Congratulations to all the presenters at EcoTas13. The award winners were:
Oral presentation winners:
Freya Thomas – University of Melbourne
Incorporating plant functional traits into a multi-species model of plant growth
Freya Thomas1,2, Cindy Hauser1,2, David Keith3 and Peter Vesk1,2
1Quantitative and Applied Ecology Group, The University of Melbourne
2ARC – Centre of Excellence for Environmental Decisions
3New South Wales Office of Environment and Heritage
Data required for optimal fire management of multiple plant species are quantitative information on ‘vital rates’ and ‘life history characteristics’, which specifically relate to growth, reproduction and survival. Our research aims to investigate the application of using plant functional traits to generalize patterns of plant growth and reproduction. Including functional traits into models of demographic rates is useful in producing predictions of growth trajectories based on trait information. Data on functional traits can be generalised across species that share similar traits and is easier to gather for many species compared to species-specific demographic data. Using hierarchical multi-species models also allows for the growth of unknown or rare species to be estimated because probability models for growth are drawn from common distributions between species.
Using height and trait data collected for multiple species along a chronosequence of time-since-fire sites in the Victorian Mallee, we built a hierarchical multi-species model of plant growth with parameters that vary by species. We use a three-parameter cumulative Weibull distribution, and functional traits (wood density, specific leaf area and seed mass) are included into this multi-species model as species-specific linear predictors of the model parameters. This approach reveals not just plant growth through time for individual species, but also how functional traits contribute to intraspecific species variation. These results will be discussed in relation to the practical application of generalising growth patterns and designating tolerable fire intervals for multiple plant species.
Freya Thomas, PhD Candidate with The Quantitative and Applied Ecology Group (qaeco.com) and The Centre for Excellence for Environmental Decisions (ceed.edu.au) at The University of Melbourne. Research interests are plant ecology, plant functional traits and fire ecology.
Sichong Chen – University of New South Wales
A mammoth mouthful? A test of the idea that big animals disperse big seeds
Chen, Si-Chong1; Moles, Angela T.1
1Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
It has been widely assumed that large seeds generally require large dispersers to ingest and disperse them, but this relationship has only been quantified in single animal groups (e.g. birds) and in a few communities. We made the first global-scale study across all vertebrate groups (fish, amphibians, reptiles, birds and mammals), to test the prediction that large animals are able to ingest both large and small seeds while small animals ingest small ones. Literature data were compiled for over 12,000 seed dispersal interactions from over 300 study sites globally. Quantile regression showed a triangular relationship between seed size and disperser size (p < 0.001 for both 95th and 5th quantiles). The slope and significance of the relationship between body weight and ingested seed size varied between animal groups, presumably because of their diversified foraging behaviours, movement modes and digestive characteristics. Both reptiles and birds showed a significantly positive relationship, whereas mammals showed the opposite, indicating that absence of some dispersers differentially affected seed dispersal of large- and small-seeded species. In conclusion, the upper-bound size of ingested seed was positively correlated with the disperser’s body weight. Our broad-scaled study confirmed that the size of ingested seeds depended on the body size and taxonomic group of the animal feeding on it, and indicated that elimination of large-bodied animals by hunting or habitat loss might impose restrictions on the regeneration of large-seeded plants.
Si-Chong Chen is a PhD student in A/Prof Angela Moles’ group, UNSW. She is interested in plant-animal interaction, ecological network, and species distribution.
