Fire timing in relation to masting: an important determinant of post-fire recruitment success for the obligate-seeding arid zone soft spinifex (Triodia pungens)

Abstract

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.

Global change impacts on arid zone ecosystems: Seedling establishment processes are threatened by temperature and water stress

“…Despite their dominance in natural ecosystems, reinstating Triodia grasslands is one of the most significant challenges for restoration practitioners (Smyth et al., 2012). Low recruitment rates from dispersed or broadcast seeds have been associated with a high prevalence of seed dormancy (Shackelford et al., 2018; Wright & Fensham, 2017) and reliance on sustained water availability to support germination and subsequent seedling emergence (Lewandrowski et al., 2017). Despite our ability to manipulate dormancy to increase the germination response of seeds under laboratory conditions (Erickson et al., 2016; Lewandrowski et al., 2018), these treatments have not translated to a comprehensive increase in the performance of seeds that are broadcasted during field trials.…”

Modes of climate variability bridge proximate and evolutionary mechanisms of masting

“…In most other regions where the environment is under the influence of major climate modes, there is evidence that ecosystem processes respond to them, and it will be interesting to see how often that results in an alignment between drivers of seed production and other ecosystem processes improving reproductive fitness. For example, negative phases of ENSO, Indian Ocean Dipole (IOD) and Southern Annular Mode (SAM) concurrently modulate rainfall in central Australia, with direct effects on the productivity [59] and seed output [86][87][88][89] of mulga (Acacia sp.) and spinifex (Triodia sp.)…”

Rainfall-Linked Megafires as Innate Fire Regime Elements in Arid Australian Spinifex (Triodia spp.) Grasslands

“…Spinifex seedlings may also contribute to the early post-fire fuel array (up to 50% of the fuel biomass under certain circumstances; Latz, 1990). However, the proportion of post-fire fuels comprised by spinifex seedlings is variable and depends on several factors, including (1) post-fire rainfall season and volume; (2) the species of spinifex involved; and (3) whether mature Triodia populations had masted recently prior to fire (masting "tops up" seed banks and maximizes seed availability for post-fire spinifex seedling recruitment) (Wright and Fensham, 2018). In spinifex grasslands dominated by resprouting Triodia, early postfire successional states are generally dominated by vegetatively regenerating spinifex hummocks rather than by short-lived nonspinifex grasses and forbs (Latz, 1990).…”

“…In the case of arid Triodia and mulga, seeding "in-synch" with arid rain-fire cycles may have been selected for because it ensures high seed-bank densities during periods when fire likelihood is high. This in turn maximizes the likelihood of dense seedling recruitment in favorable post-fire environments that are low in competition and high in moisture and nutrient availability (Wright et al, 2014;Wright and Fensham, 2018).…”