A research agenda for seed-trait functional ecology

Trait-based approaches have improved our understanding of plant evolution, community assembly and ecosystem functioning. A major challenge for the upcoming decades is to understand the functions and evolution of early life-history traits, across levels of organization and ecological strategies. Although a variety of seed traits are critical for dispersal, persistence, germination timing and seedling establishment, only seed mass has been considered systematically. Here we suggest broadening the range of morphological, physiological and biochemical seed traits to add new understanding on plant niches, population dynamics and community assembly. The diversity of seed traits and functions provides an important challenge that will require international collaboration in three areas of research. First, we present a conceptual framework for a seed ecological spectrum that builds upon current understanding of plant niches. We then lay the foundation for a seed-trait functional network, the establishment of which will underpin and facilitate trait-based inferences. Finally, we anticipate novel insights and challenges associated with incorporating diverse seed traits into predictive evolutionary ecology, community ecology and applied ecology. If the community invests in standardized seed-trait collection and the implementation of rigorous databases, major strides can be made at this exciting frontier of functional ecology

A framework for the practical science necessary to restore sustainable, resilient, and biodiverse ecosystems

Demand for restoration of resilient, self-sustaining, and biodiverse natural ecosystems as a conservation measure is increasing globally; however, restoration efforts frequently fail to meet standards appropriate for this objective. Achieving these standards requires management underpinned by input from diverse scientific disciplines including ecology, biotechnology, engineering, soil science, ecophysiology, and genetics. Despite increasing restoration research activity, a gap between the immediate needs of restoration practitioners and the outputs of restoration science often limits the effectiveness of restoration programs. Regrettably, studies often fail to identify the practical issues most critical for restoration success. We propose that part of this oversight may result from the absence of a considered statement of the necessary practical restoration science questions. Here we develop a comprehensive framework of the research required to bridge this gap and guide effective restoration. We structure questions in five themes: (1) setting targets and planning for success, (2) sourcing biological material, (3) optimizing establishment, (4) facilitating growth and survival, and (5) restoring resilience, sustainability, and landscape integration. This framework will assist restoration practitioners and scientists to identify knowledge gaps and develop strategic research focused on applied outcomes. The breadth of questions highlights the importance of cross-discipline collaboration among restoration scientists, and while the program is broad, successful restoration projects have typically invested in many or most of these themes. Achieving restoration ecology's goal of averting biodiversity losses is a vast challenge: investment in appropriate science is urgently needed for ecological restoration to fulfill its potential and meet demand as a conservation too

Seed storage behaviour of tropical members of the aquatic basal angiosperm genus Nymphaea L. (Nymphaeaceae)

Eighteen native species of Nymphaea (waterlilies) inhabit a range of freshwater wetlands in northern Australia, which are threatened by increased development and the potential impacts of climate change. To investigate conservation seed banking of these vulnerable species, we aimed to characterize their seed storage physiology by determining (i) seed desiccation tolerance and (ii) the effects of moisture content and storage temperature on seed germination and viability. Seeds of N. immutabilis, N. lukei, N. macrosperma and N. violacea (including multiple collections of three species) were placed in experimental storage at a range of temperatures (25°C, 5°C, -20°C and -190°C) following pre-equilibration at different RHs (15%, 30%, 50%, 70% or 95%). Seeds were also experimentally aged at 60% RH and 45°C to assess comparative longevity. We found seeds of all species to be desiccation tolerant. However, the responses of seeds to experimental storage conditions were complex and variable between species and collections of the same species, and seeds of many species/collections were short-lived across many of the storage treatments. In many cases decreasing storage temperature did not increase longevity. Additional protocol development is necessary before we can have confidence that ex situ seed banking is a viable long-term germplasm conservation strategy for Nymphaea