Nixie Boddy - University of Canterbury
Interacting global change drivers limit the distribution of a thermally-sensitive freshwater fish
Boddy, Nixie C. M.1; Godsoe, William K. W.1; & McIntosh, Angus R.1
1University of Canterbury
Interacting global change drivers such as invasive species, climate warming and altered disturbance regimes are likely to have major and potentially unexpected influences, especially on aquatic ecosystems. Modified water temperature and disturbance regimes will likely cause shifts in the amount and distribution of suitable habitat, and influential invasive species may alter habitat availability, thus affecting sensitive species’ fundamental and realised niche size. I examined how distributions of a thermally-sensitive freshwater fish, Galaxias paucispondylus, were influenced by interacting global change drivers, and the likely consequences for future distributions. G. paucispondylus were limited to streams with average summer water temperatures between 11 ºC and 14 ºC, and were absent when substrate sizes were < 36 mm, regardless of temperature. Additionally, invasive trout > 150 mm long excluded G. paucispondylus. These interacting factors are likely to be particularly influential in the future. When predicted temperature increases were applied to catchments’ distribution models, results were highly spatially variable and depended on the extent of the temperature increase. The configuration and characteristics of local habitat networks were particularly influential because they constrained distribution responses and determined the outcome of species interactions.
Nixie Boddy is a BSc Honours student at the University of Canterbury, researching large-scale spatial and temporal patterns in fluvial environments and how they can influence species distributions.
Society for Conservation Biology Award:
Patrick Garvey – University of Auckland
Behavioural responses of stoats to the presence of a dominant competitor
Garvey, Patrick1; Pech, Roger2; Glen, Al2; Clout, Mick1
1 School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
2 Landcare Research, PO Box 69040, Lincoln 7640, New Zealand.
Interference competition between predators strongly influences the structure and composition of ecological communities. These interactions are usually asymmetrical as larger predators dominate in aggressive encounters. Smaller predators are therefore forced to balance the conflicting demands of obtaining food while reducing the risk of a confrontation.
We tested the behavioural responses of 16 wild captured stoats (Mustela erminea) to the presence of two larger predators, the feral cat (Felis catus) and the ferret (Mustela furo). Stoats were individually released into an outdoor arena and nocturnal activities were recorded on infra-red video cameras. On treatment nights, one of the larger predators was placed inside a segregated holding cage within the arena, while a control cage was placed in the other peripheral pen. A stoats’ daily food allocation was divided into two equal portions, one placed in front of each holding cage to form a food “patch”. A stoats’ perception of risk was assessed by comparing behaviour at the high-risk versus the low-risk areas.
We found that stoats harvested significantly less food, increased levels of vigilance and avoided the area containing the larger predators both spatially and temporally. The results show that stoats alter their foraging behaviour due to interference competition when they encounter larger predators. Understanding trophic interactions is essential when making conservation decisions where mustelids are invasive species. Pest control directed specifically at feral cats and/or ferrets is likely to alter the behaviour of stoats, potentially leading to increased predation on prey species particularly susceptible to stoats.
Patrick Garvey, PhD Student, I’m interested in ecological interactions between invasive animals, the consequences of removing top predators and the preservation of ecosystem processes
Australian Flora Foundation Prize:
Anthony Manea – Macquarie University
Soil water availability mediates woody plant seedling growth to elevated CO2 in a model grassland system.
Manea, Anthony1; Leishman, Michelle1
The expansion of woody plants into grasslands has been observed worldwide and is a major threat to the integrity of these systems. It has been proposed that the expansion of woody plants into grasslands is linked to the increases in atmospheric CO2 levels that have occurred over the last 200 years. The cover of adult woody plants in grasslands is most limited by seedling establishment. This suggests that rising atmospheric CO2 levels should enhance the establishment success of woody plant seedlings in grasslands. In this study we examined the effect of CO2 concentration on the competitive interactions between C4 grasses and C3 woody plant seedlings by growing C3 woody plant seedlings in mesocosms together with C4 grasses under four competition treatments (no competition, root competition only, shoot competition only and complete competition) under ambient and elevated CO2. We found that woody plant seedling biomass was suppressed by competition from grasses with root and shoot competition having the same competitive effect on the woody plant seedlings. Woody plant seedling biomass in the complete competition treatment was significantly higher under ambient CO2 compared to elevated CO2. This result was due to less competition from the grasses for belowground space and water under ambient CO2. Our results suggest that the establishment success of woody plant seedlings and the subsequent expansion of woody plants into grasslands in the future will likely be strongly coupled to the CO2 response of the grasses within those systems.
