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Lecture

BIOL 2010 Lecture Notes - Human Overpopulation, Primary Production, Ecosystem Services


Department
Biology
Course Code
BIOL 2010
Professor
all

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Chapter 56 Ecosystems and Global Ecology (only 56.2, 56.4 and 56.5!!!)
How Does Energy Flow Through The Global Ecosystem?
all energy utilized by organisms come from the sun
fossil fuels is based on reserves of captured solar energy locked up in the remains of
organisms that lived a million years ago
energy enters ecosystems by way of plants and other photosynthetic organisms
Gross primary product rate at which energy is incorporated into the bodies of
photosynthetic organisms
Gross primary production accumulated energy
Primary producers use some of the accumulated energy for their own metabolism and
the rest is stored in their bodies or used for growth and reproduction
Net primary production energy available to organisms that eat primary producers
gross primary production the energy expended by the primary producers during their
metabolism
Only the energy of an organism’s net production is available to other organisms that
consume it
geographic distribution of the energy assimilated by primary producers reflects the
distribution of land masses, temperature and moisture on Earth
close to equator at sea level, temperatures are high throughout the year and water
supply is adequate for growth
in low and mid-latitude deserts where plant growth is limited by lack of moisture,
primary production is also low
in high latitudes where moisture is available, primary production is still low because it is
cold for much of the year
production in aquatic systems is limited by light, nutrients and temperature
human activities decreases net global primary productivity (ie. Converting forest to
grasslands and urban developments) and some increase it (ie. Intensify agriculture)
humans appropriate about 20% of the average annual net primary production
urban areas consume 300x the NPP they generate
What Services Do Ecosystems Provide?
Many benefits are irreplaceable or the technology necessary to replace them are very
expensive
potable fresh water can be provided by desalinating seawater but only at a great
cost
rapidly expanding human population has modified Earth's ecosystems to increase their
ability to provide some of the goods and services it needs
these modifications have contributed to human well-being and economic
development
short-term increases in some ecosystem goods have come at the cost of the long-term
degradation of others
efforts to increase wood and fiber have decreased the ability for some
ecosystems to provide clean water, regulate flooding and support biodiversity
the spread of agriculture into into marginal lands has increased soil degradation
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