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The potential global climate suitability of Kiwifruit bacterial canker disease (Pseudomonas syringae pv. actinidiae (Psa)) using three modelling approaches: CLIMEX, Maxent and Multimodel Framework
Get PDFIn recent years, outbreaks of kiwifruit bacterial canker (Pseudomonas syringae pv. actinidiae, Psa) have caused huge economic losses to two major global kiwifruit producers, Italy and New Zealand. To evaluate the potential global risk areas of Psa, three modelling methods (MaxEnt, CLIMEX and a Multi-Model Framework, including Support Vector Machine or SVM) were used. Current global occurrence data for Psa were collected from different sources. The long-term climate data were sourced from WorldClim and CliMond websites. The model results were combined into a consensus model to identify the hotspots. The consensus model highlighted the areas where two or three models agreed on climate suitability for Psa. All three models agreed with respect to the climate suitability of areas where Psa is currently present and identified novel areas where Psa has not established yet. The SVM model predicted large areas in Central Asia, Australia, and Europe as more highly suitable compared to MaxEnt and CLIMEX. Annual mean temperature and annual precipitation contributed most to the MaxEnt prediction. Both MaxEnt and CLIMEX showed the probability of Psa establishment increased above 5 °C and decreased above 20 °C. The annual precipitation response curve showed that excessive rain (>1200 mm/y) constrains Psa establishment. Our modelling results will provide useful information for Psa management by highlighting the climatically susceptible areas where Psa has not established, such as the USA, Iran, Denmark, Belgium and especially South Africa, where kiwifruit has been planted commercially in recent years
A summary of research results on pasture production responses to fertiliser and lime in the South Island hill and high country
No full textEarly research found that sulphur (S) alone was required on less weathered Semi-Arid and Pallic soils, but S and phosphorus (P) were required on more weathered and leached Brown soils. Sulphur was needed for legume growth before a response to P was measured on most soils, leading to the development of sulphur fortified superphosphate products. Later research determined the most effective particle size of elemental S in relation to frequency of application. More recent research showed that nitrogen (N) fertiliser could enhance resident pasture growth and added S improved the response. Molybdenum (Mo) was found to be the only trace element lacking for pasture growth. More recent research has shown that using lime to alleviate soil aluminium (Al) toxicity on acidic soils has allowed legumes to better establish and persist. Current gaps in data include; responses to P and S from legumes on easy slopes and shady aspects, S and lime on Pallic and Semi-arid soils on shady aspects, P and S requirements of pure legume swards, N for legume establishment, management to break down thatch, soil injection of lime and the use of test strips to detect lack of Mo. Such information can aid farmers in their selection of legume species and fertiliser and lime requirements
Using palaeolimnology to guide rehabilitation of a culturally significant lake in New Zealand
No full text1. Lakes are becoming degraded at an accelerating rate owing to human activity, andunderstanding their past ecology is necessary for lake management andrehabilitation. Palaeolimnology provides numerous methods that enable thehistorical state of lakes to be determined. New Zealand provides an ideal settingin which to do this as human modification of the landscape occurred later herethan in most regions of the world (approx. 1300 CE.
2. Lake Oporoa is a shallow lake that is highly significant to the local indigenousM aori community. This study used multiple proxy palaeolimnology to explorehow lake ecology shifted following M aori and European settlement in thecatchment, and how palaeolimnological data can be used to inform lakerehabilitation and conservation measures, alongside the desires of the indigenouscommunity. Sedimentary pollen, diatoms, bacterial communities, and elementaland hyperspectral imaging scanning were used to infer ecological changes in thelake and catchment from pre-human times to present.
3. Following M aori settlement (approx. 1620 CE) there was gradual vegetationchange and a rapid shift in diatom and bacterial assemblages, but not inphytoplankton pigments or sediment geochemistry. An increasing abundance ofdiatom taxa Discostella stelligera and Staurosirella cf. ovata indicates early nutrientenrichment. European pastoralism from approximately 1840 CE resulted infurther deforestation, and all proxies show evidence for enhanced primaryproductivity driven by a combination of nutrient enrichment and changing lakelevels, particularly since the 1960s. This has caused degradation in water qualityand is likely to have contributed to the decline in populations of tuna (eel,Anguilla spp.).
