ESTH 2110 Exam 2

How does population growth affect ecosystems?

Increased population increases demand

Environmental Refugees

people seeking refuge abroad due to environmental problems

Major causes of land degradation?

• overgrazing

• erosion

• deforestation

• desertification

• wetland loss

What is the most significant factor in soil degradation?

Overgrazing

The effects of Overgrazing

Loss of plant species:

• least tolerance grazing species decline or disappear

• grazing tolerant species expand to areas where graze intolerant species died off

Invader species

• if overgrazing persists, grazing tolerant species die out giving way to weed species that were not originally present

Soil erosion

• if overgrazing continues, weeds may be consumed or trampled leaving soil barren- vulnerable to erosion

Extent of overgrazing

• about 90 species of animals on federal US lands are listed as endangered or threatened due to overgrazing

• large herds of cattle, sheep gather near waterways and degrade banks which causes water pollution

Soil Erosion

loss of soil due to wind or water transport

Topsoil

organic rich layer of soil at surface that typically is high (relatively) in nutrients

• it takes 200-1000+ years to form 1 inch of good topsoil

Cause of topsoil loss

loss of soil fertility = potential loss of crop yields

1930s US Dust Bowl

lost millions of tons of rich Great Plains topsoil

What organization began researching erosion control in 1935?

Soil Conservation Service

What agricultural change increased erosion during the 1970s?

moving away from crop rotation toward continuous cropping

What resulted in lost pastureland and increased erosion?

fencepost-to-fencepost

Reducing erosion best management practices:

• terraces

• conservation tillage

• windbreaks

• no-til

• contour strip cropping

• grass waterways

Alternative plowing methods

• Conservative tillage

• No-till

• Mulch-till

• Strip-till

Conservative tillage

leaving ≥ 30% of last year’s crop residue on cropland

No-till

next crop planted in undisturbed residue of old crop

Mulch-till

entire field disturbed but minimum amount of crop residue left and some partially incorporated into soil

Strip-till

no-till variant, narrow (10-12”), raised (3-4”) strips are plowed the length of the field, leaving adjacent soil untouched

Food Security Act of 1985

offered financial incentives for farmers to take erodible or environmentally sensitive land out of production

Deforestation

permanent decline in crown cover of trees to < 10% of original extent

• Find the # that is less than that 10% value

Example:

200 of 10% = 20

• find anything on the answer choices less than 20!

Three main causes of deforestation?

• Clearing for agriculture production (#1 reason)

• Gathering of wood for fuel (#2 reason)

• Commercial lumbering (#3 reason)

What is the largest single cause of deforestation?

clearing of land for agriculture

• Mostly in African, Amazonia, Malaysia, and Indonesia

What are the two major agricultural activities contributing to deforestation?

• cattle ranching

• soybean production

Brazil’s declining rainforest

Brazilian government offered subsidies for ranching to meet increased demand for meat

Soybean production

deforestation of tropical forests in Malaysia and Indonesia likely to increase from external and internal pressures to produce palm oil.

Gathering wood for fuel biggest problems in semi-arid regions

• land defunded of vegetation → susceptible to erosion

• Increased flooding → deforestation in the Himalayans causing annual flood to occur regularly

• People searching for anything to burn

What is the major cause of deforestation in SE Asia, Central Africa, and Tropical S America?

Commercial Lumbering

• furniture, plywood, and paper pulp products

• valued tree species often mixed with “trash” species, lumber operations fell all trees and sort out the valuable or other trees during operation

Desertification

land degradation in arid, semiarid, and dry sub-humid areas resulting from various factors including climatic variations and human activities.

What is a wetland?

areas inundated or saturated by surface or groundwater at a frequency

• swamps, marshes, bogs, fens, estuaries, ponds, prairies

The 3 main wetland characteristics

• Wetland hydrology

• Wetland vegetation

• Wetland soil

What state has the largest acreage of wetlands?

Alaska

What state los the greatest % of its original wetlands?

