Why do we need forests? Create a list

• Fuelwood• Construction material• Paper• Produce oxygen• Store carbon• Slow runoff• Hold soil in place• Cycle nutrients• Support rich biodiversity (countless niches for plant and animal, fungi and bacteria)

• Recreation• Tourism• education

Forestry

• U.S. National Forest service est. 1905 (Pinchot)

• Goal: protect watersheds, extract timber

• Forest service builds roads for timber companies and oversees timber extraction

• Plantation Forestry:

• even aged stands of one species (monoculture) much like crop agriculture

• Uneven-aged stands – simulates a natural forest

Timber Harvesting

• Clear cutting: most cost efficient BUT has greatest ecological impact

• Seed tree or Shelterwood: small numbers of large trees are left to reseed the area or provide shelter for young saplings

• Selection system: A selected minority of trees are removed at one time

• No system is without environmental impact

The role of fire• For many years forest fires were

suppressed• Now, ecologists recognize the value

of prescribed / controlled burning.• Suppression leads to a build up of

dead wood (kindle for a huge fire)• Climate change brings drier warmer

weather• Prescribed burning allows

germination of certain forest species• However, it can get out of control• Salvage logging: physical removal

of dead trees• However, such trees are

ecologically valuable

Why we created Parks and Reserves

1. monumentalism: preserving unique features of the land ex. Grand canyon

2. Recreational value: hunting, fishing etc

3. Utilitarian benefit: watershed protection

4. To make use of land that is hard to develop

5. Preservation of biodiversity

The Green Revolution (Norman Borlaug)

Movement to eliminate hunger by increasing yields through the use of:– New crop cultivars– Irrigation– Fertilizers– Pesticides– Mechanization

Results:• Saved millions from starvation in India in the 1970s• Mexico tripled their wheat production • Intensification reduced the need to bring more land

under production• Increase costs of production• Increased negative environmental impact• Africa was largely unaffected

Modern conventional farming• Heavily reliant on cheap fossil fuels

• Synthetic fertilizers (cheap, derived from fossil fuel, effective, easy to transport, provide N,P,K)

• Herbicides to kill weeds (easy to use, effective)

• Pesticides to kill insects (effective, easy to use)

Negative Impacts of Modern (conventional) Agriculture

Soil• Erosion• Loss of fertility

(O.M.)• Salinization• Desertification

Water

•Aquifer depletion

•Increased runoff and flooding from land cleared to grow crops

•Fish kills from pesticide runoff

•Surface and groundwater pollution from pesticides and fertilizers

•Over fertilization of lakes >> eutrophication

Air•Greenhouse gas emissions from fossil fuels•Other air pollutants from fossil fuels•Pollutions from pesticide sprays

Negative Impacts of Modern (conventional) Agriculture…continued.

Biodiversity Loss• Loss and degradation of habitat

from clearing grasslands and forests and draining wetlands

• Fish kills from pesticide runoff• Killing of wild predators to protect

live stock• Loss of genetic diversity from

replacing thousands of wild crop strains with a few monoculture strains

Human Health•Nitrates in drinking water

•Pesticide residues in drinking water, food, and air

•Pesticide drift

•Farm workers poisoned by agri-chemicals

•Contamination of drinking and swimming water with disease organisms from livestock wastes•Air pollution from CAFO•Antibiotic resistance

Negative Impacts of Modern (conventional) Agriculture

• Pesticide resistance

• Loss of family farms

Organic Agriculture• Agriculture that relies on crop rotation,

green manure, compost, biological pest control, and mechanical cultivation to maintain soil productivity and control pests

• Synthetic fertilizers, synthetic pesticides, livestock feed additives, and genetically modified organisms are NOT allowed.

Organic Soil Management

• Healthy soil is at the center of organic agriculture

• Farmers use crop rotation to maintain soil health, manage weeds and pests

• Farmers can use compost, manure, minerals such as rock phosphate to fertilize the soil

• Alley cropping, intercropping,

• Green manure

Organic Weed management

• Hand weeding• Mulch• Corn gluten meal• Vinegar• Flame weeding• Crops such as rye

Organic Pest Management

• Biocontrol – using natural predators to control pests ex. Ladybugs, spiders

• Row covers• Crop rotation• Organic approved

pesticides ex. Surround, garlic, neem, BT, pyrethrum

Why does organic food cost more?• Organic farming involves more risk• Limits on pesticides means more hand weeding• Compost and manure are bulkier than synthetic

fertilizers so cost more to transport• Crop rotation means you can’t grow your highest

value crop every year• Demand exceeds supply• Certification costs• Organic farmers do not receive the same

subsidies

Integrated Pest Management• Combines chemical and biological

approaches to farm management

• May use biocontrol and chemicals when necessary

• Crop rotation

• Transgenic crops

GMOs pros and cons• Reduces use of

chemicals• Allows no-till farming so

less soil erosion and less carbon emissions

• Golden rice cures vitamin A deficiency

• Feed the world• Drought tolerance• Salt tolerance• More nutritious• Increases shelf life

• Morally wrong• Global food supply

dominated by a few big companies

• Transgenes might escape and pollute ecosystems

• Not safe to eat?• Herbicide resistant crops

might breed with wild plants and form “superweeds”