Biodiversity Issues

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This section will explore the issues behind biodiversity.

After a few definitions we will look at some case studies in order to study a variety of issues

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Case Study
Included below are case studies on biodiversity. Click on the links below to find article and/or information on the specific case. Additional notes are included below. Feel free to explore.

Note that this page is updated regularly and includes mostly recent cases. For older case studies see here


The variety of living things in a region

There are three kinds of biodiversity:

Genetic Diversity 
The variation in genetic makeup within a population
Species Diversity 
The number of species within an area
Ecosystem (or Ecological) Diversity 
The number of different ecosystems in an area

Ecosystem Services

Ecosystem services are the benefits provided by ecosystems that contribute to making human life both possible and worth living.

Biodiversity Loss Threatens Human Well-Being (see especially Box 1 near bottom of article)

JohnWS-Ecosystem Services.png

Types and Examples

  • Provisioning Services - products obtained directly from the ecosystem
  • Food
  • Water
  • Habitat
  • Medicines - a majority of the medicines used are derived from plant, animals, or micro-organisms
  • Regulating Services - benefits from the regulation of ecosystem processes
  • Regulation of Climate - both locally and globally
  • Water quality - wetlands can remove wastes from water
  • Protection against natural disasters - complex patches of vegetation reduce flooding and can give protection from winds and sea intrusion
  • Natural pest and disease control
  • Cultural Services - non-material benefits
  • Recreational - hiking, fishing, gardening, etc.
  • Spiritual values - for example, forest monasteries
  • Educational
  • Supporting Services - allow other services to be present
  • Nutrient Cycling
  • Soil formation
  • Pollination and seed dispersal - A large number of plants require insects and other animals for pollination and seed dispersal

Case Study: Brazil Nuts

Brazil nuts. Shown are the pod, unshelled nuts, and shelled nuts

Brazil nuts are a good example of the importance of food as an ecosystem service, as all Brazil nuts must be harvested from the wild as they required to be pollinated by large bees which are not present in deisturbed areas. They are spread by Agouti who eat some the nuts and bury the uneaten ones. These will then germinate into new trees.

One hectare of loss rainforest leads to the loss of US$40 in revenue from Brazil nuts.

Case Study: Water

Watch this video from IUCN

Case Study: Artemesinin

The major drug used to treat malaria is Artemesinin.

Its source is the plant Artemesia annua.

Naturally derived medicines are an important ecosystem service.

Case Study: Honey Bees

An example of pollination as an ecosystem service is the honey bee. They are extremely important pollinators of crops.

Honey Bees
List of crop plants pollinated by bees

However, honey bees are under serious threat from the disease colony collapse disorder:

Colony Collapse Disorder

Payments for Ecosystem Services

One area that is becoming a hot topic in wildlife conservation is:

Payment for ecosystem services (PES) Payment to a landowner, farmer, or community for the benefits recieved from the ecosystem


Genus (pl. genera) 
Group of closely related species

Species names are given as Genus species. Both words are in italic, the first is always capitalized, the second is never capitalized.


  • Felis catus - Domestic cat
  • Homo sapiens - Human

Higher groups with less closely related species (in order of most closely related to least related):

  • Species
  • Genus
  • Family
  • Order
  • Class
  • Phylum (plural Phyla)
  • Kingdom
  • Domain (controversial)

There are also intermediate levels - for example, from family to order: family, superfamily, infraorder, suborder, order

Example: Felis catus

Family: Felidae (all cats - including tigers, lions)
Order: Carnivores (carnivores)
Class: Mammalia (mammals)
Phylum: Chordata (chordates - includes all vertebrates)

Species Diversity

Did you know?

Can you answer the following questions? Click on the link to find out.

  1. What is the fastest land animal? Answer video
  2. What is the fastest animal? Answer
  3. What is the slowest animal? Answer
  4. What is the largest animal ever to have lived? Answer
  5. What is the smallest vertebrate? Answer
  6. What is the oldest living thing and how old is it? Answer

How many species?

