Biodiversity under threat Flashcards
What is species diversity?
- variety of plant and animal species present in an ecosystem.
- Diversity is needed to enable the ecosystem to carry out its functions, such as carbon cycling, with maximum efficiency.
- Species diversity bolsters an ecosystem’s resilience to withstand climate change. Removing species from, the various tropic levels can have a huge impact on energy flows and nutrient cycling.
- Species diversity has several aspects, including the total number, abundance and richness of species as well as disparity. The endemism of species is also relevant.
What is genetic diversity?
- The range of genes found within a particular species.
- Genetic diversity often determines the degree of resistance to pests and diseases. In agro-ecosystems, breeding new varieties of cereals such as rice and wheat has led to genetic erosion and genetic pollution.
- These in turn have caused a narrowing of the genetic base and a general weakening of plant resistance to disease and climate change.
- This is likely to have a major adverse impact in future global food security.
What is biodiversity?
-biodiversity means the variability among living organisms from all sources- terrestrial, marine and aquatic ecosystems and the ecological complexes of which they are part: this included diversity within species, between species and of ecosystems.’
The 3 dimensions of biodiversity
- Genetic diversity
- Species diversity (Includes species richness, endemism and species disparity)
- Ecosystem diversity
- Genetic diversity
What is ecosystem diversity?
number of different ecosystems within a given area.
- This is partly controlled by physical conditions particularly climate, geology, relief and soils.
- The ability of people to modify and eliminate ecosystems is a threat to ecosystem diversity.
What is endemism?
-the amount of unique and rare species present in a particular location
What is species diversity?
-the range of species
What is species richness?
-the amount of species
What is a biome?
-a global ecosystem
What is a ecosystem?
-a self-regulating biological community in which the living (biotic) interacts with the non-living (abiotic) in the environment.
What is succession?
-changes in vegetation which takes place in a community over time.
What is primary productivity?
-the rate at which energy is converted into organic matter. It can be measured by the amount of biomass produced each year.
What is a biodiversity hotspot?
-an area of high biodiversity. Myers – hotspots are areas with: high species richness, high levels of endemism (uniqueness) and at severe threat of human disturbance
What is a eco-footprint?
-a measure of biodiversity threat. A measure of human demand on the earth’s ecosystems. It represents the amount of productive land and sea needed to supply humans with the resources they require.
Global and continental factors influencing biodiversity
- Age and history- biodiversity is greatest in the oldest and least disturbed ecosystems, especially in the tropics where there are few physical constraints on productivity.
- Altitudinal range: A large altitudinal range means a cross section of different climates. The more climatic zones involved, the more diverse the habitats
- Isolation: Reduces the number of species but encourages endemism, as the remaining species develop in a distinctive way
- Size of area: Overall biodiversity increases with area, because large continuous biomes support a wider range of species and extensive boundaries encourage migration. e.g.a large area of polar habitat contains far fewer species than a smaller area of rainforest.
Regional factors that influence biodiversity
- Productivity: very important as high temperatures and humidity levels, rich supplies of nutrients and light for photosynthesis, and a lack of annual seasons all encourage high primary productivity and therefore abundant energy. On the other hand, cold and aridity reduce the range and number of species
- Habitat architecture: High primary productivity encourages the development of a complex trophic pyramid with many ecological niches. Supporting high levels of biodiversity
- habitat heterogeneity- a varied physical environment will support a higher biodiversity because it provides a wider range if habitats for a larger range of species,
Local factors that influence biodiversity
- Succession- biodiversity increases as species establish themselves, interact and subtly alter the environment. This can be seen in the succession of sand dunes. In general biodiversity increases with time as the species migrate into an area, establish and develop. A sequence then develops.
- Interaction with species: This can lead to competition which may drive certain species to extinction, particularly when exotic species are introduced.
- Disturbance: Major environmental disasters such as fires, flooding and storms can destroy biodiversity
- Disposal and colonisation: Individuals dispersal and colonisation rates have an impact on biodiversity. High rates of efficiency enhance biodiversity
Human factors that influence biodiversity
-Levels of protection and management, level of awareness around the environment.
Level of poverty- some of the world’s most diverse places are some of the poorest in the world.
- Direct actions exploiting flora and fauna such as hunting, fishing/ overfishing and over-harvesting
- Clearance for agriculture leading to deforestation
- Use of products such as fertilisers and pesticides on the environment.
- Growth in human population and rate of development and use of technology
- Local ecosystem factors such as succession disturbance, competition and colonisation and dispersion rates.
- Human induced climate change
The global distribution of biodiversity
-Biodiversity is strongly correlated with latitude, the highest amount of biodiversity occurring in tropical regions. The top 5 countries with the highest diversity index are located around the equator or the tropics. These regions are almost all LEDCs with the least resources available to support sophisticated conservation strategies to tackle biodiversity loss.
Countries with the lowest diversity index are found in either cold countries or ones with large areas of arid desert. There are anomalies such as the continental island of Australia which has high levels of endemism.
-Greatest biodiversity is found in tropical rainforest areas which have more than half of the world’s species but only cover 7% of the earth’s surface. Brazil has the most biodiversity as it contains the amazon rainforest.
What are biodiversity hotspots?
-Biodiversity hotspots are areas of high biodiversity. Myers – hotspots are areas with: high species richness, high levels of endemism (uniqueness) and at severe threat of human disturbance
What are provisioning services? (value of ecosystems)
- sometimes known as goods, are products derived directly from ecosystems, such as timber for fuel and building, or meat and fish for food.
