Spatial drivers of providing and receiving nature's contributions to people
Spatial drivers of providing and receiving nature's contributions to people
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at University of Canterbury
Spatial drivers of providing and receiving nature's contributions to people
(2024) O’Brien, Sophie Adelaide
Embargoed until March 2027
Land application of winery wastewater : implications for plant growth and soil quality
Land application of winery wastewater : implications for plant growth and soil quality
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at University of Canterbury
Land application of winery wastewater : implications for plant growth and soil quality
(2024) Nightingale-McMahon, Max
Winery wastewater (WW) is a high-volume biowaste that requires effective disposal systems that minimise environmental impacts and potentially capture value. In New Zealand, approximately 380,000 m3 of WW is generated annually, with the Marlborough region accounting for around 280,000 m3 yr-1. There is growing recognition of the need to improve current WW disposal practices. Land application of WW is a low-cost disposal method that could significantly reduce the environmental risks associated with direct discharge into surface and groundwater bodies. This thesis aimed to determine the likely short and long-term effects of irrigating WW to land at rates where the water and nutrients may be beneficial to soil and plants, with a focus on carbon (C) retention. The specific objectives were to: 1) Quantify how manipulation of WW and receiving soils may improve soil quality and C retention, 2) Determine if organic C (OC) in WW can increase soil C via direct sorption and under what conditions, 3) Quantify the fate of OC in terms of soil organic matter changes and losses via mineralization and leaching, and 4) Elucidate the C sequestration potential via vegetation growth in WW irrigation plots.
A field survey was conducted at three Marlborough vineyards to quantify loading rates and accumulation of WW nutrients in soil. The WW irrigation added ca. 1.8 t ha−1 yr−1 of Na and 4 t ha−1 yr−1 of total OC. WW application increased soil pH, phosphorus, and Na across sites compared to controls. However, soil C decreased under WW irrigation (mean 1.7%) relative to controls (2.3%), equivalent to a loss of ~100 t C ha−1 over 600 mm depth, despite WW adding 4 t C ha−1 yr−1. Findings recommend using K-based over Na-based cleaning chemicals to reduce sodicity. Focusing on C retention and sustainable vegetation growth could increase soil C stocks to offset emissions.
Equilibrium batch experiments aimed to quantify the adsorption capacity of an Anthrosol, representative of common soil types in New Zealand's wine regions, for OC in WW. The soil sorbed up to 1729-4165 mg C kg soil-1 from WW. Increasing WW pH from 5 to 7 led to increased organic C sorption. The use of Na-based cleaners and pH adjustment may increase OC sorption compared to K-based products, but the harmful effects of exchangeable Na on soil structure and plant health may negate potential benefits.
A glasshouse mesocosm experiment investigated changes in ecosystem C balance when WW was applied to Lolium perenne (perennial ryegrass). Irrigating WW resulted in the mesocosms being a net C sink, retaining approximately 327 g C m-2 compared to 84 g C m-2 for controls over 118 days. However, gains were mostly due to high C input from WW, with small leaching losses. Signs of necrosis were observed in WW-treated Lolium perenne, corroborated by decreased above-ground biomass production. Soil respiration could mineralise up to 40% of added C from WW during peak biomass production.
The impact of WW irrigation on nutrient dynamics and biomass production in four New Zealand native plant species (Phormium tenax, Coprosma robusta, Cordyline australis, Kunzea robusta) and Lolium perenne was investigated in a glasshouse pot trial. WW irrigation significantly increased soil pH, electrical conductivity, Na, and ammonium, and decreased nitrate. No significant differences in above-ground biomass were found for native species, but Kunzea robusta exhibited necrosis. Lolium perenne biomass significantly decreased under WW treatment. There were significant increases in Na in native plant foliage, with Kunzea robusta having the highest concentration. WW application resulted in increased leachate total C, Na, Mg, Ca, and electrical conductivity.
This thesis demonstrates that land application of WW can lead to accumulation of nutrients, particularly Na, in soil and plants. While OC in WW represents a potential resource for improving soil quality and C sequestration, the fate of this C requires further investigation as significant losses were identified in long-term WW application sites. The adsorption capacity of the studied soil for WW-derived organic C indicates loading limits to prevent leaching and infiltration issues. WW application to Lolium perenne resulted in a net C sink, but with reduced plant growth, indicating the need for appropriate application strategies. Native plant species exhibited differential responses to WW irrigation, with some showing potential for phytoremediation and C sequestration.
