3.3 Threats to biodiversity

what does IUCN stand for

International Union for Conservation of Nature

what are the factors used by the IUCN to make the Red List

population size, degree of specialization, distribution, reproductive potential, and behaviour, geographic range and degree of fragmentation, quality of habitat, trophic level and the probability of extinction

where do most tropical biomes occur

in LEDCs and there is therefore conflict between exploitation, sustainable development and conservation

what are some general facts about the about 7 million species alive

most are animals and most are terrestrial, 2/3rds are in the tropics

what percentage of tropical rainforests have been cleared by humans

50%

what is primary forest

forest that has not been degraded or destroyed by humans

what are the group with the most identified and names species

beetles (Coleoptera)

what is one way of finding and identifying insects

"fogging" the canopies of rainforest trees with short lived insecticides, making the organisms fall out of the trees, they are then counted and the numbers extrapolated

what is the average species lifespan of a mammal

one million

what percentage of the habitat needs to be protected to preserve 50% of species

5%

what is inertia

the property of an ecosystem to resist change when subjected to a disruptive force

what are natural hazards

naturally occurring events that may have a negative impact on the environment, above a certain level, the impact is so bad they are considered natural disasters

what are some examples of natural hazards

volcanic eruptions, earthquakes, floods, wild fires, hurricanes

what are environmental disasters usually caused byq

human activity

what percentage of the original forest cover remains in the Mediterranean region

10%

where is the only place that lemurs occur

madagascar

what is fragmentation of a habitat

the process whereby a large area is divided up into a patchwork of fragments, separated from each other by roads, towns, factories, fences, powerlines, pipelines or fields

what are some different types of pollution

local pollution, environmental pollution, eutrophication

what is the maximum sustainable yield of a species

the maximum which can be harvested each year and replaced by natural population growth

why are more and more people who live at subsistence level overexpoiting the environment

due to increasing rural poverty and improved methods of hunting and harvesting

what are common victims of the exotic pet trade

primates, birds and reptiles

what are some examples of introducing non-native species to new areas being a good thing

potatoes from the americas to europe, rubber trees from the amazon to south-east asia

what are some examples of introducing non-native species going badly

rhododendrons to europe from nepal have taken over many areas as they outcompete the native plants and are toxic, dutch elm disease came from imported american logs to europe and decimated elm populations, rabbits being introduced to australia

what can be the effect of the spread of disease on biodiversity

it may decrease biodiversity

when was the last population of black-footed ferrets in the wild wiped out

in 1987 by canine distemper

can diseases of domesticated animals spread to wild animals

yes, and vice versa

what are some examples of diseases that have breached the species barrier

swine flu from pigs to humans, avian flu, foot and mouth disease

what is the effect of modern agricultural practices on biodiversity

reduces it

when were rabbits introduced to australia

1859

why were rabbits able to multiply so quickly in australia

they have no predators there

what were the effects of rabbits on the australian environment

they ate the grass so there was none for sheep, rabbits caused erosion as the topsoil blew away and likely caused the extinction of many australian marsupials

what were the three main measures taken by the australian government to eradicate rabbits

building a rabbit proof fence in 1901-7, introducing myxomatosis from brazil in 1950, releasing rabbit hemorrhagic disease in 1996

what percentage of all species on earth are found in tropical rainforests

over 50%

how much of earth's land area is covered by tropical rainforests

6%

how many species can be found in one hectare of tropical rainforest

up to 300

what percentage of the oxygen that animals use is produced by tropical rainforests

about 40%

how much of the earths land surface was covered by rainforest in 1950

14%

how much rainforest is cleared per second

1.5 hectares

how many people live in the wet tropics

at least two billion

what is shifting cultivation

a small area of the forest is cleared, farmed for two or three years then move on to the next area as the soil is exhausted

when can shifting cultivation work

as long as there is enough time for the forest to regenerate before the same area is cleared again

how long does it take for the biodiversity of the primary forest to be recovered

1000 years

why are rainforest so diverse

they provide many ecological niches

where are most of the nutrients held in tropical rainforests

in the plants, not the soil or leaf litter

what are the 11 main factors that make a species prone to extinction

narrow geographical range, small population size or declining numbers - low genetic diversity, low population densities and large territories, few populations of the species, a large body, low reproductive potential, seasonal migrants, poor dispersers, specialized feeders or niche requirements, edible to humans and herding together, island organisms

why are species with a narrow geographical range prone to extinction

if a species only lives in one place and that place is damaged or destroyed, the habitat has gone and the species can no longer grow in the wild

why are species with a small population size prone to extinction

species with a small population size have smaller genetic diversity and are less resilient to change

why are species with low population densities and large territories prone to extinction

habitat fragmentation can restrict its territory, if there's not a large enough area left for each individual or if they are unable to find each other they are less likely to survive

why are species that only have a few populations left prone to extinction

if there are only one or two populations left then that is their only chance of survival, it only takes that one population to be wiped out and that species is gone

