ENSC 003 Midterm 2

Harvesting Trees

Similar to growing crops with four different types of cutting

Selective cutting

Cutting only healthy trees and leaving an unhealthy forest; leaving forest unmanaged

Selection cutting

Shelterwood cutting

Less desirable and dead trees are harvested so that by the time the younger trees are mature, the older ones can be harvested

Seed Tree Cutting

Removing all but a few trees that allows seeds to naturally regenerate

Clear Cutting

Severe form of forest cutting that removes all trees from the landscape which can be useful in disease and infestation cases; can be done in patches as well

Nitrogen immobilization

Leaving wood chips in clear cut areas so biome can eat carbon and nitrogen without the nutrient being lost

Consequence of Clear Cutting

Soil erosion and sediments washing into river

Why harvest trees?

Deforestation

Temporary or permanent clearance of large expanses of forest for agriculture or other use

Causes of deforestation

• Fire

• Clearing for agriculture

• Construction of roads

• Tree harvest

• Insect and disease

Consequences of Deforestation

• Decreased soil fertility

• Uncontrolled soil erosion

• silt build up behind dams, hydroelectric problems

• Loss of CO2 sink

• Formation of deserts

• Extinction of species

• Global climate change

Global Forestry Challenges

• Over exploitation

• Slash and burn for subsistence agriculture

• Illegal timber harvesting

• Climate change (beetle kills and forest fires)

• Causes of Tropical Rain Forest Damage

• Subsistence agriculture

• Commercial logging

• Cattle ranching

  • Mining and hydroelectric power as well

Boreal Forests

• Comprise the world’s largest biome

• Are currently the primary source of the world’s industrial wood and wood fiber

• are harvested primarily by clearcut logging

• Comprised of evergreen trees, such as spruce, fir, cedar, and hemlock

What is the percentage of carbon with Boreal forests?

13% of Earth’s biomass carbon and 43% of Earth’s soil carbon contained in forests which are released when thawed (CRITICAL FOR CLIMATE CHANGE)

Rangeland

Land that is not intensively managed and is used for grazing livestock

Rangeland Degradation and Deforestation

• Overgrazing leaves ground barren

  • Animals exceed land’s carrying capacity

• Land degradation

  • Natural or human-induced process that decreases future ability of land to support crops or livestock

• Desertification

  • Degradation of once fertile land into nonproductive desert

Desertification

Process of conversion to desert

Agricultural land

• 300 million acres of prime farmland

• Threatened by suburban sprawl

Wetlands

• Lands that are usually covered with water for at least part of the year

• Have characteristic soils (anerobic/grey soil), and water-tolerant vegetation

Benefits of wetlands

• Habitat for migratory waterfowl and wildlife

• Recharge groundwater

• Reduce damage from flooding

• Improve water quality

• Produce many commercially important products

Human threat to Wetlands

• Draining for agriculture or mosquito control

• Dredging for navigation

• Channelization

• Construction of dams, sea walls, levees

• Filling in for solid waste disposal, roads, residential / industrial development

• Conversion to aquaculture

Where do wetland losses occur the most?

• In the 48 united states, more than half of the historic wetlands are gone, mostly converted to cropland

• Most of the loss has been since 1950

• The greatest percentage declines have been in Ohio, Indiana, Iowa, and California

• The greatest total acreage declines have been in Florida, Louisiana, and Texas

Clean Water Act of 1972

No net loss of wetlands in the U.S but contention on the definition of protected wetland between homeowners and scientists

Coastlines

Natural border of coast that can protect infrastructure

Coastal Wetlands

• Provide food and habitat for many aquatic animals

• Historically regarded as wasteland

Coastline Population

Overdeveloped

Suburban and Urban Land

Prior to World War II, jobs and homes were concentrated in cities.

During the late 1940s and 1950s, homes began to move from urban centers to the suburbs.

Suburbanites commuted to the city for work.

There is an urgent need for regional planning to determine where new development should take place and where it should not.

Metropolitan areas need to make more efficient use of land that has already been developed.

High density housing with jobs and shopping nearby is a good way to minimize the human footprint on the land.

