title: Southern Hemisphere bog persists as a strong carbon sink during droughts

authors: Goodrich, Jordan Paul

abstract: Peatland ecosystems have been important global carbon sinks throughout the Holocene. Most of the research on peatland carbon budgets and effects of variable weather conditions has been done in Northern Hemisphere Sphagnum-dominated systems. Given their importance in other geographic and climatic regions, a better understanding of peatland carbon dynamics is needed across the spectrum of global peatland types. In New Zealand, much of the historic peatland area has been drained for agriculture but little is known about rates of carbon exchange and storage in unaltered peatland remnants that are dominated by the jointed wire-rush, Empodisma robustum. We used eddy covariance to measure ecosystem-scale CO₂ and CH₄ fluxes and a water balance approach to estimate the sub-surface flux of dissolved organic carbon from the largest remaining raised peat bog in New Zealand, Kopuatai bog. The net ecosystem carbon balance (NECB) was estimated over four years, which included two drought summers, a relatively wet summer, and a meteorologically average summer. In all measurement years, the bog was a substantial sink for carbon, ranging from 134.7 gC m⁻² yr⁻¹ to 216.9 gC m⁻² yr⁻¹, owing to the large annual net ecosystem production (−161.8 to −244.9 gCO2-C m⁻² yr⁻¹). Annual methane fluxes were large relative to most Northern Hemisphere peatlands (14.2 to 21.9 gCH4-C  m⁻² yr⁻¹1), although summer and autumn emissions were highly sensitive to dry conditions leading to very predictable seasonality according to water table position. The annual flux of dissolved organic carbon was similar in magnitude to methane emissions but less variable, ranging from 11.7 to 12.8 gC m⁻² yr⁻¹. Dry conditions experienced during late summer droughts led to significant reductions in annual carbon storage, which resulted nearly equally from enhanced ecosystem respiration due to lowered water tables and increased temperatures, and from reduced gross primary production due to vapor pressure deficit-related stresses to the vegetation. However, the net C uptake of Kopuatai bog during drought years was large relative to even the maximum reported NECB from Northern Hemisphere bogs. Furthermore, GWP fluxes indicated the bog was a strong sink for greenhouse gases in all years despite the relatively large annual methane emissions. Our results suggest that adaptations of E. robustum to dry conditions lead to a resilient peatland drought response of the NECB.

text: Southern Hemisphere bog persists as a strong carbon sink during droughts Peatland ecosystems have been important global carbon sinks throughout the Holocene. Most of the research on peatland carbon budgets and effects of variable weather conditions has been done in Northern Hemisphere Sphagnum-dominated systems. Given their importance in other geographic and climatic regions, a better understanding of peatland carbon dynamics is needed across the spectrum of global peatland types. In New Zealand, much of the historic peatland area has been drained for agriculture but little is known about rates of carbon exchange and storage in unaltered peatland remnants that are dominated by the jointed wire-rush, Empodisma robustum. We used eddy covariance to measure ecosystem-scale CO₂ and CH₄ fluxes and a water balance approach to estimate the sub-surface flux of dissolved organic carbon from the largest remaining raised peat bog in New Zealand, Kopuatai bog. The net ecosystem carbon balance (NECB) was estimated over four years, which included two drought summers, a relatively wet summer, and a meteorologically average summer. In all measurement years, the bog was a substantial sink for carbon, ranging from 134.7 gC m⁻² yr⁻¹ to 216.9 gC m⁻² yr⁻¹, owing to the large annual net ecosystem production (−161.8 to −244.9 gCO2-C m⁻² yr⁻¹). Annual methane fluxes were large relative to most Northern Hemisphere peatlands (14.2 to 21.9 gCH4-C  m⁻² yr⁻¹1), although summer and autumn emissions were highly sensitive to dry conditions leading to very predictable seasonality according to water table position. The annual flux of dissolved organic carbon was similar in magnitude to methane emissions but less variable, ranging from 11.7 to 12.8 gC m⁻² yr⁻¹. Dry conditions experienced during late summer droughts led to significant reductions in annual carbon storage, which resulted nearly equally from enhanced ecosystem respiration due to lowered water tables and increased temperatures, and from reduced gross primary production due to vapor pressure deficit-related stresses to the vegetation. However, the net C uptake of Kopuatai bog during drought years was large relative to even the maximum reported NECB from Northern Hemisphere bogs. Furthermore, GWP fluxes indicated the bog was a strong sink for greenhouse gases in all years despite the relatively large annual methane emissions. Our results suggest that adaptations of E. robustum to dry conditions lead to a resilient peatland drought response of the NECB.