Future research should focus on developing regional WW application guidelines based on soil properties, assessing the long-term stability of adsorbed OC, investigating Na toxicity thresholds and phytoremediation potential of native species, and optimising C retention and biomass production in WW irrigation systems. Improving WW disposal practices through effective nutrient assimilation and promoting sustainable vegetation growth could contribute to the environmental and economic sustainability of New Zealand's expanding wine industry.
Uniformity is a myth : insights from Aotearoa New Zealand Pleurotus on intraspecific variation in fungal genotypes and phenotypes
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at University of Canterbury
(2024) Hera, David
The aim of my thesis is to contribute to our understanding of intraspecific variation in fungi through the study of five Pleurotus species in Aotearoa New Zealand, exploring phenotypic and genotypic variation by applying methodology spanning systematics, ecology, biology, genomics, conservation, and food science. Intraspecific variation drives evolution, breeding, and food production practices, with implications for conservation, pathogenicity, biotechnology, and agriculture. Although well-studied in animals and plants, few mycological studies have focused directly on intraspecific variation, despite its growing recognition in the field. Edible oyster mushrooms (Pleurotus) are ideal model organisms because they experience natural selection in the wild and artificial selection in cultivation.
As a foundation to assess phenotypic and genotypic variation in Pleurotus species of Aotearoa, I first conducted a phylogenetic study to clarify the species boundaries within the genus (Chapter 2). I constructed a multi-gene phylogeny using ITS, LSU, RPB1, RPB2 and Tef markers. I discovered a cryptic indigenous subspecies within P. pulmonarius and resolved taxonomic ambiguities around P. djamor in Aotearoa. Confusion over species boundaries has previously led to the importation of this species, which has a potential for invasion and hybridisation with indigenous species. These refined species boundaries have significant implications for conservation and biosecurity.
Building on the refined species boundaries, I assessed how vegetative and reproductive growth traits vary between and within species. This study included three clonal replicates of 104 strains of five Pleurotus species grown in controlled conditions (Chapter 3). I discovered that intraspecific trait variation matched or exceeded interspecific variation, and found remarkably high levels of variation between clonal replicates of strains. Cultivated strains displayed less intraspecific variation than wild strains, suggesting the impact of cultivation history on phenotypic variation. My findings stress the necessity of true biological replication in mycology and challenge conventional definitions of individuality.
To understand genotypic variation within a wild-collected fungus, I conducted population genomic analyses and the first Pleurotus pangenome analysis using 29 P. purpureo-olivaceus strains from across the South Island (Chapter 4). I found a highly conserved core genome and overall genetic homogeneity, which was contrasted by diverse mating type loci and a large accessory genome. Instead of multiple populations isolated by distance or topographical barriers, my findings support a single panmictic South Island P. purpureo-olivaceus population with unrestricted gene flow.
Variation in fungi occurs at many levels and affects conservation, biodiversity, food production, and biotechnology. Both fundamental research and practical applications of fungi can benefit from considering the range of phenotypes and genotypes rather than species means and reference strains. My work contributes to a holistic understanding of fungal species and individuality, advancing fungal biology and informing cultivation practices and strategies for biodiversity conservation in the face of global environmental change. The diversity of Pleurotus phenotypes supports the identification of productive strains for indigenous oyster mushroom cultivation to enhance agricultural resilience, although further research and collaboration with indigenous communities – iwi Māori – are essential to ensure appropriate benefit sharing.
Development of functional food with pea cooking water and the effect on human postprandial glycaemic response
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2024) Zhang, Yanyu
High GI carbohydrates are associated with several diseases, including diabetes, obesity, and cardiovascular disease (CVD). The rate of starch digestion and absorption significantly impacts metabolic responses. Slowly digestible carbohydrates are advantageous for managing metabolic disorders such as diabetes and hyperlipidaemia and are found in legumes, pasta, and whole-grain cereals. Peas, a high-quality protein source, are typically consumed after soaking and cooking. Pea cooking water is the by-product of split yellow peas, often regarded as an ideal egg white substitute in bakery products due to its emulsifying properties. Pea cooking water (PCW) was recently reported to be rich in proteins, fibres and micronutrients. However, current research has not specifically investigated the nutritional aspects of pea cooking water, although significant nutrient loss is known to occur during cooking.