why are species with a low reproductive potential prone to extinction

it means the population takes a long time to recover

why are seasonal migrants prone to extinction

their journey is often hazardous and they need their habitats at both ends of the migration route, if one is destroyed, they get there to find no food/habitat

why are poor dispersers prone to extinction

they cannot move in time to adapt to climate change or cannot easily escape hunters

why are species that are edible to humans and herd together prone to extinction

overhunting can eradicate a species quickly

why are island organisms particularly vulnerable to extinction

populations tend to be small, islands have a high degree of endemic species, genetic diversity tends to be low in small unique island populations, islands tend to be vulnerable to the introduction of non-native predators

what does the minimum viable population size depend on

genetic diversity, rate of reproduction, mortality rate, growth rate, threats to habitats

what is the minimum viable population size of large carnivores generally considered to be

500 individuals

how many tigers are there in the world today

about 3500

how many tigers were in india at the start of the 20th century

40000

how many blue whales are thought to live in the antarctic oceans

700

how many blue whales lived in the antarctic oceans about 60 years ago

about 250,000

how does the IUCN monitor the state of the world species

through the red list of threatened species

how many species are on the IUCN red list

40,000

what are the IUCN red list categories

extinct, extinct in the wild, critically endangered, endangered, vulnerable, near threatened, least concern, data deficient, not evaluated

how much of the population size of carnaby's cockatoo in 1950 is left now

about 50%

what are some of the challenges that face carnby's cockatoo

it only produces two eggs each year, the death rate during the first few years of its life is extremely high and they are difficult to breed in captivity

what is the ecological role of carnby's cockatoo

they breed in holes in mature salmon gum trees, they feed in open heathland on seeds and insect larvae, they migrate to populated coastal areas in late summer and autumn

what are the pressures facing carnaby's cockatoo

its habitat has been lost to wheat farming during the last 100 years, nest hollows are cleared for firewood or in tidying up back yards, competition from invasive species for the nesting sites, poaching

what is the ecological role of raffelesia

the plants are single sexed and pollination must be carried out when the plants are in bloom, therefore a male and a female in the same area must both be ready for pollination at the same time, the seeds are dispersed by small rodents and must reach a host vine

what are the pressures facing raffelesia

why need very specific conditions to carry out their life cycle, they are vulnerable due to deforestation and logging which destroy their habitat, humans damage them and fewer plants means less chance of breeding

what are some ways rafflesia are being conserved

in sabah, sumatra and sarawak, there are rafflesia sancturaries

what is the tigers ecological role

top carnivore, eats various deer and large herbivores

what are the pressures on tigers

habitat destruction and fragmentation, sale of its body parts

how many tigers were in the wild at the beginning of the 20th century

around 100,000

how many tigers are in the wild today

about 4,500

what percentage of the tiger population is found in india

60%

how many tigers are lost per day

about 1

how are tigers being conserved

conservation sites have been set up, strengthening international treaties, pushing for the enforcement of laws controlling the illegal trade in tiger parts, monitoring tiger populations, working with the traditional chinese medicine community to reduce the use of tiger bone and other parts by finding alternatives

what is the ecological role of the australian saltwater crocodile

it lives in estuaries, swamps and rivers, nests are built on river banks in a heap of leaves, eggs are food for goannas, pythons, dingoes and other small animals, it is a top predator

what are the pressures on the australian saltwater crocodile

it is over exploited for skin, meat and body parts, it was hunted for sport and they were killed because of attacks on humans

what are some conservation efforts for the australian saltwater crocodile

a sustainable use policy with limited culling of wild populations, ranching and closed cycle farming, visitors tour areas to see wild crocodiles so they are now a valued species

what is the role of the golden lion tamarin

omnivores, prey to large cats, birds of prey, live territorially in family groups in the wild in tropical rainforests in the canopy

what are the pressures facing the golden lion tamarin

only 2% of their native habitat is left, poaching can get 20,000 dollars per skin, predation is great in the wild and their food source is not dependable as well as habitat destruction

what are the conservation efforts for the golden lion tamarin

captive breeding programmes some are reintroduced to the wild but with only a 30% success rate

what was the ecological role of the thylacine

it's habitat was open forest and grassland but they became restricted to dense rainforest as the population declined, thylacines lived in rocky outcrops and large, hollow logs, they were nocturnal, their typical prey were small mammals and birds but they also ate kangaroos

what were the pressures on the thylacines

whey were outcompeted by dingoes on the mainland of australia and became extinct there hundreds of years ago, they were hunted by farmers in tasmania

what were the consequences of the disappearance of the thylacine

it was a carnivorous marsupial and was a significant predator, introduced dogs have taken over the ecological role of the thylacine

what was the ecological role of the dodo

ground nesting, flightless bird

what were the pressures on the dodo

they were eaten by sailors, rats pigs and monkeys were introduced, these ate dodo eggs and humans killed them for sport

what were the consequences of the loss of the dodo

not many