- Some goods such as nuts and fruit are sustainable, but the exploitation of other goods, but the exploitation of other goods such as hardwood timber can exhaust the supply
- It is sometimes possible to place an economic value on goods, but difficult to do for servies
What are regulating services? (value of ecosystems)
- Are those which are the vital functioning of the earths systems such as forests which are the ‘green lungs’ of the world and as important carbon sinks
- Trees remove carbon dioxide from the atmosphere and release oxygen
- They also protect against flooding and against soil erosion on slopes
What cultural services?
-Include the aesthetic and spiritual enjoyment that people draw from them and the opportunities for recreation
What are supporting services?
- processes such as nutrient recycling, soil formation and primary production which are vital to the wellbeing of the ecosystems itself
- They also support the provision of wildlife habitats.
- They are not services that support people
3 categories of biodiversity hotspots
- Continental hotspots – richest in terms of biodiversity
- Large island hotspots – have distinctive species
- Small island hotspots – low in species number but contain a high proportion of endemics
ways of measuring threatened ecosystems
1) Economic Scorecard shows the ability of ecosystems to produce goods and services
2) The Living Planet Index monitors changes over time in the populations of representative animal
species in various ecosystems
3) Ecological footprint measures the human impact on the planet
4) Red List of endangered species shows species at risk of extinction
5) Millennium Ecosystem Assessment is a multi-scale assessment by the UN
What does the WRI do to assess threats to biodiversity?
- The world resources institute (WRI) - measures biodiversity using an ecosystem scorecard which shows the conditions of the world’s major ecosystems and their ability to provide goods and services.
- The world resources institute has found the freshwater ecosystems to be the most Eco stressed.
- The world resources institute links biology and geography and environment and development.
- The world resources institute looks at issues such as food, energy, water, cities, transport and forests.
6 factors that threaten biodiversity by the WRI
- An unsustainable high rate of human population growth and natural resource consumption
- Inequality in the ownership, management and flow of benefits which threatens the livelihoods of the world’s poorest people.
- The concentration of agriculture, forestry and fishing on a narrowing spectrum of products.
- Economic systems, developers & businesses that fail to value the environment & its resources
- Legal and institutional systems that promote unsustainable exploitation at the expense of more sustainable strategies.
- Lack of knowledge and understanding in the management and conservation of biodiversity
What does the World Wildlife Fund (WWF) do to assess threats to biodiversity?
- measures biodiversity using the living planet index. The living planet index is developed by monitoring populations of representative animal species (319 marker species) initially in forests, freshwater (194 marker species) and marine ecosystems (217 marker species).
- Over time the forest index fell by 12% in spite of improvements in temperate forest cover due to afforestation in MEDCs.
- Freshwater biodiversity fell by 40% and marine biodiversity by 30%however shows signs of levelling off.
- Grasslands have recently been added to the living planet index as they have shown spectacular decline due to big game hunting and desertification.
- The WWF has found that more than ¼ of mammals are endangered.
What does the IUCN red list do to assess threats to biodiversity?
- annual list of endangered species. Species are placed in 1 of 10 categories ranging from extinct to endangered, to vulnerable and to little concern.
- Extinction hotspots include tropical rainforests, tropical grasslands, polar environments and small island environments. Species with large body size are vulnerable from hunting.
- Species that have low rates of increase (such as pandas), poor dispersal and migration abilities (polar bears) and are easily predated by alien species or perceived as being a nuisance by humans (such as rats) are the most vulnerable to extinction.
- Freshwater ecosystems have the highest percentage of threatened species especially amphibians and reptiles. The red list has found that 10-30% of mammal, bird and amphibian species are currently threatened with extinction
What does the United Nations environmental programme (UNEP) do to assess threats to biodiversity?
The MEA found that world drylands (tropical grasslands) were under the greatest threat, freshwater and marine ecosystems were under the greatest threat from eutrophication and hypoxia- locally this could lead to ecosystem collapse.
-Coral reefs were seen to be particularly at risk.
Deforestation of tropical rainforests was concentrated in Brazil and Indonesia with 80% of destruction being conducted in just these 2 countries.
The MEA found that more land was converted to crop land 1950-1980 than between 1700 and 1850. ¼ of the earth’s surface is now cultivated for crops.
This increase in cultivated land has caused major areas of land degradation in the world’s drylands. The MEA has found that the number of species on the planet is declining (with freshwater systems the most threatened) at an increased rate.
Genetic diversity has declined globally especially among cultivated species.
The distribution of species is becoming more homogenous and less endemic as a result of global interconnections.
According to the MEA the areas with the most habitat loss from 1950 to 1990 were; tropical and sub-tropical dry broadleaf forests, flooded grasslands and savannahs, tropical and subtropical shrublands, temperate forests steppe and woodland and tropical and subtropical coniferous forests.
-These losses were linked to development especially in NICs such as Brazil and Indonesia due to increased pressure on land for timber and cropland.
Global factors that affect biodiversity (stern review-climate change)
The stern review on the economics of climate change argues that climate change is likely to occur too rapidly for many species to adapt.
-The global warming experienced during the last ¼ of the 20th century has already given a hint of ecosystem impacts.
Species have been moving pole wards at a rate of 6km a decade.
Phonological studies show that seasonal events such as flowering, egg laying and fruiting have been advancing getting earlier by several days each decade.
Coral bleaching from warming oceans has increased since the 1980s. This combined with ocean acidification caused by an increased concentration of CO2 in the oceans poses a threat to the wellbeing of coral reefs.
Recent research suggests that even a rise of 0.05 to 0.1˚C per decade is more than most species would be able to withstand as they would not be able to move pole wards fast enough. The pace would certainly be too rapid for the evolutionary process in situ adaptation.