Number of species

  • total described: 1.5 million
  • total estimated: 5 - 30 million
  • plants described: 300,000
  • animals described: 1 million
Relative number of species of animals by phylum. Note about three-fourths of Arthropoda are insects
Percentage of vertebrates species by type
Relative number of species of mammals by order. The two largest are rodents and bats

Endangered Species

Endangered species Those species which are at risk of extinction.

Disappearing Biodiversity

  • extinction rates are currently as much as a 1000 times higher than historical rates
  • scientists now state that we are in the sixth mass extinction event [1]
  • 34,000 plants and 5200 animal species face extinction
  • percentage of species facing extinction: bird 13%, mammals 22%, coral 33%, amphibians 41%
  • 45% of Earth's original forests are gone

The Red List and CITES

The International Union of Conservationists (IUCN) evaluates species to determine how endangered they are. These evaluations are collected into the IUCN Red List. Species are rated into Least Concerned (not endangered), Near Threatened (not currently endangered, but conditions are such they could become endangered), Vulnerable, Endangered, Critically Endangered, Extinct in Wild (only in zoos, etc.), and Extinct. Species can also be list as Data Deficient - there is not enough information to be able to evaluate the species.

Important in endangered species is to prevent trading in wildlife. The main instrument for this is the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). This is a legal treaty which restricts or prevents trade in certain species. The list of species can be found here.

Ecosystem Diversity


The world's major communities classified according to the predominant vegetation [2]

WWF Classification

The WWF has identified 14 biomes:

  1. Tropical and subtropical moist broadleaf forests - extremely diverse, may contain half of all species.
  2. Tropical and subtropical dry broadleaf forests - less common than rainforests; main biome in Thailand
  3. Tropical and subtropical coniferous forests
  4. Temperate broadleaf and mixed forests - large tracts lost to logging and other development
  5. Temperate coniferous forests - includes old growth forests, where trees are over 150 years old
  6. Boreal forests/taiga - mixed forests found Northern areas; together these store more carbon than the rainforests
  7. Tropical and subtropical savannas - grasslands, typified by the Serengeti grasslands
  8. Temperate grasslands - most native grasslands have been converted to farmland
  9. Flooded grasslands - important for many migratory birds, play important roles in flood control and water quality
  10. Montane grasslands - mountain ecosystems, often highly adapted and fragile
  11. Tundra - treeless polar climate with low vegetation, easily distrupted
  12. Mediterranean forests - hot dry summers, cool moist winters; found in only five regions of the world
  13. Deserts - dry (<25 rainfall cm per year), parts of the Atacama Desert have had no rain in the last 200 years. Many species especially adapted to conditions.
  14. Mangrove - a type of woodland found in saline coastal tropical waters, important for many aquatic animals, 20% have been lost in the last 30 years (50% in some areas)

There are also 13 freshwater biomes and 5 marine biomes

WWF further divides the Earth into 867 terrestrial and 450 freshwater ecoregions:

Terrestrial Marine Freshwater


for a larger and more readable version go here

Case Study: Mangroves

Mangroves forests are a type of woodland found in saline coastal waters, mostly in the tropics. The 2010 World Mangrove Atlas shows a 20% loss since 1980. Shrimp farming accounts for about 25% of that.

Report on declining mangrove forests

Threats to Biodiversity

Main Threats

The major threats to biodiversity are (in order of importance):

  1. Habitat loss
  2. Invasive Species
  3. Overexploitation
  4. Climate Change
  5. Pollution

Habitat Loss

Causes of habitat loss

  • Agriculture and aquaculture (including large-scale commerical crops, subsidence farming, and livestock intensification)
  • Fires
  • Habitat fragmentation (from logging and transportation)
  • Expansion of cities
  • Energy production (for example, oil and gas) and mining
  • Flow modifications of rivers (such as dams, changing route)
  • War and military exercises


As for deforestation, a 2018 study[3] shows that the major drivers are:

27% commodity crops
26% forestry
24% shifting agriculture
23% wildfires

The above are global values, for specific regions the major drivers are:

Europe - forestry (95%)
North America - forestry and wildfire (48% each)
Oceania - wildfire (62%)
Russia, China, South Asia - wildfire (59%)
Latin America - commodity-driven (64%)
Southeast Asia - commodity-driven (61%)
Africa - shifting agriculture (93%)

Invasive Species

A serious problem is invasive species - plants and animals not native to an area and disrupt the ecosystem.

