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Hoyle G.L.,Australian National University | Steadman K.J.,University of Queensland | Good R.B.,Australian National Botanic Gardens | Good R.B.,Australian National University | And 3 more authors.
Frontiers in Plant Science | Year: 2015

1. Seed germination strategies vary dramatically among species but relatively little is known about how germination traits correlate with other elements of plant strategy systems. Understanding drivers of germination strategy is critical to our understanding of the evolutionary biology of plant reproduction. 2. We present a novel assessment of seed germination strategies focussing on Australian alpine species as a case study. We describe the distribution of germination strategies and ask whether these are correlated with, or form an independent axis to, other plant functional traits. Our approach to describing germination strategy mimicked realistic temperatures that seeds experience in situ following dispersal. Strategies were subsequently assigned using an objective clustering approach. We hypothesized that two main strategies would emerge, involving dormant or non-dormant seeds, and that while these strategies would be correlated with seed traits (e.g., mass or endospermy) they would be largely independent of vegetative traits when analysed in a phylogenetically structured manner. 3. Across all species, three germination strategies emerged. The majority of species postponed germination until after a period of cold, winter-like temperatures indicating physiological and/or morphological dormancy mechanisms. Other species exhibited immediate germination at temperatures representative of those at dispersal. Interestingly, seeds of an additional 13 species “staggered” germination over time. Germination strategies were generally conserved within families. Across a broad range of ecological traits only seed mass and endospermy showed any correlation with germination strategy when phylogenetic relatedness was accounted for; vegetative traits showed no significant correlations with germination strategy. The results indicate that germination traits correlate with other aspects of seed ecology but form an independent axis relative to vegetative traits. © 2015 Hoyle, Steadman, Good, McIntosh, Galea and Nicotra. Source


Green K.,National Parks and Wildlife Service | Davis N.E.,University of Melbourne | Robinson W.A.,Charles Sturt University | McAuliffe J.,Australian National Botanic Gardens | Good R.B.,Australian National Botanic Gardens
European Journal of Wildlife Research | Year: 2013

European hares (Lepus europaeus) are grazers and open grassland specialists that are replaced in mountain areas of their natural range in the northern hemisphere by browsing/intermediate feeding mountain hares (Lepus timidus), but in their introduced range in the southern hemisphere, occupy the alpine zone. We used micro-histological identification of plant fragments and germination of seeds in faecal pellets of L. europaeus from the Snowy Mountains, Australia, to determine diet. We asked whether diet shifted and/or diet breadth expanded in response to seasonally reduced food availability, particularly during winter. If so, did the constraints of food availability in the alpine zone lead to the diet mirroring that of L. timidus in its native alpine habitat. The diet of L. europaeus was dominated by grasses, herbs and shrubs. The main diet items in summer were grasses (70 %) and herbs (28 %). Grasses declined in the diet between summer and autumn when herbs increased to co-dominance, with a further change after establishment of the winter snowpack to a greater preponderance of shrubs (43 % compared with a maximum of 3 % in snow-free months). L. europaeus selected a wider range of plants in winter (59 species compared with 39 in summer) and diet was significantly more variable in winter than in autumn or summer (and in autumn than summer). We concluded that the persistence of L. europaeus in alpine areas of the southern hemisphere is testament to their ability to expand their dietary breadth to occupy mountain climatic zones normally occupied by L. timidus. © 2013 Springer-Verlag Berlin Heidelberg. Source


Olsen J.,University of Canberra | Judge D.,University of Canberra | Trost S.,44 Wybalena Grove | Rose A.B.,College Street | And 4 more authors.
Australian Field Ornithology | Year: 2011

The diet of three Powerful Owls Ninox strenua in the Australian Capital Territory was studied in 2007. A pair in Namadgi National Park took five Sugar Gliders Petaurus breviceps, a Greater Glider Petauroides volans, birds and a crustacean. Among avian prey, the Bassian Thrush Zoothera lunulata is a new record for Powerful Owls. An Owl at the Botanic Gardens took 41 Sugar Gliders, 10 Common Ringtail Possums Pseudocheirus peregrinus and two juvenile Common Brushtail Possums Trichosurus vulpecula, the last apparently off the females' backs. This Owl was observed perching on prey items on 11.9% of the days it was seen: seven times on Sugar Gliders, twice on Ringtail Possums, and twice on Brushtail Possums. It was seen attacking Sugar Gliders and adult Brushtail Possums, but beak-clacking when attacking the Brushtail Possums (so apparently attacking them as competitors, not prey). It was agile while hunting. Its behaviour was affected by mobbing by diurnal birds. Geometric Mean Prey Weight (GMPW) of Powerful Owl prey (including four items from a previous Namadgi analysis) in the ACT was 176.48 g, and the prey/predator weight ratio was 0.118. GMPW calculated from a previous study in Canberra of Southern Boobooks Ninox novaseelandiae was 2.11 g, and the prey/predator weight ratio was 0.008, much lower than for Powerful Owls. Standardised Food Niche Breadth for Powerful Owls was 0.115, and for Southern Boobooks 0.325; i.e. dietary evenness and richness were much higher for Boobooks. Powerful Owls took 95.2% arboreal marsupials, whereas Boobooks took a wider range of species including a large proportion of insects. Source


Hoyle G.L.,Australian National University | Venn S.E.,La Trobe University | Steadman K.J.,University of Queensland | Good R.B.,Australian National Botanic Gardens | And 3 more authors.
Global Change Biology | Year: 2013

Global warming is occurring more rapidly above the treeline than at lower elevations and alpine areas are predicted to experience above average warming in the future. Temperature is a primary factor in stimulating seed germination and regulating changes in seed dormancy status. Thus, plant regeneration from seed will be crucial to the persistence, migration and post disturbance recruitment of alpine plants in future climates. Here, we present the first assessment of the impact of soil warming on germination from the persistent alpine soil seed bank. Contrary to expectations, soil warming lead to reduced overall germination from the soil seed bank. However, germination response to soil temperature was species specific such that total species richness actually increased by nine with soil warming. We further explored the system by assessing the prevalence of seed dormancy and germination response to soil disturbance, the frequency of which is predicted to increase under climate change. Seeds of a significant proportion of species demonstrated physiological dormancy mechanisms and germination of several species appeared to be intrinsically linked to soil disturbance. In addition, we found no evidence of subalpine species and little evidence of exotic weed species in the soil, suggesting that the soil seed bank will not facilitate their invasion of the alpine zone. In conclusion, changes in recruitment via the alpine soil seed bank can be expected under climate change, as a result of altered dormancy alleviation and germination cues. Furthermore, the alpine soil seed bank, and the species richness therein, has the potential to help maintain local species diversity, support species range shift and moderate species dominance. Implications for alpine management and areas for further study are also discussed. © 2013 Blackwell Publishing Ltd. Source

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