CHAPTER ONE：Environmental Interrelationships
Environment: the surrounding conditions that affect people and other organism. In a broader definition, environment is everything that affects an organism during its lifetime. 环境：与某一中心事物有关的周围事物，就是这个中心事物的环境。
Environmental Science: is an interdisciplinary area of study that includes both applied and theoretical aspects of human impact on the world.
The field of environmental science involves an understanding of scientific principles, economic influences, and political action. Environment decisions ofent involve compromise.(fig. 1.1)
International Organization
In order to solve the common environmental issues, several international organizations were founded, and several international conventions were established. The international joint commission (1909) boundary waters treaty
The united nations conference on environment and development (1992, UNCED) sustainable development and biodiversity Agenda 21 The Kyoto conference on climate change (1997) the Kyoto protocol
The United Nations Educational, Scientific, and Cultural Organization (UNESCO) supported many environmental programs. An ecosystem： is a region in which the organisms and the physical environment form interacting unit.
For solving regional environmental issues, it’s very useful to adopt ecosystem approach. No region is free of environmental concerns.
Regional vignettes in America
The Wideness North
characteristic: wilderness--areas with minimal human influence.
Much of this land is owned by governments, not by individuals, so government policies have a large effect on what happens in these regions.
The Agricultural Middle
characteristic: intensive agriculture.
Original, natural ecosystems have been replaced by managed agricultural enterprise.
nonpoint pollution sources (pollution that does not have an easily identified point of origin).
The Dry West
characteristic: inadequate rainfall, land is of low economic value, most of it is still the property of government.
Population density is low, much of the land has a wilderness character.
The Forested West
characteristic: sufficient rainfall, coniferous forests are the dominant vegetation.
Since most of these areas are not suitable for farmland, they have been maintained as forests with some grazing activity in the more open forests. timber cutting .
Environmental interests are concerned about the consequences logging would have on organisms that require mature, old-growth forests for their survival.
The Great Lakes and Industrial Northeast
characteristic: dominated by large metropolitan complexes that generate social and resource needs that are difficult to satisfy.
A major concern about these pollutants is that they bioaccumulate in the food chain.
Their major environmental priorities are cleaning up contaminated sites, providing more parks and recreation facilities, reducing air and water pollution, and improving transportation.
The Diverse South
characteristic: diverse.
The South is a microcosm of all the regions previously discussed. The petrochemical industry dominates the economies of Texas and Louisiana, and forestry and agriculture are significant elements of the economy in other parts of the region. Major metropolitan areas thrive, and much of the area is linked to the coast either directly or by the Mississippi River and its tributaries. The environmental issues faced in the South are as diverse as those in all the other regions.
Poverty has been a problem in many areas of the South. This creates a climate that encourages state and local governments to accept industrial development at the expense of other values. Often, jobs are more important than the environmental consequences of the jobs; low-paying jobs are better than no jobs.
Environmental problems are people problems. Summary
Artificial political boundaries create difficulties in managing environmental problems because most environmental units, ecosystems, do not coincide with political boundaries. Therefore, a regional approach to solving environmental problems, one that incorporates natural geographic units, is ideal. Each region of the world has certain environmental issues that are of primary concern because of the mix of population, resource use patterns, and culture.
Environmental problems become issues when someone finds a situation offensive. This inevitably leads to a confrontation between groups that have different views on what constitutes an environmental problem. Many social, economic, ethical, and scientific inputs shape a person's opinions. The process of environmental decision making must take all of these inputs into account and arrive at an acceptable compromise.Environmental problems are people problems. They occur because the uses of natural resources, which some people feel are justified, result in a diminished environment for others in the region. Environmental problems are defined by the person who perceives the problem. When perceptions differ, conflict occurs. Environmental decisions inevitably involve economic considerations because someone is receiving value from the resources being used or someone perceives an economic loss because a use has been withdrawn.
Compromise is the only way to resolve the Environmental conflicts CHAPTER THREE: Kinds of Ecosystems and Communities
Succession
The communities proceed through a series of recognizable, predictable changes in structure over time is called 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 destroyed and replaced by an new community, this progress is called secondary succession.
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 is called climax community Lichen A pioneer organism
Biomes: Major Types of Terrestrial Climax Communities
The effect of elevation on climate and vegetation Deserts: 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.
Grassland: Grasslands, also known as prairies or steppes, are widely distributed over temperate parts of the world. 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.
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. These areas of the world are typically tropical, with 50 to 150 centimeters of rain per year. The rain is not distributed evenly through-out the year.
Tropical Dry Rainforest: 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. (See figure 6.14) the rainfall may be as low as 50 centimeters or as high as 200centimeters, but since the rainfall is highly seasonal, many of the plants have special adaptations for enduring drought.
Tropical 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. (See figure 6.15.) The temperature is normally warm and relatively constant. There is no frost, and it rains nearly every day. Most areas receive in excess of 200 centimeters of rain per year. Some receive 500 centimeters or more. Because of the warm temperatures and abundant rainfall, most plants grow very rapidly; however, soils are often poor in nutrients because water tends to carry away any nutrients not immediately taken up by plants. Marine Ecosystems
Those Aquatic Ecosystems that have a high salt content are called marine ecosystems. Pelagic Marine Ecosystems: In the open ocean, many kinds of organisms floats or swim actively. Crustaceans, fish, and whales swim actively as they pursue food. Organisms that are not
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