Land and Water Use – Part IUnit 5

Topics – Part I

5.1 – The Tragedy of the Commons

(C. 1.3)

5.2 – Clearcutting

(C. 10.1)

5.3 – The Green Revolution

C. 12.2, 12.3

5.4 – Impacts of Agricultural Practices

C. 12.2, 12.3

5.5 – Irrigation Methods

(C. 13.2, 13.5)

5.6 – Pest Control Methods

(C. 12.4)

5.7 – Meat Production Methods

(C. 12.2, 12.3)

5.8 – Impacts of Overfishing

(C. 12.3)

5.9 – Impacts of Mining

(C. 11.3, 11.4)

5.10 – Impacts of Urbanization

(C. 10.5)

Topics – Part II(on PowerPoint Land and Water Use Part II)

5.11 – Ecological Footprint

(C. 1.2)

5.12 – Introduction to Sustainability

(C. 1.6)

5.13 – Methods to Reduce Urban Runoff

C. 10.5

5.14 – Integrated Pest

Management

C. 12.4

5.15 – Sustainable Agriculture

(C. 12.5)

5.16 – Aquaculture

(C. 12.5)

5.17 – Sustainable Forestry

(C. 10.1)

5.1 – The Tragedy of

the Commons(C. 1.3)

Tragedy of Commons

Can renewable resources become nonrenewable?

Tragedy of the Commons by Garrett Hardin:

“If I do not use this resource, someone else will. The little bit that I use or pollute is not enough to matter, and anyway, it’s a renewable resource.”

However the cumulative effect of many people trying to exploit a common resource leads to exhaustion or ruin

Solutions?

Use shared resources at rates below estimated sustainable yields

Convert common resources to private ownership

5.2 – Clearcutting(C. 10.1)

Methods for Harvesting Trees

Pros

Varying age stands

High profit

Cons

Increased wind →increased soil erosion

Mudslides

Decreased water quality (increased nutrient runoff and turbidity)

Increased water temperatures (increase bacterial/algal growth)

Harvesting Trees

Roads lead to:

-forest fragmentation

-increased erosion and runoff

-introduction of nonnative species

- increased access by humans

Deforestation

5.3 – The Green

Revolution

C. 12.2, 12.3

Malthusian Theory

Green Revolution and Agribusiness

~10,000 years ago was the

advent of agriculture

(cultivation of soil,

domestication animals,

selective breeding)

Monocultures of selectively

breed of GE high-yield crops

Large inputs of water, fertilizers

and pesticides

Multiple cropping

Dwarf varieties

Shifting cultivation/slash and burn in tropical

forests in developing countries. Oxidation of

carbon during burning leads to greater inputs of CO

and CO2 in the atmosphere

Nomadic herding/grazing in developing

countries. Is the most sustainable method for

soil types with low productivity.

Land

Labor

Capital

Land

Labor

Capital

Industrialized/conventional agriculturein developed countries

Intensive traditional agriculture in developing countries. In semi-arid environments, intensive

traditional agriculture may lead to desertification.

Land

Labor

Capital

Fossil fuel

energy

Land

Labor

Capital

Fossil fuel energy

5.4 – Impacts of

Agricultural PracticesC. 12.2, 12.3

Important Foods

Wheat, rice, corn, supply ~60%

of human caloric intake

Despite ~50,000 edible plant

species

Cultural cuisine gives indication

of regional primary crops

Meat is second largest

Livestock – beef, veal, pork and

lamb

Poultry – chicken, turkey and

duck

Fish and shellfish are ~7% of

world’s meat diet

Global Declines in Genetic Diversity

Declining genetic variation is also a concern for crops and livestock.

