5,178 results for Lincoln University

  • The evolution of working capital management research

    Darun, Mohd R.; Roudaki, Jamal; Radford, Joseph J.

    Journal article
    Lincoln University

    This study aims to develop an understanding about the evolutionary process of Working Capital Management (WCM) research, explaining WCM in particular environments from the 1900’s until the present. The study discusses relevant studies in the literature, exploring the relevance of models, concepts or frameworks developed to serve managers needs in particular operating environments and speculating future research directions. The evolution of WCM and influencing factors illustrate the integrative nature of WCM, appears to be dynamic as changes in managerial focus would reflect how companies manage WCM components. However, the review reveals that the WCM literature unable to provide relevant information to explain WCM in current environment. The study is particularly value in making sense of WCM research today and likely future directions. The pathway of development while vital for research exposes needs and responds that is fundamental for forecast of future prospects of WCM.

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  • Computational investigation of Amyloid-β-induced location- and subunit-specific disturbances of NMDAR at hippocampal dendritic spine in Alzheimer's disease

    Liang, Jingyi; Kulasiri, Gamalathge D.; Samarasinghe, Sandhya

    Journal article
    Lincoln University

    In Alzheimer's disease (AD), dysregulation of intracellular Ca²⁺ signalling has been observed as an early event prior to the presence of clinical symptoms and is believed to be a crucial factor contributing to AD pathogenesis. Amyloid-β oligomers (AβOs) disturb the N-methyl-D-aspartate receptor (NMDAR)-mediated postsynaptic Ca²⁺ signalling in response to presynaptic stimulation by increasing the availability of extracellular glutamate as well as directly disturbing the NMDARs. The abnormal Ca²⁺ response can further lead to impairments in long-term potentiation (LTP), an important process in memory formation. In this study, we develop a mathematical model of a CA1 pyramidal dendritic spine and conduct computational experiments. We use this model to mimic alterations by AβOs under AD conditions to investigate how they are involved in the Ca²⁺ dysregulation in the dendritic spine. The alterations in glutamate availability, as well as NMDAR availability and activity, are studied both individually and globally. The simulation results suggest that alterations in glutamate availability mostly affect the synaptic response and have limited effects on the extrasynaptic receptors. Moreover, overactivation of extrasynaptic NMDARs in AD is unlikely to be induced by presynaptic stimulation, but by upregulation of the resting level of glutamate, possibly resulting from these alterations. Furthermore, internalisation of synaptic NR2A-NMDAR shows greater damage to the postsynaptic Ca²⁺ response in comparison with the internalisation of NR2B-NMDARs; thus, the suggested neuroprotective role of the latter is very limited during synaptic transmission in AD. We integrate a CaMKII state transition model with the Ca²⁺ model to further study the effects of alterations of NMDARs in the CaMKII state transition, an important downstream event in the early phase of LTP. The model reveals that cooperation between NR2A- and NR2B-NMDAR is required for LTP induction. Under AD conditions, internalisation of membrane NMDARs is suggested to be the cause of the loss of synapse numbers by disrupting CaMKII-NMDAR formation.

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  • Apparent acquired resistance by a weevil to its parasitoid is influenced by host plant

    Goldson, Stephen; Tomasetto, Federico

    Journal article
    Lincoln University

    Field parasitism rates of the Argentine stem weevil Listronotus bonariensis (Kuschel; Coleoptera: Curculionidae) by Microctonus hyperodae Loan (Hymenoptera: Braconidae) are known to vary according to different host Lolium species that also differ in ploidy. To further investigate this, a laboratory study was conducted to examine parasitism rates on tetraploid Italian Lolium multiflorum, diploid Lolium perenne and diploid hybrid L. perenne x L. multiflorum; none of which were infected by Epichloë endophyte. At the same time, the opportunity was taken to compare the results of this study with observations made during extensive laboratory-based research and parasitoid-rearing in the 1990s using the same host plant species. This made it possible to determine whether there has been any change in weevil susceptibility to the parasitoid over a 20 year period when in the presence of the tetraploid Italian, diploid perennial and hybrid host grasses that were commonly in use in the 1990’s. The incidence of parasitism in cages, in the presence of these three grasses mirrored what has recently been observed in the field. When caged, weevil parasitism rates in the presence of a tetraploid Italian ryegrass host were significantly higher (75%) than rates that occurred in the presence of either the diploid perennial (46%) or the diploid hybrid (52%) grass, which were not significantly different from each other. This is very different to laboratory parasitism rates in the 1990s when in the presence of both of the latter grasses high rates of parasitism (c. 75%) were recorded. These high rates are typical of those still found in weevils in the presence of both field and caged tetraploid Italian grasses. In contrast, the abrupt decline in weevil parasitism rates points to the possibility of evolved resistance by the weevil to the parasitoid in the diploid and hybrid grasses, but not so in the tetraploid. The orientation of plants in the laboratory cages had no significant effect on parasitism rates under any treatment conditions suggesting that plant architecture may not be contributing to the underlying mechanism resulting in different rates of parasitism. The evolutionary implications of what appears to be plant-mediated resistance of L. bonariensis to parasitism by M. hyperodae are discussed.

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  • Assessing biomass yield of kale (Brassica oleracea var. acephala L.) fields using multi-spectral aerial photography

    Fourie, Jaco; Werner, Armin; Dagorn, N.

