环境科学复习要点师兄版.doc

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Original, natural ecosystems have been replaced by managed agricultural enterprise.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 attached to the bottom are called pelagic organisms, and the ecosystem they are a part of is called a pelagic ecosystem.
Benthic Marine Ecosystems: Organisms that live on the ocean bottom, whether attached or not, are known as benthic organisms, and the kind of ecosystem of which they are a part is called a benthic ecosystem.
Estuaries: An estuaries is a special category of marine ecosystem, that consist of shallow, partially enclosed areas where freshwater enters the ocean. The saltiness of the water in the estuary changes with tides and the flow of water from rivers. The organisms that live here are specially adapted to this set of physical conditions, and the number of species is less than in the ocean or in freshwater.
Freshwater Ecosystems
Those that have little dissolved salt are called fresh water ecosystems
Freshwater ecosystems differ from marine ecosystems in several ways. The amount of salt present is much less, the temperature of the water can change greatly, the water is in the process of moving downhill, oxygen can often be in short supply, and the organisms that inhabit freshwater systems are different.
Lakes and Ponds: Large lakes have many of the same characteristics as the ocean. If the lake is deep, there is a euphotic zone at the top.
Streams and Rivers: the water is shallow, light can penetrate easily to the bottom (except for large or extremely muddy rivers). Even so, it is difficult for photosynthetic organisms to accumulate the nutrients necessary for growth, and most streams are not very productive. Summary
Ecosystems change as one kind of organism replaces another in a process called succession. Ultimately, a relatively stable stage is reached, called the climax community. Succession may begin with bare rock or water, in which case it is called primary succession, or may occur when the original ecosystem is destroyed, in which case it is called secondary succession. The stages that lead to the climax are called successional stages.
Major regional terrestrial climax communities are called biomes. The primary determiners of the kinds of biomes that develop are the amount and yearly distribution of rainfall and the yearly temperature cycle. Major biomes are desert, grassland, savanna, tropical rainforest, temperate deciduous forest, taiga, and tundra. Each has a particular set of organisms that is adapted to the climatic conditions typical for the area. As one proceeds up a mountainside, it is possible to witness the same kind of change in biomes that occurs if one were to travel from the equator to the North Pole.
Aquatic ecosystems can be divided into marine (saltwater) and freshwater ecosystems. In the ocean, some organisms live in open water and are called pelagic organisms. Light penetrates only the upper few meters of water; therefore, this region is called the euphotic zone. Tiny photosynthetic organisms that float near the surface are called phytoplankton. They are eaten by small animals known as zooplankton, which in turn are eaten by fish and other larger organisms.
CHAPTER FOUR: Population Principles
An Essay on the Principle of Population---Thomas Malthus(1798)
Population: a group of individuals of the same species inhabiting a particular area at a specific time.
Population Characteristics
Natality（出生率）: refers to the number of individuals added to the population through reproduction.
Mortality（死亡率）: refers to the number of deaths in a population over a particular time period.
Age distribution（年龄分布）: the number of individuals in each age class as a ratio of one class to another.
Sex ratio（性别比例）: refers to the relative numbers of males and females.
Population Growth Curve 人口增长曲线
Typical population growth tends to follow a particular pattern, consisting of a lag phase, an exponential growth phase, and a stable equilibrium phase.
Four periods:
a lag phase（滞后阶段）an exponential growth phase（增长阶段）
a stable equilibrium phase（稳定平衡阶段）a death phase（死亡阶段）
Growth as normally seen under artificial conditions, e.g: lab populations
Limits to population size are:
1. Food 2.Waste product elimination 3. Disease control 4.Space
Logistic growth
Most populations are limited in growth at some carrying capacity (K) (the maximum population size a habitat can accommodate)
Environmental resistance to growth may be because of: Food and shelter llimitations ；Competition and predation by other organisms ；Unfavorable physical conditions
Carrying Capacity （承载力）
The carrying capacity of an area is the number of individuals of a species that can survive in that area over time.
Limiting Factor: a particular condition or factor that limits the size of a population. eg: Oxygen supply, Food supply, Disease, Predators, Limited space.
Reproductive Strategies
Species can be divided into two broad categories based on their reproductive strategies:
K-strategists are usually large organisms that have relatively long lives, produce few offspring, and provide care for their offspring.
R-strategist is typically a small organism that has a short life, produces many offspring, and does not reach a carrying capacity.
Human Population Growth：The human population growth curve has a long lag phase followed by a sharply rising exponential growth phase that is still rapidly increasing.
Growth will slow down either due to decreased births or increased deaths.
Summary
Population birthrate (natality) death rate (mortality)
Population growth is determined by the combined effects of the birthrate and death rate.
sex ratio Age distribution typical population growth curve
carrying capacity four major categories K-strategists
r-strategists are generally small, short-living organisms that reproduce very quickly
The human population is increasing at a rapid rate. The earth's ultimate carrying capacity for humans is not known. The causes for human population growth are not just biological but also social, political, philosophical, and theological.
第五单元 Interactions: Environment and Organisms
环境和生物间的相互作用
Every form of life and all societies require a constant input of energy
If the flow of energy through organisms or societies ceases, they stop functioning and begin to disintegrate
1 Ecological Concepts
Ecology: is the study of the ways organisms interact with each other and with their nonliving surroundings.
Environment: Everything that affects an organism during its lifetime is collectively known as its