Download climate change change in mammal status increase in atmospheric

climate change
1
23
increase in
atmospheric CO2
2
3
vegetation
change
6
pastoralism
24
change in
mammal
status
25
4
9
5
changed fire
regimes
12
7
loss of
Indigenous
management
10
17
27
weeds
29
28
18
32
19
14
changed status
of dingos
8
11
feral
herbivore
s
13
26
16
30
cane toads
31
20
15
cats
21
disease
22
exotic rodents
33
Codes to the maze.
1. Increase in atmospheric CO2 --> climate change.
q.e.d.
2. Climate change --> vegetation change.
PLAUSIBILITY: moderate-high.
IMPACT: moderate-high.
Changing climates may have direct impacts on floristics, structure, phenology and the relative
extent of vegetation.
3. Increase in atmospheric CO2 --> vegetation change
PLAUSIBILITY: high.
IMPACT: moderate-high.
Maybe a subset of 2. World-wide increase in “woodiness” of savannas is at least partly due to
increased atmospheric CO2.
4. Loss of Indigenous management --> changed fire regimes
PLAUSIBILITY: high.
IMPACT: high.
In most parts of the tropical savannas, the current fire regimes differ markedly from those
prevailing over the previous tens of thousands of years.
5. Changed fire regimes <--> vegetation change.
PLAUSIBILITY: high.
IMPACT: high.
Changed fire regimes may have direct impacts on floristics, structure (including availability
of tree hollows and hollow logs), and phenology (including timing and abundance of fruits
and seeds).
6. Pastoralism <--> vegetation change.
PLAUSIBILITY: high.
IMPACT: moderate-high.
Livestock grazing may have direct impacts on floristics, structure, and phenology.
Pastoralists may manipulate environments (e.g. by clearing) to make them more suitable for
cattle. Conversely, vegetation change (e.g. thickening caused by over-grazing, inappropriate
fire regimes and/or increased CO2) may reduce pastoral suitability.
7. Changed fire regimes <--> weeds.
PLAUSIBILITY: high.
IMPACT: moderate-high.
Particularly with some exotic pasture grasses, increased biomass produces more intense fires
that favour weeds, leading to broad-scale environmental change.
8. Weeds --> vegetation change.
PLAUSIBILITY: moderate-high.
IMPACT: moderate-high.
Increase in some weeds may have direct impacts on floristics and vegetation structure;
especially in combination with fire.
9. Feral herbivores --> vegetation change.
PLAUSIBILITY: moderate.
IMPACT: moderate.
High densities of feral herbivores may have direct impacts on floristics, structure, and
phenology.
10. Feral herbivores --> changed fire regimes.
PLAUSIBILITY: moderate.
IMPACT: moderate.
At high densities, buffalo, feral cattle, horses, donkeys etc may reduce grassy fuel loads and
hence changed fire regimes.
11. Feral herbivores --> weeds
PLAUSIBILITY: low-moderate.
IMPACT: low-moderate.
High densities of feral herbivores may increase the dominance and spread of some weed
species.
12. Pastoralism <--> weeds.
PLAUSIBILITY: high.
IMPACT: moderate-high.
Many weeds have been introduced and spread for pastoralism. Livestock grazing may also
control or spread weeds.
13. Loss of Indigenous management --> changed status of dingoes
PLAUSIBILITY: low-moderate.
IMPACT: low-moderate.
The abundance and ecology of dingoes may have been previously keyed to Indigenous
management and hunting.
14. Pastoralism --> changed status of dingoes
PLAUSIBILITY: moderate-high.
IMPACT: moderate.
Baiting in many pastoral areas has reduced the abundance (and/or changed the biology) of
dingoes.
15. Changed status of dingos --> cats.
PLAUSIBILITY: moderate-high.
IMPACT: moderate-high.
Reduction in the abundance of dingoes (e.g. through baiting by pastoralists) may have led to
increase in densities, and/or changed diets, of cats.
16. Changed fire regimes --> cats.
PLAUSIBILITY: moderate-high.
IMPACT: moderate.
Cats are likely to be more effective hunters of native mammals in open areas with few shelters
(e.g. hollow logs), hence will have more impact in areas frequently and extensively burnt.
17. Changed fire regimes --> toads.
PLAUSIBILITY: low-moderate.
IMPACT: low-moderate.
There are likely to be more toads in more open (e.g. more frequently and extensively burnt)
areas (although very intense fires may destroy some toads and their shelters).
18. Pastoralism --> cane toads
PLAUSIBILITY: low-moderate.
IMPACT: low-moderate.
Paterolasim has increased water sources suitable for toads, resulted in reduction in grass cover
(more open areas are good for toads), possibly more prey items and more shelter.
19. Feral herbivores --> cane toads
PLAUSIBILITY: low-moderate.
IMPACT: low.
As for 18, but without the new water sources.
20. Cane toads --. cats
PLAUSIBILITY: low-moderate.
IMPACT: low-moderate.
Cane toads reduce the abundance of many native predators, and hence may allow for
increased abundance of feral cats.
21. Cats --> disease
PLAUSIBILITY: low-moderate.
IMPACT: low-moderate.
Feral cats may carry diseases that are novel to native mammals: e.g. toxoplasmosis.
22. Exotic rodents --> disease.
PLAUSIBILITY: moderate.
IMPACT: moderate.
Exotic rodents may carry diseases that are novel to native mammals.
23. Climate change --> mammal status.
PLAUSIBILITY: low-moderate.
IMPACT: low-moderate.
Changing climates may have direct impacts upon the physiological tolerance of some native
mammals.
24. Vegetation change --> change in mammal status.
PLAUSIBILITY: moderate-high.
IMPACT: high.
Changes in floristics, structure, phenology and extent of vegetation will affect habitat
suitability and resource availability for many native mammal species.
25. Pastoralism --> change in mammal status.
PLAUSIBILITY: low.
IMPACT: low.
There may be some direct impacts of pastoralism on native mammals (e.g. trampling may ruin
shallow burrow systems).
26. Changed fire regimes --> change in mammal status.
PLAUSIBILITY: low-moderate.
IMPACT: low-moderate.
Changed fire regimes may have direct impacts on some native mammals (e.g. through direct
mortality in fires).
27. Weeds --> change in mammal status.
PLAUSIBILITY: low-moderate.
IMPACT: low-moderate.
Spread of weeds may have direct impacts on resource availability for some native mammals
(e.g. dense stands of gamba grass may reduce foraging efficiency).
28. Changed status of dingoes --> change in mammal status.
PLAUSIBILITY: moderate.
IMPACT: low-moderate.
Reduction in dingo abundance may, considered alone, may result in increases in some prey
species (e.g. macropods).
29. Cane toads --> change in mammal status.
PLAUSIBILITY: high.
IMPACT: moderate.
Spread of cane toads has caused substantial population declines in some native carnivorous
mammal (and other) species. (It may be feasible that such predator reduction could cause
increases in other native mammals).
30. Cats --> change in mammal status.
PLAUSIBILITY: moderate-high.
IMPACT: high.
Increased predation pressure from cats is likely to reduce status of native mammals.
31. Disease --> change in mammal status.
PLAUSIBILITY: highly uncertain (possibly moderate-high).
IMPACT: (maybe) high.
Novel diseases may reduce status of native mammals.
32. Exotic rodents --> change in mammal status.
PLAUSIBILITY: low.
IMPACT: low.
Some chance of interspecific competition between native mammals and exotic rodents.
33. Change in mammal status --> change in mammal status.
PLAUSIBILITY: low.
IMPACT: low.
Increases in some native mammal species may (through competition) lead to reductions in
other species.