Majority of livestock come from

7 mammals: donkeys, buffalo, cattle, goats, horses, pigs and sheep

4 birds: chicken, turkey, geese, and ducks

Artificial selection mainly for productivity

Global Declines in Genetic Diversity

Crops are also experiencing declines in genetic diversity due to artificial selection for increased yields

Crops are more susceptible to diseases

Lower ability to adapt to environmental change

Genetic modification (GMOs) have been ‘created’ to TRY and overcome this increase susceptibility

The Svalbard Global Seed Vault has been established in Norway as an international storage area for many varieties of crop seeds

Currently has 430,000 seeds

Slash and Burn

Energy Subsidies

Mechanization

Promoted monoculture

Increased expenditures by farmers

Beneficial to large-scale farmers

Fossil fuel combustion

Irrigation

For ~16% of world’s agricultural land and 40% of food

Can contribute to waterlogging and salinization

Monoculture

Decreased biodiversity

Increased efficiency and productivity for farmers

Increases risk of disease and erosion

Energy Subsidies

Fertilizers

Organic – composed of plants and

matter

Synthetic (inorganic) – are produced

commercially

Easy to apply, target plant needs, easily absorbed

Increased energy use, greater runoff potential, do not add to organic matter

Making nitrogen fertilizer

Tillage

Energy Subsidies

5.5 – IrrigationMethods(C. 13.2, 13.5)

Water Sources

Water is abundant but usable water is rare. Of the portion of water that is freshwater, ¼ is below groundwater, less then ¾ is locked in ice, glaciers, the

atmosphere and in the soil. Therefore, less than one percent is accessible for human use.

Freshwater Initiative

Groundwater

Aquifers are sources of usable groundwater. Unconfined aquifers are rapidly recharged by water that percolates downward from the land surface. The water table marks the upper limit of the aquifer.Confined aquifers are capped by an impermeable layer of rock or clay, which can cause water pressure to build up underground. Artesian wells are formed when a well is drilled into a confined aquifer and the natural pressure causes water to rise toward the surface.

Groundwater Recharge

Groundwater recharge is through precipitation percolating through soil.

Confined aquifers can be recharge through openings in the land called recharge areas. It generally takes 10,000 – 20,000 years to recharge.

The rate of recharge is dependent on geology and precipitation rates, and affects the long term availability for water.

Water Uses and Drawbacks

On average it is estimated that

70% of freshwater is used for

agriculture, 20% for industry and

10% for household uses.

Irrigation

The greatest potential for conserving water is by changing irrigation practices

Irrigation techniques include:

Furrow – easy and inexpensive. Trenches are filled with water that seeps through the soil. Has 65% efficiency.

Flood – floods the entire field; more disruptive to plant growth. Has 70-80% efficiency. Can lead to waterlogging

Spray – more expensive and energy consuming; sprinkler devices are used to spray water across fields. Has 75-95% efficiency

Drip – water is slowly dripped from a hose; reduces weed growth Has 95% efficiency.

Hydroponic agriculture – uses up to 95% less water

Salinization and Waterlogging

Salinization

Excessive irrigation deposits salts

Water evaporates, salts buildup

Irrigation water can be pumped at high

rates to leach out the water

Waterlogging –

When too much water is left in the soil

Raise the water table of groundwater

Inhibits plant’s ability to absorb oxygen

through their roots

Ogallala Aquifer

Groundwater of the world

The Ogallala aquifer in the Great

Plains

The largest aquifer in the U.S.

A confined aquifer with slow

recharge

Predicted, at currents rates of

water withdrawal and recharge,

to run out of water this century

Waters most of our ‘breadbasket’

Impacts on Groundwater

When water is rapidly withdrawn the following may occur:

Cone of depression – region is which there is no longer any groundwater,

causing the main well and surrounding wells to dig deeper to obtain water

Saltwater intrusion – occurs with water is rapidly withdrawn from aquifers that

are adjacent to coastlines. As water is withdrawn, the pressure in the aquifer

is reduced allowing for the infiltration of saltwater in the region.

