Research@Lincoln
Research@Lincoln is an open access institutional repository collecting the research produced by Lincoln University staff and students. You may also be interested in Data@Lincoln or Lincoln University Living Heritage.
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Item Restricted Introduction: indigenous self-governance in the Arctic States(Taylor & Francis, 2024-01-01)The theme of this special issue is indigenous self-governance in Arctic states. A common characteristic of the states that are partly located in the Arctic – Canada, Denmark, Finland, Norway, Russia, Sweden, USA – is that they all have indigenous peoples, and all have some form of self-government. There has been relatively little research on the similarities and differences between the sub-state autonomy structures within the Arctic states from a political science perspective (although with important exceptions, see below). This is somewhat surprising given the growing interest in the Arctic region during the last 15 years, where some of these autonomous units play an increasingly important role. This special issue asks how different are these self-governing units? How did they evolve into their current form? Do they have a distinct Arctic indigenous character?Item Restricted Probabilistic description of vegetation ecotones using remote sensing(Elsevier B.V., 2018-07)Ecotone transitions between vegetation types are of interest for understanding regional diversity, ecological processes and biogeographical patterns. Ecotones are seldom represented on vector, line-based vegetation maps, which imply an instantaneous change from one vegetation type to another. We use supervised, probabilistic classification of remotely sensed (RS) imagery to investigate the location, width and character of ecotones between acid Sandstone and alkaline Limestone fynbos on the Agulhas plain at the southern tip of Africa, known for rapid speciation of plants and exceptional plant biodiversity at the global scale. The resultant probability map, together with the probability graphs developed for a few transects across the transition, are able to map and describe (1) sharp, narrow ecotones (under five meters); (2) moderate ecotones that have a distinct band of transition (over a few hundred meters); and (3) complex ecotones that include slow transitions, interdigitated boundaries and outliers. The latter class of transitions include portions where vegetation types change sharply over a few meters, but due to the interdigitated boundaries they are mapped over hundreds of meters to a kilometre at a landscape scale. In this study area, our findings suggest that the character of the Agulhas limestone-acid ecotone is probably more complex than often noted. Moderate transitions and broad mosaics are difficult to indicate in a vector vegetation map, whereas RS probabilistic classifications can output images indicating core areas, important for key species and biodiversity pattern, and transitional zones, important for ecosystem processes and perhaps plant evolution, which distinction is important for conservation planning.Publication Restricted An investigation of systematic camera trap monitoring for kiwi (Apteryx spp.) : A thesis submitted in partial fulfillment of the requirements for the Degree of Doctor of Philosophy at Lincoln University(Lincoln University, 2023)Introduction: Kiwi (Apteryx spp.) are one of New Zealand’s national taonga/taoka (treasures) that are our responsibility and privilege to protect. To inform protective management, we need to monitor kiwi population responses to management, for which a non-invasive method that can detect all age classes has been lacking. Camera traps are non-invasive monitoring devices, which are increasingly used with recently developed analyses to monitor cryptic terrestrial species around the world. To apply these methods to kiwi, standardized methods need to be developed and benchmarked against existing methods. Aims: The aims of this study were to 1) summarise previous monitoring work on kiwi to develop a draft systematic camera trap monitoring method for kiwi, 2) determine optimal site selection and camera trap set-up, 3) determine optimal survey length and camera trap spacing for use with spatial presence-absence (SPA) analysis and identify whether realistic population estimates are obtained, 4) compare camera traps with a current noninvasive method using acoustic recorders to determine if they give realistic and comparable estimates when used with SPA, 5) compare camera traps with dog survey and an observer listening survey to assess kiwi population health, 6) trial alternative analyses for use with camera traps in high density sites, 7) investigate stereo cameras for their potential to add value to camera trap surveys. Materials and methods: We summarised the current literature on monitoring kiwi and the use of camera trap surveys. We deployed 34 camera traps over six seasons in Orokonui Ecosanctuary. We deployed 29 acoustic recorders and carried out detector dog surveys to compare the number of juveniles detected. We deployed 17 camera traps in Rotokare Scenic Reserve and 18 camera traps in the Cape Sanctuary to examine their effectiveness in high kiwi density areas. We constructed a stereo camera by chaining two off-the-shelf trail cameras together to trigger from one PIR sensor and briefly trialled the stereo camera at Orokonui. Results: Cameras were able to detect kiwi of all age groups and to provide credible population densities and trends. Kiwi