title: A toolbox for the use of electromagnetic induction technology and quasi-3D inversion to determine the spatial heterogeneity of soil texture and moisture in forested catchments

authors: Corbett-Lad, Priscilla

abstract: Forest soils are critical to forest health and productivity, and by recognising their spatial heterogeneity, we can optimise productivity and preserve our natural resources in the face of a changing climate. Electromagnetic induction (EMI) technology provides a repeatable, non-destructive, and cost-effective approach to studying soil heterogeneity in managed forests. Electromagnetic induction technology has proven its versatility in agricultural settings to map soil texture, moisture and crop productivity and geological and archaeological exploration to identify underground natural and anthropogenic structures. Yet, the application in forests has been limited, and it is essential to understand the impact of soil and environmental factors on apparent electrical conductivity (ECa) if attempting to use this EMI technology in a forested environment. The overarching aim of this thesis was to determine if EMI can be used in a forested environment, focusing on two contrasting Pinus radiata D. Don production forests to capture the spatial heterogeneity of soil properties. Furthermore, this thesis can serve as a 'toolbox' for measurement protocols and analysis for forest owners interested in low-cost, time-efficient methods of understanding microsite heterogeneity in their forest soils to guide management practices. The research addressed the three main questions: The impact of various environmental factors on apparent electrical conductivity (ECa), the ability of ECa to characterise soil texture and moisture across forested catchments, and the effectiveness of quasi-3D inversion software in capturing the spatial heterogeneity of forest soils in three dimensions.
To answer the first question, measurements were taken on forest litter thickness, gravimetric water content, density, soil temperature, ambient temperature, instrument temperature, and instrument voltage. The study found no significant linear relationship between ECa and these environmental factors, indicating that a correction factor for drift in ECa caused by temperature and voltage variations was not required. The insulating effect of forest soils, the forest canopy, and the instrument's housing played a role in maintaining stability. In addition, there was no significant effect of the presence or absence of forest litter on ECa, which was most likely due to the structure and makeup of forest litter, indicating that EMI technology could predict soil properties without considering the effect of forest litter.
Questions two and three aimed to evaluate the effectiveness of using apparent electrical conductivity and modelled electrical conductivity (ECm) as predictors for soil properties, including gravimetric water content (GWC), the electrical conductivity of a 1-part soil to 5-part water solution (ECe1:5), and the percentages of clay (CLAY), fine sand (FSAND), and medium sand particles (MSAND). Firstly, generalised linear mixed-effects models (GLMERs) were employed to assess the measured variables' main effects and interaction effects on ECa and ECm and the within and between site variability as a random effect. The GLMERs demonstrated that incorporating multiple predictor variables reduced unexplained variability, with specific interactions, such as GWC and ECe1:5, playing crucial roles in explaining ECm variability at particular depths. However, multicollinearity issues were observed, primarily driven by the GWC-ECe1:5 interaction. The study also discussed the findings of 3D inversion maps of ECm, which provided detailed insights into spatial distribution patterns, particularly when overlaid with topographic and soil variable data. Secondly, one-dimension and three-dimensional maps were produced and overlaid onto base maps of each catchment to identify spatial patterns within each catchment related to soil texture and moisture using standard kriging in Arc GIS Pro software and custom EM4Soil software designed to interpolate one-dimensional ECa measurements into three dimensions.
Finally, the research delved into the implications of these findings for forest owners and their management practices. It emphasised that while ECa technology is a valuable tool in predicting forest soil heterogeneity, it should not be used in isolation, and soil sampling and validation remain essential. The study recommended using EMI as a time and cost-effective tool for understanding soil heterogeneity, offering repeatable and non-destructive measurements for informed land use decisions. Overlaying spatial maps with additional geospatial data was recommended to comprehensively understand soil variability within catchments.

