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Midterm Grading. (n= 85 exams) highest= 96, median = 81.5 A, A-: 20 exams >= 87.5 B+, B & B-: 47 exams 74-86.5 C+, C & C-: 19 exams 52-73. Sustainability. Harvesting resources from the wild Fisheries Forests Farming systems Monocultures Integrated Farming Systems

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midterm grading
Midterm Grading
  • (n= 85 exams)
    • highest= 96, median = 81.5
    • A, A-: 20 exams >= 87.5
    • B+, B & B-: 47 exams 74-86.5
    • C+, C & C-: 19 exams 52-73
  • Harvesting resources from the wild
    • Fisheries
    • Forests
  • Farming systems
    • Monocultures
    • Integrated Farming Systems
  • The Human Population Problem
sustainable harvesting from fisheries forests farms
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
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


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


MSY concept is guiding principle in wildlife, forestry and fisheries management, but many problems/assumptions:1) 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.


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

achieving msys through fixed effort harvesting fixed number of trawler days or hunting days
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


“You cannot determine the potential yield from a fish stock without overexploiting it” (Hilborn & Walters 1992)in 1975, the Int’l Commission for the Conservation of Atlantic Tunas calculated sustained yield of 50,000 tons/yr with 60,000 fishing dayshowever, they couldn’t control increase in harvest, which yielded apparently much higher sustainable harvest: 110,000 tons with 240,000 fishing days


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


Beyond MSYharvesting largest fish 1) selects for smaller size and earlier reproduction2) eliminates females that produce most eggs, with >% fertilized … & in some cases, whose offspring grow faster! E.g., black rockfish (Oregon)


Beyond MSYMarine Protected Areas allow unexploited “source” populations to avoid species extinction and recolonization of overexploited fisheries

sustainable forestry

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


Sustainability of Monoculture Agriculturethese farming and animal husbandry systems maximize production, but sustainability threatened by…- plant and animal diseases- soil erosion- water availability


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


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?

global demand for water by sector developed vs developing countries distribution is central problem
Global demand for water: - by sector & - developed vs. developing countriesdistribution is central problem
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

Ecology of Pest Controlpesticides are popular because they work!

…but kill non-pests… & effectiveness declines


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


Pesticides and cotton pests in CA’s Central Valley:target 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 bugimproved system:Integrated Pest Management (IPM)- spray only June & July-interplant alfalfa (preferred by Lygus)

Integrated Pest Management & Organic Farming can increase sustainability, but…requires economic sustainability also

In case of Washington apples, organic farming had similar yields with > profitability & < energy use

But are issues with organic farming:

manure runoff & N leaching; approved pesticides, etc.


Forecasted agricultural production needs for global human population (6.5 -> 9-10 billion by 2050) further threatens sustainability & conservation of biodiversity, especially in tropics

% increase in needs for

2020 (maroon) and 2050 (green)


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 questions:1) What factors determine the rate at which the global human population will grow until 2050?In addressing this question, please incorporate these considerations:a) 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 that:a) 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)

the human population problem chap 12 2
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
global population size of homo sapiens
Global Population Size of Homo sapiens

Q: If growing exponentially since dawn of modern agriculture (10,000 yrs ago),

at today’s population growth rate (1.2%), how many people would there be now?

global population size of homo sapiens1
Global Population Size of Homo sapiens

Q: If growing exponentially since dawn of modern agriculture (10,000 yrs ago),

at today’s population growth rate (1.2%), how many people would there be now?

A: More than all the atomic particles estimated in the universe….

6 million more people per month 77 million per year
>6 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 16:10 GMT (EST+5) is


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 22:58 GMT (EST+5) is


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


Since the industrial revolution, population has exploded- growth has exceeded exponential growth!!…the growth rate has not been constant, but has accelerated over time!


Early Transition Model: Europe’s population growth rate - decline in death rate, - followed by decline in birth rate, - then narrowing of difference

population growth rate averaged for world 1965 70 2 1 yr 2005 1 1 1 2 yr peak pop growth rate
Population Growth Rate Averaged for World1965-70: 2.1%/yr 2005: 1.1-1.2%/yr (peak pop growth rate)
population growth fertility rates developing vs industrial
Population growth & fertility rates: developing vs. industrial

avg. woman:

2.9 vs. 1.6 children


Cohen’s SolutionsBigger Pie: Intensify productive capacityFewer Forks: increase access to contraception & reproductive healthBetter Manners: reform policies & practices for greater equity