year: 2017

title: Perceptual improvements for Super-Resolution of Satellite Imagery

authors: Bull, Dainel

subjects: computer science

abstract: Super-resolution of satellite imagery poses unique challenges. We propose a hybrid method comprising two existing deep network super-resolution approaches, namely a feedforward network called DeepSUM, and ESRGAN, a GAN-based approach, to super-resolve multiple low-resolution images by a factor of four to obtain a single high-resolution image. We also introduce a novel loss function, called variation loss, to better define edges and textures to create a sharper, perceptually better output. Using our hybrid, we inherit some of the advantages of both deep learning approaches, resulting in super-resolved images that better show boundaries, textures, and details.

text: Perceptual improvements for Super-Resolution of Satellite Imagery Super-resolution of satellite imagery poses unique challenges. We propose a hybrid method comprising two existing deep network super-resolution approaches, namely a feedforward network called DeepSUM, and ESRGAN, a GAN-based approach, to super-resolve multiple low-resolution images by a factor of four to obtain a single high-resolution image. We also introduce a novel loss function, called variation loss, to better define edges and textures to create a sharper, perceptually better output. Using our hybrid, we inherit some of the advantages of both deep learning approaches, resulting in super-resolved images that better show boundaries, textures, and details.

year: 2021

title: Developing a kaupapa Māori evaluation model – one size fits all?

authors: Masters-Awatere, Bridgette

subjects: Maori health

abstract: Health statistics in Aotearoa (New Zealand) highlight that Māori, the indigenous people Aotearoa have poorer health than non- Māori. In response to the statistics a number of Māori health providers have established services that address specific areas of need in their regions. Initially there were minimal accountability requirements of providers. However, changes in the health system now mean that groups wanting to establish a new service must provide accountability measures before, during and after the funding has been allocated. As a result providers need to develop a rationale behind their decisions and assess the measure of change that has taken place as a result of the service or programme to ensure continued funding. The requirements reflect the dominant Western paradigm in which health promotion is understood to be about producing specific quantifiable behaviour changes in individuals. Māori health providers on the other hand have tended to take a holistic approach to health. Thus they have found themselves in the position of trying to show change within a paradigm where measurements are not easily taken. This has created frustration amongst Māori providers who face losing their funding because of an inability to report measurable outcomes using a framework that does not apply to their culture.

text: Developing a kaupapa Māori evaluation model – one size fits all? Health statistics in Aotearoa (New Zealand) highlight that Māori, the indigenous people Aotearoa have poorer health than non- Māori. In response to the statistics a number of Māori health providers have established services that address specific areas of need in their regions. Initially there were minimal accountability requirements of providers. However, changes in the health system now mean that groups wanting to establish a new service must provide accountability measures before, during and after the funding has been allocated. As a result providers need to develop a rationale behind their decisions and assess the measure of change that has taken place as a result of the service or programme to ensure continued funding. The requirements reflect the dominant Western paradigm in which health promotion is understood to be about producing specific quantifiable behaviour changes in individuals. Māori health providers on the other hand have tended to take a holistic approach to health. Thus they have found themselves in the position of trying to show change within a paradigm where measurements are not easily taken. This has created frustration amongst Māori providers who face losing their funding because of an inability to report measurable outcomes using a framework that does not apply to their culture.

year: 2002