title: Spatially resolved spectroscopy for detecting firmness and internal disorders of horticultural products

authors: Sun, Zhe (Jason)

abstract: Nondestructive detection of firmness and internal disorders are critical for New Zealand’s horticultural industry. Soft and internally defective products can result both in loss of revenue and the supplier’s reputation for quality. This thesis presents evaluation and development of spatially resolved spectroscopy (SRS) techniques aiming to improve the detection performance of these two quality parameters. Original contributions to literature include: (1) an assessment of an SRS reflectance system and a direct comparison of SRS and near-infrared spectroscopy (NIRS) on
firmness prediction, (2) quantified understanding of NIRS on detecting internal disorders in terms of light transport and detection limitations, (3) accurate estimations of optical properties of healthy and rotten onion flesh, and (4) development of an SRS transmittance system for detecting onion rot, with the aid of finite element method (FEM) simulations.
By applying SRS measurements on the same 100 ‘Royal Gala’ apples, this work showed that the NIRS interactance system slightly outperformed the SRS-based multispectral imaging (MSI) system when applied to the same samples. The cross validation prediction error was RMSECV = 6.99 N when compared with
penetrometer firmness. Before the SRS system can be considered for commercial implementation, SRS firmness system must be further developed to accommodate the conditions and speed (10 samples/second) of a produce grader and demonstrate better performance than the existing online sensors.
Internal disorders that are small and spatially confined inside produce are difficult to detect using NIRS due to its lack of spatial resolution, but improvement might be made with better locations of light illumination and detection on the sample, i.e. optical geometry. Two optical geometries were investigated for detecting small and localised vascular browning (VAB) disorders in ‘Braeburn’ apples. Monte Carlo (MC) simulations indicated that the 180° transmission geometry allowed the light to travel much further than that of the 90ºgeometry inside a sample. However, the sensor is still only sensitive to a small portion of the internal volume, which was
further validated by the poor results from the actual measurements. The 180° geometry system could detect 80% of defective apples with a misclassification rate of 21% for healthy ones.iv
An SRS system was then developed for detecting onion neck rots that are often small and localised to the stem end. The FEM software NIRFast was used to simulate light transport with absorption coefficients determined from juice transmittance measurements. The transmittance ratio of 728/805 nm was sensitive to the presence of the rot and was independent of the onion size. This ratio at different source locations formed a spatial profile, which could indicate the size and location of the rots. Finally, the optical system was implemented using a lock-in amplifier for simultaneous measurements of the light of two lasers at 728 nm and 805 nm. A mechanical scanning system was used to investigate multiple source locations. A preliminary test of the system showed a substantial improvement on typical NIRS performance levels. Future work aims to achieve a similar measurement scheme, while the sample is moving at high speed on a grader.

text: Spatially resolved spectroscopy for detecting firmness and internal disorders of horticultural products Nondestructive detection of firmness and internal disorders are critical for New Zealand’s horticultural industry. Soft and internally defective products can result both in loss of revenue and the supplier’s reputation for quality. This thesis presents evaluation and development of spatially resolved spectroscopy (SRS) techniques aiming to improve the detection performance of these two quality parameters. Original contributions to literature include: (1) an assessment of an SRS reflectance system and a direct comparison of SRS and near-infrared spectroscopy (NIRS) on
firmness prediction, (2) quantified understanding of NIRS on detecting internal disorders in terms of light transport and detection limitations, (3) accurate estimations of optical properties of healthy and rotten onion flesh, and (4) development of an SRS transmittance system for detecting onion rot, with the aid of finite element method (FEM) simulations.
By applying SRS measurements on the same 100 ‘Royal Gala’ apples, this work showed that the NIRS interactance system slightly outperformed the SRS-based multispectral imaging (MSI) system when applied to the same samples. The cross validation prediction error was RMSECV = 6.99 N when compared with
penetrometer firmness. Before the SRS system can be considered for commercial implementation, SRS firmness system must be further developed to accommodate the conditions and speed (10 samples/second) of a produce grader and demonstrate better performance than the existing online sensors.
Internal disorders that are small and spatially confined inside produce are difficult to detect using NIRS due to its lack of spatial resolution, but improvement might be made with better locations of light illumination and detection on the sample, i.e. optical geometry. Two optical geometries were investigated for detecting small and localised vascular browning (VAB) disorders in ‘Braeburn’ apples. Monte Carlo (MC) simulations indicated that the 180° transmission geometry allowed the light to travel much further than that of the 90ºgeometry inside a sample. However, the sensor is still only sensitive to a small portion of the internal volume, which was
further validated by the poor results from the actual measurements. The 180° geometry system could detect 80% of defective apples with a misclassification rate of 21% for healthy ones.iv
An SRS system was then developed for detecting onion neck rots that are often small and localised to the stem end. The FEM software NIRFast was used to simulate light transport with absorption coefficients determined from juice transmittance measurements. The transmittance ratio of 728/805 nm was sensitive to the presence of the rot and was independent of the onion size. This ratio at different source locations formed a spatial profile, which could indicate the size and location of the rots. Finally, the optical system was implemented using a lock-in amplifier for simultaneous measurements of the light of two lasers at 728 nm and 805 nm. A mechanical scanning system was used to investigate multiple source locations. A preliminary test of the system showed a substantial improvement on typical NIRS performance levels. Future work aims to achieve a similar measurement scheme, while the sample is moving at high speed on a grader.