Cities make up what percentage of the world’s total land area?

3%

World Food Security

Increase in population has not been matched as grain per person has not increased

Famine

• Temporary but severe shortage of food

• Emerging economies in Africa, Asia and Latin America are most at risk

• More people die from starvation than famineFood

Kwashiorkor

Protein deficiency common in children

• Characteristic swollen belly

  • Caused by fluid retention

What percentage of food do Americans waste?

40%

Food Production

Invest mostly in sugarcane followed by corn, rice, and wheat

What percentage of the calories consumed are animals in high-income countries vs. in developing countries?

• Constitute 40% of the calories consumed in high-income countries

• Only comprise 5% of calories consumed in countries with emerging economies

Inefficiency of eating meat

Calories of meat lost by the time the human is eating, meaning that it is better to eat primary producers/bottom of food chain/crops

Industrialized agriculture

Modern agriculture methods that require large capital input:

• Energy

• Fertilizer

• Herbicide

• Pesticides

• Hybrid seeds

• Irrigation water

Training and experience are needed to safely conduct industrialized agriculture

• Less land and labor needed however degradation of the land can occur through chemical use

Subsistence agriculture

• Traditional agricultural methods, which are dependent on labor and large amounts of land

• Provides food for the farmer only meaning smaller yields

• Energy inputs come from humans and animals

• Large amounts of land may be used

• Shifting cultivation, Slash and burn agriculture, Nomadic herding, Intercropping

Norman Bourlaug

Father of Green Revolution by developing high-yielding, short stemmed wheat which greatly improved wheat yields around the world

Which plant did Norman Bourlang develop?

The improved high-yielding plant

Green Revolution

Between 1950 and 1985:

• Grain production tripled, from 600 to 1800 million metric tons due to the breeding of high-yielding varieties of wheat and rice.

• Population increased from 2.5 to 4.9 billion.

• Fertilizer and pesticide use increased greatly.

Genetic Engineering

• Manipulation of genes by taking specific gene from a cell of one species and placing it into the cell of an unrelated species

• Used to produce Genetically Modified (GM) food

• Plants that are tolerant to insect pests, heat, cold, drought, or acidic soils

• More productive farm animals

  • Examples: golden rice - rich in beta carotene (prevent Vitamin A deficiency in developing countries)

Are GMOS safe for human consumption?

• Yes, determined to be safe but long-term effects are not known

• Concerns about GMO seed or pollen spread

• GMO labelling

Challenges of producing more livestock

• Increasing livestock yields

  • Cloned and genetically modified animals

  • Hormone supplements

• Antibiotics

  • Increased weight

  • Increased bacteria resistance: Bacteria that survives antibiotic can procreate with new genes that are stronger

Transgenic animals

Extra genes from another animal where genes of choice are manipulated, prepared and injected into the egg of an animal which is implanted into a surrogate

Ex:

• Quicker growth of salmon

• Self-healing catfish

• Spider silk goats

• Featherless chickens

• Goats improved milk through rat protein

Benefits of the enviropig

Genetically modified pig from bacterium and mouse that releases less phosphorus through waste

How many tons of antibiotics are produced annually and what percentage of that is fed to healthy animals?

40% of the 25000 tons of antibiotics produced annually in the US are fed to healthy animals

Problems of Factory Farms

Growth Hormones

Injected or implanted _____ into animals to increase growth rate muscle mass and milk production

• Trace amounts are found in meat and milk but considered safe for humans

• However, pellet locations on animals are considered to have higher concentrations of drug

Livestock waste

Drugs can taint rivers and groundwater

Individual contributions to improve food issues

• Reducing meat consumption

• Eat animals that require less grain (chickens, fish, pork)

• Support farmers that produce meat ethically

• Mindful consumption

What are the environmental impacts of agriculture?

• Water pollution by chemicals

• Erosion and soil degradation

• Soil and groundwater salinization

• Air pollution

• Climate change from land clearing

• Deforestation

• Habitat fragmentation and wildlife endangerment

• Pesticide, antibiotic, and hormone residues in food

• Aquifer depletion

• Loss of genetic variation

Solutions to agricultural problems - sustainable agriculture

Agricultural methods that maintain soil productivity and a healthy ecological balance while having minimal long-term impacts

How can we reduce erosion and maintain fertility?