4. Conversations with local M aori, together with the palaeolimnological results,indicate that a culturally acceptable and realistic rehabilitation target for LakeOporoa aligns with ecological conditions in the 1950s. The palaeoecological data provide information to guide catchment and lake revegetation and other methodsof nutrient abatement, with the eventual aim of restoring culturally importanttuna and native fish populations
Crude oil and Islamic sectoral stocks: Asymmetric Tvp-Var connectedness and investment strategies
No full textIn this study we examine the asymmetric propagation of return spillovers between oil prices and Islamic stock prices at the sector level. To achieve that, we extend the work of Antonakakis et al. (2020a), by introducing measures of asymmetric dynamic connectedness based on a time-varying vector autoregressive (TVPVAR) model. Furthermore, in the spirit of Broadstock et al. (2020), we perform dynamic portfolio exercises based on common hedging techniques and the minimum connectedness portfolio approach to find out what better captures asymmetry. Our daily dataset includes Brent crude oil and nine Islamic sectoral stocks spanning from April 25, 2013 to September 2, 2021. The findings reveal that, with the exception of the early stages of the COVID pandemic, negative connectedness dominates the sample period, indicating that investors in Islamic markets tend to react more to negative news. In turn, the prevalence of positive connectedness in early 2020 suggests that Islamic markets were relatively resilient to the pandemic. Finally, the minimum connectedness portfolio approach captures asymmetry effectively thereby providing significant insights for portfolio management
The role of environmental processes and geographic distance in regulating local and regionally abundant and rare bacterioplankton in lakes
No full textBacteria are vital components of lake systems, driving a variety of biogeochemical cycles and ecosystem services. Bacterial communities have been shown to have a skewed distribution with a few abundant species and a large number of rare species. The contribution of environmental processes or geographic distance in structuring these components is uncertain. The discrete nature of lakes provides an ideal test case to investigate microbial biogeographical patterns. In the present study, we used 16S rRNA gene metabarcoding to examine the distribution patterns on local and regional scales of abundant and rare planktonic bacteria across 167 New Zealand lakes covering broad environmental gradients. Only a few amplicon sequence variants (ASVs) were abundant with a higher proportion of rare ASVs. The proportion of locally abundant ASVs was negatively correlated with the percentage of high productivity grassland in the catchment and positively with altitude. Regionally rare ASVs had a restricted distribution and were only found in one or a few lakes. In general, regionally abundant ASVs had higher occupancy rates, although there were some with restricted occupancy. Environmental processes made a higher contribution to structuring the regionally abundant community, while geographic distances were more important for regionally rare ASVs. A better understanding of the processes structuring the abundance and distribution of bacterial communities within lakes will assist in understand microbial biogeography and in predicting how these communities might shift with environmental change
Forecasting stock-market tail risk and connectedness in advanced economies over a century: The role of gold-to-silver and gold-to-platinum price ratios
No full textWe examine the predictive value of risk perceptions as measured in terms of the gold-to-silver and gold-to-platinum price ratios for stock-market tail risks and their connectedness in eight major industrialized economies using monthly data for the period 1916:02–2020:10 and 1968:01–2020:10, where we use four variants of the popular Conditional Autoregressive Value at Risk (CAViaR) framework to estimate the tail risks for both 1% and 5% VaRs. Our findings for the short sample period show that the gold-to-silver price ratio resembles the gold-to-platinum price ratios in that it is a useful proxy for global risk. Our findings for the long sample period show, despite some heterogeneity across economies, that the gold-to-silver price ratio often helps to out-of-sample forecast for both 1% and 5% stock market tail risks, particularly when a forecaster suffers a higher loss from underestimation of tail risks than from a corresponding overestimation of the same absolute size. We also find that using the gold-to-silver price ratio for forecasting the total connectedness of stock markets is beneficial for an investor who suffers a higher loss from an underestimation of total connectedness (i.e., an investor who otherwise would overestimate the benefits from portfolio diversification) than from a comparable overestimation
The evolution of monetary policy focal points