year: 2018

title: Urban forest restoration ecology: factors influencing native tree regeneration and practitioner decision-making processes

authors: Busbridge, Sarah

subjects: Urban ecology

abstract: Restoration ecology is a new and growing scientific field in the natural sciences. Typically restoration efforts have been focused in remote and rural landscapes. However, recently there has been a rise in the number of projects aimed at restoring native forests in urban environments. The long-term success of these projects depends on the sustainability of restoration plantings and their capacity to self-regenerate over time. Our scientific understanding of how to effectively restore functional, sustainable urban forests is increasing, yet we know little about mechanisms driving juvenile native tree regeneration and recruitment in these highly altered environments. Furthermore, ecological knowledge alone is insufficient to guide restoration outcomes in cities. Urban forests are socio-ecological systems and project outcomes are also influenced by the values and knowledge of restoration practitioners. In this thesis, I explore these ecological and social drivers of long-term urban forest restoration success in New Zealand.

In chapter 2 I investigate how drivers of juvenile native tree recruitment vary according to plant species successional status and growth stage. The long-term existence of restored forests depends on their capacity to follow the steps of ecological forest succession into maturity. It is crucial this includes recruitment of native tree seedlings into the sapling stage, especially for middle and late successional species. However, it is unclear whether the drivers that promote juvenile recruitment are generally applicable, or if they vary according to plant successional status and growth stage. Using a forest planting chronosequence approach and negative binomial generalised linear models, I investigated what drivers promote recruitment processes of early and mid-late successional native woody juveniles in 79 restored urban forests across nine New Zealand cities. I found that mid-late successional trees respond to different drivers than early successional species and the relative importance of particular drivers varies according to the trees growth stage. The effects of canopy cover appear generalizable across successional status but not growth stage, while the opposite is true for the effects of microclimate. Older forests host greater seedling abundance, and larger forest patch size is important for mid-late successional species. These results indicate that to promote urban forest successional progress and hence recruitment of native tree juveniles, management approaches should vary depending on restored forest age and site conditions.

The third chapter explores how restoration practitioners in Aotearoa (New Zealand) make decisions in their efforts to re-establish native urban forests and why there is a gap between science-based best-practice restoration and on-the-ground implementation. The science- practice gap is well-documented in the applied sciences, but little is known about how it manifests in the urban forest restoration context where there are multiple objectives and many diverse stakeholders involved. To remedy this knowledge gap, we administered an online survey to practitioners involved in urban forest restoration. We found there is a tenuous link between scientific knowledge and urban restoration practice due to breakdowns in knowledge transfer and barriers to implementation. When restoring, practitioners tend to prioritise planting or weed control over other vital elements such as project planning and quantifiable monitoring. Objectives are commonly broad, vague, and focused on restoration of simple structural ecosystem components but not important functional attributes. Results show that practitioners value interactions with ecology experts and fellow practitioners equally to traditional forms of science communication (e.g. journal articles) as sources of restoration knowledge. This chapter suggests that prioritising interactive, interpersonal science communication and encouraging collaboration between scientists and practitioners would help strengthen knowledge transfer. Additionally, providing practitioners with time- saving resources, adequate funding, and guidance to navigate socio-ecological constraints that arise in urban projects will improve restoration outcomes.

This thesis broadens our understanding of social and ecological drivers of urban forest restoration success and highlights opportunities for improving the efficacy of urban restoration efforts. This research allows us to develop restoration ecology theory and refine best-practice methods for restoration of native urban ecosystems in Aotearoa.

text: Urban forest restoration ecology: factors influencing native tree regeneration and practitioner decision-making processes Restoration ecology is a new and growing scientific field in the natural sciences. Typically restoration efforts have been focused in remote and rural landscapes. However, recently there has been a rise in the number of projects aimed at restoring native forests in urban environments. The long-term success of these projects depends on the sustainability of restoration plantings and their capacity to self-regenerate over time. Our scientific understanding of how to effectively restore functional, sustainable urban forests is increasing, yet we know little about mechanisms driving juvenile native tree regeneration and recruitment in these highly altered environments. Furthermore, ecological knowledge alone is insufficient to guide restoration outcomes in cities. Urban forests are socio-ecological systems and project outcomes are also influenced by the values and knowledge of restoration practitioners. In this thesis, I explore these ecological and social drivers of long-term urban forest restoration success in New Zealand.

