title: A study of the relationships between climate and stable isotope ratios in tree rings

authors: Grinsted, Martin James

abstract: The main objectives of this work were to find out: 
(a) how the stable isotope ratios in wood constituents such as cellulose and lignin vary with changing climate;
(b) whether such variations can be applied to the study of past climate. 
Initially rings from a New Zealand grown Pinus radiata (Monterey pine) were studied since this is a complacent tree which grows throughout the year and hence over a wide temperature range.
In order to accurately determine the stable isotope ratios in wood components the following techniques were developed:
(a) the preparation of wood constituents on a small scale;
(b) the determination of δD values in waters;
(c) the determination of δD values in plant materials;
(d) the determination of δ¹³C values in plant materials.
Several possible methods for measuring D/H ratios for cellulose are discussed. It was decided to use a technique which involves heating cellulose with a standard water to fix the D/H ratio of the exchangeable hydrogens. Using this method relative δD values have been determined to a precision of ± 0.9°/οο (1 σ). The δ¹³C method was developed so that the ¹³C content of cellulose and lignin samples could be determined to ± 0. 04°/οο (1 σ).
A new procedure for determining δ values from raw mass spectrometer results is outlined. 
δD determinations on cellulose samples from three growth rings in a specimen of Pinus radiata show that the non-exchangeable hydrogens of cellulose are more than 20°/οο depleted in the summer as compared with the winter. These δD values appear to vary with the annual temperature cycle, but in the opposite sense to that expected from thermodynamic considerations. δ¹⁸ο determinations on the same samples show a summer/winter variation of about 2°/οο and in the opposite direction to the summer/winter variation in the δD determinations.
The δD results from Pinus radiata cellulose are compared with δD determinations on cellulose from other trees. 
It is concluded that all the measurements to date suggest that an increase in temperature results in a decrease in the D/H ratio of the non-exchangeable hydrogens in cellulose. The results imply a temperature coefficient of about - 3°/oo per °C, which is opposite to that found for precipitation (+ 5. 6°/oo per °C). This temperature effect will only be useful for past climate studies if δD variations due to meteoric and/or leaf transpiration changes can be corrected for. This may be possible using δ¹⁸o determinations. 
A new model to explain the effects of environmental changes on the magnitude of carbon isotopic fractionation in C₃ plants is presented and discussed. 
δ¹³C determinations on both cellulose and lignin from the same Pinus radiata that was used for the δD determinations show an enrichment of about 2°/oo in summer wood as compared with winter wood. This summer/winter variation is probably mainly due to changes in air temperature affecting the magnitude of carbon isotope fractionation during photosynthesis. The lignin variations are similar, but significantly displaced in time with respect to the cellulose variations. This is probably the result of secondary lignification. 
δ¹³C values for cellulose prepared from individual rings in a sample of dendrochronologically dated Pseudotsuga menziesii (Douglas fir) are compared with meteorological observations during growth. A correlation between the δ¹³C values and mean late spring/early summer temperature is discussed. The temperature coefficient for this correlation is + 0.22°/oo per °C, which is in good agreement with the Pinus radiata results.
Similar determinations on individual rings from Pinus radiata are difficult to interpret in terms of climatic changes because of a relatively large depletion in ¹³C towards the centre of the tree studied. A similar depletion in ¹³C was observed for cellulose prepared from a carbon-14 dated Agathis australis (New Zealand kauri) which grew during the last 1000 years. However, no such “age” effect was observed when δ¹³C values were determined for cellulose samples prepared from two dendrochronologically dated Pinus longaeva (Bristlecone pine) trees which also grew during the last 1000 years. 
The short-term fluctuations in the cellulose δ¹³C curve for Agathis australis are probably temperature related, and therefore represent a record of warm and cold periods in New Zealand’s climate. This record is discussed together with information available from other sources. It is concluded that the fluctuations in New Zealand’s climate during the last millennium were basically similar to those in the climate of North-western Europe. 
The δ¹³C variations in Pinus longaeva cellulose appear to be climate related, although in the opposite sense to the Agathis australis variations. These δ¹³C variations in lower forest border Pinus longaeva significantly correlate with upper tree line ring width variations for the same species. It is proposed that changing water stress is the underlying cause of the δ¹³C variations. If this is the case, the correlation may be the result of a correspondence between periods of water stress at the lower forest border and warm periods at the upper tree line.
It is concluded that ¹³C/¹²C ratios in both cellulose and lignin vary with changing climate. Results from Pinus radiata and Pseudotsuga menziesii indicate a temperature dependence of about + 0.21°/oo per °C. However, other results from Pseudotsuga menziesii and Pinus longaeva indicate that, in some situations, this effect is dominated by a larger and opposite effect, attributed in this work to water stress.
Thus there is little doubt that δ¹³C variations in the wood components from each tree ring sequence studied reflect climatic changes in that particular area. For some trees the effect of plant physiological changes on such variations is little understood. At present, those trees growing in exposed situations with a plentiful water supply appear to hold most promise for elucidating past climate data from measurements of ¹³C/¹²C ratios.

