title: Enrichment planting of late-successional plant species within restored urban forests

authors: Hall, Monique

subjects: Urban ecology

abstract: Successful ecological restoration of early-successional forests should result in highly biodiverse, stable, self-perpetuating ecosystems. This often requires active intervention to transition them to a late-successional state. However, little research has explored specific conditions required for introducing late-successional plant species into urban forests undergoing restoration, especially for different plant functional guilds. This research gap is addressed in this thesis by exploring restored urban forest development with a focus on identifying optimal environmental conditions for re-introducing juveniles of three late-successional species from different functional guilds in Aotearoa New Zealand. Late-successional plant species can have narrow microclimate tolerances and these conditions, e.g., humidity and air temperature, may only be present at certain stages of forest development.
To explore these microclimatic tolerances, three model enrichment plant species were planted and monitored for survival and growth, while recording key abiotic environmental conditions, these included: an epiphyte (Griselinia lucida, akapuka), an understorey shrub (Piper excelsum, kawakawa) and a large canopy tree (Dacrydium cupressinum, rimu). Plants were introduced into 27 forest patches in three North Island cities (Hamilton, New Plymouth and Napier) spanning a chronosequence of 5–47 years since initial forest restoration planting began. This chronosequence design allowed observation of enrichment species’ responses under differing stages of forest development. Linear regression models were used to see how canopy openness, air and soil temperature, relative humidity and non-native herbaceous weed cover within the restored urban forest sites affected the growth and survival of the three model enrichment plant species.
After one year, juvenile enrichment plant survival was 75.5% (G. lucida), 100% (P. excelsum), and 75% (D. cupressinum). As forests developed, the canopies closed, buffering the understorey from the external macroclimate to create a microclimate below. When the forest canopy reached 10.88 years old, there was a significant threshold where canopy closure rates slowed, markedly restricting light reaching the forest floor. Relative humidity fluctuations in the understorey stabilised at 33.86 years of forest age, when the canopy was about 80% closed.
The late-successional plant species from different functional guilds responded differently to changing understorey environmental conditions, driven by the developing forest canopy.
Griselinia lucida growth increased under more open canopies, suggesting a primary dependence on light availability. In contrast, P. excelsum growth increased under more closed canopies with higher relative humidity. Dacrydium cupressinum showed alternate biomass allocation responses to different understorey conditions. Under cooler and wider fluctuations in air temperature, plants were shorter with wider stems. However, under stable, warmer air temperatures, plants grew taller with narrower stems. Further, D. cupressinum growth seemed somewhat uncoupled from canopy cover and responded instead to competition with forest floor plants like non-native herbaceous weeds.
This thesis broadens understanding of enrichment planting approaches for late-successional plant species in forests undergoing restoration. During restoration planning, the requirements of plants’ functional guilds should be considered. Re-introduction of G. lucida should be higher within the canopies of older, taller forests. Piper excelsum should be planted under closed canopies. Dacrydium cupressinum juveniles should be planted within warm, stable temperatures with little non-native plant competition. These conditions generally occur ~10+ years following initial forest restoration planting. These research results highlight the importance of considering timing and thresholds in forest development and the environmental constraints of different plant guilds to ensure successful, biodiverse and long-lived urban forest restoration.