Alien invasion is second only to habitat loss as a cause of endangered species and extinction


Brown Tree Snake
Cane toads in Australia Asian Toad in Madagascar
Zebra mussel
Stoats in New Zealand
Red-eared Silder
Blackberries invading Galapagos Islands

100 of the World's Worst Invasive Alien Species


Overexploitation includes:

  • Overfishing - ("gone fishing, fish gone") (see the section on Fisheries)
  • Overhunting - hunting for trophies, poaching for bushmeat and body parts, etc.
  • Excessive logging - for wood and paper/pulp
  • Illegal wildlife trade

Illegal wildlife trade

Illegal wildlife trade is the third largest illegal trade after drugs and arms. Many endangered species have been affected including: tigers, pangolins (the most illegally traded animal), elephants (ivory), rhinoceros, primates, parrots, turtles, lizards, teak, and rosewood.

Protecting Biodiversity


In order to protect biodivesity we need to:

  • Studying and identifying biodiversity, ecosystems, and endangered species (in order to know how to save it)
  • Treaties and international law
  • Legal protection of endangered species, including enforcement
  • Propagation of endangered species in captivity and their reintroduction to the wild
  • Elimination or reduction of invasive species
  • Establishment and management of protected areas (see below)
  • Restoration of degraded areas (see below)

Biodiversity Hotspots

When studying biodiversity sometimes we need to make priorities for what to study. One way is to use the concept of Hotspots.

Some areas have greater biodiversity than others. Tropical rain forests, mangroves, and coral reefs are examples with high biodiversity.

One of the best list of hotspots is Conservation International's Biodiversity Hotspots. They have identified 35 areas which are both highly diverse and face serious threats. They have also identified 5 other areas with high biodiversity, but with fewer threats.

Biodiversity Hotspots Map.jpg

Protected areas

The most important of the methods for protecting biodiversity is protected areas, also called bioreserves.

IUCN classifies protected areas into categories. These categories are (more details can be found HERE):

  • Category Ia. Strict Nature Reserves - (only human use is for scientific studying, monitoring, and education)
  • Category IB. Wilderness Areas (similar to Ia, but less strict)
  • Category II. National Parks
  • Category III. Natural Monuments (smaller focused on a single species)
  • Category IV. Habitat or Species Management Area (similar to III, but a single habitat or species)
  • Category V. Protected Landscape/Seascape (allows for-profit activities)
  • Category VI. Protected Area with Sustainable Development (humans may live in area)

Restoration Ecology

In addition to protecting wildlife, it is also important to restore already degraded areas.

Methods of restoration include:

  • Removing causes of degradation (roads, pollution sources, etc.)
  • Reforestation and replanting grasslands
  • Controlling invasive species
  • Reestablishing fauna
  • Fire management
  • Water management (especially for wetlands)
  • Reclamation (repairing the damaged lands including polluted areas)
  • Monitoring

Genetic Diversity


With current practices in agriculture:

  • Wheat, rice, and corn account for more than half the food energy intake
  • 30 crops account for 95% of food energy intake
  • In last 100 years, 75% of agricultural genetic diversity has been lost

Plants and animals are bred to have different genetic traits. These traits either:

  1. Increase production (e.g. more milk)
  2. Increase resistant to disease

Little genetic diversity in an agricultural species can lead to susceptibility to a disease wiping out the entire crop.

An example of this happening is the Potato famine in Ireland.


Genetic diversity is also important for wildlife. High genetic diversity allows a species to adapt and survive. Low genetic diversity allows diseases to spread rapidly and causes problems with reproduction.


  2. Campbell, N.A. 1996. Biology, 4th Edition. The Benjamin/Cummings Publishing Company, Inc., Menlo Park, California