This paper reports on the ethnobotany of Eucalyptus pachyphylla F.Muell. (Myrtaceae) (Pintupi name warrilyu), an understudied Eucalyptus species with a distribution largely restricted to the Gibson Desert region of Western Australia and the southern Northern Territory. Seeds of this and certain other Eucalyptus species were traditionally consumed as uncooked “seed pastes” by desert Aboriginal peoples (Cane 1987; Gillen 2017; Johnstone and Cleland 1943; Latz 2018; Roth 1897; Walsh and Douglas 2011). However, unfortunately, as with many other arid zone seed foods that were utilized intermittently depending on seasonal availability, there seems to be little or no written record of the specific techniques used to process E. pachyphylla seeds. Moreover, the nutritional status of the seeds is unknown. Here, we provide an ethnographic account of the harvesting and processing of E. pachyphylla seeds and present empirical data on seed collection rates and the nutritional value of processed seed flour. In our discussion, we highlight the importance of E. pachyphylla seed in the traditional economy of Gibson Desert people and consider the possibility/feasibility of seed harvest for commercial purposes.

Alternative stable state theory predicts that diferent disturbance regimes may support contrasting ecosystem states under otherwise analogous environmental conditions. In fre-prone systems, this theory is often invoked to explain abrupt ecotones, especially when adjacent vegetation types have contrasting fammabilities and difering tolerances to pyric perturbation. Despite being well-documented in forest-savanna transitions, unambiguous examples of fre-driven alternate stable states (FDASS) in arid systems are rare. The current study examined whether fammable spinifex (Triodia spp.) grasslands and fre-sensitive waputi (Aluta maisonneuvei subsp. maisonneuvei) shrublands in Australia’s Gibson Desert represent FDASS. Specifcally, analyses of soil and topographic variables assessed whether environmental diferences explain habitat zonation. To determine whether diferent fammabilities of Aluta and Triodia systems may perpetuate alternative states via vegetationfre feedback processes, community-level fuelloads were quantifed to provide an indirect measure of fammability. To determine the propensity for fre to trigger ‘state-shifting’, community responses to a single high-severity fre were evaluated. Habitat segregation did not relate to between-site environmental diferences, and the fuel-load study indicated that the more pyrophytic community (Triodia grassland) is more fammable, and hence more likely to experience higher frequency frecycles. Fire was identifed as a potential vector of ‘state-change’, because although both systems regenerated well after fre, Triodia reproduced more prolifcally at a younger age than Aluta, and hence should tolerate shorter fre-return intervals. In the absence of between-community topographic and edaphic diferences, or herbivores that consume either plant, it is likely that Aluta shrublands and Triodia grasslands represent fre-mediated alternative equilibrium states.

• Background and Aims Plant species with fire-triggered germination are common in many fire-prone ecosystems. For such plants, fire timing in relation to the timing of reproduction may strongly influence post-fire population regeneration if: (a) flowering occurs infrequently (e.g. plants are mast seeders); and (b) seed survival rates are low and input from the current year’s flowering therefore contributes a large proportion of the viable dormant seedbank. The role of fire timing in relation to masting as a driver of post-fire recruitment has rarely been examined directly, so this study tested the hypothesis that fires shortly after masting trigger increased recruitment of the obligate-seeding arid zone spinifex, Triodia pungens R. Br., an iteroparous masting grass with smoke-cued germination.

• Methods Phenological monitoring of T. pungens was conducted over 5 years, while a longitudinal seedbank study assessed the influence of seeding events on soil-stored seedbank dynamics. Concurrently, a fire experiment with randomized blocking was undertaken to test whether T. pungens hummocks burnt shortly after masting have greater post-fire recruitment than hummocks burnt when there has not been recent input of seeds.

• Key Results Triodia pungens flowered in all years, though most flowerings were characterized by high rates of flower abortion. A mast flowering with high seed set in 2012 triggered approx. 200-fold increases in seedbank densities, and seedbank densities remained elevated for 24 months after this event. The fire experiment showed significantly higher recruitment around hummocks burnt 6 months after the 2012 mast event than a round hummocks that were burnt but prevented from masting by having inflorescences clipped.

• Conclusions Fires shortly after masting trigger mass recruitment in T. pungens because such fires synchronize an appropriate germination cue (smoke) with periods when seedbank densities are elevated. Interactions between natural fire regimes, seedbank dynamics and fire management prescriptions must be considered carefully when managing fire-sensitive masting plants such as T. pungens.

In arid Australia, fires in different seasons often result in markedly different recruitment rates of woody plants, and this can have important and long-lasting impacts on post-fire community structure and composition. The current study investigated ecological mechanisms behind this effect in four widespread arid Acacia species: Acacia aptaneura, Maslin & J.E.Reid Acacia kempeana F.Muell., Acacia maitlandii F.Muell. and Acacia melleodora Pedley. Specifically, the study examined whether increased recruitment after summer compared with winter burning relates to (1) higher soil temperatures during summer fires having increased capacity to overcome dormancy of seeds with heatstimulated germination" (2) warmer soil temperature conditions after summer fires providing more favourable incubation temperatures for germination" and/or (3) summer fires coinciding with seasonal fluxes in seedbank densities, which may occur in response to granivory and/or rapid rates of seed deterioration after dispersal. Results supported hypotheses (1) and (2), as germination of all species responded positively to heat shock and warmer incubation temperatures. Some support was also demonstrated for hypothesis (3), as seedbank densities were shown to fluctuate seasonally, most likely in response to strong granivory. This multi-species study provides insights into mechanisms behind enhanced shrub recruitment after arid zone summer fires" and reinforces the notion that season of burn can be a strong determinant of regeneration trajectories of woody plants after fire.