BIODIVERSITY

THE ECOSYSTEM APPROACH

Human impacts on biodiversity

Degradation of the 50% of the earth's land surface We are affecting to the aquatic biodiversityPremature extinction of speciesAll these threats are projected to increase by 2018

Human impacts on biodiversity

Some of the species that are in extreme danger of extinction:

Human impacts on biodiversity

How to reduce biodiversity loss

Protect population of species in their natural habitats Preserve areas of habitats in different biomes and

aquatic systems Eliminate or reduce populations of nonnative

species from protected areas

Biodiversity loss

Salt cedar is an aggresive plant that crowds out native plants, they cause ground water levels to dropFishermen illegally

introduce German brown trout (left) into high Sierra lakes and it devours the golden trout (right)

Land use in the world

Managing and sustaining forests

Typical clasification of forests:

− 47 % tropical − 33% boreal− 11% temperate− 9% subtropical

Managing and sustaining forests

Managing and sustaining forests

Ecologists clasification:

Old-growth or frontier forests (uncut forests, not disturbed by humans)

Second-growth forests (secondary ecological succesion)

Tree farms (trees replanted and clear-cut again in on regularly cicles)

Managing and sustaining forests

Managing and sustaining forests

Forests management systems:

Even-aged management (trees about the same age and size)

Uneven-aged management (wide variety of tree species)

Tree Harvest

Selective cutting (mature trees are cutting singly or in small groups)

Shelterwood cutting (removes all mature trees)

Seed-tree cutting (they harvest nearly all but leave a few uniformly distributed)

Clear-cutting (removes all trees in a single cutting)

What's happening to forests?

Human activities have reduced the earth's original forest cover by 50%.

Economic value (the income from the earth's natural capital is at least $36 trillion per year.)

More threats to forests

Pathogens and insects (we can clear-cut infeted areas or treat trees with antibiotics or pesticides)

Fire

More threats to forests

Air pollution and climate change (with less precipitations as a result of global warming, forest fires would

increase)

Tropical deforestation

Tropical forests cover about 6% of the earth's land areaBrazil has about 50% of

these in the Amazon

Almost 15% have been deforested

National Parks

People invaded most of these parks in search of wood, cropland, game animals, and other natural products for their survival.Most national parks are too small to sustain many

large animal species Some of them suffer invasion of nonnative

species, that reduce population of native ones

Nature reservesMost ecologists believe that this is best way to

preserve biodiversityThe management of biodiversity reserves should

be guided by three ecological principles:Ecosystems cannot be locked up and protected from human

disturbancesEcosystems experiencing frequent but moderate disturbances have

the greatest diversity of speciesWe should view most reserves as habitant islands surronded by a

sea of developed and fragmented land

Nature reserves

Costa Rica has consolidated its parks and reserves into eight megareserves designed to sustain about 80% of the country's rich biodiversity

Nature reserves

BIODIVERSITY

THE SPECIES APPROACH

SPECIES EXTINCTIONTypes of Extinction

• Local Extinction:Species is not found in an area it inhabited but still found elsewhere in the world

• Ecological Extinction:

Few members of a species are leftBiological Extinction:

Species is no longer found anywhere on the earth

SPECIES EXTINCTIONEndangered and Threatened Species

• Endangered Species: Has so few individual survivors that the species could soon become extinct

• Threatened Species: Still abundant but because of declining number is likely to become endangered

SPECIES EXTINCTIONEstimate Extinction Rates

99.9% of all the species that have ever existed are now extinct. Species-Area Relationship: 90% loss of habitat causes the extinction of about 50% of the species living in that habitat. Theory of island biogeography: Estimates the risk that a species will become extinct within a certain time.Minimum area of suitable habitat: Ensure the survival of a population in a region for a specified time.

SPECIES EXTINCTIONHuman Activities Effects

Before humans: Estimated extinction rate was 0.0001% per year.Current rate of extinction is at least 0.1% to 1% per year.With1% a year extinction rate:− 20% of the world’s current animal and plant

species could be gone by 2030 − 50% by the end of this century

HABITAT LOSS AND DEGRADATIONGreatest eliminator of Species

Destruction of coral reefs and wetlandsPlowing of grasslandsPollution of aquatic systems

Deforestation of tropical forest

HABITAT LOSS AND DEGRADATIONHabitat Fragmentation

• Habitat fragmentation occurs when a large area of habitat is divided into isolated areas.

