title: Evaporation at Kopuatai bog: An investigation of dry and wet canopy evaporation regimes

authors: Speranskaya, Leeza

abstract: Peatlands store disproportionately large amounts of carbon (C) per unit area compared to other ecosystems, a function that depends on maintaining a high and stable water table. Water table levels are in turn influenced by evaporation (E), which consists of surface E, transpiration, and interception loss (Eint) components. In boreal peatlands, E rates have been predicted to increase due to climate change-induced increases in vapour pressure deficit (VPD), potentially causing water table drawdown and threatening the ability of peatlands to store C. However, the response of E to VPD has not yet been quantified for Aotearoa New Zealand peatlands dominated by a very water-conservative vegetation species, Empodisma robustum. In addition, the Eint component of E has not been extensively investigated in these peatlands. Therefore, to gain a better understanding of the E regimes of this peatland type, this thesis firstly investigated the extent of E restrictions by E. robustum and the response of E to increasing VPD at Kopuatai bog, using an 11-year eddy covariance (EC) dataset. This analysis was replicated on a 20-year dataset from Mer Bleue bog, a ‘typical’ shrub and moss-dominated Northern Hemisphere peatland. Mean annual E was 45% lower than mean annual equilibrium E (Eeq) at Kopuatai but only 16% lower at Mer Bleue, demonstrating much greater limitations on E at the former. The mean midday (10:00–14:30) dry canopy Bowen ratio (β) at Kopuatai was 1.96, compared to 0.77 at Mer Bleue, as the sensible heat flux (H) dominated over the latent heat flux (LE) at Kopuatai, and vice versa at Mer Bleue. In addition, the response of E to VPD at Kopuatai indicated that more water was conserved at high VPD than at Mer Bleue. This likely occurred due to stronger stomatal limitation of transpiration at Kopuatai, while at Mer Bleue the effect of stomatal limitation by shrubs may have been offset by a high moss E. 

The second component of this thesis determined the magnitude of Eint at Kopuatai using two Eint modelling approaches and a canopy water balance field experiment. The field data overestimated Eint, while modelling produced much lower and more realistic estimates. Therefore, the models likely provided the best estimates of Eint as a proportion of gross rainfall (Eint/Pg) and total E (Eint/E), with annual-scale values of 15.5–18.3% and 31.3–36.6%, respectively, and a canopy storage capacity of 1.5 mm. Controls on Eint/Pg were rain event size, net radiation, and canopy height/density. 

This research has shown that, during dry canopy conditions, E. robustum enables a much more conservative E regime at Kopuatai compared to Mer Bleue, potentially enabling greater “hydrological resistance” to increased VPD under future climate warming compared to Northern Hemisphere peatlands. This may be a crucial factor in ensuring resilience of the C sink function at Kopuatai under a warming and drying climate. During wet canopy conditions, however, Eint enables much greater water loss from Kopuatai than when the canopy is dry.

text: Evaporation at Kopuatai bog: An investigation of dry and wet canopy evaporation regimes Peatlands store disproportionately large amounts of carbon (C) per unit area compared to other ecosystems, a function that depends on maintaining a high and stable water table. Water table levels are in turn influenced by evaporation (E), which consists of surface E, transpiration, and interception loss (Eint) components. In boreal peatlands, E rates have been predicted to increase due to climate change-induced increases in vapour pressure deficit (VPD), potentially causing water table drawdown and threatening the ability of peatlands to store C. However, the response of E to VPD has not yet been quantified for Aotearoa New Zealand peatlands dominated by a very water-conservative vegetation species, Empodisma robustum. In addition, the Eint component of E has not been extensively investigated in these peatlands. Therefore, to gain a better understanding of the E regimes of this peatland type, this thesis firstly investigated the extent of E restrictions by E. robustum and the response of E to increasing VPD at Kopuatai bog, using an 11-year eddy covariance (EC) dataset. This analysis was replicated on a 20-year dataset from Mer Bleue bog, a ‘typical’ shrub and moss-dominated Northern Hemisphere peatland. Mean annual E was 45% lower than mean annual equilibrium E (Eeq) at Kopuatai but only 16% lower at Mer Bleue, demonstrating much greater limitations on E at the former. The mean midday (10:00–14:30) dry canopy Bowen ratio (β) at Kopuatai was 1.96, compared to 0.77 at Mer Bleue, as the sensible heat flux (H) dominated over the latent heat flux (LE) at Kopuatai, and vice versa at Mer Bleue. In addition, the response of E to VPD at Kopuatai indicated that more water was conserved at high VPD than at Mer Bleue. This likely occurred due to stronger stomatal limitation of transpiration at Kopuatai, while at Mer Bleue the effect of stomatal limitation by shrubs may have been offset by a high moss E. 

