Humans in the biosphere6.1 A changing landscape

How do our daily activities affect the environment? •Humans affect both regional

and global environments

•Have major impacts on the quality of Earth’s natural resources• Agriculture

• Monoculture and fertilisers

• Development• City waste disposal

• Industrial Growth• Factories – emissions and waste

Sustainable development•Ecosystem goods and services

• Many such as air and water are taken for granted • Are provided free of charge….

•But, when a service such as water is disrupted – fixing it can be costly• Mechanical and chemical treatment of water is expensive!

What is the difference between Renewable and Non Renewable resources

•Renewable resources: can be produced or replaced by a healthy ecosystem

•Non renewable: Natural processes can not replenish them in a reasonable amount of time• When used up essentially gone

forever

Are trees/forests a renewable or non renewable resource?

• It depends on whether the trees will be able to grow back in a reasonable time

Sustainable resource use

•Provides for human needs while preserving the ecosystem that produces the natural resource• Should cause no long term harm• Consume little energy and materials• Survive environmental stresses• Economic impacts

• Enable people to improve their situation

Writing assignment

•How can sustainable development help reduce the negative impacts of agriculture and devlopment?

Using resources wiselySection 6.2

Natural resources

•We need natural resources for our survival

•Are we threatening our future existence with our current actions?

•3 types of resources• Soil resources• Freshwater resources• Atmospheric resources

Soil resources

•Why is soil so important?• Agriculture and forestry

•Topsoil – key for supporting life• Made from healthy interactions

between plants and soil• Can take centuries to form, but can be

destroyed very quickly

What happened here in the 1930s?

Soil Erosion

• In the dust bowl, the conversion of prairie land to cropland left soil vulnerable to erosion• Soil erosion – loss of soil due to

water or wind• Worse when land is plowed and

left barren – why?• All the fertile topsoil can be lost• Can lead to desertification

• 40% of Earth’s land is at risk

Deforestation

•Removing trees can increase soil erosion

•When rainforest destroyed for farming – soil is often only good fr a few years, why?

Sustainable soil usage

• Soil erosion can me minimized through careful management of agriculture and forestry

Sustainable forestry

Are freshwater resources always renewable? •No!

•Only 3% of Earth’s water is freshwater

•Most of that is in polar ice caps

•Many aquifers have taken millions of years to accumulate

Water pollution•Point source – one specific source

•Nonpoint source – released in small amounts by multiple different sources

•Primary sources – industrial and agricultural chemicals, sewage and nonpoint sources

Industrial and agricultural chemicals

•Heavy metals like mercury, cadmium zinc

•DDT – widely used as a herbicide – cheap and effective

•Monoculture has lead to reliance on herbicides and pesticides

•Run off into ecosystem and have disastrous consequences

•New initiatives limit pesticide usage• E.g. biological pest control

Biological magnification

•As you move up through a food chain, the concentration of a pollutant will increase

•Can reach 10 million times the concentration of the primary producers

•DDT was banned in the 1970s

•Mercury is still a problem

Sewage

•Highly rich in nitrogen and phosphorous

• In small amounts can be handled by an ecosystem

• In large amounts destroy entire ecosystems through eutrophication

Watershed conservation

•Watershed – all the land whose groundwater, streams and rivers drain into the same place – e.g. a lake

•When considering water pollution – the entire watershed and all of it’s ecosystems must be considered

•Wetlands and forests are nature’s water treatment plants

Atmospheric resources

•Earth’s atmosphere is naturally maintained through biogeochemical cycles

•Humans are disrupting these cycles, which can have long lasting effects on our atmosphere

Air pollution•Common forms are Smog,

acid rain, greenhouse gases and particulates• Smog caused by ozone at

ground level• Can cause respiratory illnesses

• Acid rain – formed from nitrogen and sulphur released from fossil fuel burning• Can also release dangerous

metals such as mercury from soil

Air pollution continued

•Greenhouse gas emissions (CO2 and methane) is leading to global warming

•Particulates – microscopic ash and dust particles • Can cause health problems such as

asthma

Emissions

• Developed countries such as Europe and USA have had many initiatives to improve air quality• For example

leaded gasoline were phased out between 1973 - 1996

Section 6.3Biodiversity

Why is biodiversity important?