• minimum tillage

• contour plowing

• crop rotation

How can we reduce chemical use?

• introduction of predators (natural predator-prey relationship like ladybugs)

• nitrogen-fixing crops (legumes)

• crop breeding for disease resistance

• use biodegradable chemicals

Integrated Pest Management

Limited use of pesticides with sustainable agriculture practice

Who owns the open ocean?

No nation lays claim to open ocean

• Resource susceptible to overuse and degradation

Over harvesting fisheries

• Many species are at point of severe depletion

• 62% of world’s fish stock are in need of management action

  • Sophisticated fishing equipment

  • Bycatch killed off

Purse Seining Process

Problems of bottom trawling

Deep trawling with nets held open by heavy doors bulldoze the seabed and catch sea life indiscriminately - more than 50% of catch is disgarded

• Bycatch

• fishes, marine mammals, sea turtles,
  seabirds, and other animals caught
  unintentionally are called bycatch

• Dumped back into ocean, dead

• Bycatch makes up ~25% of all fishes
  caught

Ocean Pollution

• Dumping ground

• Oil

• Heavy metals

• Deliberate litter dumping

• Storm water runoff from cities and agricultural areas

Aquaculture

• Growing aquatic organisms for human
  consumption (fish farming)

• Great potential to supply food

Improvements for Aquaculture

• As opposed to raising carnivorous fish such as salmon and stripped bass which require fish meal

  • Salmon eat 5kg of fish meal to gain 1kg of weight

Is it better to eat at the top or bottom of the food chain?

Bottom of the food chain

Layers of atmosphere

1. Exosphere

2. Thermosphere

3. Mesosphere

4. Stratosphere

5. Troposphere

Troposphere

• Extends from the ground to 10 miles up

• 90% of all the air is in this first layer

Atmosphere as a Resource

• Atmosphere Composition:

  • Nitrogen: 78.08%

  • Oxygen: 20.95%

  • Argon: 0.93%

  • Carbon Dioxide: 0.04%

Functions of atmosphere

• Provides many ecosystem services:

  • Supports life with oxygen and carbon dioxide

  • Nitrogen needed for soil/plant/atmosphere cycle

Air Pollution

• Chemicals added to the atmosphere by natural events or human activities in high enough concentrations to be harmful

• Two categories:

  • Primary air pollutant

  • Secondary

Effects of Air Pollution

• Low level exposure:

  • Eye irration

  • Inflammation of

  • Greater health risk to children who are more likely to develop asthma

• Prolonged exposure can develop into chronic respiratory diseases

Air Pollutants in US

Major Drivers of Air Pollutants

Major classes of air pollutants

• Particulate materials

• Nitrogen oxides

• Sulfur oxides

• Carbon oxides

• Hydrocarbons

• Ozone

Particulate material

• Thousands of different solid or liquid

Nitrogen Oxides

• Gases produced by the chemical interactions between atmospheric nitrogen and oxygen

• Can cause difficulty breathing

• Can acidify precipitation through nitric acid

What is nitrogen oxide summed up into?

NOx which can be NO or NO2

• NO (nitric oxide) produced during high temperature combustion (auto engines)

• Emitted from soils

• React with hydrocarbons (HC), oxygen, and sunlight to produce photochemical smog

What is sulfur oxides summed up into?