No full textWith near-zero policy rates becoming the norm in many advanced economies, the focus on long-term bond yields has strengthened considerably. The unconventional monetary policy decision by the Bank of Japan (BOJ) in September 2016 to explicitly target the ten-year Japanese government bond (JGB) yield institutionalized this process—by effectively creating a new monetary policy focal point. In this article, we study the importance of such focal points. Empirically, we also investigate how JGB benchmark maturities ranging from one to thirty years has affected other benchmark maturities over time. We find that the ten-year bond, indeed, became more influential in 2016. However, the effect was surprisingly short-lived. The results suggest that once financial market participants anchored their expectations of the ten-year JGB yield to the new BOJ target, the attention merely shifted towards even longer maturities. Contrary to the logic of the monetary transmission mechanism, we also find the short end of the yield curve has been an absorber, rather than transmitter, of influence during the last decades
Plant and dairy-based yogurts: A comparison of consumer sensory acceptability linked to textural analysis
Get PDFYogurt, readily available in plant and dairy-based formulations, is widely consumed and linked with health benefits. This research is aimed to understand the sensory and textural spectrum of commercially available dairy and plant-based yogurts. In a preliminary study, qualitative focus group discussions (4 groups; n = 32) were used to determine perceptions of 28 dairy and plant-based yogurts, identifying positive consumer perceptions of plant-based yogurts. A smaller subset of five spoonable and one drinkable yogurts—(Reference, Soy, Coconut, Cookies, Berry, and Drinkable) was subsequently selected for rheological and structural measurements, showing wide variations in the microstructure and rheology of selected yogurt samples. A quantitative blind sensory tasting (n = 117) showed varying yogurt acceptability, with Berry being the least-liked and Cookies being the most-liked yogurt, in terms of overall liking. The multi-factor analysis confirmed that compositional and textural elements, including protein content, gel firmness, and consistency coefficient, displayed a positive relationship with overall liking. In contrast, fat, sugar, and calories were negatively correlated to the overall liking. This research showed that texture and other compositional factors are significant determinants of the consumer acceptability of yogurt products and are essential properties to consider in product development
Grazing personality genetics of beef cattle in New Zealand rangelands : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
Get PDFThe uneven distribution of grazing cattle on pastures and rangelands has been of concern to livestock managers since the very early days of grassland science, not least because of the effects of grazing patterns on ecosystem functions and the sustainability of farming systems. Mountainous terrain imposes additional limitations for free-range grazing animals; which may avoid using vegetation at higher altitudes, on steeper slopes, or at greater distance from drinking water. Consequently, areas that are more easily accessible might be overgrazed, potentially leading to diminished ecological functions and reduced productivity. In recent years, animal personality theory has suggested that individual animals do not behave in the same way, and instead display consistent and distinctive sets of behaviours or ‘personality’. Animal personality could explain the distinct grazing patterns reported for free-range cattle, where individual animals have preference for certain habitats over others as a result of their behaviour. Preliminary studies have also reported associations between cattle gene regions (i.e., quantitative trait loci) and indexes that describe terrain use, suggesting the potential for genes that might explain variation in the grazing personality of beef cattle.
This thesis contains the following chapters:
A literature review about grazing behaviour and personality (Chapter 1). While grazing lands can offer a diverse range of forages, individuals within herds appear to prefer to graze some habitats and not others. They can have consistent differences in grazing patterns and occupy specific spatial domains, whilst developing tactics and strategies for foraging that are individual specific. Accordingly, in this chapter, a new understanding of grazing personality was developed. This entailed the development of a ‘grazing personality model’ (GP-model) that accounts for the personality of individual animals and for the collective behaviour of herds. The GP-model postulates that the grazing personalities of ruminants and other large herbivores are determined genetically and tempered epigenetically in interaction with the social and biophysical environments of the cattle. They may also reflect the emotional state of animals.
While the selection of one grazing personality may be adequate for homogeneous pastoral systems, the design of herds with a range of grazing personalities that are matched to the habitat diversity may be a better approach to improving the distribution of grazing animals, thus potentially enhancing ecosystem services and maximizing productivity.
