Biodiversity Flashcards
what is biodiversity
- the number of species in a given area (plus some measure of the evenness of their abundances)
- the number of vegetation types within a site
- the number of habitats within a lansdcape
- the number of ecosystems in a country
how much biodiversity is there?
- current estimates lie between 5 and 100 million species
- only 2.5 million species described and only about 100,000 are well known
what controls local diversity?
- balance between colonisation and local extinction / speciation and extinction
- Spatial factors: predation intensity, spatial heterogeneity, environmental harshness
- Temporal factors: climate variation, distribution, age
diversity hotspots
- biodiversity hotspots refer to regions of the world that are high in endemic species (& usually threatened)
- endemic species refers to a species native to a particular place and only found there
habitat destruction
- deforestation
- more land was converted to cropland in the 30 years after 1950 than between 1700-1850
- 5-10% of the area of five biomes was converted between 1950 and 1990
reasons for loss of species
- habitat destruction
- hunting and over-exploitation
- species introductions
changes in species diversity
- the distribution of species on earth is becoming more homogenous
- the population size or range of the majority of species across a range of taxonomic groups is declining
- humans have increased the species extinction rate by as much as 1000x over background rates typical over the planets history
- 10-30% of mammal, bird and amphibian species are currently threatened with extinction
Intrinsic (inherent) value of wildlife
- organisms have interest of their own (growth and reproduction)
- inherent value irrespective of value to us
- related to philosophical and religious beliefs
- accessed by some (biocentrists) rejected by others (anthropocentrists)
instrumental (utilitarian) value
- anthropocentric
- concept of goods and service provided by biodiversity
provisioning services
- food and drink
- medicines
- industrial materials
- biofuels
cultural services
- recreation and tourism
- inspiration for artists
- psychological value
- ethical, religious or philosophical beliefs
regulating and supporting services
Biodiversity provides a variety of ecosystem services that provide directly or indirectly a range of benefits to human
- regulation of climatic processes
- protection of water resources
- breakdown of wastes and pollutants
- biological control of pest species
- soil formation and protection
- maintenance of soil fertility and recycling of nutrients
- pollination of food plants
millennium ecosystem assessment (MEA): degradation of ecosystem services
- a global study shows loss of many services provided by biodiversity, primarily as a result of ecosystem destruction and degradation
- approximately 60% of the ecosystem services evaluated in MEA are being degraded or used unsustainably
- the degradation of ecosystem service often causes significant harm to human well being and represents a loss of a natural asset or wealth of a country
diversity and ecosystem function
- species richness is largely irrelevant: what is important is that the biomass of primary producers, consumers, decomposes etc. is maintained, and ecological processes will function normally with very few species
environmental unpredictability
Most experimental studies of the relationship between biodiversity and ecosystem function:
- focus on primary productivity
- are carried out for short time periods
- are carried out under constant environmental conditions
