Environmental Science——A Study of Interrelationships

Environmental Science——A Study of Interrelationships

Cui JianshengHebei University of Science and Technology

Cui JianshengHebei University of Science and Technology

CH06 Kinds of Ecosystems and Communities

CH06 Kinds of Ecosystems and Communities

Chapter Objectives Chapter Objectives

After reading this chapter, you should be able to:

● Recognize the difference between primary and secondary succession.● Describe the process of succession from pioneer to climax community in both terrestrial and aquatic situations.● Associate typical plants and animals with the various terrestrial biomes.● Recognize the physical environmental factors that determine the kind of climax community that will develop.● Differentiate the forest biomes that develop based on temperature and rainfall.● Describe the various kinds of aquatic ecosystems and the factorsthat determine their characteristics.

Chapter Outline Chapter Outline

SuccessionPrimary SuccessionSecondary SuccessionModern Concepts of Succession

and ClimaxBiomes: Major Types of Terrestrial Climax Communities

The Effect of Elevation on Climate and Vegetation

DesertGrassland

Environmental Close-Up:Grassland Succession

SavannaMediterranean Shrublands

(Chaparral)Tropical Dry Forest

Global Perspective: Tropical Rainforests—A Special Case?

Tropical Rainforest Environmental Close-Up: Forest Canopy Studies

Temperate Deciduous ForestTaiga, Northern Coniferous

Forest, or Boreal ForestTundra

Major Aquatic EcosystemsdMarine EcosystemsFreshwater Ecosystems

Issues—Analysis: Protecting Old-Growth Temperate Rainforests of thePacific Northwest

SuccessionSuccession

The concept that communities proceed through a series of recognizable, predictable changes in structure over time is called succession. The relatively stable, long-lasting community that is the result of succession is called a climax community.

Primary succession is a successional progressionthat begins with a total lack of organisms and bare mineral surfaces or water.

Secondary succession is much more commonly observed and generally proceeds more rapidly, because it begins with the destruction or disturbance of an existing ecosystem.

Primary SuccessionPrimary Succession

Pioneer Organism

The lichen growing on this rock is able to accumulate bits of debris, carry on photosynthesis, and aid in breaking down the rock. All of these activities contribute to the formation of a thin layer of soil, which is necessary for plant growth in the early stages of succession. This collection of organisms is known as the pioneer community because it is the first to colonize bare rock.

Terrestrial Primary SuccessionTerrestrial Primary Succession

Each step in this process from pioneer community to climax community is called a successional stage, or seralstage, and the entire sequence of stages—from pioneer community to climax community—is called a sere.

Primary Succession on Land

Primary SuccessionPrimary Succession

Primary Succession from a Pond to a Wet Meadow

Aquatic Primary SuccessionAquatic Primary Succession

In many northern regions, sphagnum moss forms a floating mat that can be colonized by plants that tolerate wet soils. A network of roots ties the mat together to form a floating community.

Aquatic Primary SuccessionAquatic Primary Succession

Floating Bog

Secondary SuccessionSecondary Succession

Secondary Succession on Land

Secondary SuccessionSecondary Succession

Secondary Succession from a Beaver Pond

Biomes: Major Types of Terrestrial Climax CommunitiesBiomes: Major Types of Terrestrial Climax Communities

Biomes are terrestrial climax communities with wide geographic distribution.

Biomes of the World

Influence of Precipitation and Temperature on Vegetation

The Effect of Elevation on Climate and VegetationThe Effect of Elevation on Climate and Vegetation

Relationship Between Height above Sea Level, Latitude, and Vegetation

DesertDesert

Desert

Deserts are areas that generally average less than 25 centimeters (10 inches) of precipitation per year.

GrasslandGrassland

Grassland

Grasslands, also known as prairies or steppes, are widely distributed over temperate parts of the world.

SavannaSavanna

Savanna

Tropical parts of Africa, South America, and Australia have extensive grasslands spotted with occasional trees or patches of trees. This kind of a biome is often called a savanna.

Mediterranean Shrublands (Chaparral)Mediterranean Shrublands (Chaparral)

Mediterranean Shrublands

The Mediterranean shrublands are located near an ocean and have wet, cool winters and hot, dry summers. Rainfall is 40 to 100 centimeters (15 to 40 inches) per year.

Tropical Dry ForestTropical Dry Forest

Another biome that is heavily influenced by seasonal rainfall is known as the tropical dry forest.

