name the planetary boundaries (look in book to test on causes and effects)
- climate change boundary
- biosphere integrity
- biogeochemical flow
- land system change
- stratospheric ozone
- freshwater use
- ocean acidification
- atmospheric aerosol loading
- introduction of novel entities
define the term ‘planetary boundary’
limits between which global systems must operate to prevent abrupt and irreversible change
which boundaries have been crossed, avoided, avoidable and not quantified?
- crossed: climate change, biosphere integrity, land system change, biogeochemical flow
- avoided: stratospheric ozone
- avoidable: freshwater use, ocean acidification
- not quantified: atmospheric aerosol loading, introduction to novel entities
what is the definition of ‘biodiversity’?
the number of species and the number of individuals of each species in a given area
what is the definition of ‘endangered species’?
a species that is at risk of becoming extinct
list reasons why some species are at risk
- natural selection (don’t have ability to survive in a changing environment)
- pollution (toxic and carcinogenic)
- over-hunting and collecting (eg. ivory, for fashion, pets)
- competition from re-introduced/domestic species
- deforestation (eg. for palm oil plantations)
- habitat destruction (eg. wetland drainage or hedgerow removal to increase field size for machine use- loss of wildlife corridors)
what is meant by the term ‘conservation’
the sensible management of the biosphere to maintain habitats and enhance biodiversity, whilst allowing human activity
why is conservation important?
- ethical reasons (responsibility to preserve environment)
- possible medical uses (drugs extracted from plants)
- maintaining a healthy gene pool (protects against environmental changes)
- agriculture (learning to selectively choose alleles so crops can grow in harsher environments)
list conservation methods
- using nature reserves and SSSI’s (sites of special scientific interest): protect areas rich in biodiversity from being damaged, can be surveyed
- breeding programs: endangered species can be taken into zoos and bred before being returned
- sperm/seed banks: can store material in a controlled environment and ensures genetic variety, even in habitat loss
- legislation/ restrictions on trade (eg. CITES agreement): reduces killing but difficult to enforce as can be carried out illegally
- species re-introduction: if conditions are still favourable for the success of the species
- education/ raising awareness and ecotoursim: provides education and raises money to fund local efforts
what is meant by the term ‘agricultural exploitation’?
the way in which food production has had to increase in efficiency and intensity to maximise crop yieldsin order to feed a growing pop.
what is the problem with agricultural exploitation?
there is a conflict between the demand for production and the need for conservation
what are the strategies to increase agricultural exploitation?
- PESTICIDES reduces competition from other plants, reduces damage and disease but less biodiversity as weeds/natural predators killed
- ARTIFICIAL FERTILISERS: higher yields, nutrients no longer limiting, reduces biodiversity as grass grows and out-competes, washing causes eutrophication
- REMOVAL OF HEDGES increases field size, allows large machinery to be used but loss of habitats/wildlife
- DRAINAGE OF WATER MEADOWS: more land can be farmed, soil is more fertile (conditions good for nitrifying bacteria), loss of wetland habitat
- MONOCULTURE (cultivation of single crop species): increased efficiency, crop with best product can be widely grown, greater potential for soil nutrient deficiency and less biodiversity
list the causes of deforestation
- use of land for agriculture
- clear space for new roads/ infrastructure
- palm oil plantations
- timber extraction
- cattle ranching
what are the consequences of deforestation?
- desertification
- burning releases large amounts of CO2 into atmosphere: global warming/greenhouse effect
- loss of habitat, leading to loss of biodiversity
- tree roots bind soil together to trap water and protect from heavy rain so soil erosion and flooding
- less transpiration so less water being returned to atmosphere- less rainfall
what is ‘coppicing’?
trunk is cut, stool is left to regenerate and is then harvested
what are the advantages and disadvantages of coppicing?
AD: allows light onto forest floor, increases plant growth and therefore biodiversity
DIS: takes time to produce new poles
what is selective cutting?
individual trees are removed, leaving space for remaining trees to grow
what are the advantages and disadvantages of selective cutting?
AD: useful on slopes as removing all trees would lead to soil erosion- helps maintain soil fertility
DIS: only a small amount of timber is removed each year
what are the advantages and disadvantages of a long rotation time?
AD: many years left between harvesting so a variety of wildlife and habitats can develop
DIS: long time intervals between harvesting wood for human use
explain how over-fishing has led to a loss in biodiversity
- introduction of large vessels and new technology allows more fish to be caught
- fewer fish are able to breed
- reduces amount of prey available to predators
list the methods used to combat over-fishing
- exclusion zones
- removing subsidies
- reduction in vessel/fleet size
- quotas
- controlling mesh size in nets
- fish farms
what are the problems that come with fish farming?
- fish are densely stocked so disease/parasites spread quickly, overuse of antibiotics/pesticides can lead to resistance and pollution
- carnivorous species require large amount of food which can be a waste of resources
- fish excretory products are converted into nitrates by bacteria, leads to eutrophication
- fish can escape and out-compete native species for food
why is it important to monitor pop. where human development is planned?
so that diverse areas can be avoided and any changes that bring about damage can be stopped/migrated
why is it important for scientists to be involved in decision making?
they are able to analyse and evaluate data objectively
