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Biodiversity and

Sustainable Agriculture

FAB-465 (Lecture 6)

This Lecture

• Definitions of sustainable development and sustainable agriculture

• Significance of biodiversity in the ecosystem

• Significance of biodiversity in agriculture

• Biodiversity issues in intensive agriculture

• Causes of decline in biodiversity

• Main approaches and practices in agriculture to conserve biodiversity

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Sustainable Development

“development which meets the needs of the present without compromising the ability of the

future generations to meet their own needs.” (The World Commission on Environment and Development)

Sustainable Agriculture

a) Conserves the resources on which it depends b) Restricts itself to a minimum input of production

means, which do not have their origin in the same farming system

c) Controls pests and diseases by internal control mechanisms as much as possible

d) Provides natural resources with the ability to recover from disturbances through cultivation means and harvesting by processes of natural succession.

http://www.britannica.com/science/ecological-succession

Stinner and House, 1990

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Habitat

• “Place of residence” or type of site

• Adaptation and ability to occupy

• Existing ecological conditions (factors) facilitate survival and reproduction of species

• If habitat conditions change, or species requirement fluctuate, it leads to displacement

• The term “biodiversity” is a contraction of the phrase “biological diversity”.

• Biodiversity means the richness and variety of life - of genes, species and ecosystems.

Biodiversity

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Benefits of Biodiversity

• Biodiversity maintains the health of the earth and its people.

• It provides us with food and medicine and contributes to our economy.

• It tells us a lot about the health of the biosphere.

• The greater the variety of species, the healthier the biosphere.

• The more links in a food web, the more stable it is. • Removing one link from a food web that has many links

does not affect it as much as if there were very few links.

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Biodiversity and Sustainability

• The biodiversity of an ecosystem contributes to the sustainability of that ecosystem.

• Higher/more biodiversity = more sustainable

• Lower/less biodiversity = less sustainable

• High biodiversity in an ecosystem means that there is a great variety of genes and species in that ecosystem.

• The more sustainable an ecosystem is, the better it is for the environment and for people.

• People use ecosystems as sources of food, medicine and economy.

• Thus, it is in everyone’s best interest to increase the sustainability of ecosystems.

• How can we do this?

Biodiversity and Sustainability

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The Challenge

Production Ecology

Conservation Biology

Intensive Food Production

+ Biodiversity

Conservation

Sustainability!

Today’s problem…

Unprecedented loss of species due to human activity that

degrades habitat and creates pollution.

Estimated total number of species today – 10 million.

If only 10% of each type of natural habitat eventually remains

(considered optimistic), around 50% of all species are projected to

survive.

Background rate of extinction – 1 to 10 extinctions each decade;

estimated rate of extinction over the last century – 100 to 10,000

species per year;

1/4 of all mammals, 1/10 of all birds, 1/3 of all fish – at risk of

extinction;

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Today’s problem… Habitat disturbance, loss and fragmentation – the leading direct cause of extinction.

Disturbance in aquatic and terrestrial habitat – Habitat conversion to agriculture and urbanization species loss

Human Population

Growth

Water diversion

Agricultural expansion

Urban sprawl.

Rural settlement expansion,

Agriculture Biodiversity - the dimension

Diversity of species:

• 10 million species of animals, plants and micro-organisms

• 7000 cultivated plant species

• 120 plant species important for food and agriculture

• 30 crops provide 95% of food (energy and protein)

Intra species diversity in agriculture:

• 4,000 potato “varieties”

• 100,000 rice “varieties”

Dramatic loss of agric.diversity:

• Estimations: 3/4 of agricultural plants are lost

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“The decline of Earth’s biodiversity is an unintended consequence of multiple factors that have been enhanced by human activity. They can be summarized by the acronym HIPPO, with the order of the letters corresponding to their rank in destructiveness.”

H Habitat loss, including that caused by human-induced climate change.

I Invasive species (harmful aliens, including predators, diseases, and competitors that displace native species

P Pollution

P Population, Human overpopulation to be exact, a root cause of the other four factors

O Overharvesting, Overuse (hunting, fishing, gathering)

E. O. Wilson “The Creation”

Habitat loss/destruction Habitat loss is the greatest reason for biodiversity loss. Habitat loss is due to: • Conversion of natural areas to

farms, houses, etc

• Fragmentation of ecosystems by human activities, housing, transportation, agriculture etc.