NONNATIVE SPECIESDeliberately Introduced Species

• Introduction of nonnative species can be beneficial or harmful.

• It depends on the species and where they are introduced.

• Due to:– No natural predators– No competitors– No parasites– No pathogens

NONNATIVE SPECIES Accidentally Introduced Species

• Argentina fire ant was introduced accidentally into the United States.

• May have arrived on shiploads of lumber or coffee imported from South America

• They reduced 90% of native ant populations• Results:

– Killed birds, pets and at least 80 people allergic to their venom

– Invaded cars and caused accidents by attacking drivers

– Disrupted phone service and electrical power– Caused fires by chewing through underground

cables• Cost the United States an estimated $600 million

per year

NONNATIVE SPECIES How to reduce the Threat

• Identify characteristics that allow species to become successful invaders

• Inspect types of goods coming into a country

• Pass international laws banning their transfer from one country to another

• Require ships to discharge their ballast water and replace it with salt water at sea before entering ports

HUNTING AND POACHINGCommercial Hunting and Poaching

• Demand comes from Asia, the Middle-East, North America and Europe.

• At least two-thirds of all live animals illegally smuggled around the world die in transit.

• As species become endangered, the demand for them on the black market soars.

• This increases their chances of premature extinction.

OTHER EXTINCTION THREATSMarket for Exotic Pets and Decorative Plants

• For every live animal captured and sold in the pet market, an estimated 50 other animals are killed.

• About 25 million U.S. households have exotic birds as pets, 85% of them imported. But ...

A 1992 study suggested that keeping a pet bird indoors for more than 10 years doubles a person’s chances of getting lung cancer from inhaling tiny particles of bird dander !!

OTHER EXTINCTION THREATSClimate Change and Pollution

Most natural climate changes in the past have taken place over long periods of timeA rapid climate change will happen during this century due to human activities like:− Greenhouse gas emissions − Deforestation

Projected climate changes may benefit some species but can have harmful effects on other speciesSome species may not have enough time to adapt or migrateSpecies that can thrive in a warmer climate may expand their populations

THE RESEARCH AND LEGAL APPROACHInternational Treaties

1975 Convention on International Trade in Endangered Species (CITES).Signed by 160 countries,List some 900 species that cannot be commercially traded.

THE RESEARCH AND LEGAL APPROACHThreatened and Endangered Marine Species

• Sea turtle:– Three of eight sea turtle species are endangered and the rest are threatened. – Loss or degradation of beach habitat (where they come to lay their eggs) – Legal and illegal taking of their eggs. – Unintentional capture by commercial fishing boats – Increase use as sources of food or medicinal ingredients

THE RESEARCH AND LEGAL APPROACHThreatened and Endangered Marine Species

The most important problems to protect marine biodiversity are:− The lack of knowledge about marine species− The difficulty in monitoring them

THE RESEARCH AND LEGAL APPROACHShould We Try to Protect them?

Only a few endangered and threatened species can be saved due to:− Limited funds− Limited information− Limited trained personnel

We should focus on which species play keystone roles and are tolerant to enviromental change.

THE SANCTUARY APPROACHGene Banks and Botanical Gardens

• Gene or seed banks:– Preserve genetic

information.– Preserve endangered

plant species– Stores seeds in

refrigerated, low-humidity enviroments.

THE SANCTUARY APPROACHGene Banks and Botanical Gardens

• Botanical gardens:– Cultivates rare and

endagered plant species.

– Help educate an estimated 150 million visitors a year about the need for plant conservation.

THE SANCTUARY APPROACHZoos and Aquariums

• Are being used to preserve endangered animal species

• Long-term goal: reintroducing the species into protected wild habitats

• Critics see most of them as prisons for wild animals.

• Educate visitors about the need to preserve natural habitats

• In some zoos elephants and other animals that roam free in habitat areas during the day are chained up in a barn at night.

WILDLIFE MANAGEMENTSport Hunting

• Developed countries use it to manage populations of game animals

• Licensed hunters are allowed to hunt only during certain times of the year

• Limits are also set on:– The size, number, and sex of

animal that can be killed– On the number of hunters

allowed in a given area