title: Changes in social security eligibility and the international mobility of New Zealand citizens in Australia

authors: Poot, Jacques

subjects: international migration

abstract: This paper is concerned with the international mobility of New Zealanders who migrate to Australia. One in ten New Zealand citizens lives in Australia and their settlement and subsequent mobility is important from demographic, socio-economic and policy perspectives in both countries. Using a unique longitudinal dataset on New Zealand citizens arriving for a stay of 12 months or longer between 1 August 1999 and 31 July 2002, we track all subsequent moves of these migrants out of and back into Australia, up to July 2005. This allows us to assess the impact of the removal of labour market-related social security eligibility and some other policy changes affecting New Zealand migrants to Australia, implemented between February and June 2001. United Kingdom migrants to Australia, who were not affected by the policy changes, provide a ‘control group’.

Using hazard models, we find that the policy changes increased the probability of remigration from Australia among those who had intended to settle permanently. Competing risk models suggested no difference between the impact of the policy changes on onward or return moves. Settlers arriving after the policy changes spend less time Australia and make more trips away than earlier migrants.

text: Changes in social security eligibility and the international mobility of New Zealand citizens in Australia This paper is concerned with the international mobility of New Zealanders who migrate to Australia. One in ten New Zealand citizens lives in Australia and their settlement and subsequent mobility is important from demographic, socio-economic and policy perspectives in both countries. Using a unique longitudinal dataset on New Zealand citizens arriving for a stay of 12 months or longer between 1 August 1999 and 31 July 2002, we track all subsequent moves of these migrants out of and back into Australia, up to July 2005. This allows us to assess the impact of the removal of labour market-related social security eligibility and some other policy changes affecting New Zealand migrants to Australia, implemented between February and June 2001. United Kingdom migrants to Australia, who were not affected by the policy changes, provide a ‘control group’.

Using hazard models, we find that the policy changes increased the probability of remigration from Australia among those who had intended to settle permanently. Competing risk models suggested no difference between the impact of the policy changes on onward or return moves. Settlers arriving after the policy changes spend less time Australia and make more trips away than earlier migrants.

year: 2007-06

title: Functional trait variation along a hydrological gradient and trait-based predictions of the composition of a wetland plant community

authors: Purcell, Adam

subjects: functional trait

abstract: Predicting the assembly of plant communities is considered the Holy Grail of functional ecology and has never been more important as we head into an era of environmental change. Studying plant functional traits provides the best opportunity for understanding the community assembly processes that determine the abundance and distribution of plant species. Plant functional traits provide information on the direct physiological adaptations of plants to various environmental conditions. The assembly of plant communities is driven by filtering processes that select for or against certain functional traits and a plant can only be present within a community if it contains the functional traits necessary to germinate, survive and compete in the environment of the community. An understanding of how functional traits are filtered by the environment and biotic interactions provides the foundations for predictive community assembly models. However, the understanding of how functional traits are filtered along hydrological gradients is poor for the majority of functional traits. 
In this thesis I aimed to identify how plant functional traits respond to variation in soil hydrology in the presence and absence of grazing and determine whether a trait-based model of environmental filtering could predict the composition of an ephemeral wetland plant community. To achieve these aims, I performed a survey of the plant community in an ephemeral wetland in grazed and ungrazed transects. The survey was conducted along a hydrological gradient that was split into an elevation gradient above the flood line and a flooding gradient below the flood line. I measured nine root, leaf and shoot traits on 885 plant samples collected during the community survey and investigated the response of community-weighted and individual-level traits along the hydrological gradient using Generalized Additive Models (GAMs) and Generalized Linear Models (GLMs). To determine whether a trait-based model of environmental filtering could predict the composition of the plant community, I incorporated the individual-level trait relationships into a community assembly model known as Traitspace and predicted the relative abundance of the 23 most common species found within the Kettlehole.
Community-weighted root traits were more strongly related to the hydrological gradient than aboveground traits. Root aerenchyma increased as the number of days submerged increased while root dry matter content (RDMC), specific root length (SRL), root tissue density (RTD) and root branching intensity (RBI) decreased with increasing flooding. Community-weighted specific leaf area (SLA) and root tissue density were more closely related to the elevation gradient than any other traits. SLA decreased as elevation above the flood line increased while RTD increased with elevation. The relationships between individual-level traits and the elevation and flooding gradients were far weaker than community-weighted traits but showed similar trends in the directions of trait responses along the gradients. Grazing reduced the community-weighted trait values of all traits except SLA and aboveground dry matter content (AGDMC) along the flooding gradient and had little effect on the trait values observed along the elevation gradient.
Using environmental filtering of functional traits, the Traitspace model was able to predict the distribution and abundance of a number of key species within the wetland plant community but was unable to accurately predict the abundance and distribution of other species. The accuracy of the Traitspace model was best when all nine functional traits were used to produce predictions of species abundances but SLA and height were recognised as the two traits to provide the most predictive ability.
The strong filtering of root traits illustrate the important information that root traits provide in terms of the adaptations of plants in environments with varied soil hydrology. Easily measurable aboveground traits are often favoured in functional ecology but these results highlight the importance of measuring root traits in trait-based research. Traitspace has the ability to predict the abundance and distribution of some species within a wetland plant community using environmental filtering of functional traits. Community assembly at small spatial scales is mostly driven by biotic interactions rather than environmental filtering which may limit the power of current predictive models. The inclusion of biotic interactions into trait-based models will improve the predictions of community composition at small spatial scales in wetland ecosystems and help us to progress towards achieving the goal of accurately predicting the composition of plant communities.