The second component of this thesis determined the magnitude of Eint at Kopuatai using two Eint modelling approaches and a canopy water balance field experiment. The field data overestimated Eint, while modelling produced much lower and more realistic estimates. Therefore, the models likely provided the best estimates of Eint as a proportion of gross rainfall (Eint/Pg) and total E (Eint/E), with annual-scale values of 15.5–18.3% and 31.3–36.6%, respectively, and a canopy storage capacity of 1.5 mm. Controls on Eint/Pg were rain event size, net radiation, and canopy height/density. 

This research has shown that, during dry canopy conditions, E. robustum enables a much more conservative E regime at Kopuatai compared to Mer Bleue, potentially enabling greater “hydrological resistance” to increased VPD under future climate warming compared to Northern Hemisphere peatlands. This may be a crucial factor in ensuring resilience of the C sink function at Kopuatai under a warming and drying climate. During wet canopy conditions, however, Eint enables much greater water loss from Kopuatai than when the canopy is dry.

year: 2023

title: Terms of empowerment: Gender, ecology, and ICTs for development

authors: Kurian, Priya A.

subjects: technology

abstract: The obsession with technology as a primary tool for development without any regard for the social and cultural needs of society has not done much to help the cause of women or other disempowered groups. The accent on technology for technology’s sake is part of a masculinist worldview characterised by the tendency to equate technical competence with male gender identity (Judy Wajcman 1995). As a counter, a feminist approach to technology looks at ways of dealing with core life-sustaining issues of food, clothing, shelter, education, and a general sense of well being (Debashish Munshi and Priya Kurian 2003). Indeed, as Ingunn Moser (1995: 6) points out, science and technology are not only “social and cultural projects, formed in power structures and coloured by dominating values in the societies and the cultures in which they occur” but are political as well.

text: Terms of empowerment: Gender, ecology, and ICTs for development The obsession with technology as a primary tool for development without any regard for the social and cultural needs of society has not done much to help the cause of women or other disempowered groups. The accent on technology for technology’s sake is part of a masculinist worldview characterised by the tendency to equate technical competence with male gender identity (Judy Wajcman 1995). As a counter, a feminist approach to technology looks at ways of dealing with core life-sustaining issues of food, clothing, shelter, education, and a general sense of well being (Debashish Munshi and Priya Kurian 2003). Indeed, as Ingunn Moser (1995: 6) points out, science and technology are not only “social and cultural projects, formed in power structures and coloured by dominating values in the societies and the cultures in which they occur” but are political as well.

year: 2003

title: Applying Kaupapa Māori Processes to Documentary Film.

authors: Waititi, Kahurangi Rora

subjects: Maori documentary

abstract: This thesis explores the application of Kaupapa Māori processes to documentary filmmaking through practiced-led research. The need for this research came to light through the experience of witnessing unacceptable behaviour shown by film crews towards kaumātua who were attending the 2006 28th Māori Battalion Reunion. In reflecting on this experience and considering my own filming experience as a person with a Te Ao Māori background, the basis for this argument was conceived. This thesis argues that there are alternative ways in which filming can be conducted by considering processes that already exist within Māori practices and philosophies.          

This Thesis, therefore, investigates alternative processes of filming that have developed from a Kaupapa Māori perspective through practical filming experience.  An historical overview of the relationship between Māori, media and filming practices have been provided to give context to this discussion.  The application of Kaupapa Māori processes to film was considered through the use of Marae protocol and philosophies. The application of these concepts was supported by the creative research which was utilised by referencing specific examples. The reader is, therefore, instructed to refer to the DVD in the front of the thesis as referenced in the written text.

text: Applying Kaupapa Māori Processes to Documentary Film. This thesis explores the application of Kaupapa Māori processes to documentary filmmaking through practiced-led research. The need for this research came to light through the experience of witnessing unacceptable behaviour shown by film crews towards kaumātua who were attending the 2006 28th Māori Battalion Reunion. In reflecting on this experience and considering my own filming experience as a person with a Te Ao Māori background, the basis for this argument was conceived. This thesis argues that there are alternative ways in which filming can be conducted by considering processes that already exist within Māori practices and philosophies.          

This Thesis, therefore, investigates alternative processes of filming that have developed from a Kaupapa Māori perspective through practical filming experience.  An historical overview of the relationship between Māori, media and filming practices have been provided to give context to this discussion.  The application of Kaupapa Māori processes to film was considered through the use of Marae protocol and philosophies. The application of these concepts was supported by the creative research which was utilised by referencing specific examples. The reader is, therefore, instructed to refer to the DVD in the front of the thesis as referenced in the written text.

year: 2007