California

What state lost the most area of wetland

Florida

What are the causes of wetland loss?

• Natural → erosion, land subsidence, storms, or salt-water intrusion

• Anthropogenic causes (the main reason!!!!!)

Anthropogenic causes

1. drainage for agriculture production (main reason)

• 80% of current wetland loss

2. coastal development

• Wetland loss: road construction

What was the 1985 Farm Bill’s “Swamp Buster Provision”

loss of federal farm program benefits if they drain more wetlands

Why are wetlands important?

wetlands provide valuable ecological benefits and environmental services.

• flood control

• pollution filters

• aquatic habitat and nurseries

• wildlife habitat

• toursim hunting, education

• social

How can we prevent loss in wetlands?

wetland creation, restoration, and conservation

Creation

“engineered” wetlands designed to control stormwater runoff, reduce nutrients, and/or treat waste; or taking land out of use to allow nature to rebalance

Restoration

manipulating a former or degraded wetland’s physical, chemical, or biological characteristics to return to its normal functioning

Conservation

providing habitat for wildlife and aquatic organisms to improve community resilience and allow human use

How many species have been extinct since 1500 CE?

at least 882 (up to 260,000)

Biological Diversity

ecological stability, esp among plants

• loss of a plant can deconstruct entire ecosystems

What % of all pharmaceutical products bought by Americans contain active ingredients derived from plant products?

25%

What is CITES?

regulates international trade in specified animal and plant products and prohibits trading products of endangered species.

What year did CITES begin?

1973

Invasive Species

deliberate or accidental introduction of nonnative plants, animals, or microbes into new environments

• they cause $137 billion annually in direct damages or in expenditures to control them

• >6000 exotic plant and animals now established in the US

Invasive Alien Species

the most threatening type of invasive species

• these species proliferate uncontrollably, threaten native ecosystems, and cause economic damages

• often lack natural predators in new habitat

Principle of Competitive Exclusion

when two species are competing for the same limited resources, only one will survive

What invasive bird was released into Central Park in New York?

European Starlings

What invasive species damaged water intake pipes and overwhelmed native mussle species?

Zebra mussels

What invasive insect threatened species of hardwood trees such as maples?

Asian Longhorn Beetle

What invasive species spread throughout N. America and kill millions of ash trees?

Emerald Ash Borer

What invasive species was imported by farmers in the early 1970s to control algae and sediment in ponds?

Asian Carp

What state had the most known plant and bird extinctions?

Hawaii with 75%

Where are the effects of non-native species especially severe?

They felt greatest on island ecosystems

Why has modern transportation increased invasive species?

faster global travel moves species intentionally and unintentionally

Limits of Tolerance

plants and animals with a wide range of tolerance for variations in environmental living conditions have the widest distribution.

Narrower range = limits distribution

What is the greatest threat to biodiversity?

Habitat destruction

• it is most difficult to control

Habitat Destruction

loss of natural areas that wildlife require for breeding, feeding, or migrating

Protected areas

areas of natural beauty or significance that are set aside

Biodiversity hot spots

areas with exceptionally high numbers of native species facing likely extinction due to extensive habitat loss

• scientists have identified 35 hot spots

Why can protected areas be destined for failure?

areas are too small, scattered, and fragmented to sustain biotic communities for long term

• overcrowding; edge effects → differing environmental condition

Some areas protected only in name, lack of resources to police

• Humans are part of the ecosystem

Community-based conservation

rely on grass roots efforts, allowing locals to have a say so in management strategies rather than government

Biodiversity prospecting

enlisting residents of species-rich tropical countries to assist in the search for plants and animals of various medicinal, pesticidal, agricultural value

What law is the most effective weapon for ensuring survival of native plants and animals?

Endangered Species Act (1973)

• prohibits killing, collecting, harassing, or capture of any species listed as endangered or threatened by US Fish and Wildlife services

Opposition of the endangered species act

threaten jobs and economy, weakens individual property rights

• developers

• shrimpers

• loggers

Habitat Conservation Planning

allows development of property with endangered species if they agree to minimize loss of critical habitat or offset loss by providing additional habitat nearby.