• Simplification of genetic diversity and complex ecosystems by planting/selecting monocultures.

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Invasive / Exotic Species

Invasive, exotic species introduced from elsewhere outcompete native species because they: •Have no natural predators •Colonize ,disturbed habitats quickly •Have a high biotic potential

http://en.wikipedia.org/wiki/File:Kudzu_on_trees_in_Atlanta,_Georgia.jpg

http://en.wikipedia.org/wiki/File:Bufo_marinus_from_Australia.JPG

Cane Toads

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Cane Toad (Bufo marinus)

• The cane toad, Bufo marinus, was introduced to Australia by the sugar cane industry to control two pests of sugar cane, the grey backed cane beetle and the frenchie beetle.

• One hundred and one toads arrived at Edmonton in North Queensland in June 1935.

• Unseasonal breeding occurred almost immediately, and within 6 months over 60,000 young toads had been released.

• B. marinus adapted well to the Australian environment and spread throughout coastal Queensland.

• The rate of spread was accelerated

- They are environmentally challenging breeding machines that have formed a daunting northbound march since they crossed the Queensland/Northern Territory border about 20 years ago.

- By any stretch of the imagination, cane toads are unpleasant: in the Dry they keep their shelters moist, sometimes through urination, males attempt to copulate with literally anything and females lay up to 50,000 eggs more than once a year.

- They come close to wiping out native quoll populations, poison large masses of goannas and disturb the food supply of many native animals.

- Also, there appears to be few predators for all life stages of toads, mainly because of their poison glands (which contains a steroid that affects heart muscle, and thus kills whatever tries to eat them).

Environmental Impact of the Cane Toad

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QUOLL

GOANNA

Pollution

Pollution (Oil spills, human agricultural waste, fertilization, pesticides, acid deposition, greenhouse gases etc) caused by human activities has a negative

effect on biodiversity

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Population, Human overpopulation

8 Billion and counting. The expansion of human population and affluence, especially in the developing world harms natural ecosystems.

http://en.wikipedia.org/wiki/File:World_population.svg

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Overharvesting, Overuse, Overexploitation

Overhunting, overfishing, destructive harvesting practices (cyanide, dynamite), illegal trade, exotic

pet industry

Human Population

Increase

Increasing Economic

Activity

Increased use of technology

Social, political and cultural

factors

Land use change (Habitat loss)

Increasing Economic

Activity

Increased use of technology

Social, political and cultural

factors

Indirect (Underlying

causes)

Direct causes

Declining Biological Diversity

Raven, Berg, and Hassenzahl put it this way

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Characteristics shared by many endangered species include:

• Low reproductive rate (biotic potential) • Feed at high trophic levels (apex predator) • Large body size • Specialist

Specialized feeding habits Specialized nesting and/or breeding areas Fixed migratory patterns Found in one specific place or region

• Rare • Commercially valuable • Negative human interactions including attacks on

people or livestock

How can humanity

protect biodiversity?

http://en.wikipedia.org/wiki/File:Siproeta_epaphus_Galawebdesign.jpg

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Land Sharing vs Land Sparing

Land sharing

• Integration of production and conservation on the same land

• Wild-life friendly farming

• (Eco-agriculture Approach)

• Crop, livestock, land diversification

• Multifunctionality of agriculture

Land sparing

• Segregation of natural land from production land

• Conservation of biodiversity and ecosystem

• (Intensive Agriculture Approach)

• Specialised use of land

• Intensive practices

Possible Trade-offs between Agricultural Production and Biodiversity

Brussaard et al. 2010

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Soil Biodiversity

Intercropping

• Cultivating two or more crops in the same space at the same time – Crop demands meeting available

resources

– Greater yield on a given piece of land

– Growth resources – rooting ability, canopy structure, nutrient requirements

– Soil Health Soil fertility – biological nitrogen fixation

– Reduction of pest incidence

– Economic and environmental benefits (insurance against crop failure, artificial fertilizers, pesticides)