The spatial extent of terrestrial vegetation types reliant on groundwater in arid Australia is poorly known, largely because they are located in remote areas that are expensive to survey. In previous attempts, the use of traditional remote sensing approaches failed to discriminate vegetation using groundwater from surrounding vegetation. Difficulties in discerning vegetation groundwater use by remote sensing may be exacerbated by the unpredictable rainfall patterns and lack of annual wet and dry seasons common in arid Australia. This study presents a novel approach to mapping terrestrial groundwater-dependent ecosystems (GDEs) by applying singular value decomposition (SVD) to time-series of vegetation indices derived from Landsat-8 data, to isolate the temporal and spatial sources of variation associated with groundwater use. In-situ data from 442 sites were used to supervise and validate logistic regression models and neural networks, to determine whether sites could be correctly classified as GDEs using components obtained from the SVD. These results were used to produce a probability map of GDE occurrence across a 557 000 ha study area. Overall accuracy of the final classification map was 79%, with 72% of sites correctly identified as GDEs (true positives) and 16% incorrectly classified as GDEs (false positives). The approach is broadly applicable in arid regions globally, and is easily validated if general background knowledge of regional vegetation exists. Globally, and going forward, increased water extraction is expected to severely limit water available for GDEs. Successfully mapping GDEs in arid environments is a critical step towards their sustainable management, and the human and natural systems reliant upon them.

Currently, the impact of introduced predators on small mammal population decline is a focal research direction in the Australian desert literature. In all likelihood though, single-factor explanation of population dynamics is inadequate, leaving gaps in our knowledge of the multitude of potential influences on small mammal abundance and occupancy patterns in time and space. Here, we investigated floristic gradients across four potential refuge sites of the central rock-rat, Zyzomys pedunculatus, a granivore rodent (50-120 g) that is endemic to central Australia and is categorised as critically endangered. The study took place in Tjoritja/West MacDonnell National Park in the MacDonnell Ranges bioregion. Floristic sampling was allocated across the four sites, the locations of which were predetermined by an established monitoring and management programme for the central rock-rat. Our aim was to examine the relationship between environmental gradients and floristic composition across the four sites, and thereby test the extent to which the patterns of food type and food availability can inform central rock-rat spatio-temporal dynamics. We found high site-scale floristic patterning that related foremost to elevation and then to antecedent rainfall and time-since-fire and fire-severity effects. To interpret these results, we applied the principles of refuge theory and we described a gradient from core refuge habitat to intermittent and then marginal habitat within the current central rock-rat stronghold area. Overall, our results implied a strong floristic basis to central rock-rat site occurrence, and they thus compel us to take explicit account of spatial (elevation) and temporal (rainfall-productivity and fire-disturbance) influences on the food axis of potential refuge sites of this critically endangered species.