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: Brown bullhead catfish (ameiurus nebulosus) in Lake Taupo

authors: Barnes, Grant E.

subjects: brown bullhead catfish

abstract: Brown bullhead catfish (Ameiurus nebulosus) were first discovered in Lake Taupo during the early 1980s and are believed to have originated from an illegal liberation into the southern end of the lake. A native of the southern and eastern states of America, these catfish have been in New Zealand since 1878 and are now widespread throughout the Waikato region. In 1995 the population structure, abundance, age, growth rate and diet of catfish in the littoral zone (<5 m deep) of Lake Taupo were examined by setting fyke nets overnight in three different habitat types. A total of 6247 catfish was caught from 269 fyke-net sets (mean CPUE 23 fish net–1 night–1). Catfish abundance was greatest in shallow, sheltered, macrophyte-dominated bays, where the population was skewed towards small catfish (<150 mm FL). Adjacent rocky headlands and escarpments supported populations of large fish (>150 mm FL) and small fish. Low numbers of catfish across all size classes were caught from exposed sandy sites. The diet of catfish was size and habitat dependent. Small catfish (<150 mm FL) fed predominantly on chironomids, Cladocera, gastropods, caddisfly larvae, plant material and detritus. Larger catfish were found to prey to a greater extent on koura (Paranephrops planifrons), fish and terrestrial invertebrates.

text: Brown bullhead catfish (ameiurus nebulosus) in Lake Taupo Brown bullhead catfish (Ameiurus nebulosus) were first discovered in Lake Taupo during the early 1980s and are believed to have originated from an illegal liberation into the southern end of the lake. A native of the southern and eastern states of America, these catfish have been in New Zealand since 1878 and are now widespread throughout the Waikato region. In 1995 the population structure, abundance, age, growth rate and diet of catfish in the littoral zone (<5 m deep) of Lake Taupo were examined by setting fyke nets overnight in three different habitat types. A total of 6247 catfish was caught from 269 fyke-net sets (mean CPUE 23 fish net–1 night–1). Catfish abundance was greatest in shallow, sheltered, macrophyte-dominated bays, where the population was skewed towards small catfish (<150 mm FL). Adjacent rocky headlands and escarpments supported populations of large fish (>150 mm FL) and small fish. Low numbers of catfish across all size classes were caught from exposed sandy sites. The diet of catfish was size and habitat dependent. Small catfish (<150 mm FL) fed predominantly on chironomids, Cladocera, gastropods, caddisfly larvae, plant material and detritus. Larger catfish were found to prey to a greater extent on koura (Paranephrops planifrons), fish and terrestrial invertebrates.

year: 2003

title: Indigenous human rights and knowledge in archives, museums, and libraries: Some international perspectives with specific reference to New Zealand and Canada

authors: Morse, Bradford W.

subjects: indigenous records

abstract: This article highlights the extent to which international law has changed rapidly in recent years in relation to the rights of Indigenous peoples generally and in particular how this impacts upon the legal status of traditional knowledge and culture. It reviews the recognition of the unique legal status of Māori in Aotearoa and Aboriginal peoples in Canada in relation to self-determination and how their changing place within these nations are affecting the operations of museums, libraries, and archives as case studies, illustrating some of the key legal and practical challenges that now impinge upon the work of archivists and related professionals in many countries.

text: Indigenous human rights and knowledge in archives, museums, and libraries: Some international perspectives with specific reference to New Zealand and Canada This article highlights the extent to which international law has changed rapidly in recent years in relation to the rights of Indigenous peoples generally and in particular how this impacts upon the legal status of traditional knowledge and culture. It reviews the recognition of the unique legal status of Māori in Aotearoa and Aboriginal peoples in Canada in relation to self-determination and how their changing place within these nations are affecting the operations of museums, libraries, and archives as case studies, illustrating some of the key legal and practical challenges that now impinge upon the work of archivists and related professionals in many countries.

year: 2012