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Biology 2014-2015

Sec. 6-1 A Changing Landscape
SWS Biology
SWS Life Science

Earth as an Island

       Earth is similar to as island because all the organisms that live on Earth share a limited resource base and depend on it for their long-term survival.


Human Activities

       Humans participate in food webs and chemical cycles which provide breathable air, drinkable water, and fertile soil.

       Ecosystem processes provide us with “services” such as storage and recycling of nutrients.

       If we don’t get these “goods and services” from the environment, we will need to spend money to produce them

       The human activities that affect the biosphere are:

       Hunting and gathering



       Urban development


Hunting and Gathering

       Our ancestors obtained food by hunting and gathering.

       This practice caused a mass extinction of animals in North America about 12,000 years ago.

       Today, groups of people scattered around the world still follow the hunter-gatherer way of life to some degree.

       Most of them use some form of technology, such as guns, snowmobiles, or manufactured tools.



       By the end of the last ice age-about 11,000 years ago, humans began the practice of farming, or agriculture.

       The development of agriculture also included raising animals.

       The spread of agriculture was among the most important developments in human history.

       It provides a dependable supply of food that can be produced in large quantity and stored for later use.

       This lead to large settlements and stable communities.


From Traditional to Modern Agriculture

       Farmers eventually acquired machinery to help with cultivation.

       World exploration led to an exchange of crops around the globe.

       Advances in technology also lead to large scale irrigation in dry areas such as the western United States allowing deserts to become breadbaskets.

       Agricultural scientists developed new varieties of crops that produce higher yields.

       These crops were grown using monoculture in which large fields are planted with a single variety year after year.

       Chemical fertilizers boosted plant growth and pesticides controlled crop-damaging insects.


The Green Revolution

       The green revolution greatly increased the world’s food supply.

       Plant breeder’s developed highly productive “miracle strains” of wheat and rice.

       Modern techniques were also introduced to countries that were suffering from food shortages.

v      Mexican farmers increased their wheat production ten times in 20 years.

v      India and China produced enough food to feed their own people for the first time in years.

       The green revolution has helped world food production double.


Challenges for the Future

       Modern agriculture has created ecological challenges.

       Insect pests and diseases cause farmers to increase the use of pesticides which:

       Contaminate water supplies

       Damage beneficial insects

       Accumulate in the environment


       Finding enough water for irrigation

       The West and Midwest depend on the Ogallala aquifer (underground water deposit).

       It is expected to run dry within 20 to 40 years.

       Ecologists conclude we need to maintain the benefits of modern agriculture while developing new approaches to protect natural resources.


Industrial Growth and Urban Development

       The Industrial Revolution transformed human society by adding machines and factories during the 1800’s.

       Mass-produced farm machinery makes efficient, large-scale agriculture possible.

       Automobiles give us mobility.

       Energy is produced from fossil fuels-coal, oil, and natural gas.

       Certain kinds of industrial processes pollute air, water, and soil.

       Dense human communities produce wastes that must be disposed of.

       Suburban growth consumes farmland and natural habitats placing stress on plant and animal populations.