环境科学概论教学课件(第三讲)

cactus
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camel
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Temperate grassland: also known as prairies or steppes, are widely distributed over temperate parts of the world. Climate: As with deserts, the major factor that contributes to the establishment of a grassland is the amount of available moisture. Grasslands generally receive between 25 and 75 centimeters of precipitation per year. These areas are windy with hot summers and cold to mild winters.
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1. Succession
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Succession The communities proceed through a series of recognizable, predictable changes in structure over time is called succession. Primary Succession Primary succession is a successional progression that begins with a total lack of organisms and bare mineral surfaces or water. Terrestrial Primary Succession Aquatic Primary Succession Secondary Succession An original community is a successional progression that begins with destruction or disturbance of an existing ecosystem.
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Primary succession can begin on a bare rock surface, or in standing water.
A pioneer organism ：Lichen (Terrestrial ecosystem)
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Terrestrial primary succession
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Emergent plants
Early stages – Aquatic vegetation
Wet meadow
Grassland
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Later stages – Transition to Terrestrial communities
广东工业大学 环境科学与工程学院
2 Biomes are determined by climate Biomes
广东工业大学 环境科学与工程学院
3 Major biomes of the world
广东工业大学 环境科学与工程学院
The effect of elevation on climate and vegetation Deserts: Climate: A lack of water is the primary factor that determines that an area will be desert. Deserts are areas that generally receive fewer than 25 centimeters of precipitation per year. Organisms: few species of organisms live in the desert. There are many species, but they typically have low numbers of individuals.
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Pioneer stages
Intermediate stages
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Climax community
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Process of terrestrial succession
Aquatic primary succession Floating plants Submerged plants
Observing aquatic succession
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Most aquatic ecosystems are considered temporary (except ocean).
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Secondary Succession

广东工业大学 环境科学与工程学院
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广东工业大学 环境科学与工程学院
Community: is an assemblage of all the interacting populations of different species of organisms in an area. Climax community: The relatively stable, long-lasting community that is result of succession.
CHAPTER THREE: Kinds of Ecosystems and Communities
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Forest
Coral reef
Desert
Swamp
广东工业大学 环境科学与工程学院
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. Describe how the concepts of succession and climax community developed and how they are used today. Identify the major environmental factors that determine the kind of community that develops in an area. State major abiotic and biotic characteristics of the various terrestrial biomes. State abiotic difference between marine and fresh water ecosystem. State how pelagic and benthic ecosystem differ. Describe the role of phytoplankton and zooplankton in aquatic ecosystems. State biotic differences between marine and freshwater ecosystems.
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Tropical Dry Rainforest: is heavily influenced by seasonal rainfall.
Climate: Many of the tropical dry forests have a monsoon climate in which several months of heavy rainfall are followed by extensive dry periods ranging from a few to as many as eight months. the rainfall may be as low as 50 centimeters or as high as 200 centimeters, but since the rainfall is highly seasonal, many of the plants have special adaptations for enduring drought. Organism: many of the plants have special adaptations for enduring drought.
Organisms: The plants and animals time their reproductive activities to coincide with the rainy period.
广东工业大学 环境科学与工程学院 Mediterranean Shrublands (Chaparral): are located near oceans and are dominated by shrubby plants. Climate: have a climate with wet, cool winters and hot, dry summer. Rainfall is 40 to 100 centimeters per year. Organisms: the vegetation is dominated by woody shrubs that are adapted to withstand the hot, dry summer.