text: A study of the relationships between climate and stable isotope ratios in tree rings The main objectives of this work were to find out: 
(a) how the stable isotope ratios in wood constituents such as cellulose and lignin vary with changing climate;
(b) whether such variations can be applied to the study of past climate. 
Initially rings from a New Zealand grown Pinus radiata (Monterey pine) were studied since this is a complacent tree which grows throughout the year and hence over a wide temperature range.
In order to accurately determine the stable isotope ratios in wood components the following techniques were developed:
(a) the preparation of wood constituents on a small scale;
(b) the determination of δD values in waters;
(c) the determination of δD values in plant materials;
(d) the determination of δ¹³C values in plant materials.
Several possible methods for measuring D/H ratios for cellulose are discussed. It was decided to use a technique which involves heating cellulose with a standard water to fix the D/H ratio of the exchangeable hydrogens. Using this method relative δD values have been determined to a precision of ± 0.9°/οο (1 σ). The δ¹³C method was developed so that the ¹³C content of cellulose and lignin samples could be determined to ± 0. 04°/οο (1 σ).
A new procedure for determining δ values from raw mass spectrometer results is outlined. 
δD determinations on cellulose samples from three growth rings in a specimen of Pinus radiata show that the non-exchangeable hydrogens of cellulose are more than 20°/οο depleted in the summer as compared with the winter. These δD values appear to vary with the annual temperature cycle, but in the opposite sense to that expected from thermodynamic considerations. δ¹⁸ο determinations on the same samples show a summer/winter variation of about 2°/οο and in the opposite direction to the summer/winter variation in the δD determinations.
The δD results from Pinus radiata cellulose are compared with δD determinations on cellulose from other trees. 
It is concluded that all the measurements to date suggest that an increase in temperature results in a decrease in the D/H ratio of the non-exchangeable hydrogens in cellulose. The results imply a temperature coefficient of about - 3°/oo per °C, which is opposite to that found for precipitation (+ 5. 6°/oo per °C). This temperature effect will only be useful for past climate studies if δD variations due to meteoric and/or leaf transpiration changes can be corrected for. This may be possible using δ¹⁸o determinations. 
A new model to explain the effects of environmental changes on the magnitude of carbon isotopic fractionation in C₃ plants is presented and discussed. 
δ¹³C determinations on both cellulose and lignin from the same Pinus radiata that was used for the δD determinations show an enrichment of about 2°/oo in summer wood as compared with winter wood. This summer/winter variation is probably mainly due to changes in air temperature affecting the magnitude of carbon isotope fractionation during photosynthesis. The lignin variations are similar, but significantly displaced in time with respect to the cellulose variations. This is probably the result of secondary lignification. 
δ¹³C values for cellulose prepared from individual rings in a sample of dendrochronologically dated Pseudotsuga menziesii (Douglas fir) are compared with meteorological observations during growth. A correlation between the δ¹³C values and mean late spring/early summer temperature is discussed. The temperature coefficient for this correlation is + 0.22°/oo per °C, which is in good agreement with the Pinus radiata results.
Similar determinations on individual rings from Pinus radiata are difficult to interpret in terms of climatic changes because of a relatively large depletion in ¹³C towards the centre of the tree studied. A similar depletion in ¹³C was observed for cellulose prepared from a carbon-14 dated Agathis australis (New Zealand kauri) which grew during the last 1000 years. However, no such “age” effect was observed when δ¹³C values were determined for cellulose samples prepared from two dendrochronologically dated Pinus longaeva (Bristlecone pine) trees which also grew during the last 1000 years. 
The short-term fluctuations in the cellulose δ¹³C curve for Agathis australis are probably temperature related, and therefore represent a record of warm and cold periods in New Zealand’s climate. This record is discussed together with information available from other sources. It is concluded that the fluctuations in New Zealand’s climate during the last millennium were basically similar to those in the climate of North-western Europe. 
The δ¹³C variations in Pinus longaeva cellulose appear to be climate related, although in the opposite sense to the Agathis australis variations. These δ¹³C variations in lower forest border Pinus longaeva significantly correlate with upper tree line ring width variations for the same species. It is proposed that changing water stress is the underlying cause of the δ¹³C variations. If this is the case, the correlation may be the result of a correspondence between periods of water stress at the lower forest border and warm periods at the upper tree line.
It is concluded that ¹³C/¹²C ratios in both cellulose and lignin vary with changing climate. Results from Pinus radiata and Pseudotsuga menziesii indicate a temperature dependence of about + 0.21°/oo per °C. However, other results from Pseudotsuga menziesii and Pinus longaeva indicate that, in some situations, this effect is dominated by a larger and opposite effect, attributed in this work to water stress.
Thus there is little doubt that δ¹³C variations in the wood components from each tree ring sequence studied reflect climatic changes in that particular area. For some trees the effect of plant physiological changes on such variations is little understood. At present, those trees growing in exposed situations with a plentiful water supply appear to hold most promise for elucidating past climate data from measurements of ¹³C/¹²C ratios.