Anthony Manea is a PhD candidate in the Plant Invasion and Restoration Ecology Laboratory at Macquarie University. His research interests include grass/woody plant competitive interactions, grassland responses to extreme drought and grassland flammability under elevated CO2.
ESA Marilyn Fox Award:
Kathryn Hand – University of Otago
Finding nature in the city: biodiversity and children’s habitat-use in the urban environment
Hand, Kathryn1; Seddon, Philip1; Freeman, Claire2; Van Heezik, Yolanda1
1Department of Zoology, University of Otago, Dunedin, New Zealand
2Department of Geography, University of Otago, Dunedin, New Zealand
Today nearly half of the world’s children will grow up in the highly modified and artificial urban landscape. For these children urban green spaces provide a residual link to the natural world, preserving opportunities to experience and connect to biodiversity. However, the distribution and quality of urban green space across cities is patchy and increasing parental safety concerns may restrict access to even nearby natural areas. As such many urban children may be in danger of growing up in isolation from nature and the developmental and well-being benefits it affords. Here we seek to answer whether this is occurring in New Zealand’s cities by combining methods from social and ecological fields to describe children’s home ranges and habitat selection preferences. Children’s most visited places will be identified by children themselves during interviews on their time spent outdoors. This information will be used to estimate home range areas and available biodiversity will be estimated within these areas using data collected on flora and fauna richness across urban habitats. We will then test whether children seek out the more biodiverse areas that are available to them using resource selection functions. This presentation will report on the results of these analyses from over 100 children living in New Zealand’s two major urban centres, Auckland and Wellington. This novel approach combining wildlife methodology to children’s geography will provide insights for urban planning and management of urban green spaces, as well as answering whether children are still able to experience nature in the city.
Kathryn Hand is currently a Master’s candidate at the University of Otago. Current research interests include urban ecology and conservation, wildlife habitat-use and environmental psychology.
Claire Wainwright – University of Queensland
Positive interactions in a novel annual plant community
Wainwright, Claire1; Hobbs, Richard2; Buckley, Yvonne1; Dwyer, John1; Mayfield, Margaret M1
1The Ecology Centre, The University of Queensland, Brisbane, Queensland 4072, Australia
2 Ecosystem Restoration & Intervention Ecology Group, The University of Western Australia, Crawley, Western Australia 6009, Australia
Species introductions often lead to novel species associations and interactions, which in turn affect local community structure in recipient ecosystems. An important goal in modern ecology is to quantify how these novel communities function differently from those they are replacing. Despite widespread acknowledgment that novel communities will become increasingly common under global change, empirical evaluations are still needed to understand their ecological significance.
Using a guild of common annual plants found in a fragmented woodland ecosystem in Western Australia, we explored biotic interactions in native and novel communities containing both native and introduced annuals. We evaluated (by comparing biomass yields) complementarity and selection effects, two components encapsulating patterns of productivity and functioning in multispecies assemblages, and how these components differed between community types.
Both native and novel assemblages tended to overyield due to a combination of positive complementarity and selection effects. Positive complementarity values revealed that species’ average yields in mixture were greater than in monoculture, indicative of positive interactions or niche partitioning. Positive selection arose because particular species contributed more to community biomass than predicted by their relative abundance alone, a trend driven by consistent overyielding of a native forb, Waitzia acuminata, in multispecies assemblages. Surprisingly, both complementarity and selection effects were more positive in novel assemblages than in native assemblages, and appear to be due to the presence of a diminutive exotic annual grass, Aira caryophyllea.
Claire Wainwright is a PhD student working jointly at The Ecology Centre (UQ) and Ecosystem Restoration and Intervention Ecology Group (UWA). She is interested in native plant conservation and the potential for community assembly theory to inform management and restoration.
