Pollen Loads and Allergic Rhinitis in Darwin, Australia: A Potential Health Outcome of the Grass-Fire Cycle

Johnston, Fay H.; Hanigan, Ivan; Bowman, David M. J. S.

doi:10.1007/s10393-009-0225-1

Cited by 39 publications

(24 citation statements)

References 40 publications

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“…However, some other grasses are less flammable than surrounding vegetation, for example dense swards of Australian alpine Poa compared to surrounding heathlands (Williams et al, 2006). While invasive grasses can drive a grass fire cycle (D'Antonio and Vitousek, 1992; Setterfield et al, 2010), it is important to note that in many situations this feedback loop is driven by high anthropogenic ignitions and an absence of co-evolved grazers. More investigation of the flammable traits of grasses, and their evolutionary pathways, including co-evolutionary relationships with grazers (e.g., Linder and Rudall, 2005; Antonelli et al, 2011; McGlone et al, 2014) are warranted.…”

Section: Discussionmentioning

confidence: 99%

Have plants evolved to self-immolate?

2014

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By definition fire prone ecosystems have highly combustible plants, leading to the hypothesis, first formally stated by Mutch in 1970, that community flammability is the product of natural selection of flammable traits. However, proving the “Mutch hypothesis” has presented an enormous challenge for fire ecologists given the difficulty in establishing cause and effect between landscape fire and flammable plant traits. Individual plant traits (such as leaf moisture content, retention of dead branches and foliage, oil rich foliage) are known to affect the flammability of plants but there is no evidence these characters evolved specifically to self-immolate, although some of these traits may have been secondarily modified to increase the propensity to burn. Demonstrating individual benefits from self-immolation is extraordinarily difficult, given the intersection of the physical environmental factors that control landscape fire (fuel production, dryness and ignitions) with community flammability properties that emerge from numerous traits of multiple species (canopy cover and litter bed bulk density). It is more parsimonious to conclude plants have evolved mechanisms to tolerate, but not promote, landscape fire.

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Section: Discussionmentioning

confidence: 99%

Have plants evolved to self-immolate?

2014

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“…Despite the fact that physical space is not a consumable resource (McConnaughay and Bazzaz, 1991; Bazzaz, 1996), its effects on the access to other resources such as water, nutrients, and light could play an important role in determining the outcomes of resource competition between alien and native species. The majority of studies referring to space constraints have examined patterns of invasions following disturbances creating gaps (increases in light availability) that can be colonized by ruderal invaders (e.g., D'Antonio and Vitousek, 1992; Hobbs and Huenneke, 1992; Thompson et al, 2001; Buckley et al, 2007), while the effects of space on competitive interactions between invasive and native species represent a major research need (Gao et al, 2014) that requires further investigation.…”

Section: Competitive Ability In Invasive Speciesmentioning

confidence: 99%

Resource competition in plant invasions: emerging patterns and research needs

2014

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Invasions by alien plants provide a unique opportunity to examine competitive interactions among plants. While resource competition has long been regarded as a major mechanism responsible for successful invasions, given a well-known capacity for many invaders to become dominant and reduce plant diversity in the invaded communities, few studies have measured resource competition directly or have assessed its importance relative to that of other mechanisms, at different stages of an invasion process. Here, we review evidence comparing the competitive ability of invasive species vs. that of co-occurring native plants, along a range of environmental gradients, showing that many invasive species have a superior competitive ability over native species, although invasive congeners are not necessarily competitively superior over native congeners, nor are alien dominants are better competitors than native dominants. We discuss how the outcomes of competition depend on a number of factors, such as the heterogeneous distribution of resources, the stage of the invasion process, as well as phenotypic plasticity and evolutionary adaptation, which may result in increased or decreased competitive ability in both invasive and native species. Competitive advantages of invasive species over natives are often transient and only important at the early stages of an invasion process. It remains unclear how important resource competition is relative to other mechanisms (competition avoidance via phenological differences, niche differentiation in space associated with phylogenetic distance, recruitment and dispersal limitation, indirect competition, and allelopathy). Finally, we identify the conceptual and methodological issues characterizing competition studies in plant invasions, and we discuss future research needs, including examination of resource competition dynamics and the impact of global environmental change on competitive interactions between invasive and native species.

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“…Introduced ryegrass ( Lolium perenne) has been identified as one of the most significant aeroallergens of southern temperate Australia (Ford and Baldo 1986; Schäppi et al 1999). Tropical and subtropical regions have received less attention in the study of respiratory allergy although C 4 grasses are recognized as significant contributors to allergic disease in northern Australia (Johnston et al 2009; Davies et al 2012). The C 4 grasses of the Chloridoideae and Panicoideae subfamilies contain allergenic pollen (as reviewed in Davies 2014).…”

Section: Introductionmentioning

confidence: 99%

Regional and seasonal variation in airborne grass pollen levels between cities of Australia and New Zealand

et al. 2015

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Although grass pollen is widely regarded as the major outdoor aeroallergen source in Australia and New Zealand (NZ), no assemblage of airborne pollen data for the region has been previously compiled. Grass pollen count data collected at 14 urban sites in Australia and NZ over periods ranging from 1 to 17 years were acquired, assembled and compared, revealing considerable spatiotemporal variability. Although direct comparison between these data is problematic due to methodological differences between monitoring sites, the following patterns are apparent. Grass pollen seasons tended to have more than one peak from tropics to latitudes of 37°S and single peaks at sites south of this latitude. A longer grass pollen season was therefore found at sites below 37°S, driven by later seasonal end dates for grass growth and flowering. Daily pollen counts increased with latitude; subtropical regions had seasons of both high intensity and long duration. At higher latitude sites, the single springtime grass pollen peak is potentially due to a cooler growing season and a predominance of pollen from C3 grasses. The multiple peaks at lower latitude sites may be due to a warmer season and the predominance of pollen from C4 grasses. Prevalence and duration of seasonal allergies may reflect the differing pollen seasons across Australia and NZ. It must be emphasized that these findings are tentative due to limitations in the available data, reinforcing the need to implement standardized pollen-monitoring methods across Australasia. Furthermore, spatiotemporal differences in grass pollen counts indicate that local, current, standardized pollen monitoring would assist with the management of pollen allergen exposure for patients at risk of allergic rhinitis and asthma.

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Pollen Loads and Allergic Rhinitis in Darwin, Australia: A Potential Health Outcome of the Grass-Fire Cycle

Cited by 39 publications

References 40 publications

Have plants evolved to self-immolate?

Have plants evolved to self-immolate?

Resource competition in plant invasions: emerging patterns and research needs

Regional and seasonal variation in airborne grass pollen levels between cities of Australia and New Zealand

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