Ecosystems Flashcards
whats an ecosystem
concept is 100yrs old
complex of interacting organisms and environment. includes biotic and abiotic. characterised by transfer of material between components.
ecosystem processes
biogeochemical cycles(water,carbon,nirate) biological (pollination) food webs genes geophysical processes climate regulation
ecosystem functions
processes in which other attributes depend
ecosystem processe–>ecosystem functions–>ecosystem services
biodiversity
measure of diversity of life on earth - genetic, species or ecosystem
what % of insects are threatened with extinction
40%
what sort of biodiversity do we need?
resilience, species complimentary, insurance, rivet popping hypothesis
whats the rivet popping hypothesis
may lose biodiversity slowly and not notice till all at once there’s a full on collapse
what are keystone species
single species with a disproportionately large effect on its environment relative to its abundance - if removed the whole system would change rapidly
who said its impossible to know the keystone species by looking at a food web
Hall, S and Raffaelli, D 1991
whats ecological restoration
the return of an ecosystem to its condition prior to disturbance
e.g. of a restoration plan(biodiversity offsetting)
- site preparation e.g. denitrification
- introduction of relevant plants in suitable proportions
- manipulation of management techniques
restoration on man made ecosystems thoughts
seen as positive, but many rejected as danger to traditional conservation and preservation of the environment
critique of restoration
- don’t restore, just let it be?
- restoration is anthropogenic conceit
- restoration is designed, but nature is not
is loss of wealth due to ecosystem degration reflected in economic accounts?
no
e.g. a country could cut down all forest and get all fish out of sea and it would look like a gain in GDP - not corresponding decline in assets
in 1996 a filtration plant for NYCs water supply system was estimated at …
$8-10billion