Poster Presentation Winners:
Paul Battersby – University of Auckland
Relating serotiny in Leptospermum scoparium to known fire histories in New Zealand.
Battersby, Paul1; Perry George1; Wilmshurst, Janet2; McGlone, Matt2; Curran, Tim3
1School of Environment, University of Auckland, Private Bag 92019 Auckland, New Zealand
2Landcare Research, P.O Box 69, Lincoln 8152, New Zealand
3Department of Ecology, P.O Box 84, Lincoln University, Canterbury 7647, New Zealand
Globally, fire is an important driver of ecological processes. However, across most of the Holocene fire activity in New Zealand was extremely low, although charcoal records suggest increased fire frequencies in the last 3000 years. Irrespective, human arrival approximately 750 years BP radically altered the natural fire regime, reducing return times to approximately 7-14 years. Mānuka (Leptospermum scoparium) is one of the few members of the New Zealand flora to show fire adaptations, most notable serotiny, defined as retention of seeds in the canopy over consecutive seasons. Previous studies have investigated geographical variation in serotiny in mānuka as an indicator of past fire regimes, but they have not incorporated known fire histories from palaeocharcoal records. Serotiny was assessed at thirty sites throughout NZ after being placed into four categories of fire exposure; long (10 000BP-700), medium (700-300BP), late (300BP-present) and no fire. Environmental characteristics (i.e. vegetation cover, altitude) were recorded for each site. Mānuka is weakly serotinous with a bimodal distribution of closed capsules between and within populations and weakening as latitude increases. While we found an association between serotiny and fire history, environmental factors such as altitude are more important in driving serotiny in Mānuka in New Zealand.
Paul Battersby is an MSc student in the School of Environment at The University of Auckland, supervised by Associate Professor George Perry. Research interests include plant ecology, aquatic ecology and restoration ecology.
Jennifer Dent – Lincoln University
The influence of dead material on flammability in common gorse (Ulex europaeus)
Dent, Jennifer1; Buckley, Hannah1; Curran, Timothy1
1 Department of Ecology, PO Box 84, Lincoln University, Canterbury, New Zealand
Fire is an important disturbance event in many ecosystems worldwide. A key determinant of local fire behaviour is the flammability of constituent plants. One species known to be very flammable due to an accumulation of dead biomass is common gorse (Ulex europaeus), which is an invasive weed in many countries. The aim of this study was to experimentally quantify the nature of this relationship between dead fuel accumulation and flammability. Shoots of Ulex europaeus with varying proportions of dead material were ignited in a purpose-built plant-burner. Samples were assessed in terms of three components of flammability: sustainability (flame duration), consumability (proportion burnt biomass) and combustibility (maximum temperature). While sustainability and consumability had a positive linear relationship with the proportion of dead material, the combustibility response was positive but non-linear. All three flammability components were reduced to a single variable using principal components analysis; the relationship between this and the proportion of dead material was also shown to be non-linear. The response of combustibility and overall flammability to dead material plateaued at 65%. These findings have important implications for the management of habitats invaded by gorse; in order to mitigate fire risk associated with gorse, stands should be kept at a relatively young age.
Jennifer Dent is an Honours student at Lincoln University and is interested in plant physiology and animal behaviour. This research was conducted as part of a research placement course in late 2012.
James Brock – University of Auckland
Investigating the role of tree ferns in forest succession
School of Biological Sciences, University of Auckland, Auckland, New Zealand
New Zealand’s forests are fragmented, and losses to indigenous vegetation cover are ongoing. These fragments are experiencing plant diversity loss, in part due to the failure of species to successfully establish, and the long-term viability of these ecological islands is decreasing. Effective stewardship and positive management of degraded habitat, along with biodiversity restoration, mitigation and habitat creation projects, requires an understanding of the process of succession and the ecosystem engineers that influence this process. Therefore, identifying ecosystem engineers and understanding their mechanisms of action are critical steps in our ability to restore biodiversity and recreate natural communities. In New Zealand natural forests, tree ferns are a common component of the understory and early successional habitats yet little is known of their roles in influencing overstorey composition, density, basal area, productivity and overall species diversity. In particular the role of tree ferns in succession and regeneration has not been examined as a function of the forest communities. Given the age and ubiquitousness of this group of species, it is considered likely that they will function as foundation species within forest communities.
