title: Plant traits and their role in determining forest community structure along a soil fertility gradient

authors: Jager, Melissa Maria

subjects: Puketī Forest

abstract: Previous studies have shown that changes in community composition in mature kauri forests are driven by topographical gradients. The extent to which functional traits influence the patterns detected in these forests has not been well-studied. The overall objective of this thesis was to enhance our understanding of what drives community assembly in these forests by testing the importance of functional traits in mediating the relationship between environmental factors and community composition.
 
Puketī Forest (Northland, New Zealand) was selected as the study site because rapid turnover of species composition occurs over very strong topographic and edaphic gradients. Community composition was determined using forty permanent 400 m² plots that spanned the full gradient in soil properties and topographic variation. Leaf, height and wood traits were measured in thirty of these plots on three individuals (> 10 cm dbh) for each species on each plot. A total of 30 species were studied; the criteria for a species to be included was that the species had to attain a relative abundance of at least 0.05 within a single plot and occur on at least 10 percent of the forty plots sampled. Fully-expanded, mature, healthy, well-lit leaves were collected from the canopy using a pole pruner, shotgun or slingshot. Cores were collected using an increment borer. The relationships between community-weighted mean traits and environmental gradients were analysed using linear regression.

Results showed that there is a continuous compositional change along this environmental gradient and consequently there are few visually abrupt changes that occur between forest types. The exception to this is the kauri-dominated stands that are found in low fertility environments that are present on ridges. Soil variables and topography were found to be correlated, and the environmental variables that explain the majority of the variation in the community composition and functional trait data were soil carbon: nitrogen ratio, total soil phosphorus and soil pH, rather than topography. 

Trait – environment regressions showed that traits are filtered along the soil fertility gradient. Species that have high SLA, high leaf and litter nitrogen, low leaf thickness, large seeds and low wood densities were found in the more fertile environments, which have a low soil carbon: nitrogen ratio, high total soil phosphorus and a high pH, such as a gully habitat. At the other end of this gradient, species that have low SLA, low leaf and litter nitrogen, high leaf thickness, small seeds and high wood densities were present in less fertile environments, which have a high soil carbon: nitrogen ratio, low total soil phosphorus and a low pH, such as a ridge top habitat. 

Functional diversity indices indicate that the strength of environmental filtering changes along the soil fertility gradient. These indices show that trait variability does vary along the soil fertility gradient and that there are different community assembly processes operating in different places. The strength of the soil fertility as an environmental filter is strongest in low fertility soils, as environmental filtering results in convergence towards traits that confer a resource-retaining strategy.
Previous studies in kauri forests have shown changes in community composition to be determined by topography. This study has shown that these well-known patterns are driven by the filtering of leaf and wood traits along the topographically-driven soil fertility gradient.

text: Plant traits and their role in determining forest community structure along a soil fertility gradient Previous studies have shown that changes in community composition in mature kauri forests are driven by topographical gradients. The extent to which functional traits influence the patterns detected in these forests has not been well-studied. The overall objective of this thesis was to enhance our understanding of what drives community assembly in these forests by testing the importance of functional traits in mediating the relationship between environmental factors and community composition.
 
Puketī Forest (Northland, New Zealand) was selected as the study site because rapid turnover of species composition occurs over very strong topographic and edaphic gradients. Community composition was determined using forty permanent 400 m² plots that spanned the full gradient in soil properties and topographic variation. Leaf, height and wood traits were measured in thirty of these plots on three individuals (> 10 cm dbh) for each species on each plot. A total of 30 species were studied; the criteria for a species to be included was that the species had to attain a relative abundance of at least 0.05 within a single plot and occur on at least 10 percent of the forty plots sampled. Fully-expanded, mature, healthy, well-lit leaves were collected from the canopy using a pole pruner, shotgun or slingshot. Cores were collected using an increment borer. The relationships between community-weighted mean traits and environmental gradients were analysed using linear regression.

Results showed that there is a continuous compositional change along this environmental gradient and consequently there are few visually abrupt changes that occur between forest types. The exception to this is the kauri-dominated stands that are found in low fertility environments that are present on ridges. Soil variables and topography were found to be correlated, and the environmental variables that explain the majority of the variation in the community composition and functional trait data were soil carbon: nitrogen ratio, total soil phosphorus and soil pH, rather than topography. 