Tropical Dry Forest

Tropical RainforestTropical Rainforest

Tropical rainforests are located near the equator in Central and South America, Africa, Southeast Asia, and some islands in the Caribbean Sea and Pacific Ocean.

Tropical Rainforest

Temperate Deciduous ForestTemperate Deciduous Forest

Forests in temperate areas of the world that have a winter-summer change of seasons typically have trees that lose their leaves during the winter and replace them the following spring. This kind of forest is called a temperate deciduous forest.

Temperate Deciduous Forest

Taiga, Northern Coniferous Forest, or Boreal ForestTaiga, Northern Coniferous Forest, or Boreal Forest

Throughout the southern half of Canada, parts of northern Europe, and much of Russia, there is an evergreen coniferous forest known as the taiga, northern coniferous forest, or boreal forest.

Taiga, Northern Coniferous Forest, or Boreal Forest

TundraTundra

North of the taiga is the tundra, a biome that lacks trees and has a permanently frozen subsurface soil. This frozen soil layer is known as permafrost.

Tundra

Major Aquatic EcosystemsMajor Aquatic Ecosystems

An important determiner of the nature of aquatic ecosystems is the amount of salt dissolved in the water. Those that have little dissolved salt are calledfreshwater ecosystems, and those that have a high salt content are called marine ecosystems.

Marine EcosystemsMarine Ecosystems

Pelagic Marine EcosystemsPelagic Marine Ecosystems

Organisms that are not attached to the bottom are called pelagic organisms, and the ecosystem they are a part of is called a pelagic ecosystem.

The term plankton is used to describe aquatic organisms that are so small and weakly swimming that they are simply carried by currents. As with all ecosystems, the organisms at the bottom of the energy pyramid carry on photosynthesis. The planktonicorganisms that carry on photosynthesis are calledphytoplankton.

The upper layer of the ocean, where the sun’s rays penetrate, is known as the euphotic zone.

Small, weakly swimming animals of many kinds, known as zooplankton, feed on the phytoplankton.

Marine Ecosystems

Benthic Marine EcosystemsBenthic Marine Ecosystems

Organisms that live on the ocean bottom, whether attached or not, are known as benthic organisms, and the ecosystem of which they are a part is called abenthic ecosystem. Some fish, clams, oysters, various crustaceans, sponges, sea anemones, and many other kinds of organisms live on the bottom. In shallow water, sunlight can penetrate to the bottom, and a variety of attached photosynthetic organisms commonly calledseaweeds are common. Since they are attached and some, like kelp, can grow to very large size, many other bottom-dwelling organisms, such as sea urchins, worms, and fish, are associated with them.

Rocky Shore

Sandy Shore

Coral reef ecosystems are produced by coral animals that build cup-shaped external skeletons around themselves.

Mangrove swamp ecosystems occupy a region near the shore. The dominant organisms are special kinds of trees that are able to tolerate the high salt content of the ocean. In areas where the water is shallow and wave action is not too great, the trees can become established.

EstuariesEstuaries

An estuary is a special category of aquatic ecosystem, that consists of shallow, partially enclosed areas where freshwater enters the ocean.

Freshwater EcosystemsFreshwater Ecosystems

Lakes and PondsLakes and Ponds

Along the shore and in the shallower parts of lakes, many kinds of flowering plants are rooted in the bottom. Some have leaves that float on the surface or protrude above the water and are called emergent plants.

Rooted plants that stay submerged below the surface of the water are called submerged plants.

Lake Ecosystem

littoral zone

limnetic zone

Farming and construction expose soil and release nutrients, as do other human activities such as depositing sewage into streams and lakes. Deep, clear, cold, nutrient-poor lakes are low in productivity and are called oligotrophic lakes. Shallow, murky, warm, nutrient-rich lakes are called eutrophic lakes.

The amount of oxygen used by decomposers to break down a specific amount of organic matter is called the biochemical oxygen demand or BOD.

Streams and RiversStreams and Rivers

Streams and rivers are a second category of freshwater ecosystem. Since the water is moving, planktonic organisms are less important than are attached organisms. Most algae grow attached to rocks and other objects on the bottom. This collection of attached algae, animals, and fungi is called the periphyton.

Swamps are wetlands that contain trees that are able to live in places that are either permanentlyflooded or flooded for a major part of the year.

Marshes are wetlands that are dominated by grasses and reeds. Many swamps and marshes are successional states that eventually become totallyterrestrial communities.