Challenges To Biodiversity Flashcards
What is an invasive species?
Species introduced into areas outside of native range
Can cause/have caused harm in their new area
May outcompete native species for resources, habitat = alters community structure and could lead to extinctions
E.g. invasive plant
Kudzu
Prickly pear
Describe invasive species kudzu
- Japanese arrowroot
- e.g. of species introduced into new ecosystem with high resources and few preauthorise
- introduced to USA from Asia in late 1800s as ornamental plant
- planted widely in south USA in early 1900s to reduce soil erosion
- plants grow very rapidly and enshrouds almost everything including other plants and even houses in vines
Describe invasive species prickly pear
- were imported into Australia in 19th century: natural agricultural fence, established cochineal dye industry
- rendered 40,000 km2 of farm land unproductive
- moth from South America; larvae eat prickly pear so was introduced in 1925 and almost wiped out pop = successful biological pest control
What are the effects of introduced species
Sometimes there is a time lag after introduction of a species before spread and exert impact
Introduced species do constitute major ongoing global change
Recognised as second greatest cause of species endangerment and extinction (after habitat change)
What are the types of impact of invasive species
- habitat modification
- predation
- herbivore
- parasites and pathogens
- competition
- hybridisation
Describe habitat modification
LOOK AT SLIDES FOR E.G.s
- grazing, browsing and rooting by introduced mammals
- aquatic introduced plants overgrow and shade out native plants
- introduced plants modify natural fire regimes
- introduced plants change habitat by using vast amounts of water
- plants fix nitrogen; when such species invade nitrogen-poor areas, they fertilise the soil
Describe predation
LOOK AT SLIDES FOR E.G.s
- some invasions reduce or eliminate one/a few native species
- some invasions lead to community-level changes
Describe herbivory
LOOK AT SLIDES FOR E.G.s
- often devastates native plant species and sometimes entire communities
Describe parasites and pathogens
LOOK AT SLIDES FOR E.G.s
- introduced parasites and diseases can affect individual native species and occasionally entire communities
Describe competition
- introduced species can compete with native species to the point of extinction
- e.g American grey squirrel caused drastic decline in pop of native red squirrel in the UK(similar may happen in Europe as grey squirrel spreads north form Italy)
- e.g. house gecko, caused decline several native lizard populations on Pacific islands by outcompeting natives for insect prey
Describe hybridisation
-subtle but devastating impact
E.g.
- both New Zealand grey duck and Hawaiian duck hybridise with introduced North American mallard
- in Europe North American ruddy ducks hybridise with the dwindling native white headed duck, now restricted to Spain
- females of declining European mink hybridise with male introduced North American mink. Embryos are inevitably aborted but females removed for a year from the breeding population.
What are the characteristics of invasive species
- fast growth.
- rapid reproduction
- high dispersal ability
- phenotypic plasticity (the ability to alter growth form to suit current conditions)
- tolerance of a wide range of environmental
- ability to live off of a wide range of food types
- association with humans
- prior successful invasion history
Describe Japanese knotweed (fallopia japonica)
- listed by world conservation union as one of the worlds worst invasive species
- invasive root system and strong growth = damages even concrete foundations, pavements and roads
- reduces the capacity of channels in flood defences
- coloniser of temperate riparian ecosystems, roadsides and waste places
- forms thick dense colonies that completely crowd out any other herbaceous species
- success partially attributed to tolerance of wide range of soil types, PH and salinity, can survive temps of -35C, can extend 7m horizontally and 3m deep. - plant resilient to cutting, resprouts from the roots
- is an offence to plant or cause it to grow in the wildm or spread it intentionally or unintentionally
- householders and landlords who dont control gardens can be fined or persecuted
- requires disposal at licensed landfill sites
- species is expensive to remove: costs 70 million to eradicate knotweed from 10acres of the London 2012 Olympic Games velodrome and aquatic centre
- national eradication programme estimated 1.56 billion
Controlled release trials began in South Wales in 2016
How much of the population lived in the city by the turn of the 20th century
15%
What year witnessed the turning point when more than 50% of the world population were living in cities for the first time in human history.and who claims this?
2007
United Nations
What is urbanisation
- population shift from rural to urban areas
- process by which towns and cities are formed
How much of the developed and developing world will be urbanised by 2050?
Developed = 64%
Developing = 86%
(3 billion urbanites)
In 2050, which continents will exceed 70% urban populations and which populations will exceed 90%
Asia and Africa = 70%
New Zealand and North America = 90%
What are the environmental effects of urbanisation
- urban heat islands: formed when industrial and urban areas produce and retain heat
- in rural areas solar energy consumed by evaporation of water from vegetation and soil
- in cities, where less vegetation and exposed soil, sun’s energy absorbed by buildings and asphalt; leading to higher surface temperatures
- cities often 1 to 3C warmer than surrounding landscapes
What causes ecological degradation
Extinction
Land use change
Ecosystem processes
Ecosystem services
What is a built habitat
Buildings and sealed surfaces such as roads
What is managed vegetation
Residential, commercial and other regularly maintained green spaces
Ruderal vegetation
Empty lots, abandoned farmland and other green space that is cleared but not managed
What is natural remnant vegetation
Remaining islands of original vegetation (usually subject to substantial non-native plant invasion)
What is eutrophication
When rain occurs in large cities, it filters down pollutants such as CO2 onto the ground below.
Chemicals washed directly into rivers, streams and oceans, causing a decline in water quality and damaging marine ecosystems
How many pollinating species are in decline
60%
How many colonies of honey bees have been lost since 1985
54%
What are urban avoiders
Very sensitive to human habitat disturbances
E.g. large mammals (bison), old forest birds, late successional plants
What are urban adapters
Frequently found in sub-urban matrix areas
E.g. cultivated plants and weedy species, ‘edge species’ animals, and omnivore birds
What are urban explorers
Synanthropes - even dependant on Human Resources
E.g. grasses and annuals, birds and mammals that inhabit and exploit human dwellings
Describe light pollution
Presence of anthropogenic light in the night environment
- a major side effect of urbanisation: is blamed for compromising health, disrupting ecosystems and spilling aesthetic environments
The effects of light pollution
- alters natural patterns of light and dark
- circadian rhythms can be affected
- many species specialise in activities in particular lighting conditions
- nocturnal processes of repair and recovery interrupted
- decisions to forage at night related to lighting evils
- light at night tend to favour predators
- interference with spatial orientation
How to combat light pollution
- unnecessary lights extinguished or not installed
- spectrum chosen to minimise impacts (not UV or blue)
- as bright as necessary for purpose
- directed only where needed
- only illuminated as long as necessary
The effects of urbanisation on human health
- on average rural health better than urban
- poor urban areas e.g. slums differ disproportionately from disease, injury and premature death
- urbanisation associated with improvements in public hygiene, sanitation and access to health care. Results in changes and occupational dietary and exercise patterns:
- in children, urbanisation is associated with higher risk of overweight
- body mass index and cholesterol levels increase sharply with national income and the degree of urbanisation
- chronic diseases more prevalent in urban environments