This study investigated the potential of pea cooking water to manage glycaemic responses in carbohydrate-rich foods by examining its effects on human glycaemic levels as well as the structural and textural properties of these foods. This study examines the structural and nutritional modifications that occour to pasta when PCW or pea flour (PF) are incorporated into the formulation. The inclusion of freeze-dried PCW (PCWFD) in pasta significantly (P<0.05) reduced the optimal cooking time (OCT) and altered water absorption capacity due to its unique structural attributes. Compared to traditional wheat pasta, PCWP exhibited a lower OCT (P<0.05), reduced swelling index (P<0.05), and higher cooking loss when substituting 20% of semolina with PCWFD (P<0.05). Additionally, pasta substituted semlina with 10% and 20% PCWFD showed increased tensile strength and decreased cutting force (P<0.05), maintaining an intact microstructure and consistent particle size distribution.
The incorporation of PCWFD modified protein-starch network of the pasta. The modified protein-starch networks in PCWP and PFP resulted in slower glucose release and a lower glycaemic response (P<0.05). The study explored the impact of varying cooking times and PCWFD levels, finding that longer cooking times and higher PCWFD concentrations affect cooking loss and water absorption, influencing glycaemic response. PCWP performs comparably or better than traditional pea flour pasta in in vitro glucose digestion tests. The food matrix does not disrupt the effect of PCW in reducing and slowing glucose release, as demonstrated by comparisons with rice boiled in PCW versus normal water.
PCW incorporation significantly reduced postprandial glycaemic responses in human subjects (P<0.05), attributed to the high protein content and fibre effects on gastric emptying. The lower glycaemic index (GI) effect is also due to the higher protein content, lower starch content, and protein-starch interactions. Despite a fully gelatinized structure, PCWP maintain a reduced glycaemic response. These findings highlight the potential of PCW as a functional ingredient to enhance the nutritional profile of pasta, reduce glycaemic responses, and promote sustainable food processing practices. The present work addressed the potential health benefits of PCW to develop of functional food by investigating the effect on human postprandial glycaemic response. It represented a functional and innovative approach to food development while promoting environmentally sustainable practices.
Spatial agroecology: modelling multiple ecosystem services in periurban landscapes
Spatial agroecology: modelling multiple ecosystem services in periurban landscapes
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2024) Morris, Richard Minton
Urban growth and agricultural intensification share a common trait of reducing landscapes' capacity of producing the critical ecosystem services (ES) on which they depend. The objective of the work described in this thesis was to develop a spatially explicit ES-based design method for the configuration of landscapes to generate regulating ES. Literature review, which is described in Chapter 2, identified a nexus of four research fields - Ecological Urbanism, Landscape Ecology, ES science and agroecology - as an unexplored framework for this ES-based design approach. The method used in this work is described in Chapter 3, where a key flaw in current ES modelling tools forms the basis for a Geographic Information Systems (GIS)-based conceptual model, ESMAX. Present models are characterised by 'the biophysical gap', an oversight of spatial interactions between ES-supplying landscape components. This inhibits their application to spatial design i.e., the configuration of those components to enhance ES performance. ESMAX is structured around the fundamental natural phenomena of distance-decay as exhibited by all regulating ES, enabling an original method of quantifying and visualising regulating ES produced by different configurations of landscape components. The results of Chapter 3 conceptually validated the model and provided the data for Chapter 4, which proposed a model for assessing landscape multifunctionality (or simultaneous supply of multiple ES) from different landscape configurations. Importantly, the results for different configuration options generate a solution space with which to negotiate specific ES demands and specific contextual spatial constraints. Chapter 5 applied ESMAX and the solution space in an agricultural context. This spatial agroecological approach determined that different configurations of the same total area of trees in a 1 ha paddock produce markedly different levels of ES performance, and that this approach may be useful in supporting an adaptive transition from conventional agriculture to agroecologically based farming systems. Chapter 6 applied spatial agroecology to a 190 ha periurban development site, demonstrating how the same apportioned area of agroecological systems, when subdivided and distributed differently across the site, has a significant bearing on multiple ES production. This suggests that urgent consideration should be given not only to placing trees on farm, but how trees should be placed on farm. Similarly, it supports not only the integration of agriculture with urban systems, but the specific spatial design of agroecological systems to address the regulating ES demands of the urban system. The spatial agricultural approach outlined in this thesis highlights the potential for agroecology in the Anthropocene as a spatially effective source of multiple regulating ES to surrounding communities at various scales.