An investigation of whether the movement of cattle and potential measures of their grazing personalities might be determined genetically, was undertaken in chapter 2. Genetic variation within the glutamate metabotropic receptor 5 gene (GRM5 ), a ‘grazing gene’ candidate was investigated. Associations between variation in that gene and variation in grazing personality behaviours (GP-behaviours) were tested with mature cows (n = 303) under free-range management during winter grazing in the steep and rugged rangelands of New Zealand. Grazing behaviours were calculated using data from global positioning system (GPS) tracking collars and, satellite-derived data. Eight GP-behaviours were fitted into mixed models to ascertain their associations with variant sequences and genotypes of GRM5 . Three new GRM5 variants (A, B and C ) were discovered and six possible genotypes were identified in the cattle studied. The mixed models revealed that A was associated (P < 0.05) with elevation range, home range and movement tortuosity. Similarly, GRM5 genotypes were significantly associated (P < 0.05) with home range and movement tortuosity, while trends towards association (P < 0.1) were revealed for elevation range and horizontal distance travelled. Most of the GP-behaviour models were improved when corrected with the ‘cow age-class’ factor and the results suggested that grazing personality might be stable when cows reached 4 years of age. Home range and movement tortuosity were not only associated with GRM5 variation, but also negatively correlated with each other (r = -0.27, P < 0.001). Thus, there seems to be a genetically determined trade-off between home range and movement tortuosity that may be useful in beef cattle breeding programmes that aim to improve the grazing distribution and utilisation of steep and rugged rangelands.
The results of Chapter 2 suggested that differences in grazing patterns are associated with nucleotide sequence variation in GRM5 . Association analyses require large datasets to detect genotype-phenotype associations, hence, most large-scale studies aiming to identify behavioural linkages with grazing genes typically apply random sampling from existing setups without a priori control over the genotypic composition of the sample. This can lead to unbalanced experiments with over or under representation of any given group analysed. An alternative approach (Chapter 3) was used to perform a discriminant analysis of a balanced dataset that was generated by under-sampling the larger dataset (n = 303) described in Chapter 2. In this analysis, a training dataset of mature cows (n = 80) that equally represented five of the six GRM5 genotypes and four farms were selected. The GP-behaviours were derived from 5-min GPS relocations measured over 15 d and the analysis aimed to select a combination of GP-behaviours that assist the identification of specific GRM5 genotypes, and to investigate behavioural differences between cows of various genotypes of this ‘grazing gene’. Two sets of grazing behaviours were selected to build quadratic discriminant models (QDMs) that achieved 87% of accuracy in ascertain GRM5 genotype with a training balanced dataset. An ‘exploration discriminant model’ built with the GP-behaviours related to elevation, slope and exploration correctly predicted the genotypes of 85% of the individuals of a testing dataset that were not included in the model’s training. MANOVA and ANOVA analyses highlighted the relative importance of GP-behaviours to discriminate between GRM5 genotypes and showed behavioural differences between cows of various GRM5 genotypes. The results extend the list of key behaviours linked to GRM5 in agreement with genotypephenotype associations between GRM5 and GP-behaviours reported in chapter 2 and in the literature. In conclusion, sets of key GP-behaviours might be useful for predicting the variation in putative ‘grazing genes’ and QDMs applied to small-scale experiments with balanced designs seems to be a promising approach for behavioural genetics.
Overall, this research proposed a model for individual and collective grazing personalities for cattle. The analysis suggested consistent differences between individuals associated with GRM5 variation. Furthermore, linkages between bovine GRM5 and key grazing behaviours may characterise specific genotypes and assist with their identification. The research provides a conceptual model of grazing personality and experimental evidence suggesting possible applications of behavioural genetics to potentially optimise the distribution of beef cattle in steep and rugged terrain. More research is however needed to validate these findings
Addressing mental health challenges in young farmers
Get PDFThis article provides some insight into the conditions and stressors that lead to rural mental health challenges in New Zealand and highlights some key strategies for combating the upward trend