5.6 – Pest Control

Methods(C. 12.4)

Pesticides

Types of Pesticides (general)

Insecticides and herbicides

Broad spectrum – affect wide range of pests

Selective – affect target pests

Persistent – ex. DDT, can bioaccumulate/biomagnifiy

Nonpersistent – ex. Roundup (glyphosate)

Inorganic – arsenic, copper, lead, mercury

Highly toxic, persistent and bioaccumulate

Organic or natural – derived from plants such as tobacco and chrysanthemum

Pesticides

Types of Pesticides (detailed)

Biological – Bacillus thuringiensis (Bt), Ladybugs

Carbamates - affects nervous system of pests, more water soluble than chlorinated hydrocarbons

Aldicarb, aminocarb, carbaryl (Sevin), carbofuran, Mirex

Chlorinated Hydrocarbons - affects nervous system

Aldrin, Chlordane, DDT, dieldrin, lindaneand paradichlorobenzene

Fumigants are used to sterilize soil and prevent grain infestation (methyl bromide, formaldehyde)

Organophosphates – extremely toxic, low persistence

Malathion, parthion, chlophyrifos, acepate, propetamphos and trichlofon, glyphosate (round up; produced by Monsanto)

Pros to Pesticide Use Kill unwanted pests that

carry disease (rats, mosquitoes, Tse-Tse flies)

Increase food supplies

More food means food is less expensive

Effective and fast-acting

Newer pesticides are safer, more specific

Reduces labor costs on farms

Food looks better

Agriculture is more profitable

Cons of Pesticides

Bioaccumulation and biomagnification

Pests develop resistance – 500 species so far

Resistance creates pesticide treadmill

Financial treadmill - Estimates are $5-10 in damage done for $1 spent on pesticide

Pesticide runoff

Destroy bees - $200 million

Threaten endangered species

Pollute the environment

Aerial spraying, runoff, seepage

~20,000 human deaths/year

Genetically Engineered Food

Pros

Increased yield and quality

Add vitamin a to rice (golden rice) to

reduce blindness

Reduce growing times thus expenditures

Reduce need for pesticides (Bt soil

bacterium) and fertilizers

Cons

Heavy reliance on GMOs

Safety for humans?

Increased allergies?

Effect on biodiversity?

Who Regulates?

5.7 – Meat Production

Methods(C. 12.2, 12.3)

High Density Animal Farming

• Concentrated animal feeding

operations (CAFOs)/Feedlots

• Minimize

• operational costs

• Land use

• Energy use

• Increase

• Antibiotics and nutrient supplements

• Antibiotic resistance

• Waste/surface runoff

• High density

Free Range Grazing

• Allows animals to graze on

grass during their lifecycle

• Tends to be free from

antibiotics

• Organic waste from livestock

act as fertilizer

• Requires large expanses of

land

• More expensive for consumers

Managing Rangelands

Semiarid environments used primarily for cattle grazing

Pluses

Grazing on lands too dry to be farmed

Less energy than raising in feedlots

Negatives

Overgrazing

Loss of vegetation can acceleration soil erosion and desertification

BLM Manages

Taylor Grazing Act of 1934 to prevent overgrazing

Ensures healthy watersheds, maintains ecological processes

5.8 – Impacts of Overfishing(C. 12.3)

Overfishing

Maximum Sustainable Yield Max number harvestable

Difficult to assess

Skewed numbers from fishermen

Food web connections

Difficult to enforce

Optimum sustainable yield

(OSY)

MSY with more room for error

Multispecies management

Food - web connections

Precautionary Principle

5.9 – Impacts of Mining(C. 11.3, 11.4)

Unequal Distribution of Mineral

Resources

Need to understand distribution and types of minerals to manage their extraction and conservation

Ores – economically valuable accumulation of minerals (i.e.: bauxite)

Metals – copper, aluminium

Nonmetallic minerals – sand, limestone

Reserves – the known quantity of a resource that can be economically recovered

Supplies of Resources

Economic depletion Reuse/recycle, waste and use less

Depletion time How long until 80% is left

Ecomonics Free market costs are based on

supply and demand

Artificially low costs due to gov’t subsidies

Types of Mining

Surface

Strip mining – removal of strips of soil and rock to expose ore (coal and sand)

Must remove large volume of overburden (spoils), extract the resource and return mining tailings (the wastes from ores when the gangue is removed during resource extraction). Smelting may be used to separate metal from the gangue.

