The ecology, evolution and management of mast reproduction in Australian plants

Abstract

Australia is home to a diverse assemblage of plant species that display marked population-level variation in inter-annual flower or seed output (i.e. masting). These include a semelparous bamboo with an estimated inter-crop period of 40–50 years, numerous iteroparous masting gymnosperms, angiosperms that include landscape-dominant eucalypts, arid-zone wattles and spinifex (Triodia spp.) grasses, and a rich selection of species that display disturbance-related forms of masting such as pyrogenic flowering and environmental prediction. Despite the prevalence of masting in the Australian flora, there has been a paucity of research on these plants. Nevertheless, from the literature available, it appears that, similar to other parts of the world, a continuum of inter-year reproductive variability exists, with a small number of species displaying extreme–high inter-annual seeding variability. From experimental studies and many anecdotal reports, most of the fitness benefits associated with masting evident overseas also operate in Australia (e.g. predator satiation, improved pollination efficiency, and environmental prediction). Additionally, some Australian masting species offer periodically important food resources for Aboriginal nations in the form of seed or fruit. These include the bunya pine (Araucaria bidwillii), members of the cycad genera Cycas and Macrozamia, spinifex (Triodia) grasses, and mulga shrubs (Acacia aneura). Key future research areas for effective conservation of Australian masting plants include (1) improved understanding of how management interventions such as burning and silvicultural thinning influence regeneration dynamics and higher-order trophic interactions, (2) further longitudinal monitoring across a range of habitats to identify other, as yet unknown, species that display reproductive intermittency, and (3) elucidation of how changes to temperature, precipitation and fire regimes under climate change will affect reproduction and regeneration dynamics of the Australian masting flora.

Population trends in the vulnerable Grey-headed flying-fox, Pteropus poliocephalus; results from a long-term, range-wide study

“…Our survey data also shows large seasonal changes in counted populations, and changes between years, so necessitating long term monitoring. In Australia, where myrtaceous plants can be episodic and unpredictable [86][87][88] in their flowering, any regional perceptions of change, must be countered with exploration of where the population may have moved to.…”

Habitat fragmentation decouples fire-stimulated flowering from plant reproductive fitness

“…This study contributes fundamental insights into the fitness benefits of synchronized reproduction. Synchronized interannual reproductive variation (e.g., masting) is prevalent among long-lived iteroparous plants ( 10 , 11 , 18 , 42 , 43 ). To explain the potential adaptive significance of this reproductive synchrony, researchers often point to density-dependent processes such as predator satiation and pollination efficiency ( 18 , 44 ).…”

“…Synchronized interannual reproductive variation (e.g., masting) is prevalent among long-lived iteroparous plants ( 10 , 11 , 18 , 42 , 43 ). To explain the potential adaptive significance of this reproductive synchrony, researchers often point to density-dependent processes such as predator satiation and pollination efficiency ( 18 , 44 ). Yet, few empirical studies of synchronized reproduction employ the stratified sampling necessary to identify critical population thresholds in the efficacy of such density-dependent processes.…”

“…Despite the prevalence of fire-stimulated flowering in historically fire-dependent habitats such as South African fynbos ( 10 , 17 ), Australian shrublands ( 10 , 18 ), Brazilian cerrado ( 11 , 19 ), North American longleaf pine savannas ( 12 , 20 ), and North American tallgrass prairie ( 13 , 21 , 22 ), the expected association between increased reproductive effort after fire and increased seed production has been empirically examined in only a handful of species and almost exclusively within large populations ( 13 , 15 , 23 ). Annual reproductive effort in perennial plants largely reflects patterns of resource availability, acquisition, and storage ( 15 , 21 ).…”

Masting, fire‐stimulated flowering, and the evolutionary ecology of synchronized reproduction

“…2. (Q2) How does interannual variation in fire-stimulated flowering species compare with canonically masting species (Herrera et al, 1998;Pearse et al, 2020;Wright et al, 2022)? 3.…”