Australian rainfall patterns and the southern oscillation. 1. A continental perspective

Vines, R. G.; Noble, J. C.; Marsden, S. G.

doi:10.1071/pc040028

Cited by 7 publications

(5 citation statements)

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“…Intermittent droughts of variable length are apparently due to the El Niño Southern Oscillation (ENSO) cycle of approximately 10–11 years (Cane, Zebiak & Dean, 1986; Vines, Noble & Marsden, 2004). The ENSO cycle affects nearly all of Australia because tropical sea temperature variations are greatest in the Pacific, and weather systems can cross Australia from tropical to temperate latitudes unimpeded by topographic barriers.…”

Section: The Physical Environment Of Australiamentioning

confidence: 99%

Ecology of Australia: the effects of nutrient‐poor soils and intense fires

2007

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Australia, the flattest, driest, and geologically oldest vegetated continent, has a uniquely high proportion of nutrient-poor soils. We develop a "Nutrient-Poverty/Intense-Fire Theory," which postulates that most anomalous features of organisms and ecosystems of Australia are the evolutionary consequences of adaptations to nutrient poverty, compounded by intense fire that tends to occur as a result of nutrient poverty. The fundamental tenet of the theory is that plants growing in environments with plentiful light and periodic adequate moisture, but on soils poor in phosphorus, zinc, and other indispensible nutrients, can synthesize carbohydrates in excess of the amount that can be combined with, or catalyzed by, these nutrients for metabolism and production of nutrient-rich foliage and reproductive tissues. They use this "expendable energy" to produce well-defended foliage, large quantities of lignified tissues, and readily digestible exudates. Rapid accumulation of nutrient-poor biomass, a result of low rates of herbivory, provides fuel for intense fire. Intense fire exacerbates nutrient poverty by volatilizing certain micronutrients critical for animals. Anomalous features of organisms of Australia that can be explained by this theory, rather than by climate or phylogenetic history alone, include the following: most woody plants have long-lived, durable foliage; plants defend their tissues primarily with carbon-rich but nutrient-poor compounds; an unusually high proportion of plants protects seeds from fire and granivores in sturdy, woody capsules or follicles; plants allocate unusually large amounts of expendable energy to production of carbon-based exudates, such as nectar and gums; an unusually high proportion of plant species is pollinated by vertebrates that average larger size than pollinators on other continents; herbivores are small and have slow metabolism; there are no ruminants, mammals that eat mainly subterranean plant matter, or fungus-culturing termites and ants; vegetation dominated by leaf-spinescent plants is more extensive than vegetation dominated by stem-spinescent plants; nitrogen-fixing plants are major components of most vegetation types; there is a higher proportion of myrmecochorous plant species than on any other continent; there are hardly any stem-succulent and few leaf-succulent, perennial, non-halophytic plant species; and an unusually high proportion of bird species breeds cooperatively. Although the Nutrient-Poverty/Intense-Fire Theory can provide plausible explanations for these anomalous features, some puzzles remain, among them the great success of introduced herbivores, the lack of grazers on extensive grasslands on cracking clays, the apparently low productivity of ants, and the prominence of the parasitic plants of Australia. By examining the ratios of available energy to nutrients, particularly scarce nutrients, ecologists may identify processes not previously recognized as important for life forms or biotic adaptation on other continents.

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Section: The Physical Environment Of Australiamentioning

confidence: 99%

Ecology of Australia: the effects of nutrient‐poor soils and intense fires

2007

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“…Drought is common in Australia, a product of El Niño–Southern Oscillation cycles that cause large interannual variation in precipitation (Vines et al ., ) and significantly affects net primary productivity in grasslands (Morgan et al ., ). It is also known to compromise post‐fire regeneration of grasses (Carter et al ., ; Russell et al ., ) by reducing the metabolic functions and recovery rates of C 4 grasses (Knapp, ), a photosynthetic pathway that is generally assumed to be resilient to arid conditions (Ripley et al ., ; Taylor et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Effects of drought and fire on resprouting capacity of 52 temperate Australian perennial native grasses

2018

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It remains uncertain how perennial grasses with different photosynthetic pathways respond to fire, and how this response varies with stress at the time of burning. Resprouting after fire was examined in relation to experimentally manipulated pre-fire watering frequencies. We asked the following questions: are there response differences to fire between C and C grasses? And, how does post-fire resprouting vary with pre-fire drought stress? Fifty-two perennial Australian grasses (37 genera, 13 tribes) were studied. Three watering frequencies were applied to simulate increasing drought. Pre-fire tiller number, tiller density, specific leaf area and leaf dry matter content were measured as explanatory variables to assess response. Most species (90%) and individuals (79%) resprouted following experimental burning. C grasses had higher probabilities of surviving fire relative to C grasses. Responses were not related to phylogeny or tribe. High leaf dry matter content reduced the probability of dying, but also reduced the re-emergence of tillers. Post-fire tiller number increased with increasing drought, regardless of photosynthetic type, suggesting that drought plays a role in the ability of grasses to recover after fire. This has implications for understanding the persistence of species in landscapes where fire management is practiced.

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“…Groves 1965;McDougall 1989;Morgan et al 2017) and elsewhere (Knapp and Smith 2001). Year-dependent effects on primary production are particularly important in Australian grasslands because the El Niño-Southern Oscillation cycles cause large inter-annual variation in precipitation (Vines et al 2004). This introduces the potential for significant variation in the rates of canopy recovery after disturbance, seedling recruitment opportunities, as well as species coexistence processes.…”

Section: Resource Variationmentioning

confidence: 99%

Multivariate drivers of diversity in temperate Australian native grasslands

et al. 2019

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Disturbance has been considered essential for maintaining biodiversity in temperate grassy ecosystems in Australia. This has been particularly well demonstrated for inter-tussock plant species in C4 Themeda-dominated grasslands in mesic environments. Disturbance is also thought crucial to maintain the structure of preferred habitat for some animals. Relationships between disturbance and diversity may be contingent on ecosystem productivity, but little is known about the generality of the disturbance-promoting-diversity paradigm across the range of temperate grasslands. To date, the disturbance-promoting-diversity paradigm has taken a univariate approach to the drivers of biodiversity; rainfall is seen as a key driver of productivity, which then drives diversity, mediated by disturbance. We argue that this framework is too simplistic as biodiversity drivers are multivariate. We suggest that the accumulation of phytomass (live and dead plant material) is an important determinant of diversity in grassy ecosystems and that phytomass accumulation is governed by multiple drivers (of which disturbance is just one). For fauna, it is structure – not biomass – that determines habitat suitability, and this can be moderated by both abiotic and biotic drivers. The assumption that there is a consistent effect of disturbance on diversity through the range of temperate grassland settings in southern Australia ignores the likelihood that biodiversity also responds to other factors such as spatial heterogeneity in the environment, resource availability and climatic variation. We developed a conceptual model of the multivariate drivers of grassland diversity that explores mechanisms underpinning patterns of species richness. Despite four decades of research, it is clear that our understanding of the multivariate drivers of diversity across the range of temperate grasslands in Australia is still incomplete. Further research into the conditions under which disturbance is required to maintain biodiversity in grasslands is integral to conservation planning in these endangered systems.

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Australian rainfall patterns and the southern oscillation. 1. A continental perspective

Cited by 7 publications

References 0 publications

Ecology of Australia: the effects of nutrient‐poor soils and intense fires

Ecology of Australia: the effects of nutrient‐poor soils and intense fires

Effects of drought and fire on resprouting capacity of 52 temperate Australian perennial native grasses

Multivariate drivers of diversity in temperate Australian native grasslands

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