial Retreat

PIONEER SPECIES: The first species to populate an area after Primary Succession. Usually lichen and can grow on rock

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

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.

Pre-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

Succession in a Marine EcosystemLarge whale dies and

sinks to barren ocean floor. Attracts scavengers and decomposers.

Within a year, most of the tissue has been eaten, the decomposition of the whale enriches the surrounding sediments.

When only the skeleton remains, bacteria begin to decompose the bones.

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