E&E PhD Exit Seminar: A multi-scale exploration of the drivers and implications of germination strategy in Australian alpine plants

Date & time

4–5pm 6 December 2017

Location

Gould Seminar Room (Rm 235), Bldg 116, Gould Building, Daley Road, ANU

Speakers

Annisa Satyanti, Nicotra Group, E&E, RSB

Contacts

 Audra Johnstone
 6125 2866

Description

Alpine ecosystems are considered to be particularly sensitive to the effect of global warming because they are characterized by species adapted to low temperatures. Plant responses to a changing climate will depend on their potential to establish and recruit following seed germination. Establishment from seed will therefore determine the potential to recruits in situ following disturbance or to disperse to follow climate change. The effects of climate change on regeneration from seeds will be expressed in the fate of seed after dispersal as well as through seed maturation and seed persistence – how long seeds remain viable after dispersal. Germination strategy, among the earliest life history traits expressed, reflects germination timing and pattern across the progression of seasons after seed dispersal.

I conducted experimental studies that investigate how germination success in future climate climate scenarios will differ from under ambient climate and whether germination strategy moderates the germination responses across 39 species. This study highlights that when comparing across species, germination strategy has potential to moderate the effect of changing climate on germination success. Additionally, I explored the seed intrinsic lifespan (longevity) and their correlates across 56 species. I showed that Australian alpine seeds are short-lived similar to alpine seeds elsewhere and relatively shorter-lived compared to non-alpine Australian seeds. Further, I examined the germination strategy variation within-species to specify the climate variables driving variation in germination strategy. I found that within alpine herb Oreomyrrhis eriopoda, variation in germination strategies is determined by temperature variability in the climate of origin. I also examined the consequences of germination strategy on  plants life history, including early establishment, vegetative and reproductive traits and phenology, under ambient and future climate scenarios. Under warmer soil temperatures, survival was reduced and lifetime (time to senesce) as well as reproductive period were condensed. Several vegetative and reproductive traits were affected by warming and the response indeed differed across strategies. This finding also highlights that within-species germination strategy may also enable species to express different patterns in life history traits across development, not just germination timings. Lastly, I also tested whether germination strategy is plastic across generations. Intraspecific germination strategies in O. eriopoda were not plastic across generations, even though labile in the species. Together the findings of this thesis contribute to improved understanding of alpine seed and seedling ecology with both applied and pure ecological and evolutionary relevance to Australia and will make a substantive contribution to our global understanding of alpine plants.

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