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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.