Using portfolio analysis to assess diverse agricultural landscapes under climate change: A case study in the Marlborough wine region
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2024) Barry, Michelle
Farmers and growers are increasingly aware of climate change related risks for their operations as they observe a greater frequency in extreme weather events and changes in crop growth cycles. While reactive adaptation by farmers to climatic variability has always occurred, this may not be sufficient in the long term when anticipatory and planned adaptation is required, e.g., changes in cultivar or the development of new markets. Geographical and biological diversification of agricultural production systems has been proposed as a potential climate change adaptation strategy. Understanding how alternative crops, land-uses and management practices will perform under future climates and deliver to stakeholder goals is critical before extensive land-use and practice change occurs. Developing this understanding is difficult due to the high degree of uncertainty of future climatic conditions and the ability of commonly applied economic analysis tools to account for this deep uncertainty. To address these challenges, this PhD developed a stakeholder centred climate change adaptation process that utilises Portfolio Analysis to identify diversified vineyard portfolios and characterised their riskiness across a range of climate change scenarios. In developing this process, the study applied a mixed methods framework, integrating qualitative and quantitative approaches. These included a literature review, stakeholder mapping, focus groups, biophysical assessment and economic modelling, integrated in a case study on Marlborough Sauvignon Blanc.The research found that Portfolio Analysis can be effectively integrated with social and biophysical science to develop diversified vineyard portfolios that are more robust against a range of possible climate futures, helping to inform decision making in the context of deep uncertainty. To accelerate adoption, adaptation needs to be integrated into wider wine business and industry decision making and strategy development. Recognising that adaptation sits alongside existing ambitions and priorities, particularly around environmental sustainability, is also critical.
A transdisciplinary approach to understanding the connections between soil and people, through food production
A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
(Lincoln University, 2024) Gillespie, Julie
There is a disconnect between soil, food, and people, that is being exacerbated as our populations become increasingly urban-based. This presents a ‘wicked’ challenge for soil and food security that soil science alone is unable to address. Resolving this issue requires understanding the extent and nature of the current (dis)connections, providing an opportunity to extend beyond the disciplinary boundaries of soil science. This research aims to develop an understanding of the (dis)connections between soil and people through the conduit of food in a place-based context by operating at the interface of mātauraka Māori (Māori knowledge) and soil science. This thesis provides two soil-centred examples of TDR in an Aotearoa New Zealand context, applying the He Awa Whiria (braided rivers) epistemological framework to guide the weaving of knowledges.
To develop insight into how soil science and mātauraka Māori can be woven together and gain an understanding of historical connections between soil, food, and people, a case study guided by the questions of Mana Whenua regarding their past horticultural land use at Pōhatu (Flea Bay), Te Pātaka o Rākaihautū (Banks Peninsula), is undertaken. In this study, mātauraka Māori identified likely māra (garden) sites in the bay with oral histories identifying features such as gravel additions to the soil to improve drainage and retain warmth. Analysis of soil horizons modified with rounded beach gravels identified phytoliths with a morphotype consistent with kūmara leaves. Undertaking this study has demonstrated the importance of relationships when weaving knowledges, and the benefits of recognising equal value of the knowledges involved.
Building on the results and learnings from the Pōhatu case study, a TDR methodology is applied to develop the place-based Food-Landscape Networks (FLN) framework, placing soil at its centre. The FLN framework applies a holistic approach to understanding the reciprocal connections between soil, food, and people in contemporary local food production systems. To assess the suitability of the FLN framework for understanding connections between soil, food, and people, it has been applied to three food-landscapes in Waitaha (Canterbury). Applying the framework makes visible the (dis)connections between soil, food, and people in three food-landscapes with the primary disconnection being people and soil across all three food-landscapes, as well as identifying where interdisciplinary collaboration is needed.
This thesis enhances understanding and demonstrates the importance of engaging with mātauraka Māori as a knowledge of equal value to soil science for addressing complex, soil-centred environmental challenges facing Aotearoa New Zealand. The application of the transdisciplinary FLN framework illustrates the complexity of understanding the reciprocal connections between soil and people, highlighting the limitations of soil science in understanding and addressing this disconnect alone. This signals the need for interdisciplinary approaches, nested within TDR, for consumer disconnects to be addressed. The co-production of knowledge by weaving knowledges together to assess and understand these connections provides an opportunity to connect, and reconnect, people with where food comes from to work towards soil and food security.