text: A toolbox for the use of electromagnetic induction technology and quasi-3D inversion to determine the spatial heterogeneity of soil texture and moisture in forested catchments Forest soils are critical to forest health and productivity, and by recognising their spatial heterogeneity, we can optimise productivity and preserve our natural resources in the face of a changing climate. Electromagnetic induction (EMI) technology provides a repeatable, non-destructive, and cost-effective approach to studying soil heterogeneity in managed forests. Electromagnetic induction technology has proven its versatility in agricultural settings to map soil texture, moisture and crop productivity and geological and archaeological exploration to identify underground natural and anthropogenic structures. Yet, the application in forests has been limited, and it is essential to understand the impact of soil and environmental factors on apparent electrical conductivity (ECa) if attempting to use this EMI technology in a forested environment. The overarching aim of this thesis was to determine if EMI can be used in a forested environment, focusing on two contrasting Pinus radiata D. Don production forests to capture the spatial heterogeneity of soil properties. Furthermore, this thesis can serve as a 'toolbox' for measurement protocols and analysis for forest owners interested in low-cost, time-efficient methods of understanding microsite heterogeneity in their forest soils to guide management practices. The research addressed the three main questions: The impact of various environmental factors on apparent electrical conductivity (ECa), the ability of ECa to characterise soil texture and moisture across forested catchments, and the effectiveness of quasi-3D inversion software in capturing the spatial heterogeneity of forest soils in three dimensions.
To answer the first question, measurements were taken on forest litter thickness, gravimetric water content, density, soil temperature, ambient temperature, instrument temperature, and instrument voltage. The study found no significant linear relationship between ECa and these environmental factors, indicating that a correction factor for drift in ECa caused by temperature and voltage variations was not required. The insulating effect of forest soils, the forest canopy, and the instrument's housing played a role in maintaining stability. In addition, there was no significant effect of the presence or absence of forest litter on ECa, which was most likely due to the structure and makeup of forest litter, indicating that EMI technology could predict soil properties without considering the effect of forest litter.
Questions two and three aimed to evaluate the effectiveness of using apparent electrical conductivity and modelled electrical conductivity (ECm) as predictors for soil properties, including gravimetric water content (GWC), the electrical conductivity of a 1-part soil to 5-part water solution (ECe1:5), and the percentages of clay (CLAY), fine sand (FSAND), and medium sand particles (MSAND). Firstly, generalised linear mixed-effects models (GLMERs) were employed to assess the measured variables' main effects and interaction effects on ECa and ECm and the within and between site variability as a random effect. The GLMERs demonstrated that incorporating multiple predictor variables reduced unexplained variability, with specific interactions, such as GWC and ECe1:5, playing crucial roles in explaining ECm variability at particular depths. However, multicollinearity issues were observed, primarily driven by the GWC-ECe1:5 interaction. The study also discussed the findings of 3D inversion maps of ECm, which provided detailed insights into spatial distribution patterns, particularly when overlaid with topographic and soil variable data. Secondly, one-dimension and three-dimensional maps were produced and overlaid onto base maps of each catchment to identify spatial patterns within each catchment related to soil texture and moisture using standard kriging in Arc GIS Pro software and custom EM4Soil software designed to interpolate one-dimensional ECa measurements into three dimensions.
Finally, the research delved into the implications of these findings for forest owners and their management practices. It emphasised that while ECa technology is a valuable tool in predicting forest soil heterogeneity, it should not be used in isolation, and soil sampling and validation remain essential. The study recommended using EMI as a time and cost-effective tool for understanding soil heterogeneity, offering repeatable and non-destructive measurements for informed land use decisions. Overlaying spatial maps with additional geospatial data was recommended to comprehensively understand soil variability within catchments.

year: 2023

title: Maintenance of cyanotoxin production by cryopreserved cyanobacteria in the New Zealand culture collection

authors: Wood, Susanna A.

subjects: dimethyl sulfoxide

abstract: A culture collection of freshwater planktonic and benthic cyanobacteria collected from sites across New Zealand has been established at the Cawthron Institute, Nelson, New Zealand. Limited resources led to uncertainty regarding the long-term maintenance of this collection. The present study demonstrates cryopreservation to be a viable method for long-term storage of cyanobacteria. Seventeen of 20 strains evaluated were successfully cryopreserved using the permeating cryopreservation agent dimethyl sulfoxide (Me2 SO), at a final concentration of 15% (v/v). Cyanotoxin analysis was undertaken on selected strains known to produce microcystins, nodularin, anatoxin-a, and saxitoxins. All strains retained their ability to produce these toxins following cryopreservation.