text: Functional trait variation along a hydrological gradient and trait-based predictions of the composition of a wetland plant community Predicting the assembly of plant communities is considered the Holy Grail of functional ecology and has never been more important as we head into an era of environmental change. Studying plant functional traits provides the best opportunity for understanding the community assembly processes that determine the abundance and distribution of plant species. Plant functional traits provide information on the direct physiological adaptations of plants to various environmental conditions. The assembly of plant communities is driven by filtering processes that select for or against certain functional traits and a plant can only be present within a community if it contains the functional traits necessary to germinate, survive and compete in the environment of the community. An understanding of how functional traits are filtered by the environment and biotic interactions provides the foundations for predictive community assembly models. However, the understanding of how functional traits are filtered along hydrological gradients is poor for the majority of functional traits. 
In this thesis I aimed to identify how plant functional traits respond to variation in soil hydrology in the presence and absence of grazing and determine whether a trait-based model of environmental filtering could predict the composition of an ephemeral wetland plant community. To achieve these aims, I performed a survey of the plant community in an ephemeral wetland in grazed and ungrazed transects. The survey was conducted along a hydrological gradient that was split into an elevation gradient above the flood line and a flooding gradient below the flood line. I measured nine root, leaf and shoot traits on 885 plant samples collected during the community survey and investigated the response of community-weighted and individual-level traits along the hydrological gradient using Generalized Additive Models (GAMs) and Generalized Linear Models (GLMs). To determine whether a trait-based model of environmental filtering could predict the composition of the plant community, I incorporated the individual-level trait relationships into a community assembly model known as Traitspace and predicted the relative abundance of the 23 most common species found within the Kettlehole.
Community-weighted root traits were more strongly related to the hydrological gradient than aboveground traits. Root aerenchyma increased as the number of days submerged increased while root dry matter content (RDMC), specific root length (SRL), root tissue density (RTD) and root branching intensity (RBI) decreased with increasing flooding. Community-weighted specific leaf area (SLA) and root tissue density were more closely related to the elevation gradient than any other traits. SLA decreased as elevation above the flood line increased while RTD increased with elevation. The relationships between individual-level traits and the elevation and flooding gradients were far weaker than community-weighted traits but showed similar trends in the directions of trait responses along the gradients. Grazing reduced the community-weighted trait values of all traits except SLA and aboveground dry matter content (AGDMC) along the flooding gradient and had little effect on the trait values observed along the elevation gradient.
Using environmental filtering of functional traits, the Traitspace model was able to predict the distribution and abundance of a number of key species within the wetland plant community but was unable to accurately predict the abundance and distribution of other species. The accuracy of the Traitspace model was best when all nine functional traits were used to produce predictions of species abundances but SLA and height were recognised as the two traits to provide the most predictive ability.
The strong filtering of root traits illustrate the important information that root traits provide in terms of the adaptations of plants in environments with varied soil hydrology. Easily measurable aboveground traits are often favoured in functional ecology but these results highlight the importance of measuring root traits in trait-based research. Traitspace has the ability to predict the abundance and distribution of some species within a wetland plant community using environmental filtering of functional traits. Community assembly at small spatial scales is mostly driven by biotic interactions rather than environmental filtering which may limit the power of current predictive models. The inclusion of biotic interactions into trait-based models will improve the predictions of community composition at small spatial scales in wetland ecosystems and help us to progress towards achieving the goal of accurately predicting the composition of plant communities.

year: 2016

title: Māori and Pacific language data in linguistics classes

authors: Barbour, Julie Renee

abstract: Māori and Pacific language data rarely appears in introductory linguistic text books. In a discipline with a dearth of Māori and Pacific scholars, there is an opportunity to reflect on our teaching materials and consider ways in which we can make our classes more inclusive spaces. In this presentation, we share some of the materials and associated activities that we incorporate into undergraduate linguistics classes, in an effort to make our disciplinary content more attractive to students who join our classes with a variety of heritage languages.

text: Māori and Pacific language data in linguistics classes Māori and Pacific language data rarely appears in introductory linguistic text books. In a discipline with a dearth of Māori and Pacific scholars, there is an opportunity to reflect on our teaching materials and consider ways in which we can make our classes more inclusive spaces. In this presentation, we share some of the materials and associated activities that we incorporate into undergraduate linguistics classes, in an effort to make our disciplinary content more attractive to students who join our classes with a variety of heritage languages.

year: 2023