title: Methane emission hotspots from a drained peat soil under dairy grazing

authors: Hamill, Jacob

subjects: Methane

abstract: Methane (CH4) is a greenhouse gas that is emitted from natural peatland ecosystems due to their high water tables. However, large areas of natural peatlands have been drained for agricultural purposes, resulting in a reduction in overall methane emissions. However, where soil is saturated, such as within or adjacent to drainage ditches, methane emission can remain high. The aim of this research was to determine the magnitude of soil- and drainage ditch-derived methane emissions from a drained Waikato peatland under dairy grazing and where and when these emissions occur.

Gamma Farm is a pastoral dairy farm located on the remnants of the Moanatuatua peatland and drained by shallow surface “spinner” drains that discharge into deeper field-border drains. The paddocks were classified into four different landforms based on the location and hydrology of the drainage features. These landforms are crown, slope, ditch edge and drainage ditch. To adequately determine the spatial and temporal variation in methane fluxes chamber measurements of methane fluxes were undertaken along a transect across the width of the study site, approximately perpendicular to the border drains. A campaign approach was used, with chamber measurements being undertaken from autumn through to winter to capture methane fluxes under different environmental conditions. To measure seasonal and annual-scale methane emissions an eddy covariance flux tower was used.
Based on chamber measurements drainage ditches were shown to have average methane emissions of 0.071 ± 0.005 mg CH4 m-2 h-1 . Conversely, the soil of the crown, slope and ditch edges were shown to be a net methane sink, with average net methane oxidation of ‒0.019 ± 0.006, ‒0.01 ± 0.008 and ‒0.023 ± 0.006 mg CH4 m-2 h-1 respectively. Weighting the chamber measurements by landform area it was concluded that the study site was primarily a minor net methane sink. However, eddy covariance measurements indicated that the study site was a net source of methane with annual emissions of 44.72 kg CH4 ha-1 yr-1 . This large discrepancy between the chamber and eddy covariance measurements is likely caused by the large spatial and temporal scale differences between the two measurement techniques.

In addition, it was found that there was no relationship between soil methane fluxes and the soil temperature, Olsen-P, and nitrate concentration. However, methane fluxes were shown to decrease as the ammonium concentration and depth to the water table increased. In addition, methane fluxes decreased as volumetric moisture content (VMC) decreased, but at low VMCs (<40%) methane fluxes tended towards zero. For the water-borne methane fluxes there was no relationship found between methane fluxes and any measured variable (pH, dissolved oxygen, electrical conductivity, water temperature, water depth, nitrate concentration or dissolved phosphorus). However, at longer time scales such as monthly averages of eddy covariance measurements, methane fluxes were positively correlated with soil temperature and air temperature. Additionally, both seasonal and diurnal cycles in the eddy covariance methane fluxes were observed.

text: Methane emission hotspots from a drained peat soil under dairy grazing Methane (CH4) is a greenhouse gas that is emitted from natural peatland ecosystems due to their high water tables. However, large areas of natural peatlands have been drained for agricultural purposes, resulting in a reduction in overall methane emissions. However, where soil is saturated, such as within or adjacent to drainage ditches, methane emission can remain high. The aim of this research was to determine the magnitude of soil- and drainage ditch-derived methane emissions from a drained Waikato peatland under dairy grazing and where and when these emissions occur.

Gamma Farm is a pastoral dairy farm located on the remnants of the Moanatuatua peatland and drained by shallow surface “spinner” drains that discharge into deeper field-border drains. The paddocks were classified into four different landforms based on the location and hydrology of the drainage features. These landforms are crown, slope, ditch edge and drainage ditch. To adequately determine the spatial and temporal variation in methane fluxes chamber measurements of methane fluxes were undertaken along a transect across the width of the study site, approximately perpendicular to the border drains. A campaign approach was used, with chamber measurements being undertaken from autumn through to winter to capture methane fluxes under different environmental conditions. To measure seasonal and annual-scale methane emissions an eddy covariance flux tower was used.
Based on chamber measurements drainage ditches were shown to have average methane emissions of 0.071 ± 0.005 mg CH4 m-2 h-1 . Conversely, the soil of the crown, slope and ditch edges were shown to be a net methane sink, with average net methane oxidation of ‒0.019 ± 0.006, ‒0.01 ± 0.008 and ‒0.023 ± 0.006 mg CH4 m-2 h-1 respectively. Weighting the chamber measurements by landform area it was concluded that the study site was primarily a minor net methane sink. However, eddy covariance measurements indicated that the study site was a net source of methane with annual emissions of 44.72 kg CH4 ha-1 yr-1 . This large discrepancy between the chamber and eddy covariance measurements is likely caused by the large spatial and temporal scale differences between the two measurement techniques.