Contour – follows the contour of the land and strip with high walls

Area – follows the strip and generates large spoil banks

Open-pit mining – open hole in the ground (copper)

Mountaintop removal – blasts tops of mountains to remove resources below

Placer mining – sifting of water or sediment looking for precious gems or metals

Dredging – scooping underwater deposits

Types of Mining – Surface Mining

Types of Mining

Subsurface Mining

Longwall mining uses steel to

prop up the roof during ore

removal

Room and pillar mining uses

pillars of ore to prop up roof

Less land disturbance but

great threat to human life

from explosions, cave-ins and

lung disease (black lung,

mesothelioma)

Resource Extraction

Ore mineral

Smelted after removal of gangue

In gold mining, smelting can use mercury or cyanide

Gangue

Removed to tailings

Toxics can contaminate surface and/or groundwater

Example - Gold Extraction

Can also

use

mercury

in the

smelting

process.

Mining, Safety and Environment

Type of Mining

Air Water Soil Biodiversity Humans

Surface Significant dust Contamination from percolation through tailings

Most soil must be removed

Habitat alteration and destruction

Air and water quality may affectnearby residences

Subsurface

Emissions from mining equipment

Acid min drainage fromcontamination from percolation through tailings

Cave-ins Habitat fragmentation from roadconstruction

Occupational hazards

Environmental Effects of Mineral Mining

Mining Regulation

Mining Law of 1872

Allows individuals and companies to recover ores from federal lands

Bureau of Mining (1910)

Manages safety of mines

Surface Mining Control and Reclamation Act of 1977

Mined lands must be restored to pre-mining conditions

Mining companies taxed to restore pre-1977 sites

Limited success

Clean Air Act, Clean Water Act and Superfund Act also play a role

5.10 – Impacts of

Urbanization(C. 10.5)

Definitions

Urban (metropolitan) area

town plus its suburbs

Rural area

an area with a population less than 2,500 people

Urban Sprawl

The creation of urbanized areas that spread into rural areas and remove clear boundaries between the two

Megaopolis/Megacities

Long chains of metropolitan areas

Northeast U.S., Tokyo, L.A.

75% of the US population live in

urban areas occupying 3% of the country’s land area

Causes of Urban Sprawl

Urban growth due to:

natural increase - births

immigration - poor are pulled to urban areas or are pushed from rural areas

Encouraged by:- availability of cheap land, (forests, agriculture

fields etc.).- government loans guarantees for new single-

family homes- government & state funding of highways- low-cost gasoline encourage car use- low interest mortgage

Policies for Urban Sprawl

Highway Trust Fund

Maintains and ‘updates’ roads

to ease traffic congestion

Zoning

Classifying land areas for use –residential, commercial, mixed,

multifamily

Federal Housing Administration

(FHA) – government assistance

housing to encourage

movement to suburban areas

Concentric (New York)

Sector (San Fran)

MulitpleNuclei

(Miami)

Environmental Issues

Benefits of urbanization:

recycling more economically feasible

decreased birth rates reduces environmental pressures

per capita expenditures on environmental protection high in urban areas

population concentration impacts biodiversity less

Consequences:

Cities produce little of own food

Urban heat island effect --> dust dome

Water supply and flooding problems

Overwithdrawal from aquifers leading to saltwater intrusion

High pollution exposure

Urban Heat Island Effect

•The enormous amount of heat generated creates an urban heat island

•Additional heat changes climate of surrounding area

•Traps pollution over city

Noise Pollution

Excessive noise exposure health effects

Hearing loss, hypertension, muscle tension, migraines, headaches, higher cholesterol levels, gastric ulcers, irritability, insomnia, psychological disorders, aggression

Noise levels measured in decibels that run on a power of ten scale