text: Maintenance of cyanotoxin production by cryopreserved cyanobacteria in the New Zealand culture collection A culture collection of freshwater planktonic and benthic cyanobacteria collected from sites across New Zealand has been established at the Cawthron Institute, Nelson, New Zealand. Limited resources led to uncertainty regarding the long-term maintenance of this collection. The present study demonstrates cryopreservation to be a viable method for long-term storage of cyanobacteria. Seventeen of 20 strains evaluated were successfully cryopreserved using the permeating cryopreservation agent dimethyl sulfoxide (Me2 SO), at a final concentration of 15% (v/v). Cyanotoxin analysis was undertaken on selected strains known to produce microcystins, nodularin, anatoxin-a, and saxitoxins. All strains retained their ability to produce these toxins following cryopreservation.

year: 2008

title: Māori child rearing and infant sleep practices

authors: Jones, Horiana Majorie

abstract: Sleep is important to a healthy lifestyle for parents and children, and having effective ways of putting a child to sleep contributes significantly to mental and physical wellbeing. Cultural groups around the world have developed a variety of approaches to this task, for example, rocking, co-sleeping, bed-sharing, breastfeeding to sleep, and encouraging infants to self soothe through various methods of infant sleep training. In New Zealand the continuation of traditional Māori approaches to infant sleep, e.g. co-sleeping, bed-sharing, responsivity to infant cues have been over-shadowed by its negative association with sudden infant death syndrome (SIDS) and dependence on parent interaction when initiating infant sleep. In this study, we were interested in the approaches Māori parents used to put their pēpi (child, 2 months-2 years of age) to sleep and the various factors that have influenced these approaches. Data were collected through online surveys (n =58) and face-to-face interviews (n =10) with Māori parents. Survey results indicated that being held and breast or bottle fed to sleep were the most practiced techniques by Māori parents. Parent assisted approaches, e.g., rocking, feeding, lying with baby until they go to sleep, were the most practiced. Many parents planned for their babies to sleep separately but very few actually persisted with self-soothing approaches due to a number of factors, such as discomfort with listening to their babies cry, culture, whānau (extended families) influences safety, and convenience. The majority of participants expressed a desire for separate sleep; however, few within the interview group actually successfully practiced separate sleep regularly.

text: Māori child rearing and infant sleep practices Sleep is important to a healthy lifestyle for parents and children, and having effective ways of putting a child to sleep contributes significantly to mental and physical wellbeing. Cultural groups around the world have developed a variety of approaches to this task, for example, rocking, co-sleeping, bed-sharing, breastfeeding to sleep, and encouraging infants to self soothe through various methods of infant sleep training. In New Zealand the continuation of traditional Māori approaches to infant sleep, e.g. co-sleeping, bed-sharing, responsivity to infant cues have been over-shadowed by its negative association with sudden infant death syndrome (SIDS) and dependence on parent interaction when initiating infant sleep. In this study, we were interested in the approaches Māori parents used to put their pēpi (child, 2 months-2 years of age) to sleep and the various factors that have influenced these approaches. Data were collected through online surveys (n =58) and face-to-face interviews (n =10) with Māori parents. Survey results indicated that being held and breast or bottle fed to sleep were the most practiced techniques by Māori parents. Parent assisted approaches, e.g., rocking, feeding, lying with baby until they go to sleep, were the most practiced. Many parents planned for their babies to sleep separately but very few actually persisted with self-soothing approaches due to a number of factors, such as discomfort with listening to their babies cry, culture, whānau (extended families) influences safety, and convenience. The majority of participants expressed a desire for separate sleep; however, few within the interview group actually successfully practiced separate sleep regularly.

year: 2017