In addition, it was found that there was no relationship between soil methane fluxes and the soil temperature, Olsen-P, and nitrate concentration. However, methane fluxes were shown to decrease as the ammonium concentration and depth to the water table increased. In addition, methane fluxes decreased as volumetric moisture content (VMC) decreased, but at low VMCs (<40%) methane fluxes tended towards zero. For the water-borne methane fluxes there was no relationship found between methane fluxes and any measured variable (pH, dissolved oxygen, electrical conductivity, water temperature, water depth, nitrate concentration or dissolved phosphorus). However, at longer time scales such as monthly averages of eddy covariance measurements, methane fluxes were positively correlated with soil temperature and air temperature. Additionally, both seasonal and diurnal cycles in the eddy covariance methane fluxes were observed.

year: 2019

title: Steps to improve gender diversity in coastal geoscience and engineering

authors: Vila-Concejo, Ana

abstract: Robust data are the base of effective gender diversity policy. Evidence shows that gender inequality is still pervasive in science, technology, engineering and mathematics (STEM). Coastal geoscience and engineering (CGE) encompasses professionals working on coastal processes, integrating expertise across physics, geomorphology, engineering, planning and management. The article presents novel results of gender inequality and experiences of gender bias in CGE, and proposes practical steps to address it. It analyses the gender representation in 9 societies, 25 journals, and 10 conferences in CGE and establishes that women represent 30% of the international CGE community, yet there is underrepresentation in prestige roles such as journal editorial board members (15% women) and conference organisers (18% women). The data show that female underrepresentation is less prominent when the path to prestige roles is clearly outlined and candidates can selfnominate or volunteer instead of the traditional invitation-only pathway. By analysing the views of 314 survey respondents (34% male, 65% female, and 1% ‘‘other’’), we show that 81% perceive the lack of female role models as a key hurdle for gender equity, and a significantly larger proportion of females (47%) felt held back in their careers due to their gender in comparison with males (9%). The lack of women in prestige roles and senior positions contributes to 81% of survey respondents perceiving the lack of female role models in CGE as a key hurdle for gender equality. While it is clear that having more women as role models is important, this is not enough to effect change. Here seven practical steps towards achieving gender equity in CGE are presented: (1) Advocate for more women in prestige roles; (2) Promote high-achieving females; (3) Create awareness of gender bias; (4) Speak up; (5) Get better support for return to work; (6) Redefine success; and, (7) Encourage more women to enter the discipline at a young age. Some of these steps can be successfully implemented immediately (steps 1-4), while others need institutional engagement and represent major societal overhauls. In any case, these seven practical steps require actions that can start immediately.