The poster presentation will outline my initial PhD research examining the ecology of New Zealand tree ferns; the focus of the research is the functional role of these species in secondary succession within native forest. The presentation will highlight the research to date which will include: macro-scale assessment of tree fern distribution and habitat/species associations; gametophyte establishment conditions, and field studies of a chronosequence of sites dominated by Cyathea medullaris.
James Brock, PhD Candidate at the University of Auckland: My research interests are epiphytes of tree ferns, successional trends within forests, and restoration ecology and conservation management. I also have strong interests in habitat creation, biodiversity offsetting and sustainable development.
Australia Flora Foundation Prize:
Ruth Mallett – University of Tasmania
Density and assemblage influences on the species richness-productivity relationship in Australian dry sclerophyll species
Mallett, Ruth1; Hovenden, Mark1
1University of Tasmania
At any given site, a more species-rich community is thought to be more productive than a species-poor community, although this understanding comes largely from grasslands. We aimed to determine the nature of the species richness-productivity relationship in a southern-hemisphere sclerophyll forest system given its importance from a basic, theoretical perspective as well as for applied ecology. Using three levels of sowing density and three different species assemblages, the impacts of these variables on productivity, plant density and plant biomass were investigated. In each assemblage a different dominant tree species from local forest was grown as a monoculture and included in every subsequent level of species richness. Communities were grown in a glasshouse pot experiment for four months, harvested and above-ground biomass measured. We found no general species richness-productivity relationship in the early-stage communities studied. There were no overall increases in productivity as species richness increased; in most cases the productivity of communities with 4 and 8 species was lower than monocultures of the dominants. 15 species mixtures were equal to or exceeded the biomass of monocultures, primarily due to the addition of another highly productive species. Density influenced the way richness affected productivity and this effect was dependent upon assemblage, indicating species identity is a key determinant of productivity. These results demonstrate important ecological principles in a novel system, regarding the impact a factor such as density has on the species richness-productivity relationship, suggesting the generally believed relationship between richness and productivity may not exist universally in terrestrial plant ecosystems.
Ruth Mallett is in her first year as a research assistant in the school of Plant Science at the University of Tasmania. Research interests include community ecological processes and the importance of biodiversity in the context of changing climates.
Mark Hamilton – Lincoln University
Powelliphanta land snails ‐ assessing the accuracy of the standard monitoring method
Hamilton, Mark1, 2
2 MBC Contracting Ltd
There are currently no proven techniques for monitoring populations of land snails in the genus Powelliphanta. The Department of Conservation has developed a method for establishing an index of abundance. Although this method is routinely used, its reliability remains unclear. Many Powelliphanta species and sub-species are currently listed as threatened. Improving estimates of population trends and assessing the effectiveness of conservation management is therefore critical. The main aim of this research is to improve the techniques used for assessing and monitoring populations of these animals. The study is split in to three main parts: an assessment of the current monitoring technique, a description of a newly developed mark-recapture technique, and an analysis of the ancillary data that can be collected when utilising a mark-recapture method, which may provide vital information to conservation managers. This poster presentation relates to part one of the study: an assessment of the current monitoring technique.
Mark Hamilton, postgraduate student at Lincoln University and General Manager at MBC, an environmental services contractor of approximately 50 staff. Main area of interest is the management of flora & fauna, particularly in the mining sector. Particular interests include the management of Powelliphanta land snails, with specific reference to survey and monitoring techniques and translocations.