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”