3.2.3: Biodiversity under threat Flashcards
Biodiversity
The number and variety of organisms within an area.
What is often used as a measure of health of ecosystems
biodiversity
When did biodiversity become a widely used term
1980s
Indicators used to measure biodiversity
4
species richness
ecosystem/habitat biodiversity
genetic biodiversity
species evenness
Species richness
number of different species
Ecosystem/habitat biodiversity
variety of habitats/ecosystems
Genetic biodiversity
genetic diversity in a population
Species evenness
How evenly distributed species are
Why is biodiversity important
4 reasons
- genetic biodiversity can control an ecosystems resistance to pests/diseases
- provides essential goods and services
- has aesthetic and spiritual value
- supports complex interactions between plants and animals
Threats to biodiversity
4
human, physical
indirect, direct
Direct threats to biodiversity
Mostly regulate land management practices
Direct threats to biodiversity
examples
5
industry, agriculture, mining, tourism, urbanisation
Indirect threats to biodiversity
and examples
4
- changing temperature and rainfall patterns
- sea level rise
- increased severity of storms and events such as cyclones
- ocean acidification
Indirect threats to biodiversity
Mostly associated with human induced climate change
Humans have degraded
percentage of land and oceans
75% of land degraded
66% of oceans degraded
The living planet index
A measure of the state of global biological diversity based on population trends of vertebrate species from around the world
Other biodiversity health indexes
3
red list index
species habitat index
biodiversity intactness index
Why are tropical rainforests fragile?
6 reasons
- High biodiversity
- Loss of ecological niches effects food webs largely
- Biomass loss reduces carbon storage
- Most nutrients stored in biomass store
- Inputs of organic matter to soil stores reduced by deforestation
- Loss of a canopy cover results in increased loss of nutrients through leaching and overland flow
Threats to tropical rainforests
4
- climate change
- acid rain
- invasive species
- deforestation
Three most at risk ecosystems
tropical rainforests, coral reefs, wetlands
ITCZ
inter tropical convergence zone
Inter tropical convergence zone
where trade winds meet at the equator
Why are coral reefs fragile?
6
- Increasing temps. of seas, coral lose algae
- Acidification of oceans, result of CO2 emissions
- Direct threats from overfishing and tourism
- Support 25% of marine species even though make up less than 0.1% of the ocean floor
- vertical growth & complexity provide numerous habitats
- Support valuable fish stocks
Wetland
definition
Flooded area of land that has a distinct ecosystem and vegetation adapted for life in water-saturated soils.
Factors which cause variation in wetlands
7
- Difference in soils
- Topography
- Climate
- Hydrology
- Water chemistry
- Vegetation
- Human disturbance
Two types of wetlands
coastal/tidal wetlands
inland/ non-tidal wetlands
Distribution of wetlands
found on every continent except Antarctica
Freshwater ecosystems occupy …& of the Earth’s surface
less than 1%
Wetlands since 1900
Over half the World’s wetlands have gone since 1900
Direct threats to wetlands
4
commercial development
drainage
overfishing
extraction of minerals and peat
Indirect threat to wetlands
leads to
climate change,
leading to
-swamping of shallow wetlands which submerges and drowns some species
-drought, drying up of others