Morphophysiological dormancy in the basal angiosperm order Nymphaeales

Background and Aims: Substantial evidence supports the hypothesis that morphophysiological dormancy (MPD) is the basal kind of seed dormancy in the angiosperms. However, only physiological dormancy (PD) is reported in seeds of the ANA-grade genus Nymphaea. The primary aim of this study was to determine the kind of dormancy in seeds of six species of Nymphaea from the wet-dry tropics of Australia. Methods: The effects of temperature, light and germination stimulants on germination were tested on multiple collections of seeds of N. immutabilis, N. lukei, N. macrosperma, N. ondinea, N. pubescens and N. violacea. Embryo growth prior to hypocotyl emergence was monitored. Key Results: Germination was generally <10 % after 28 d in control treatments. Germination percentage was highest at 30 or 35 °C for seeds exposed to light and treated with ethylene or in anoxic conditions in sealed vials of water, and it differed significantly between collections of N. lukei, N. macrosperma and N. violacea. Seeds of N. pubescens did not germinate under any of the conditions. Embryo growth (8-37 % in length) occurred before hypocotyl emergence (germination) in seeds of the five species that germinated. Conclusions: Fresh seeds were dormant, and the amount of pregermination embryo growth in seeds of N. lukei and N. immutabilis was relatively small, while in seeds of N. macrosperma, N. ondinea and N. violacea it was relatively large. Thus, seeds of N. lukei and N. immutabilis had PD and those of N. macrosperma, N. ondinea and N. violacea had MPD. Overall, we found that seeds in the most phylogenetically derived clades within Nymphaea have MPD, suggesting that PD is the most likely basal trait within the Nymphaeales. This study also highlights the broad range of dormancy types and germination strategies in the ANA-grade angiosperms

Benefits of adopting seed-based technologies for rehabilitation in the mining sector: A Pilbara perspective

© 2017 CSIRO. All rights reserved. The use of native plant seeds is fundamental to large-scale rehabilitation and the re-establishment of self-sustaining ecosystems after high-impact mining activity has ceased. However, many of the biological attributes of seeds are often overlooked in large-scale rehabilitation programs. Multi-disciplinary, long-Term research collaborations are required to improve seed-based mine rehabilitation. In this paper, we review the steps that BHP Western Australia Iron Ore (WAIO), a large iron ore mining company that operates in the Pilbara bioregion of north-west Western Australia, has taken over the past 9 years to ensure continuous improvement in rehabilitation procedures. We introduce the mining activities that WAIO undertake in the Pilbara, and emphasise specific examples of how research findings have led to incremental improvements in the seed management cycle, growth media management and mine rehabilitation practices. Specifically, we outline how the implementation of structured seed collection and storage programs has created the capacity to maintain high-quality seed stocks sufficient for 3-5 years of future rehabilitation. Research has documented the prevalence of seed dormancy in the flora ( > 70% of 105 species examined produce dormant seeds), with physical and physiological classes of dormancy most commonly encountered. We discuss the development of seed-Treatments such as optimised wet-heat and dry after-ripening that have increased the germination capacity of many previously dormant seed batches. In addition, we highlight how seed enhancement technologies, such as hydro-priming with smoke-derived germination stimulants and polymer seed coating, and a greater understanding of the biological and physical limitations present in the growing environment, have vastly improved seedling emergence performance under field conditions for key framework Triodia species. Ongoing industry support (e.g. construction of a purpose-built rain manipulation shelter) has ensured research in the Pilbara will continue to unpack and resolve the complex challenges associated with seed regeneration of biodiverse native plant communities after mining

Alleviation of morphophysiological dormancy in seeds of the Australian arid-zone endemic shrub, Hibbertia glaberrima F. Muell. (Dilleniaceae)