SOx

• SOX is one of the most damaging air pollutants

• SOX results from burning of fossil fuels that contain sulfur

• SO2 causes eye and lung irritation at low
  concentrations

• SO2 can be deadly at high concentrations

• Plants are very sensitive to SO2

• SO2 is the main cause of acid rain

• SOX is mainly emitted by coal-burning power plants (88%)

NO + HC

Peroxyacyl nitrates (PAN)

NO2 + O2 + sunlight

NO + O3 (Ozone)

Sulfure Oxides

• Gases produced by the chemical interactions between sulfur and oxygen

• Acidifies precipitation through sulfuric acid

Acid Rain

• NO2 + H2O = HNO3 (Nitric acid)

• Methyl red is a pH indicator

  • Yellow at pH > 7

  • Red in acid

Carbon Oxides

• Carbon monoxide (CO) and carbon dioxide (CO2)

• CO is an indirect greenhouse gas

• CO2 is a greenhouse gas

Hydrocarbons

• Diverse group of organic compounds that contain only hydrogen and carbon (ex: CH4 - methane)

• Some are related to photochemical smog and greenhouse gases

Carbon Monoxide (CO)

• CO results from incomplete combustion such as poor air supply or low burning temperature

• CO attaches to blood cells more easily than O2

• It causes headaches and dizziness at low concentrations

• It is deadly in high concentrations because it reduces oxygen
  transport in the blood

  • CO binds irreversibly to hemoglobin; O2 then unable to bind to hemoglobin.

• It does not affect plants

• It is mainly emitted by transportation (78%) and forest fires.

Tropospheric Ozone

• BAD

• Man-made pollutant in the lower atmosphere

• Secondary air pollutant

• Component of photochemical smog

Stratospheric ozone

• GOOD

• Essential component that screens out UV
  radiation in the upper atmosphere

• Man-made pollutants (ex: CFCs) and N2O (from agriculture) can destroy it

Sources of Outdoor air pollution

• Two main sources:

  • Transportation

  • Industry

  • Intentional forest fires are also high

Urban air pollution

Photochemical smog

• Brownish-orange haze formed by chemical reactions involving sunlight, nitrogen oxides, and hydrocarbons

N2 + O2 + engine temp.

2NO (Nitric oxide)

• NO is a colorless gas

• Smog

2NO + O2 (air temp.)

2NO2 (nitrogen dioxide)

• NO2 is a reddish-brown gas

• Smog

Causes of Urban Air Pollution

• Automobiles are major sources of pollutants.

• The pollutants are trapped in a layer of air next to the ground. A thermal inversion causes the air to be trapped.

• A thermal inversion occurs when cold air near the ground is overlain by warmer air.
  During the day, the air warms near the ground. At night, cool, dense air from the ocean slides inland, under the warm air. This sets up the inversion.

Inversion Layer

Warm air

Air Toxics

Lead, formaldehyde, radon and other
radioactive elements, hydrochloric acid, hydrofluoric acid, arsenic, asbestos, and synthetic organic chemicals

• The Clean Air Amendment of 1990 lists more than 180 hazardous air toxics that are now regulated.

• Since 1977 the lead concentration has dropped more than 97% due to the elimination of leaded gasoline.

• Lead substantially reduces IQ, and causes hypertension in adults (high blood pressure).

Indoor Air Pollution

• Pollutants can be 5-100x greater than outdoors

• Radon, cigarette smoke, carbon monoxide, nitrogen dioxide, formaldehyde pesticides, lead, cleaning solvents, ozone, and asbestos

• Most people are more exposed to air toxics indoors than outside

Controlling Air Pollution

• Smokestacks with electrostatic
  precipitator or scrubbers

• Electrode imparts negative charge on the
  air pollutants

• Negatively charged pollutants are then attracted to positively charged walls- fall into collector

Controlling Vehicle Emissions

• The procedures that lower CO and VOC emissions (complete combustion, high temperatures) tend to raise NOX emissions

• The best solution is the two-stage catalytic converter

• Nitrogen oxides are converted in the first stage to N2 by removing oxygen

• CO and VOC are removed in the second stage by oxidation to CO2 and H2O

• Fine platinum particles catalyze the reactions

Alternative Car Fuels

• Modern diesel engines

• Alternative fuels: methanol and ethanol

• Oxygenation of fuel

• Electric cars

• Hybrid cars

• Fuel cell cars

Fuel Oxygenation

• Blending gasoline with ethanol or methanol.

• It is used to reduce CO levels by encouraging complete oxidation to CO2

• It also reduces VOC emissions

• Fuel is burnt less efficiently in a cold engine.
  Oxygenates solve this problem