• a compromise can be reached

Municipal Solid Waste

every sector of our national economy generates waste

• MSWs are more heterogenous than wastes from agriculture, mining, or specific industries

What are the two most challenging waste management sectors?

Municipal and industrial hazardous wastes

Top 3 MSW generated by material in 2017

1. Paper and Paperbound (25.0%)

2. Food (15.2%)

3. Plastics (13.2%)

How much do we waste?

In 2017, the US generated 268 million tons of MSW

• 4.5 lb of refuse per person per day (every day)

• 1650 lbs per person per year

Electronic waste from computers, cell phones, video games is one of the fastest growing segments of the waste industry

What municipal waste collection is an important public health concern?

regular and frequent refuse collection

What happens if regular and frequent urban refuse breakdown?

can increase pest and rodent problems as well as odor and litter issues

What recommendation does the public health service give about refuse collection?

twice weekly in residential areas and daily from restaurants, hotels, and large apartment complexes

What past method of refuse disposal was banned in the late 1950s

Uncooked garbage fed to hogs

What was most common method of refuse disposal until the 1970s?

Open dumping

• refuse was hauled to a location on the edge of a town and dumped on the ground- cheap and convenient.

today it is viewed as environmentally unacceptable:

• harbor for vectors and pests → these invaded nearby households

• Leachate from these sites contaminate adjacent groundwater and surface water

• Burning of refuse to prevent litter blowout or reduce volume threatens air quality

What is the most common present-day method for managing MSW?

Sanitary landfilling (the #1 way we manage waste)

Other alternatives:

• bioreactors

• source reduction

• recycling

• composting

• waste combustion

Sanitary Landfills

economically feasible, environmentally acceptable alternative to open dumping

• refuse is spread in thin layers and compacted by bulldozers

What happens when the layers exceed 8 to 10ft deep?

they are covered with 6 inches of dirt and compacted again

Why are layers covered with a thin layer of soil?

to prevent odor, pests, and litter blowout

What happens when a sanitary landfill has reached its capacity?

2ft of soil is used to cover the landfill and land is converted into recreational facilities

What is one of the most serious environmental problems associated with landfills?

Leachate contaminating nearby streams and underlying aquifers

Leachate

water that forms when waste interacts with water; contaminates underlying aquifers

What barriers can help prevent leachate contamination?

impermeable clay liner or synthetic liner

What does RCRA Subtitle D require landfills to install?

groundwater wells and methane detection systems

What must new landfill cells contain?

double liners and leachate collection systems to promote “dry tombing” of waste

Bioreactors

new landfill design that recirculate leachate from the bottom layer throughout the bioreactor to facilitate microbial growth

What do many bioreactors recirculate in addition to leachate?

Air

What is the major benefit of recirculating leachate and air?

It accelerates decomposition and biological stabilization of landfilled wastes relative to conventional landfills

What is the best and cheapest way to manage wastes?

Source reduction

• don’t produce them in the first place

Consumer preference

be a selective shopper - buy items with less packaging, single-use packages, and shop at yard sales

Manufacturer’s role

reducing the amount of materials in production

• design products products that can be repaired, instead of “planned obsolescence”

Governmental role

• move away from flat-rate fees for hauling - unit based pricing instead

• taxes on hard-to-dispose of items at time of purchase

• banning certain times (plastic bags, plastic straws, single use cutlery)

Recycling

broadly referred to as resource recovery

• used to be viewed as a patriotic duty for the war effort during World War II

What are the three multiple benefits of recycling?

• resource conservation

• energy conservation

• pollution abatement

What recycling goal launched in 2002?

EPA launched its resource conservation challenge with the goal to boost the national recycling rate to 35%

When was the 35% recycling goal reached?

2007; the current goal is 50% (“50 by 30”)

Convenience is king

curbside pick-up of recyclables