© Cambridge University Press 2018. Morphophysiological dormancy (MPD) is predominantly found in seeds of temperate regions and is uncommon in arid biomes. MPD has been reported in a number of Hibbertia (Dilleniaceae) species of temperate Australia, and in a single species of the arid zone, H. glaberrima. This study aimed to examine the dormancy and germination ecology of seeds of H. glaberrima. Seeds were subjected to temperature stratification treatments designed to mimic summer and autumn conditions in the Pilbara region of Western Australia. Seed germination and embryo growth were measured. We also tested the interaction between temperature stratification and cycles of drying and wetting designed to mimic sporadic rainfall events. All temperature and moisture treatments were tested in combination (+/-) with the smoke-derived chemical karrikinolide (KAR1). Exposing dormant seeds to temperatures suitable for warm stratification (35°C) for = 8 weeks, followed by incubation at 25°C, resulted in significantly higher germination compared with non-stratified seeds. Exposing seeds to dry/wet cycling in conjunction with temperature stratification did not significantly increase germination. Exposure to KAR1 increased germination under most conditions. Once seeds are shed during October to December, they are exposed to hot and sporadically wet conditions over summer, allowing MPD to be overcome in a proportion of the seed population. Seeds may germinate in autumn (March to April), in conjunction with cooler temperatures. More deeply dormant individuals may require more than one summer to overcome dormancy. Similar to other species occurring in fire-prone ecosystems, fire also plays a crucial role in the germination ecology of H. glaberrima

Danger may enhance communication: predator calls alert females to male displays

Sexual displays are typically given in the absence of predators. One possible exception to this is seen in male splendid fairy-wrens (Malurus splendens), which sing display-like vocalizations (Type II song) in response to predator calls. In this study, we explored the function of this vocal "hitchhiking" using playback experiments. We documented that: 1) males responded to Type II songs of other males as if they were displays intended for conspecifics, 2) females became more attentive after hearing a predator vocalization than a control (nonpredator) vocalization, and 3) females tended to respond more strongly to Type II songs when the songs were preceded by a predator vocalization than when they were given solo. Males of all age and status classes produced Type II songs and production was not dependent on any of 3 morphological measures of male quality, so we do not find evidence to support the hypothesis that Type II singing behavior is condition dependent. Because predator calls increased female attentiveness and tended to increase subsequent response to Type II songs, it appears that males may be using predator vocalizations as alerting signals for their own conspecific-directed displays. Copyright 2010, Oxford University Press.

Ecological niche and bet-hedging strategies for Triodia (R.Br.) seed germination

Background and Aims: Regeneration dynamics in many arid zone grass species are regulated by innate seed dormancy mechanisms and environmental cues (temperature, moisture and fire) that result in infrequent germination following rainfall. This study investigated bet-hedging strategies associated with dormancy and germination in arid zone Triodia species from north-west Australia, by assessing (1) the effects of the mechanical restriction imposed by the indehiscent floral bracts (i.e. floret) covering the seed and (2) the impact of dormancy alleviation on florets and cleaned seeds (i.e. florets removed) when germinated under water stress. Methods: The initial dormancy status and germination for six species were tested on intact florets and cleaned seeds, across temperatures (10–40 °C) with and without the fire-related stimulant karrikinolide (KAR1), and under alternating light or constant dark conditions. Physiological dormancy alleviation was assessed by wet/dry cycling florets over a period of 10 weeks, and germination was compared against untreated florets, and cleaned seeds across a water potential gradient between 0 and –1.5 MPa. Key Results: Florets restricted germination (<45 %) at all temperatures and, despite partial alleviation of physiological dormancy (wet/dry cycling for 8 weeks), intact florets germinated only at high water potentials. Cleaned seeds showed the highest germination (40–90 %) across temperatures when treated with KAR1, and germinated at much lower water potentials (–0.4 and –0.9 MPa). Triodia pungens was the most responsive to KAR1, with both seeds and florets responding, while for the remaining five species, KAR1 had a positive effect for seeds only. Conclusions: Only after seed dormancy was alleviated by removing florets and when KAR1was applied did germination under water stress increase. This suggests that seeds of these Triodia species are cued to recruit following fire and during periods of high precipitation. Climate change, driven by large shifts in rainfall patterns, is likely to impact Triodia recruitment further in arid zone grasslands