•Biodiversity – total of all the genetically based variation in all organisms in the biosphere

•3 types• Ecosystem diversity• Species diversity• Genetic diversity

Biodiversity as a natural resource

• Biodiversity and medicine• Many medicines come from wild species• e.g. aspirin, antibiotics• Genetic information in species is like a natural

library from which we have much to learn

• Biodiversity and agriculture• Many crop plants have wild relatives, like

potatoes• Wild plants carry genes that may be useful for

crop plants – e.g. gene resistance

• Biodiversity and ecosystem services• Number and variety of species can influence

an ecosystem’s stability and productivity

Threats to biodiversity • 99 %of all species that have existed

are now extinct • Humans are causing the greatest

wave of extinctions since the dinosaurs• Current rate – 1000 times the

typical rate• Humans reduce biodiversity by:

• Altering habitats• Hunting• Invasive species• Pollution• Climate change

Altering habitats

•When natural land is developed for farms or cities, species are threatened

•Development often splits ecosystems into smaller pieces – habitat fragmentation• Habitat, or biological islands• The smaller the island the fewer

species it can support and the more susceptible it is to a disturbance

Hunting• 1800s the passenger pigeon and the

Carolina parakeet were wiped out• Many countries protect endangered

species, but not all• Laws are difficult to enforce in

remote areas

• Animals can be hunted for • Meat• Products e.g. hide, medicinal

properties• Pets – e.g. parrots

• Fragmentation increases access to hunters and limits hiding spaces

Introduced species

• Introduced organisms can become invasive and threaten natural biodiversity

Pollution

•DDT for example prevented birds from laying healthy eggs

•Acid rain can place stress on organisms

•Carbon dioxide is making oceans more acidic, threatening coral reefs

Climate change• Organisms are adapted to their

environment and have specific tolerance ranges• If conditions change, organisms must

move or face extinction• Fragmented habitats are a key

problem – as organisms may not be able to move• If increase of 2.5 °C, 30 % of studied

species are likely to face an increased threat of extinction• If increase of above 3.5 °C, 40 – 70 %

likely to face extinction

Conserving biodiversity• Should we focus on specific organisms, or

entire ecosystems?

• We must do both, but also take into account humans• Make it worth their while

• Preserving species• Captive breeding program• Mating pairs managed to ensure survival of

species• Goal is to reintroduce to the wild

• Preserving ecosystems• Goal to preserve interactions of many species• Land set aside as parks and reserves• National parks and national forests• Marine sanctuaries

Ecological hotspots

• Area must contain 1500 species of native vascular plants

• And it must have at least 70 % of it’s natural habitat

• Current hotspots include 50 % of worlds plants and 42 % of worlds vertebrates

Local interests

•Often local inhabitants need to change their way of life

• In USA, tax credits exist for solar panels or hybrid cars

•Many countries use national parks for tourism

• Internationally, a system of carbon credits exist

•Companies can buy or sell carbon• Pollution is capped

Meeting Ecological challenges

Section 6.4

What is an ecological footprint?

• Describes the total area of functioning land and water ecosystems need both to provide the resources and individual/population uses and o absorb and make harmless any waste

• Take into account energy, food, water, shelter

• Allow ecologists to calculate carrying capacity• Can apply to individual countries of the

world’s population• No universal way to calculate an ecological

footprint

Comparing footprints

• It is easier to compare than calculate absolute footprints

• The average American’s footprint is 4 times larger than global average. Is this a good thing? • The per person use of

resources is almost twice that of England

• Over twice that of Japan

• Six times that of china

How can ecology guide us to a sustainable future? •Ecology allows us to:

• Recognize a problem• Research the cause• Change our behavior to mitigate the effect

•3 case studies• Atmospheric Ozone• North Atlantic fishing• Climate change