CHEM 1001 Lecture Notes - Primary Production, Human Overpopulation, Ecosystem Services

472 views3 pages
Published on 22 Aug 2012
School
York University
Department
Chemistry
Course
CHEM 1001
Professor
Page:
of 3
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 and reduced ability of ecosystems to provide clean water
pesticides reduces populations of pollinators
damage from tsunami of 2004 would have been less if the mangrove
forests that protect the coasts had had not been cut down
Hurricane Katrina would not have caused as much flooding if the
wetlands surrounding area had been left intact
Millennium Ecosystem Assessment – a project that involved more than a
thousand scientists and managers worldwide to provide a global assessment
of Earth's ecosystems, determine trends in the services they provide and
assess their importance to human well-being
divided ecosystem services into 4 categories: provisioning services,
regulating services, cultural services, supporting services
most important driver of alterations in ecosystems has been changes in land
use as natural ecosystems have been converted to other more intensive uses
more land was converted to crop land from 1950-1980 than from 1700-1850
conversions in tropical and subtropical terrestrial ecosystems have been
particularly rapid
from 1970-2000, about 20% of coral reefs were lost and another 20% were
degraded
6 times as much water is held in reservoirs then in natural rivers
amount of water withdrawn from rivers has doubled
food production contributes the most to economic development and
employment
22% of of world's population is employed in agriculture
40% live in agriculturally based households
What Options Exist To Manage Ecosystems Sustainably?
Total economic value of a sustainably managed ecosystem is higher than that
of an intensively exploited one (ie. clear-cut logging or intensive agriculture)
collapse of the Newfoundland cod fishery in the 1990s due to overfishing
resulted in the loss of many jobs
many ecosystems are considered public goods that have no market value
elimination of subsidies that promote excessive exploitation of ecosystems
may encourage sustainable ecosystem management
from 2001-2003 governments of developed countries subsidized
domestic agriculture by more than $324B
led to greater food production than mark warranted and promoted
excessive use of fertilizers
sustainable use of freshwater can be achieved by charging users full
cost of providing the water, using water more effectively in
agriculture and alter allocation of water rights
sustainable use of marine fisheries can be achieved by establishing
more marine protected reserves and flexible no-take zones where
fish can grow
implement a limit to the number of fishing permits can
increase economic value of fishery

Document Summary

Chapter 56 ecosystems and global ecology (only 56. 2, 56. 4 and 56. 5!!!) 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. 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.