What are the 6 main threats to biodiversity?
Climate change
Habitat loss
Pollution
Invasive species
Overexploitation
Disease
What are the leading causes of declines in biological diversity worldwide?
Habitat destruction and degradation
What is habitat loss?
Occurs any time a piece of land is converted from it current state to some other land use or land cover type.
Loss refers to the fact that the overall area of native habitat has been reduced
What is habitat fragmentation?
The process whereby a large, continuous area of habitat is both reduced in area and divided into two or more fragments.
What are the 5 main factors driving deforestation in North America?
- Agriculture
- Urban development, transportation, recreation
- Forest roads
- Hydroelectricity
- Industry and resource extraction
How does habitat fragmentation affect biodiversity?
- Reduction in habitat area=loss of species diversity: small habitat patches may not be able to support the same number or diversity as larger, continuous
- Disrupted migration/movement and dispersal: species rely on corridors for migration ,food, mating, etc.
- Disruption of predator/prey dynamics
- Genetic Isolation: smaller, isolated populations reduces gene flow, leads to inbreeding, genetic drift
- Edge effects: fragmented habitats have more edges that have different environmental conditions, which can be inhospitable for some species
What is overexploitation?
Intense harvest of a species or resource that results in its decline or loss
What are exotic species?
Species that occur outside their natural ranges because of human activity.
Majority do not become establishes in new environments because they are not suitable to their need or because they have not arrived in sufficient numbers
What are invasive species?
Species does establish themselves
Spreads and increase in abundance rapidly, sometimes displacing native species through competing for limited resources
How do species become introduced?
European colonization: settlers arriving at new colonies released hundreds of different species
What are the main causes of pollution?
Fertilizers
Pesticides/Herbicides/Fungicides
Sewage
Industrial and chemical wastes
Emissions (factories and cars)
Oil spills
Pharmaceuticals
What are the ecological impact of climate change?
- Climate effects on sea ice, lakes and coastal ecosystems: sea levels are rising, threatening habitat and infrastructure
- Changes in precipitation: droughts in some areas (leads to wildfires), heavy rainfall in other areas (leads to flooding)
- Winter warming: exposes soils, root mortality, survival of pest species
- Ocean acidification
- Biome shifts: shifts in plants species distributions are changing the characteristics of biomes, terrestrial ecosystems shifting poleward and upward (elevation)
Effect of climate change on phenology
Long distance migration:
timing of migration may be uncoupled from the timing of resources used by birds on their breeding grounds
Positive impacts of climate change on agriculture
Positive:
- Increased productivity from warmer temperatures
- Possibility of growing new crops
- Longer growing seasons
- Increased productivity from enhanced CO2
- Accelerated maturation rates
- Decreased moisture stress
Negative impacts of climate change on agriculture
- Increased insect infestations
- Crop damage from extreme heat
- Planning problems due to less reliable forecasts
- Increased soil erosion
- Increased weed growth and disease outbreaks
- Decreased herbicide and pesticide efficacy
- Increased moisture stress and droughts
What are the 4 categories of value of biodiversity?
- Direct use values: products harvested by people
- Indirect use value: benefits provided by biological diversity do not involve harvesting or destroying the resource
- Option value: prospect for possible future benefits for human society
- existence value: non-use value that can be assigned to biodiversity
What is MVP?
Minimum Viable Population: an estimate on how large a population must be to ensure long term survival
What is the extinction vortex?
- Small populations lead to inbreeding and genetic drift
- This leads to loss of genetic variability
- Reduction in individual fitness and population adaptability
- Lower reproduction and higher mortality
- Even smaller population
What is the purpose of establishing new animal populations?
Establishing new wild and semi-wild populations of rare and endangered species and increasing the size of existing populations allow species to regain their ecological and evolutionary roles within the biological
What is the importance of widely dispersed populations?
WDP are less likely to be destroyed by catastrophes than isolated wild populations occupying only small areas.
What is a protected area?
An area of land or sea dedicated by law or tradition to (and managed for) the protection of biodiversity and associated natural and cultural resources
Prioritization: What should be protected?
- Distinctiveness (or irreplaceability): An ecosystem composed or rare endemic species or that has unusual attributed is given higher priority
- Endangerment (or vulnerability): species in danger of extinction are of greater concern, ecosystems threatened with destruction
- Species that have present or potential value to people are given more conservation priority than species of no obvious use to people
Factors to consider when designing protected areas
- Ecosystems completely protected
- Larger reserves
- Unfragmented reserve
- More reserves
- Corridors maintained between reserves
- “Stepping stones” to facilitate movement
- Diverse habitats (ex. mountains, lakes, forests) protected
- Reserve shape closer to round (fewer edge effects)
- Mix of small and large reserves
- Reserves managed regionally
- Human integration buffer zones
Factors that can increase the success of reserves
- Having more than one population of a rare species within protected area will increase the probability of survival
- Well-placed small reserves are able to include a greater variety of habitat types and more populations of rare species
- Creating more reserves (even if small) decreases the possibility that a single catastrophe will destroy an entire species
