threats to biodiversity

Question 1

extinctions : prehistory

Answer 1

arrival of humans on land mass coincides with disapperance of megafauna (correlation)

Question 2

extinctions : 1600 - present

Answer 2

data shows exponential correlation - year on year the number of extinctions increase

data likely underestimates as strong bias towards:

• higher plants/birds/mammals
• islands (71% mammal extinctions from islands)
• terrestrial and fresh water ( 4 (5) extinct marine species )
• described species ( most are not )

Question 3

extinct

Answer 3

when there is no reasonable doubt that the last individual has died

Question 4

extinct in the wild

Answer 4

when exhaustive surveys in known/expected habitat, at appropriate times throughout its historical range have failed to record an individual

Question 5

threats : direct expolitation

Answer 5

hunt exploit too last individuals/viable population

for example :
- bush meat
places without exploitation dont exist
- fuelwood
over 1/3 of humankind, directly dependent soley on fuelwoods for energy
- marine fisheries
reorganisation of structure of remaining species, incidental capture/killing (bycatch), habitat destruction

Question 6

threats : habitat loss

Answer 6

restructing distribution of habitats or vegatation types - persistant feature of humakind

human disturbance in every biome

land-use changes - species lost as predicted by species-area relationship

habitat degradiation and pollution

land-use also changing due to climate change - habitats and distributions changing

land-use bringing humans and wildlife into closer contact

Question 7

biome

Answer 7

large naturally occuring community of fauna anf flora occupying a major habitat

Question 8

threats : introduced species

Answer 8

intentially/unintentially introduction of non-domesticated species

approx 400,000 species introduced ( 10% become established. 10% of established become pests )

pests - major agents of global climate change.

Question 9

threats : extinction cascades

Answer 9

extinction of one species leads to extinction of others

Question 10

primary production ( scale of human enterprise )

Answer 10

use/destroy 35-40% total terrestrial primary production, 8% of aquatic primary production (disproportionately nearshore and freshwaters)

Question 11

energy use ( scale of human enterprise )

Answer 11

from agricultural revolution to present
power consumption x > 10k
global commercial energy production > 160000 Tetrawatts

Question 12

water ( scale of human enterprise )

Answer 12

use 25% of total rainfall
use 50% of total runoff

42% attributable to agriculture
14% attributable to industry

Question 13

global economy ( scale of human enterprise )

Answer 13

global increases in consumption outpace population increase