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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.