text: Steps to improve gender diversity in coastal geoscience and engineering Robust data are the base of effective gender diversity policy. Evidence shows that gender inequality is still pervasive in science, technology, engineering and mathematics (STEM). Coastal geoscience and engineering (CGE) encompasses professionals working on coastal processes, integrating expertise across physics, geomorphology, engineering, planning and management. The article presents novel results of gender inequality and experiences of gender bias in CGE, and proposes practical steps to address it. It analyses the gender representation in 9 societies, 25 journals, and 10 conferences in CGE and establishes that women represent 30% of the international CGE community, yet there is underrepresentation in prestige roles such as journal editorial board members (15% women) and conference organisers (18% women). The data show that female underrepresentation is less prominent when the path to prestige roles is clearly outlined and candidates can selfnominate or volunteer instead of the traditional invitation-only pathway. By analysing the views of 314 survey respondents (34% male, 65% female, and 1% ‘‘other’’), we show that 81% perceive the lack of female role models as a key hurdle for gender equity, and a significantly larger proportion of females (47%) felt held back in their careers due to their gender in comparison with males (9%). The lack of women in prestige roles and senior positions contributes to 81% of survey respondents perceiving the lack of female role models in CGE as a key hurdle for gender equality. While it is clear that having more women as role models is important, this is not enough to effect change. Here seven practical steps towards achieving gender equity in CGE are presented: (1) Advocate for more women in prestige roles; (2) Promote high-achieving females; (3) Create awareness of gender bias; (4) Speak up; (5) Get better support for return to work; (6) Redefine success; and, (7) Encourage more women to enter the discipline at a young age. Some of these steps can be successfully implemented immediately (steps 1-4), while others need institutional engagement and represent major societal overhauls. In any case, these seven practical steps require actions that can start immediately.

year: 2018

title: 'Kōrero Tuku Iho': Reconfiguring Oral History and Oral Tradition

authors: Mahuika, Nepia

subjects: History

abstract: The studies of oral history and oral tradition each have their own distinctive bodies of literature and preferred methodologies, yet share significant overlaps that make them difficult to differentiate. For many indigenous peoples, oral histories and traditions are key to their their past, present, and future lives, and are rarely considered separate. This thesis examines the differences and similarities between the studies of oral history and oral tradition. It explores how these areas of research converge and diverge in form, politics, practice, and theory, and the extent to which they resonate within a specific ‘indigenous’ context and community.
The thesis draws on the life narrative interviews of four generations of Ngāti Porou descendents, the second largest tribal group in New Zealand, whose home boundaries extend from Potikirua in the north to Te Toka-a-Taiau in the south on the East Coast of the North Island. Drawing on these voices, this study offers a commentary on the form and nature of oral traditions and histories from an indigenous perspective, and explores the ways they converge and depart from ‘international’ understandings. An exploration of these intersections offers insights to the ways oral history and oral traditions might be reconsidered as distinctive fields of study. Reconfigured through an indigenous frame of reference, this thesis challenges scholars of both oral history and oral tradition to expand their conceptions. Likewise, it urges indigenous scholars to consider more deeply the work of oral historians and oral traditionalists to further enhance their scholarship. Moreover, this thesis revisits the intellectual and conceptual territory that names and claims oral history and oral tradition, and invites all those who work in these areas to develop a more extensive comprehension of the interconnections that exist between each area of study.

text: 'Kōrero Tuku Iho': Reconfiguring Oral History and Oral Tradition The studies of oral history and oral tradition each have their own distinctive bodies of literature and preferred methodologies, yet share significant overlaps that make them difficult to differentiate. For many indigenous peoples, oral histories and traditions are key to their their past, present, and future lives, and are rarely considered separate. This thesis examines the differences and similarities between the studies of oral history and oral tradition. It explores how these areas of research converge and diverge in form, politics, practice, and theory, and the extent to which they resonate within a specific ‘indigenous’ context and community.
The thesis draws on the life narrative interviews of four generations of Ngāti Porou descendents, the second largest tribal group in New Zealand, whose home boundaries extend from Potikirua in the north to Te Toka-a-Taiau in the south on the East Coast of the North Island. Drawing on these voices, this study offers a commentary on the form and nature of oral traditions and histories from an indigenous perspective, and explores the ways they converge and depart from ‘international’ understandings. An exploration of these intersections offers insights to the ways oral history and oral traditions might be reconsidered as distinctive fields of study. Reconfigured through an indigenous frame of reference, this thesis challenges scholars of both oral history and oral tradition to expand their conceptions. Likewise, it urges indigenous scholars to consider more deeply the work of oral historians and oral traditionalists to further enhance their scholarship. Moreover, this thesis revisits the intellectual and conceptual territory that names and claims oral history and oral tradition, and invites all those who work in these areas to develop a more extensive comprehension of the interconnections that exist between each area of study.

year: 2012