Trait – environment regressions showed that traits are filtered along the soil fertility gradient. Species that have high SLA, high leaf and litter nitrogen, low leaf thickness, large seeds and low wood densities were found in the more fertile environments, which have a low soil carbon: nitrogen ratio, high total soil phosphorus and a high pH, such as a gully habitat. At the other end of this gradient, species that have low SLA, low leaf and litter nitrogen, high leaf thickness, small seeds and high wood densities were present in less fertile environments, which have a high soil carbon: nitrogen ratio, low total soil phosphorus and a low pH, such as a ridge top habitat. 

Functional diversity indices indicate that the strength of environmental filtering changes along the soil fertility gradient. These indices show that trait variability does vary along the soil fertility gradient and that there are different community assembly processes operating in different places. The strength of the soil fertility as an environmental filter is strongest in low fertility soils, as environmental filtering results in convergence towards traits that confer a resource-retaining strategy.
Previous studies in kauri forests have shown changes in community composition to be determined by topography. This study has shown that these well-known patterns are driven by the filtering of leaf and wood traits along the topographically-driven soil fertility gradient.

year: 2014

title: The regional economic impact of the 2009 New Zealand National Masters Hockey Tournament

authors: Daldy, Bridget

subjects: input-output

abstract: This paper analyses the direct and subsequent flow-on expenditure resulting from the weeklong National Masters Hockey Tournament held in Hamilton, New Zealand in March 2009. During the tournament, information was collected on the expenditure from a sample of participating players and officials and from the host association, Waikato Hockey. The information was averaged over all participants and used in a regional economic model. The economic impact of the 2009 tournament was also compared to the outcome for the Hamilton tournament held previously in 2003. Total direct expenditure in the Waikato region from the 2009 tournament was approximately $2.5 million compared to $1.2 million in 2003. The 2009 expenditure led subsequently to an extra $1.13 million of value-added to the regional economy mainly in the hospitality and accommodation sectors.

text: The regional economic impact of the 2009 New Zealand National Masters Hockey Tournament This paper analyses the direct and subsequent flow-on expenditure resulting from the weeklong National Masters Hockey Tournament held in Hamilton, New Zealand in March 2009. During the tournament, information was collected on the expenditure from a sample of participating players and officials and from the host association, Waikato Hockey. The information was averaged over all participants and used in a regional economic model. The economic impact of the 2009 tournament was also compared to the outcome for the Hamilton tournament held previously in 2003. Total direct expenditure in the Waikato region from the 2009 tournament was approximately $2.5 million compared to $1.2 million in 2003. The 2009 expenditure led subsequently to an extra $1.13 million of value-added to the regional economy mainly in the hospitality and accommodation sectors.

year: 2010-11

title: Investigating Māori approaches to trauma informed care

authors: Pihama, Leonie

subjects: Māori health and wellbeing

abstract: This article gives an overview of a three-year Health Research Council funded research project “He Oranga Ngākau: Māori approaches to trauma-informed care”. The study is informed by Kaupapa Māori which provides both the theoretical and methodological foundation for understanding the world, exploring and conceptualising issues. The need for contextualised and culturally safe health and social services is well recognised within Aotearoa and particularly within Mental Health and Addiction Services. While trauma is an experience that can impact on all people, Māori experience trauma in distinct ways that are linked to the experience of colonisation, racism and discrimination, negative stereotyping and subsequent unequal rates of violence, poverty and ill health. Given that Māori are impacted by trauma in specific ways, it is important to explore and identify practice principles that contribute to the development of a framework that supports Māori Providers, counsellors, clinicians and healers in working with Māori. (Authors' abstract).

text: Investigating Māori approaches to trauma informed care This article gives an overview of a three-year Health Research Council funded research project “He Oranga Ngākau: Māori approaches to trauma-informed care”. The study is informed by Kaupapa Māori which provides both the theoretical and methodological foundation for understanding the world, exploring and conceptualising issues. The need for contextualised and culturally safe health and social services is well recognised within Aotearoa and particularly within Mental Health and Addiction Services. While trauma is an experience that can impact on all people, Māori experience trauma in distinct ways that are linked to the experience of colonisation, racism and discrimination, negative stereotyping and subsequent unequal rates of violence, poverty and ill health. Given that Māori are impacted by trauma in specific ways, it is important to explore and identify practice principles that contribute to the development of a framework that supports Māori Providers, counsellors, clinicians and healers in working with Māori. (Authors' abstract).

year: 2017