detections can be maximised by using a detector dog team to select camera sites and through camera orientation. Comparable population estimates were obtained using spatial presence-absence (SPA) analysis with an optimal survey length of four months, during peak incubation, and optimal camera spacing of 350 m. Cameras and acoustic recorders gave comparable population estimates using SPA. Estimates were realistic based on matrix population model projection. Camera traps and detector dog surveys found a similar number of juvenile kiwi. Estimates obtained using Royle-Nichols analysis likely underestimated population size but correctly indicated population trend direction and magnitude, while the index-manipuation-index method did not give a biologically possible estimate of population density. The stereo camera method using two trail cameras was capable of giving surprisingly accurate bill measurements, but further work in necessary to achieve repeatability. Discussion and conclusions: Systematic camera trapping is capable of monitoring the whole kiwi population, including female and young kiwi that are usually under-recorded by other methods. Systematic camera trapping paired with spatial presence-absence analysis performed well in a low density population. Camera monitoring shows much promise as another useful noninvasive tool in the kiwi monitoring toolbox.Item Restricted Ovine KRT81 variants and their influence on selected wool traits of commercial value(MDPI, 2024-06)Keratins are the main structural protein components of wool fibres, and variation in them and their genes (KRTs) is thought to influence wool structure and characteristics. The PCR–single strand conformation polymorphism technique has been used previously to investigate genetic variation in selected coding and intron regions of the type II sheep keratin gene KRT81, but no variation was identified. In this study, we used the same technique to explore the 5′ untranslated region of KRT81 and detected three sequence variants (A, B and C) that contain four single nucleotide polymorphisms. Among the 389 Merino × Southdown cross sheep investigated, variant B was linked to a reduction in clean fleece weight, while C was associated with an increase in both greasy fleece weight and clean fleece weight. No discernible effects on staple length or mean-fibre-diameter-related traits were observed. These findings suggest that variation in ovine KRT81 might influence wool growth by changing the density of wool follicles in the skin, the density of individual fibres, or the area of the skin producing fibre, as opposed to changing the rate of extrusion of fibres or their diameter.Publication Open Access Ryegrass endophyte mixtures for improved animal health : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University(Lincoln University, 2024)In New Zealand, perennial ryegrass (Lolium perenne) with endophyte (Epichloë festucae var. lolii) is a standard ingredient of pastures where insect pests challenge the persistence of the ryegrass. Farmers currently have multiple ryegrass cultivar x endophyte strain combinations from which to choose the best match for their requirements. However, no single cultivar x strain combination provides both the highest insect protection and lowest occurrence of ryegrass staggers and heat stress in animals grazing pasture with endophyte. Furthermore, the current industry protocol for testing the safety of animals grazing a grass x endophyte combination involves exposing the animals to a simulated worst- case scenario and needs reassessment. This research aimed to examine the effects of endophyte diversity in perennial ryegrass on the health and performance of sheep using a modelling approach so that an animal response of any mixture could be predicted as a function of the mixture’s endophyte proportions, thus minimising the need for animal testing in the future. At Barenbrug Plant Breeding Station, Courtenay, Canterbury, eight pasture treatments of Maxsyn perennial ryegrass – seven that varied widely in sown proportions of three endophyte strains – nea3, nea12, and standard endophyte (SE) – and an endophyte-free control (nil), were tested over four experimental runs from February 2020 to December 2021. There were three monocultures (100% of each strain), three binary mixtures (50% of each of two strains) and one ternary mixture (33.3% of each strain) of endophyte based on a simplex centroid design. The eight treatments were randomised in three blocks of 0.156-ha plots. The animal responses of interest were ryegrass staggers, liveweight gain, heat stress, and diet selection of grazing sheep. The first experiment run was a test for ryegrass staggers in February 2020. Endophyte toxicity in late summer is typically near its annual maximum in Canterbury, so the timing of this run created a ‘worst-case scenario’ for ryegrass staggers. The pastures were managed in the previous spring so as to accumulate a large herbage dry matter (DM) mass (about 3700 kg DM/ha above a cutting height of 40–50 mm) of low nutritive quality feed (metabolisable energy (ME) = 8.7 MJ/kg DM and crude protein (CP) = 4.9%). The pasture available (kg DM/ha) was high enough for lambs to remain in the same plots for a 4-week testing period at a stocking rate of 64.1 lambs/ha. Ryegrass staggers was severe (score 4–5) in the lambs grazing the SE pasture after 8 days and in all other endophyte monocultures and mixtures after 22 days. Mixture models fitted to the staggers response data predicted the staggers score for any