3.3 Threats to Biodiversity Flashcards
how many described species
1.8m, but scientists can only estimate how many other organisms remain undiscovered
why is the number of species poorly known
- some habitats are difficult to reach (i.e. the canopy of topical rainforests)
- lack of finance for scientific research
- difficulties with classification
- only a relatively small numbers of taxonomists globally are involved in identifying and describing new species
natural events that lead to the loss of biodiversity
- volcanic activity
- droughts
- floods
- ice ages
- meteor impacts
human actions that can lead to a loss of biodiversity (A HIPPO)
Agriculture
Habitat Loss
Invasive species
Pollution
Population (i.e. the effects of pop. growth)
Overhunting
what does the rate of biodiversity loss from country to country vary on
- the ecosystems present
- the protection policies and monitoring systems in place
- EVSs of the local residents
- the stage of economic development (i.e. LEDC or MEDC)
conflict between exploitation, sustainable development, and conservation in tropical biomes
most tropical biomes occur in less economically developed countries
- clearance of ecosystems provides land for cash-crops such as oil palm
- plantations provide financial income for local communities + employment
- clearance leads to biodiversity loss
- willingness, dependent on social, economic and political views
alternatives:
- selective logging methods -> less damaging, allow for faster regeneration of forest, preserves forest structure/biodiversity
- ecotourism -> provides ongoing income wihtout destroying natural capital
- needs local support + political will
factors that make species prone to extinction
- low reproductive potential
- small population size (lower genetic diversity)
- narrow geographical range
- seasonal migrants (long hazardous journey, reliant on multiple habitats)
- poor dispersers (cannot easily move to new habitats or non-flying animals)
- Specialised feeder or niche requirements
- a large body (10% rule means predators are rare, danger for humans, compete w humans for food)
- edible to humans + herding together (overhunted for food or for fun and can eradicate easily, especially if found in groups)
- island organisms (small populations, restricted genetic diversity human alterations of land through use of an already-limited habitat)
species based on factors that make them prone to extinction
- limited distribution (golden lion tamarin monkey)
- small population size (lower genetic diversity) (Asiatic cheetah)
IUCN
The International Union of Conservation of Nature
IUCN Red List purposes
- to identify species requiring some level of conservation
- to identify species for which there is concern about their conservation status
- to catalogue plants and animals facing a high risk of global extinction
- to raise awareness of animals and plants that face a higher risk of global extinction than others and require conservation efforts
factors that are used to determine a species conservation status on the IUCN red list
- pop. size (smaller pop. are more likely to go extinct)
- reduction of pop. site
- degree of specialisation
- geographic range
- degree of fragmentation
- distribution
- degree of endemicity
- quality of habitat
- trophic level
- probability of extinction
- reproductive potential and behaviour
sliding scale IUCN red list
- Not Evaluated
- Data Deficient
- Least Concern
- Near Threatened
- Vulnerable
- Endangered
- Critically Endangered
- Extinct in the Wild
- Extinct.
species critically endangered
Sumatran Tiger: CRITICALLY ENDANGERED
- Indonesian island, Sumatra
ecological role:
- apex predator
- keystone species
pressures:
-> loss of habitat (tropical rainforest)
-> it is seen as a danger to humans and livestock so its hunted
-> fragmentation of habitat makes breeding difficult
-> poaching
-> species only found on Sumatra island
-> top predator = pop is small bc little energy reaches the top
method of restoring:
- strengthening law enforcement
- anti-poaching capacity
- jail time for poachers
- fines for poachers
species currently endangered but whos status has improved
GIANT PANDA
- eats bamboo, forest in china
ecological role:
- seed dispersers through droppings
- keystone species
pressures:
-previous habitat loss
- small isolated populations
- seperate populations
-> increased vulnerability
-> loss of genetic diversity
method of restoring:
- china joined the convention of international trade in endangered species
-> makes trade of panda skills illegal
species that has become extinct
ELEPHANT BIRD
- endemic to island of Madagascar
- humans arrived on island from Southeast Asia 100 years ago:
-> forest species relied on was cleared and burned
-> around 80% of natural vegetation lost
-> habitat was cleared to create land for farming
-> eggs were eaten by humans bc highly nutritious
why are tropical rainforests so vulnerable?
- logging
- species have specialised niches
- 50% of earths known niches
- slow vegetation rate bc of slow/poor soil quality (year round nutrient cycling)
- changing one part of the ecosystem → alters entire web of relationships
human impacts, example deforestation social perspective
provides employment, construct towns or dams
human impacts, example deforestation soil
- soil exposed to wind and rain, reducing its ability to remain intact. The loss of vegetation leads to more soil being washed or blown away.
- without leaf litter and organic matter provided by trees, soil nutrient levels decline, reducing its productivity and ability to support future plant growth.
human impacts, example deforisation climate
reducing evaporative cooling
(canopy decreases)
- area for sun to warm surface
- no evaporation possible
carbon cycle
- more co2 -> joins oxygen + released into atmosphere
- global warming -> enhances greenhouse effect
evaluation of human impacts on tropical biomes positives
Programs that integrate indigenous knowledge and involve local communities in conservation efforts have shown success in maintaining biodiversity and ecosystem services.
evaluation of human impacts on tropic biomes negatives
- introduce invasive species -> may not have natural predators -> environment unstable
- rainforest needs long time to recover
- overexploit other species: fishing, hunting, harvesting
- globally 1hectare of rainforest destroyed every second -> 60 hectares every minute
- transform the environment w/ roads, cities, agriculture
case study threats of biodiversity from human activity in a given natural area of biological significance
Madagascar
- mine in Fort Dauphin Madagascar -> operating since 2005
- permit to dredge 6000 hectares -> extract ilmenite (industrial whitener used in different products i.e. toothpaste, paint, etc)
- operation has been removing last strands of forest (southeastern edge of island) -> culturally and biologically diverse areas of the world
- preservation projects (as said by company)
works by restricting local communities on their forest use
