國際貿易地理知識(編輯修改稿)

　

【文章內容簡介】 ped Countries have lower agricultural densities because technology and finance allow a few people to farm extensive land areas and feed many people.254。 To understand the relationship between population and resources in a country, geographers examine its physiological and agricultural densities together. F Look at Table 21:Egypt and Netherlands: the physiological densities of both Egypt (2147) and the Netherlands (1450) are high, but the Dutch (58) have a much lower agricultural density than the Egyptians (737). That means that both the Dutch and Egyptians put heavy pressure on the land to produce food, but the more efficient Dutch agricultural system requires many fewer farmers than does the Egyptian system.India and Netherlands: the Netherlands (1450) has a much higher physiological density than does India (556), but a much lower agricultural density. This shows that the Dutch have extremely limited arable land to meet the needs of their population (they built dikes and created polders圩田，圍海造田). However, the highly efficient Dutch farmers can generate a large food supply from a limited resource. (Dutch Lady, no Egyptian Lady, J)l Where has the world’s population increased?1. Measures of population change252。 Crude birth rate (CBR): The total number of live births in a year for every 1000 people alive in the society。 A CDR of 20 means that for every 1000 people in a country, 20 babies are born over a 1year period.252。 Crude death rate (CDR):The total number of deaths in a year for every 1000 people alive in the society.252。 Natural increase rate (NIR): NIR (%) = CBR CDRThe percentage by which a population grows in a year.. NIR = CBR (20) – CDR (5) = 15 per 1000 = %“Natural” means a country’s growth rate excludes migration. During the 1990s, the world natural increase rate was , meaning that world population grew each year by %. This rate affects the doubling time, which is the number of years needed to double a population, assuming a constant rate of natural increase. At the current NIR of % per year, world population would double in about 50 years.2. Distribution of natural increase of world’s population252。 Distribution of natural increase rate:It shows very large regional differences. The NIR exceeds % in a number of countries in central Africa, the Middle East, and Central America. At the other extreme, the NIR rate is 0% or even negative in much of Europe, meaning that their population is actually declining in the absence of immigrants.252。 Distribution of population growth:All the growth is concentrated in poorer countries. Over the past 3 decades, about 54% of the world’s population growth has been in Asia,15% each in subSahara Africa and the Middle East,10% in Latin America。Europe and North America each account for only 3% of global population growth.254。 Regional differences in NIR mean that virtually all the world’s additional people live in the countries that are least able to maintain them.Wetlands252。 A wetland is a vegetated area that is permanently or periodically covered by water, either fresh or salt. Marshes, swamps, bayouts and bogs are among the typical wetland environments.252。 Wetlands are among the most productive ecosystems on earth. As hybrid environment – neither land nor water, wetlands provide living space and food to different species.252。 Video script: “The world’s wetlands are in danger. People ditch them, drain them, dike them, dump waste into them, and drown them behind dams. Swamps, bogs, and marshes are lost to create land to farm or build upon. As a consequence, the world’s losing its natural water filter, its buffers against floods and erosions, and the critical habitats and nurseries for a myriad of species.”252。 The 1971 Ramsar Convention aims to designate and preserve wetlands and protect wildfowls. By the late 1990s, more than 100 countries have signed the treaty.l Why is population increasing at different rates in different countries?1. The demographic transitionAll countries have experienced some changes in natural increase at different times and at different rates. While rates vary among countries, a similar process of change in a society’s population, know as demographic transition, is operating.The demographic transition is a process with several stages, and every country is in one of them. The process has a beginning, middle, and end, and it is irreversible. Once a country moves from one stage of the process to the next, it does not revert to an earlier stage. F Figure 213 1Stage 1 – Low Growth – very high birth and death rates produce virtually no longterm natural increase:For most of human kind’s several hundredthousandyear occupancy of Earth, they were in stage 1 of the demographic transition. The natural increase rate was essentially zero, and Earth’s population was unchanged, at perhaps onehalf million. During most of this period, people depended on hunting and gathering for food. Between 8000 . and . 1750, Earth’s human population increased from approximately 5 million to 800 million. The burst of population growth around 8000 . was caused by agricultural revolution, which was the time when human beings first domesticated plants and animals. Despite such revolution, the human population remained in stage 1, because food supplies were still unpredictable due to climatic conditions, wars or diseases that stayed out of human control. Most of human history was spent in stage 1 of the demographic transition, but today no such country remains there. Every country has moved on to at least stage 2 and with that transition has experienced profound changes in population.Stage 2 – High Growth – rapidly declining death rates bined with very high birth rates produce very high natural increase: After around . 1750, the world’s population suddenly began to grow 10 times faster than in the past. The sudden burst of population growth occurred because in the