text: Enrichment planting of late-successional plant species within restored urban forests Successful ecological restoration of early-successional forests should result in highly biodiverse, stable, self-perpetuating ecosystems. This often requires active intervention to transition them to a late-successional state. However, little research has explored specific conditions required for introducing late-successional plant species into urban forests undergoing restoration, especially for different plant functional guilds. This research gap is addressed in this thesis by exploring restored urban forest development with a focus on identifying optimal environmental conditions for re-introducing juveniles of three late-successional species from different functional guilds in Aotearoa New Zealand. Late-successional plant species can have narrow microclimate tolerances and these conditions, e.g., humidity and air temperature, may only be present at certain stages of forest development.
To explore these microclimatic tolerances, three model enrichment plant species were planted and monitored for survival and growth, while recording key abiotic environmental conditions, these included: an epiphyte (Griselinia lucida, akapuka), an understorey shrub (Piper excelsum, kawakawa) and a large canopy tree (Dacrydium cupressinum, rimu). Plants were introduced into 27 forest patches in three North Island cities (Hamilton, New Plymouth and Napier) spanning a chronosequence of 5–47 years since initial forest restoration planting began. This chronosequence design allowed observation of enrichment species’ responses under differing stages of forest development. Linear regression models were used to see how canopy openness, air and soil temperature, relative humidity and non-native herbaceous weed cover within the restored urban forest sites affected the growth and survival of the three model enrichment plant species.
After one year, juvenile enrichment plant survival was 75.5% (G. lucida), 100% (P. excelsum), and 75% (D. cupressinum). As forests developed, the canopies closed, buffering the understorey from the external macroclimate to create a microclimate below. When the forest canopy reached 10.88 years old, there was a significant threshold where canopy closure rates slowed, markedly restricting light reaching the forest floor. Relative humidity fluctuations in the understorey stabilised at 33.86 years of forest age, when the canopy was about 80% closed.
The late-successional plant species from different functional guilds responded differently to changing understorey environmental conditions, driven by the developing forest canopy.
Griselinia lucida growth increased under more open canopies, suggesting a primary dependence on light availability. In contrast, P. excelsum growth increased under more closed canopies with higher relative humidity. Dacrydium cupressinum showed alternate biomass allocation responses to different understorey conditions. Under cooler and wider fluctuations in air temperature, plants were shorter with wider stems. However, under stable, warmer air temperatures, plants grew taller with narrower stems. Further, D. cupressinum growth seemed somewhat uncoupled from canopy cover and responded instead to competition with forest floor plants like non-native herbaceous weeds.
This thesis broadens understanding of enrichment planting approaches for late-successional plant species in forests undergoing restoration. During restoration planning, the requirements of plants’ functional guilds should be considered. Re-introduction of G. lucida should be higher within the canopies of older, taller forests. Piper excelsum should be planted under closed canopies. Dacrydium cupressinum juveniles should be planted within warm, stable temperatures with little non-native plant competition. These conditions generally occur ~10+ years following initial forest restoration planting. These research results highlight the importance of considering timing and thresholds in forest development and the environmental constraints of different plant guilds to ensure successful, biodiverse and long-lived urban forest restoration.

year: 2020

title: Fabrication of TiAl target by mechanical alloying and applications in physical vapour deposition coating

authors: Gabbitas, Brian

subjects: mechanical alloying

abstract: The research involves the development of a powder metallurgical route for producing good quality TiAl targets for making physical vapour deposition (PVD) coatings. Mixtures of elemental titanium and aluminium powders were mechanically milled using a novel discus milling technique under various conditions. Hot isostatic pressing (HIP) was then employed for consolidation of the mechanically alloyed powders. A cathodic arc vapour deposition process was applied to produce a TiAIN coating. A microstructural examination was conducted on the target material and PVD coatings, using X-ray diffractometry (XRD), X-ray photoelectron spectrometry (XPS) and scanning electron microscopy (SEM). It has been found that combining mechanical alloying and HIP enable us to produce a fairly good quality of TiAl based target. The PVD coatings obtained from the TiAl target showed very high microhardness values.

text: Fabrication of TiAl target by mechanical alloying and applications in physical vapour deposition coating The research involves the development of a powder metallurgical route for producing good quality TiAl targets for making physical vapour deposition (PVD) coatings. Mixtures of elemental titanium and aluminium powders were mechanically milled using a novel discus milling technique under various conditions. Hot isostatic pressing (HIP) was then employed for consolidation of the mechanically alloyed powders. A cathodic arc vapour deposition process was applied to produce a TiAIN coating. A microstructural examination was conducted on the target material and PVD coatings, using X-ray diffractometry (XRD), X-ray photoelectron spectrometry (XPS) and scanning electron microscopy (SEM). It has been found that combining mechanical alloying and HIP enable us to produce a fairly good quality of TiAl based target. The PVD coatings obtained from the TiAl target showed very high microhardness values.

