Sustainability

1
Sustainability

• The Human Population Problem
• Harvesting resources from the wild
• Fisheries
• Forests
• Farming systems
• Monocultures
• Integrated Farming Systems

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Essay 2 Human Population Ecology
Understanding past global human population
growth and projecting its future is critically
important for the sustainability of the Earth.
Your essay should address two questions1) What
factors determine the rate at which the global
human population will grow until 2050?In
addressing this question, please incorporate
these considerationsa) Spatial variation in
current population size and projected growth
rates, especially considering differences between
rich vs. poor countries.b) Variations in
different combinations of fertility vs. mortality
in population growth rates.c) Patterns in
demographic age structure and implications for
future growth rates.d) Assumptions underlying
medium, high and low projections for population
size in year 2050. 2) Which ecological factors
will act in a density-dependent manner to
eventually stabilize or regulate human population
growth? In addressing this, consider factors
thata) Might importantly operate only in some
geographic areas.b) Influence only fertility or
mortality, or both.c) Are ecological or
environmental factors, rather than sociopolitical
or cultural.Sources - Scientific American
article by Joel Cohen, Human population grows
up (Sept. 2005) - web sources (U. S. Census
Bureau, many others)
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The Human Population Problem (chap 12.2)

• Sustainability of global human population
  possible problems
• Not size, but distribution over Earth that is
  unsustainable
• Present population size unsustainably high
• Not size, but age distribution that is
  unsustainable
• Present rate of population growth unsustainably
  high
• Not size, but uneven distribution of resources
  within pop that is unsustainable

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Global Population Size of Homo sapiens 6.74
billion
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Global Population Size of Homo sapiens
Q If growing exponentially since dawn of modern
agriculture (10,000 yrs ago), at todays
population growth rate (1.2), how many people
would there be now?
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Global Population Size of Homo sapiens
Q If growing exponentially since dawn of modern
agriculture (10,000 yrs ago), at todays
population growth rate (1.2), how many people
would there be now? A More than all the atomic
particles estimated in the universe.
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gt6 million more people per month, 77 million per
year
World POPClock Projection According to the
International Programs Center, U.S. Census
Bureau, the total population of the World,
projected to 11/26/07 at 1610 GMT (EST5)
is 6,633,657,737 Monthly World population
figures 07/01/07 6,602,274,812 08/01/07
6,608,818,475 09/01/07 6,615,362,139 10/01/07
6,621,694,717 11/01/07 6,628,238,381 12/01/07
6,634,570,959 01/01/08 6,641,114,623 02/01/
08 6,647,658,287 03/01/08
6,653,779,780 04/01/08 6,660,323,443 05/01/08
6,666,656,022 06/01/08 6,673,199,685 07/01/08
6,679,532,264
World POPClock Projection According to the
International Programs Center, U.S. Census
Bureau, the total population of the World,
projected to 12/04/08 at 2258 GMT (EST5)
is 6,741,287,491 Monthly World population
figures 07/01/08 6,706,992,932 08/01/08
6,713,766,305 09/01/08 6,720,539,678 10/01/08
6,727,094,555 11/01/08 6,733,867,928 12/01/08
6,740,422,806 01/01/09 6,747,196,179 02/01/
09 6,753,969,552 03/01/09
6,760,087,438 04/01/09 6,766,860,811 05/01/09
6,773,415,688 06/01/09 6,780,189,061 07/01/09
6,786,743,939
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Since the industrial revolution, population has
exploded - growth has exceeded exponential
growth!!the growth rate has not been
constant, but has accelerated over time!
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Early Transition Model Europes population
growth rate - decline in death rate, - followed
by decline in birth rate, - then narrowing of
difference
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Population Growth Rate Averaged for World
1965-70 2.1/yr 2005 1.1-1.2/yr
(peak pop growth rate)
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Population growth fertility rates developing
vs. industrial
avg. woman 2.9 vs. 1.6 children
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Cohen,2005
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Recent Predictions of Earths Carrying Capacity
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Cohens Solutions Bigger Pie Intensify
productive capacityFewer Forks increase access
to contraception reproductive healthBetter
Manners reform policies practices for greater
equity
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Sustainable Harvesting from Fisheries, Forests
Farms