year: 1977

title: Educational leadership for international partnerships between New Zealand and east Asian Chinese higher education institutions

authors: Ho, Ai-Hsin

subjects: educational leadership

abstract: This study examines how higher education leaders in different socio-cultural contexts are involved in the practice of distributed leadership in international partnerships. This study employs socio-cultural theorising to help explain the 22 New Zealand, Singaporean, Chinese and Taiwanese higher education leaders' multiple experiences, perceptions and practices in international partnerships. In this study, socio-cultural theorising entails a view of constructivist epistemology and the ontology of constructive realism. Grounded theory methodology and Wallner's strangifications were employed to acquire, analyse, interpret and compare qualitative data across different contexts in this study. Semi-structured interviewing and document collection were the methods used for data generation. 
The findings suggest that distributed leadership in international higher education partnerships should move beyond simply arranging formal leadership roles, responsibilities, and resources. Distributed leadership in such cross-cultural contexts should be conceived as an inclusive approach to multiple leadership practices. Five interrelated key elements of distributed leadership emerged. They are formal arrangements, enhanced leadership opportunities, understanding the context, sustainability and learning. All the key elements entailed certain levels and aspects of learning. Learning and distributed leadership practices are closely intertwined and informing each other.
A conceptual framework for the learning and practice of distributed leadership in international partnership is proposed to theorise the relationship between three sources of learning of distributed leadership, and multiple distributed leadership practices. The three sources of learning identified in this study are understandings of the context (in actuality), prior knowledge (in lifeworlds), and knowledge of leadership capital, issues and factors (in microworlds). This study provides wider implications for education practitioners in other contexts to explore in international partnerships how social, cultural and economic forms leadership capital can be successfully distributed, exchanged and sustained, and how higher education leaders at all levels can actively participate and learn in international partnerships. Recommendations for researchers to conduct cross-cultural studies are provided.

text: Educational leadership for international partnerships between New Zealand and east Asian Chinese higher education institutions This study examines how higher education leaders in different socio-cultural contexts are involved in the practice of distributed leadership in international partnerships. This study employs socio-cultural theorising to help explain the 22 New Zealand, Singaporean, Chinese and Taiwanese higher education leaders' multiple experiences, perceptions and practices in international partnerships. In this study, socio-cultural theorising entails a view of constructivist epistemology and the ontology of constructive realism. Grounded theory methodology and Wallner's strangifications were employed to acquire, analyse, interpret and compare qualitative data across different contexts in this study. Semi-structured interviewing and document collection were the methods used for data generation. 
The findings suggest that distributed leadership in international higher education partnerships should move beyond simply arranging formal leadership roles, responsibilities, and resources. Distributed leadership in such cross-cultural contexts should be conceived as an inclusive approach to multiple leadership practices. Five interrelated key elements of distributed leadership emerged. They are formal arrangements, enhanced leadership opportunities, understanding the context, sustainability and learning. All the key elements entailed certain levels and aspects of learning. Learning and distributed leadership practices are closely intertwined and informing each other.
A conceptual framework for the learning and practice of distributed leadership in international partnership is proposed to theorise the relationship between three sources of learning of distributed leadership, and multiple distributed leadership practices. The three sources of learning identified in this study are understandings of the context (in actuality), prior knowledge (in lifeworlds), and knowledge of leadership capital, issues and factors (in microworlds). This study provides wider implications for education practitioners in other contexts to explore in international partnerships how social, cultural and economic forms leadership capital can be successfully distributed, exchanged and sustained, and how higher education leaders at all levels can actively participate and learn in international partnerships. Recommendations for researchers to conduct cross-cultural studies are provided.