year: 2007

title: Examining Culturally Responsive Leadership: An investigation into how one school leader, in a primary school setting, provides culturally responsive leadership that ensures Maori students achieve

authors: Ford, Therese

subjects: Culture

abstract: Addressing the achievement disparities that exist within New Zealand education between Maori and non-Maori is a major government priority and is identified by the Ministry of Education as being a critical challenge for school leadership (Ministry of Education, 2008a). Therefore, an important question for school leaders to contemplate is: How do we raise Maori student achievement and eliminate the ‘gap’, or more specifically, what are the teaching and leadership practices that will make a difference? The research project presented in this thesis examines how one school leader, in a mainstream primary school setting, provides culturally responsive leadership practice that ensures Maori students achieve. This case study was conducted within a kaupapa Maori theoretical framework and used a mixed methods approach that incorporated the triangulation of quantitative and qualitative data. Quantitative data included student achievement data in reading, while qualitative data collection and analysis included school documents, participant observations of the principal, a series of semi-structured interviews and a stimulated recall interview with the principal and focus group interviews with the school leadership team and a group of teachers. The literature reviewed highlighted the centrality of culture in education, the implications for relationships and interactions between teachers and students that are born out of cultural deficit theorising and the potential culturally responsive teaching practices hold for students from minority groups. It also identified a series of effective leadership practices that enable school leaders to influence classroom teaching and have a subsequent impact on student outcomes. The case study school reflects a mainstream primary school context where the majority of Maori students are achieving at or above national expectations in reading. The findings indicate that the principal is implementing many of the practices that characterise effective leadership in successful schools. The principal’s leadership practice is guided by her understandings of culturally responsive leadership, which emphasises the importance of developing quality relationships and quality teaching and learning. Consequently, she has focused her leadership practice on three interrelated strategies that reflect this theorising. The strategies include: prioritising the development of relationships with and between school stakeholders, establishing systems and structures to support the development of relationships and creating a school culture of learning where teachers reject deficit theorising, accept ownership for the performance of students, implement culturally responsive teaching practices and are critically reflective about their practice. This study suggests that further research examining culturally responsive leadership in mainstream education is needed to provide a more comprehensive profile of a culturally responsive leader in the New Zealand context. However, this report does provide an interesting point for reflection and discussion amongst school leaders who want to raise Maori student achievement and reduce disparities.

text: Examining Culturally Responsive Leadership: An investigation into how one school leader, in a primary school setting, provides culturally responsive leadership that ensures Maori students achieve Addressing the achievement disparities that exist within New Zealand education between Maori and non-Maori is a major government priority and is identified by the Ministry of Education as being a critical challenge for school leadership (Ministry of Education, 2008a). Therefore, an important question for school leaders to contemplate is: How do we raise Maori student achievement and eliminate the ‘gap’, or more specifically, what are the teaching and leadership practices that will make a difference? The research project presented in this thesis examines how one school leader, in a mainstream primary school setting, provides culturally responsive leadership practice that ensures Maori students achieve. This case study was conducted within a kaupapa Maori theoretical framework and used a mixed methods approach that incorporated the triangulation of quantitative and qualitative data. Quantitative data included student achievement data in reading, while qualitative data collection and analysis included school documents, participant observations of the principal, a series of semi-structured interviews and a stimulated recall interview with the principal and focus group interviews with the school leadership team and a group of teachers. The literature reviewed highlighted the centrality of culture in education, the implications for relationships and interactions between teachers and students that are born out of cultural deficit theorising and the potential culturally responsive teaching practices hold for students from minority groups. It also identified a series of effective leadership practices that enable school leaders to influence classroom teaching and have a subsequent impact on student outcomes. The case study school reflects a mainstream primary school context where the majority of Maori students are achieving at or above national expectations in reading. The findings indicate that the principal is implementing many of the practices that characterise effective leadership in successful schools. The principal’s leadership practice is guided by her understandings of culturally responsive leadership, which emphasises the importance of developing quality relationships and quality teaching and learning. Consequently, she has focused her leadership practice on three interrelated strategies that reflect this theorising. The strategies include: prioritising the development of relationships with and between school stakeholders, establishing systems and structures to support the development of relationships and creating a school culture of learning where teachers reject deficit theorising, accept ownership for the performance of students, implement culturally responsive teaching practices and are critically reflective about their practice. This study suggests that further research examining culturally responsive leadership in mainstream education is needed to provide a more comprehensive profile of a culturally responsive leader in the New Zealand context. However, this report does provide an interesting point for reflection and discussion amongst school leaders who want to raise Maori student achievement and reduce disparities.

year: 2010