• An activity is sustainable if it can be continued
  for the foreseeable future
• Only foreseeable because many factors or forces
  influencing an ecological system remain unknown
  or unpredictable
• From Conservation to Sustainable Use
• 1991 ESA IUCN/UNEP/WWF Publications
• 1992 Rio Conference on Sustainable Development
• 2005 Millenium Ecosystem Assessment

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Changes in of fisheries in different
development stages- global marine catches rose
5-fold from 1950-1989
No more unexploited marine fisheries since 1970
now most declining (2006)
Developing fisheries are underexploited
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How to best exploit a population? assume it is
crowdedExploitation reduces competition, net
recruitment highest at intermediate population
size, defining a point of Maximum Sustainable
Yield (MSY)
net recruitment births - deaths
Dome-shaped net recruitment curves a) brown
trout, b) fruit flies, c) herring
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MSY concept is guiding principle in wildlife,
forestry and fisheries management, but many
problems/assumptions1) assumes population
consists of identical individuals no size or age
classes their differential growth, survivorship
reproduction2) treats environment as
unvarying (a single recruitment curve for all
times places)3) because of survey sampling
errors, MSY estimated poorly4) success in
management of harvesting should be based not only
on MSY but employment, conservation of community
biodiversity, etc.
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The danger of overexploitation under fixed quota
harvesting - the MSY harvesting rate drives a
large population to the optimal harvesting
density, but a smaller population to extinction
- the equilibrium pop density at the high quota
rate is zero (extinction)
In a world of imperfect estimates of MSY and
fluctuating environments, fixed quotas invite
disaster
e.g., Catch history of the Peruvian anchoveta
fishery overexploitation under a fixed quota
strategy of MSY
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Achieving MSYs through fixed effort harvesting
(fixed number of trawler days or hunting days)
Population equilibrium is achieved over range of
densities at various harvesting rates only very
high rates drive population to extinction
Yield then varies with population density, so can
be large annual fluctuations in harvest -Need to
legislate rules police compliance
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You cannot determine the potential yield from a
fish stock without overexploiting it (Hilborn
Walters 1992)in 1975, the Intl Commission for
the Conservation of Atlantic Tunas calculated
sustained yield of 50,000 tons/yr with 60,000
fishing dayshowever, they couldnt control
increase in harvest, which yielded apparently
much higher sustainable harvest 110,000 tons
with 240,000 fishing days
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Dynamic pool approach to sustainable harvesting
reality is complex.
23
Beyond MSYimpact of harvesting strategy on
recruitment and density should take into account
age- or size-specific growth, mortality and
fecunditythis model recommended for the
Arco-Norwegion cod industry recommended low
intensity harvesting and large mesh size to
ensure higher levels of long-term harvest but
due to political reasons, recommendations ignored
and cod fishery collapsed
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Beyond MSYharvesting largest fish 1) selects
for smaller size and earlier reproduction2)
eliminates females that produce most eggs, with
gt fertilized in some cases, whose offspring
grow faster! E.g., black rockfish (Oregon)
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Beyond MSYMarine Protected Areas allow
unexploited source populations to avoid species
extinction and recolonization of overexploited
fisheries
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Sustainable Forestry

