II. Succession and Biomes

A. Ecological Succession: Predictable orderly replacement of communities in an ecosystem

Young Stage: Pioneer

Intermediate Stage: Seral

Mature Stage: Climax

Plant Succession

Succession Stages1. Pioneer species- first organisms to inhabit an

environment. Usually adapted to low nutrient needs. (Bacteria, algae, fungus, lichen and weeds)

a) These grow, thrive and die and add nutrients to the system

b) The addition of nutrients is called eutrophication2. Seral community- intermediate community that

alters the physical factors of the area in a way that makes it impossible for the community to regenerate itself

3. Climax community- relatively stable, almost permanent community that creates conditions in which its young can regenerate the community

B. Primary Vs. Secondary Succession1. Primary succession: begins with bare rock

exposed by geologic activity a) Example: rock -> lichen -> moss -> grass -> shrub -

> trees -> oak hickory forest

b) Pictures

2. Secondary succession: begins on soil from which previous community has been removed (by fire, agriculture, etc.)

a) Example: grass -> shrub -> trees -> oak hickory forest

b) secondary succession can proceed much faster because the soil has been prepared by the previous community

Earth’s Major Biomes

C. Terrestrial Biomes: Ecosystems that covers a large regions of earth

1.Tropical Rain Forest

a) Found in equatorial regions Warm all year round

b) Abundant Rainfall

c) Most diverse. 50% of all species on earth are found in tropical rain forests

d) Man’s use of slash and burn agriculture has endangered this biome

2. Savanna

a) A savanna is a rolling grassland scattered with shrubs and isolated trees.

b) Savannas have warm temperature year round with a wet and dry season

c) Animals like lions, zebras, elephants, and giraffes graze and hunt.

3. Deserts

a) Land areas receiving less than 30 cm of rain a year.

b) Temperature vary greatly

c) Desert plant and animals have many adaptations that allow them to survive with very little rainfall

4. Chaparral

a) Temperate costal biome dominated by dry evergreen shrubs which are adapted to survive brush fires

b) Mild rainy winters and dry hot summers

c) Many animals including deer, birds, rodents, snakes and lizards

5. Grassland

a) Deep nutrient rich soil supports a wide variety of grass species. The size of the vegetation depends on the yearly rainfall

b) Winters are cold and this biome experiences seasonal droughts

c) Animals include worms, arthropods, rodents, coyotes, snakes, lizards, and large herbivores such as bison and pronghorns

6. Deciduous Foresta) Plentiful precipitation allows

the growth of dense stands of deciduous trees such as oaks, beech, hickory and maples.

b) Winters are often very cold while summers are very hot

c) Many microorganisms inhabit the soil along with fungus and arthropods. Many mammal species including deer squirrels, chipmunks, foxes and bears

7. Coniferous Forest: Taiga

a) Large cone bearing evergreen trees such as pine, spruce, fir and hemlock dominate this biome

b) Trees are adapted to long cold winters with a lot of snow

c) Animals include hares, moose, elk, wolves and bears

8. Tundraa) Bitter cold winters with high

winds characterize the tundra. Because of the cold temperature, the subsoil is always frozen. This is called permafrost

b) The shallow soil only allows the growth of small plants such as mosses, lichen and grasses.

c) Mosquitoes, lemmings, caribou and reindeer are common animals

D. Aquatic Biomes1. Ponds and Lakes

a) Fresh water ecosystems where the water is not flowing. The zones of the water are divided by depth

b) The photic zone is at the top and because light is readily available, many phytoplankton live in this zone.

c) The deep murky areas of a lake that do not receive enough light to support photosythesis is called the aphotic zone.

d) The benthic zone consists of the rock, sand and sediment at the bottom of a lake or pond

2. Streams and Rivers

a) Flowing fresh water

b) Upstream, rivers are usually cold, low in nutrient and clear.

c) Down stream, rivers generally become wider and deeper with more phytoplankton

d) Communities vary greatly

3. Estuaries

a) Areas where freshwater streams and rivers merge with oceans.

b) Nutrient rich soil is often deposited is estuaries and results in a very productive ecosystem

c) Important breeding ground for a variety of organisms including crabs, oysters, clams, fish and birds

4. Ocean Zones

Benthic Zone

Neritic zone Oceanic Zone

Intertidal Zone

a) Intertidal zone is the shore area pounded by waves between high tide and low tide

b) Neritic Zone is the area from low tide out to the end of the continental shelf

c) Oceanic zone is the vast open ocean from the continental shelf outward