combination of sown endophyte proportions and identified an optimum of 65% nea3 and 35% nea12 which delayed severe staggers by 1 week. Ryegrass staggers was associated with tremorgenic alkaloids in the herbage above 40–50 mm: epoxy-janthitrem I of nea12 (1 ppm), paxilline and terpendole C of nea3 (0.1 and 1.2 ppm), and lolitrem B, paxilline and terpendole C of SE (2.2, 0.2, and 1.1 ppm). The second experimental run was a study of liveweight gain and ryegrass staggers under low toxicity conditions from September to December 2020. The spring pastures provided optimal conditions for liveweight gain and the stocking rate was kept consistent at 44.9 hoggets/ha. Pre-grazing pasture mass was ca. 1600 kg DM/ha, ME was 12 MJ/kg DM and CP was 20% above 40–50 mm. The average daily gain for all mixtures was 271 g/day over the first 4 weeks, and 20 g/day for weeks 4–8. The mixture models fitted to the liveweight gain data identified the optimum endophyte formulation that maximised liveweight gain to be a monoculture of nea12 so that the responses were equal to the monoculture performance in the first and second 4 weeks of grazing (292 and 25 g/day). Ergovaline, the alkaloid linked to suppressed liveweight, was present in nea3 and SE pastures at 0.32 and 0.16 ppm. Staggers scoring at the onset of symptoms after 10 weeks of grazing revealed mild staggers (score <2) in SE that persisted until the experiment ended at 12 weeks. The model analysis showed that any mixture containing at least 60% nea3 and up to 40% nea12 and/or SE would result in no staggers (score 0). Alkaloids associated with staggers were in lower concentrations compared to the summer test: 0.8 ppm of epoxy-janthitrem I was present in nea12 pastures while lolitrem B, paxilline, and Terpendole C were present in SE pastures at 1, 0.1, and 0.3 ppm. The third experimental run tested the assumption that endophyte strain proportions in the diet were equal to the sown proportions. Plot fences within replicates were removed, 51–56 hoggets were allocated to each replicate (40.9–44.9 hoggets/ha), and sward height decrease was measured 15 times between 15 February and 16 March 2021. Herbage mass, ME, and CP values at the beginning of grazing were circa 1400 kg DM/ha, 11.5 MJ/kg DM, and 11%. Analysis of variance showed no differences (P>0.05) in sward height decrease between sown treatments, including nil, over the whole grazing period. Mixture models of each measurement date and the average of all dates only showed differences (P<0.05) between linear terms (monocultures) on day 2 and further analysis confirmed the sward height decrease of SE was greater than nea12 (P<0.05), but not nea3. Quadratic terms (binary mixtures) were not different on any date. The mixture model analysis for the whole period predicted that a mixture containing 39% nea3 and 61% SE would maximise sward height decline despite lolitrem B concentrations of SE pastures being sufficient to cause ryegrass staggers (1.4 ppm) and ergovaline levels in nea3 pastures of 0.37 ppm. The lack of deterrence to these alkaloids indicates that animals were unable to differentiate between endophyte strains. The fourth experimental run was a repeat liveweight gain test followed by a heat stress study from October to December 2021. Pasture conditions were similar to the previous liveweight gain test at the start of grazing (ca. 2400 kg DM/ha, 12 MJ ME/kg DM, 15% CP). The same number of hoggets were used as in the previous liveweight gain study, but a higher starting liveweight and greater pre- grazing pasture mass resulted in greater liveweight gain across mixtures in the first and second 4 weeks (397 and 67 g/day) compared to the previous spring. The model analysis predicted an optimum mixture containing 16% nea3, 65% nea12, and 20% SE would result in maximum liveweight gains of 402 and 85 g/day in the first and second 4 weeks of the test. Data loggers attached to controlled internal drug release (CIDR) devices recorded vaginal temperatures in selected mixtures (nea3, nea12, nea3–nea12, and nil) during the final 8 days of the 8-week grazing period. Average temperature for the three mixtures was 39.07°C compared to 38.96°C in the nil endophyte control. Hoggets grazing nea12 had the lowest temperature of the three mixtures (38.94°C; P<0.05). Consequently, the mixture model predicted the optimum mixture would only contain nea12. Ergovaline concentrations were 0.7 and 0.5 ppm in nea3 and SE. An endophyte diversity model that included ryegrass staggers and liveweight gain responses from experimental runs 1, 2, and 4 as multivariates, predicted a mixture containing 77% nea12 and 23% nea3 would give the best overall combination of responses. Although temperature was not included in the model, the vaginal temperature response of this optimal mixture was predicted to be 39.02°C, just 0.06°C higher than the nil endophyte control. This thesis showed that endophyte mixtures can improve the health of grazing sheep and provides the industry with a new option for mitigating health issues associated with endophyte without searching for novel strains. Such mixtures would be best suited to scenarios where insect pest pressure requires the use of endophyte strains that can increase the risk of ryegrass staggers and/or suppressed liveweight gain. The endophyte diversity modelling approach can predict responses to sown strain proportions beyond those included in the experiment, reducing the number of animal entries required for testing.
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