• Sustainable forest management (from Wikipedia,
  the free encyclopedia)
• Sustainable forest management (SFM) is a sub-set
  of sustainable development. It is also the
  current culmination in a progression of basic
  forest management concepts preceded by
  Sustainable forestry and sustainable yield
  forestry before that. Sustainable forest
  management is the term currently used to describe
  approaches to forest management that set very
  broad social and environmental goals. A range of
  forestry institutions now practice various forms
  of sustainable forest management and a broad
  range of methods and tools are available that
  have been tested over time.The Forest Principles
  adopted at The United Nations Conference on
  Environment and Development (UNCED) in Rio de
  Janeiro in 1992 captured the general
  international understanding of sustainable forest
  management at that time. A number of sets of
  criteria and indicators have since been developed
  to evaluate the achievement of SFM at both the
  country and management unit level. These were all
  attempts to codify and provide for independent
  assessment of the degree to which the broader
  objectives of sustainable forest management are
  being achieved in practice.
• A definition of the present day understanding of
  the term sustainable forest management was
  developed by the Ministerial Conference on the
  Protection of Forests in Europe (MCPFE), and has
  since been adopted by the Food and Agriculture
  Organization (FAO).1 It defines sustainable
  forest management as the stewardship and use of
  forests and forest lands in a way, and at a rate,
  that maintains their biodiversity, productivity,
  regeneration capacity, vitality and their
  potential to fulfill, now and in the future,
  relevant ecological, economic and social
  functions, at local, national, and global levels,
  and that does not cause damage to other
  ecosystems.
• Key issues in sustainable natural forest
  management
• Adequate regeneration or enrichment planting
  required?
• Which species to harvest at which sizes?
• Growth yield models (age- size-specific
  growth)
• Sustainability of growth after repeated harvests
  (depleted nutrients?)
• Control of fire, disease, etc
• Financial analysis policy issues

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Sustainability of Monoculture Agriculturethese
farming and animal husbandry systems maximize
production, but sustainability threatened by-
plant and animal diseases- soil erosion- water
availability
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Indigenous Agroecosystems vs. Monoculture
Agricultureshifting ( slash burn)
cultivation systems- manage soil erosion and
prevents disease outbreaks- provide diverse
food, fiber and medicinal products by managing
diverse fallow succession- are ecologically
sustainable and wonderfully adaptive! But.
also - require large land areas (5-25
ha/family) - are unproductive (few tons
food/ha/yr) - do not typically provide cash
income So farmers convert to monocultures
..such as rubber oil
palm
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Sustainability of Water- Humans now use more
than half of all accessible water supply- water
availability per capita variable (like all other
resources!)- the resource of future wars?
30
Global demand for water - by sector -
developed vs. developing countriesdistribution
is central problem
31
Ecology of Pest Control pesticides are popular
because they work!
Manage for the EIL (economic injury
level) Population fluctuations of a) pest, b)
non-pest c) potential pest
but kill non-pests effectiveness declines

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Biological control Replacing chemicals with
natural enemiesa) import enemy from native
area- cottony cushion scale insect (Australia)
on CA citrus crops (1890)- Cryptochaetum larva
(fly)-coastal CA- Vedalia (Rodalia ladybird
beetle)-inlandb) repeated inoculation- spider
mite attacking vegetables- Phytoseiulus mites-
Encarsia parasitoid wasps- by 1985 500 my/yr
released in Europe c) inundate (like
pesticide)but introductions may have bad
effects- Rhinocyllus conicus weevils
thistles- outcompetes Paracantha fly control
agent
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Biological Control of scale insect on St. Helena
island
Orthezia urticae scale
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Pesticides and cotton pests in CAs Central
Valleytarget pest emergence a) bollworms
increase because natural predators decline when
pesticide Azodrin appliedsecondary pest
outbreaks from pesticide use against Lygus bugs
b) cabbage loopers c) beet army wormsd)
evolution of chemical resistence - Lygus
mortality vs. Azodrin mg per bug improved
system Integrated Pest Management (IPM) - spray
only June July-interplant alfalfa (preferred
by Lygus)
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Decision Control Chart for IPM of Potato Tuber
Moths
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Integrated Pest Management Organic Farming
can increase sustainability, butrequires
economic sustainability also
In case of Washington apples, organic farming had
similar yields with gt profitability lt energy
use
But are issues with organic farming manure
runoff N leaching approved pesticides, etc.
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Forecasted agricultural production needs for
global human population (6.5 -gt 9-10 my by 2050)
further threatens sustainability conservation
of biodiversity, especially in tropics
increase in needs for 2020 (maroon) and 2050
(green)