year: 2009

title: Caregiver Health Related Quality of Life and Burden When Caring for Children with Traumatic Brain Injury

authors: Rose, Wallis

subjects: Caregiver Burden

abstract: Often family members take on the responsibility of caregiver when another family member sustains a traumatic brain injury (TBI). The caregiving role is a stressful task which may impact negatively upon caregivers’ psychological and physical health. Variables which may contribute to caregiver burden include: caregiver age, educational attainment, income, gender, ethnicity, marital status, supports, time post-injury, and child clinical variables: TBI severity, behavioural functioning and adaptive functioning. The literature varies in its reporting of which areas of health are most affected, and the degree to which sociodemographic and child variables impact upon negative health related quality of life (HRQoL) and burden. To address this the current study explored health outcomes for TBI caregivers using a battery of measures (Medical Study Short Form-36, Hospital Anxiety and Depression Scale, DSM-IV Depression Diagnostic Scale, BAKAS Caregiving Outcomes Scale); questionnaires were also used to collect sociodemographic information and information relating to supports and services used in the rehabilitation of the TBI child. The Behavioural Assessment System for Children was used to collect behavioural and adaptability information from the caregivers about the child. Assessments were carried out at baseline, 1-month, 6-months and 12-months post TBI from a sample of 94 TBI caregivers and at baseline from a sample of 43 Control caregivers.

TBI caregivers experienced poorer overall health and higher levels of depression and were less likely to report positive life changes compared to Control caregivers. Older age and higher income predicted positive life changes. In addition to this higher income predicted better physical and overall health. Ethnicity was found to predict depression with the Māori/‘other ethnicity’ group suffering higher levels of depression. Children’s dysfunctional behaviour was found to predict poorer caregiver health outcomes across several domains; these include physical health, overall health, and depression; while the child’s adaptive functioning was not found to be a predictive factor in any caregiver health domains. New Zealand European and Māori TBI caregivers experienced similar health outcomes and received similar levels of support. However, Māori experienced more positive life changes than New Zealand Europeans. Caregivers’ physical and psychological well-being was found to improve over time, these changes were the greatest between the 1-month and 12-month period.
As a high percentage of children’s TBI’s occur in the home and at school, education aimed at schools and parents to inform of the effects of TBI upon children and families will bring an awareness which may encourage families to seek medical help. In doing so will offer the opportunity to receive or seek support in the initial period post TBI in the hope of reducing the burden for caregivers and producing better health outcomes. Bringing these families into contact with medical services may also help in identifying caregivers at higher risk of poorer health outcomes. Findings of more positive life changes for Māori may suggest cultural ideology is a protective factor in caregiver burden, further investigation may be necessary to understand these cultural differences and how they impact upon the caregiving role.

text: Caregiver Health Related Quality of Life and Burden When Caring for Children with Traumatic Brain Injury Often family members take on the responsibility of caregiver when another family member sustains a traumatic brain injury (TBI). The caregiving role is a stressful task which may impact negatively upon caregivers’ psychological and physical health. Variables which may contribute to caregiver burden include: caregiver age, educational attainment, income, gender, ethnicity, marital status, supports, time post-injury, and child clinical variables: TBI severity, behavioural functioning and adaptive functioning. The literature varies in its reporting of which areas of health are most affected, and the degree to which sociodemographic and child variables impact upon negative health related quality of life (HRQoL) and burden. To address this the current study explored health outcomes for TBI caregivers using a battery of measures (Medical Study Short Form-36, Hospital Anxiety and Depression Scale, DSM-IV Depression Diagnostic Scale, BAKAS Caregiving Outcomes Scale); questionnaires were also used to collect sociodemographic information and information relating to supports and services used in the rehabilitation of the TBI child. The Behavioural Assessment System for Children was used to collect behavioural and adaptability information from the caregivers about the child. Assessments were carried out at baseline, 1-month, 6-months and 12-months post TBI from a sample of 94 TBI caregivers and at baseline from a sample of 43 Control caregivers.

TBI caregivers experienced poorer overall health and higher levels of depression and were less likely to report positive life changes compared to Control caregivers. Older age and higher income predicted positive life changes. In addition to this higher income predicted better physical and overall health. Ethnicity was found to predict depression with the Māori/‘other ethnicity’ group suffering higher levels of depression. Children’s dysfunctional behaviour was found to predict poorer caregiver health outcomes across several domains; these include physical health, overall health, and depression; while the child’s adaptive functioning was not found to be a predictive factor in any caregiver health domains. New Zealand European and Māori TBI caregivers experienced similar health outcomes and received similar levels of support. However, Māori experienced more positive life changes than New Zealand Europeans. Caregivers’ physical and psychological well-being was found to improve over time, these changes were the greatest between the 1-month and 12-month period.
As a high percentage of children’s TBI’s occur in the home and at school, education aimed at schools and parents to inform of the effects of TBI upon children and families will bring an awareness which may encourage families to seek medical help. In doing so will offer the opportunity to receive or seek support in the initial period post TBI in the hope of reducing the burden for caregivers and producing better health outcomes. Bringing these families into contact with medical services may also help in identifying caregivers at higher risk of poorer health outcomes. Findings of more positive life changes for Māori may suggest cultural ideology is a protective factor in caregiver burden, further investigation may be necessary to understand these cultural differences and how they impact upon the caregiving role.

year: 2012