In chapter 2 I investigate how drivers of juvenile native tree recruitment vary according to plant species successional status and growth stage. The long-term existence of restored forests depends on their capacity to follow the steps of ecological forest succession into maturity. It is crucial this includes recruitment of native tree seedlings into the sapling stage, especially for middle and late successional species. However, it is unclear whether the drivers that promote juvenile recruitment are generally applicable, or if they vary according to plant successional status and growth stage. Using a forest planting chronosequence approach and negative binomial generalised linear models, I investigated what drivers promote recruitment processes of early and mid-late successional native woody juveniles in 79 restored urban forests across nine New Zealand cities. I found that mid-late successional trees respond to different drivers than early successional species and the relative importance of particular drivers varies according to the trees growth stage. The effects of canopy cover appear generalizable across successional status but not growth stage, while the opposite is true for the effects of microclimate. Older forests host greater seedling abundance, and larger forest patch size is important for mid-late successional species. These results indicate that to promote urban forest successional progress and hence recruitment of native tree juveniles, management approaches should vary depending on restored forest age and site conditions.

The third chapter explores how restoration practitioners in Aotearoa (New Zealand) make decisions in their efforts to re-establish native urban forests and why there is a gap between science-based best-practice restoration and on-the-ground implementation. The science- practice gap is well-documented in the applied sciences, but little is known about how it manifests in the urban forest restoration context where there are multiple objectives and many diverse stakeholders involved. To remedy this knowledge gap, we administered an online survey to practitioners involved in urban forest restoration. We found there is a tenuous link between scientific knowledge and urban restoration practice due to breakdowns in knowledge transfer and barriers to implementation. When restoring, practitioners tend to prioritise planting or weed control over other vital elements such as project planning and quantifiable monitoring. Objectives are commonly broad, vague, and focused on restoration of simple structural ecosystem components but not important functional attributes. Results show that practitioners value interactions with ecology experts and fellow practitioners equally to traditional forms of science communication (e.g. journal articles) as sources of restoration knowledge. This chapter suggests that prioritising interactive, interpersonal science communication and encouraging collaboration between scientists and practitioners would help strengthen knowledge transfer. Additionally, providing practitioners with time- saving resources, adequate funding, and guidance to navigate socio-ecological constraints that arise in urban projects will improve restoration outcomes.

This thesis broadens our understanding of social and ecological drivers of urban forest restoration success and highlights opportunities for improving the efficacy of urban restoration efforts. This research allows us to develop restoration ecology theory and refine best-practice methods for restoration of native urban ecosystems in Aotearoa.

year: 2020

title: Indigenous challenges to enhance freshwater governance and management in Aotearoa New Zealand - the Waikato river settlement

authors: Te Aho, Linda

subjects: New Zealand

abstract: Co-management of environmental resources is an idea that has been developing for some time in Aotearoa New Zealand as a strategy that recognises Indigenous interests in the environment, and the different ways that people view the world. The contest for control of New Zealand's rivers has generally arisen from successive governments purporting to secure rights based upon English common law. Precepts of that law were completely foreign to the Indigenous Maori who had their own conceptions of rivers. Through the eyes of the Maori, rivers have their own life force, their own spiritual energy and their own powerful identities. Rivers are inextricably linked to tribal identities. Over time a raft of policies was employed and legislation passed by parliament in the name of development and the national interest which did not take into account Maori understandings of the river and its ecosystems, nor their rights, interests, or authority. Excluded from decision-making processes, Maori have long brought matters to the attention of courts by using any basis to assert our rights and interests, and to have our concerns about the deteriorating health and wellbeing of our rivers taken seriously. The search for redress has been relentless. The Resource Management Act 1991 formalised a range of legal rights, but such rights can be meaningless if presented as just one of many other considerations that decision-makers have to take into account. This article explores the notion of collaborative management and the development of co-management models as a background to the emergent Waikato River settlement ± a legal solution embedded in the Waikato-Tainui Raupatu Claims (Waikato River) Settlement Act 2010 that generates a more robust opportunity to bring to an end a paradigm of exclusion and usher in a new era that promises enhanced governance and management of a significant waterway.

text: Indigenous challenges to enhance freshwater governance and management in Aotearoa New Zealand - the Waikato river settlement Co-management of environmental resources is an idea that has been developing for some time in Aotearoa New Zealand as a strategy that recognises Indigenous interests in the environment, and the different ways that people view the world. The contest for control of New Zealand's rivers has generally arisen from successive governments purporting to secure rights based upon English common law. Precepts of that law were completely foreign to the Indigenous Maori who had their own conceptions of rivers. Through the eyes of the Maori, rivers have their own life force, their own spiritual energy and their own powerful identities. Rivers are inextricably linked to tribal identities. Over time a raft of policies was employed and legislation passed by parliament in the name of development and the national interest which did not take into account Maori understandings of the river and its ecosystems, nor their rights, interests, or authority. Excluded from decision-making processes, Maori have long brought matters to the attention of courts by using any basis to assert our rights and interests, and to have our concerns about the deteriorating health and wellbeing of our rivers taken seriously. The search for redress has been relentless. The Resource Management Act 1991 formalised a range of legal rights, but such rights can be meaningless if presented as just one of many other considerations that decision-makers have to take into account. This article explores the notion of collaborative management and the development of co-management models as a background to the emergent Waikato River settlement ± a legal solution embedded in the Waikato-Tainui Raupatu Claims (Waikato River) Settlement Act 2010 that generates a more robust opportunity to bring to an end a paradigm of exclusion and usher in a new era that promises enhanced governance and management of a significant waterway.

year: 2010