    Conference Contribution - Published
    Lincoln University

    Aerial images were taken in June 2014 with a multispectral VIS/NIR camera of the canopy from 14 kale (Brassica oleracea var. acephala L.) fields in Canterbury, New Zealand before this forage was grazed by cows. Images were taken at 716m and at 1,372m flying altitude. Calculating the Green Normalised Difference Vegetation Index (GNDVI) from green and NIR channels proved to be the best representation of yield (dry matter) variation from manual biomass cuts in these fields. Several hundreds of individual images covering parts of the fields were semi-automatically stitched to composite images covering full blocks of fields. Highest coefficients of variation (CV) of GNDVI values in a field are linked with low yield averages, often found at vary patchy fields (CVs of 20%). High yielding fields were less patchy and had CVs of less than 8%. A non-linear calibration curve was derived from the presented data. This functional relationship can explain 70% of the variance of the measured biomass yield data with reflection data of the canopy from these fields. This explaining power does not change when data from aerial images from higher altitudes were analysed. This independency of the preliminary model from height will allow using such an approach with standard high resolution cameras from various platforms (e.g. conventional aircraft, UAV/RPAS). Grouping the GNDVI data also allows delineating zones of similar yield levels within the forage fields. Such zoning enables farmers to adapt fertilizer application to the yield expectation of such zones or to manage the feed provision for their grazing cows in a spatial variable way across and between fields. The zones can be used for directing the manual sampling of biomass in cases when farmers deem estimations of biomass yield from aerial imagery to be inaccurate. For all these steps higher resolutions - associated with lower flying altitudes - are necessary.

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  • Active light sensing of canopies in crop management: Pastures and arable crops

    Roberts, Jessica; Schäbitz, B.; Werner, Armin

    Conference Contribution - Published
    Lincoln University

    A field spectrometer with an active light source was tested as a potential canopy sensor for dairy pastures (‘TEC-5’, YARA). To study the applicability of the sensor on pasture for the intensive radiation conditions of NZ we first conducted two sensitivity experiments. Additionally, a plot experiment was designed to calibrate sensors on ryegrass and white clover canopies fertilised with five different nitrogen amounts. The pasture plots were sensed with the spectrometer and results compared with measured biomass amount and nitrogen content.

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  • The influence of tannin and tannin with salivary protein on the volatility and the perceived intensity of ethyl hexanoate in a wine-like solution

    Yang, Yi

    Thesis
    Lincoln University

    The present study investigated the influence of tannin and tannin-mucin interaction on the volatility and the perceived aroma intensity of ethyl hexanoate at 300 µg/L. Data from the instrumental analysis showed that, without mucin, with the increase of tannin concentration, the headspace concentration of ethyl hexanoate was decreased (from 0 to 0.6 g/L of tannins) and then increased (from 0.6 to 16.2 g/L of tannins), in which at 16.2 g/L of tannins, the headspace concentration of ethyl hexanoate measured by HS-SPME-GC-MS was almost the same as found in the control sample that had no tannin. With mucin added to the samples, at higher tannin concentrations, the influence of tannins on the volatility of ethyl hexanoate was disrupted, resulting in the decreased volatility of ethyl hexanoate in the tannin samples with mucin. Sensory experiments were carried out using the method provided by ASTM E679. The results from the sensory experiments illustrated that increasing tannin concentration significantly increased the proportion of panelists (n=36, at 5% significant criterion) correctly choosing the tannin sample as the odd sample. The addition of mucin did not significantly change the sensory responses from the panelists. The group best estimated threshold (BET) values obtained before and after the addition of mucin did not show a significant difference (P>0.05). Therefore, it seemed that the perception changes detected by the panelists were not the result by the changes in the volatility of ethyl hexanoate.

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  • Development of a tomato/root knot nematode bioassay to screen beneficial microbes

    Aalders, L. T.; Minchin, Rhys F.; Hill, Robert A.; Braithwaite, Mark; Bell, N. L.; Stewart, Alison

    Journal article
    Lincoln University

    In common with other root knot nematodes Meloidogyne hapla is a serious plant pest. A rapid screening system for candidate microbes that benefit plant growth is a first step to developing screening bioassays in other plant–nematode systems. Cultures of M. hapla established on tomatoes were used to define the nematode damage function, and required bioassay duration for this plant-pest system, followed by scale-up to a glasshouse level. The quantities of Meloidogyne inoculum were chosen such that they would cause minor, moderate or severe plant damage; hence the degree of protection afforded by the microbes in bioassays could be readily evaluated. An inoculation rate of 3542 eggs/plant caused a significant reduction in shoot weight (30%) and an increase in root galling in excess of 50%. Percentage of root gall and root gall index were good indicators of nematode impact and provide a relatively quick method of assessment.

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  • Root zone losses are just the beginning

    Stenger, Roland; Clague, Juliet; Woodward, Simon; Moorhead, B.; Wilson, Scott; Shokri, Ali; Wöhling, T.; Canard, H.

    Conference Contribution - Published
    Lincoln University

    Minimising root zone losses has rightly been the main focus in recent years of measures to reduce agricultural land use impacts on freshwater quality. However, root zone losses are just the beginning, as far as managing to water quality limits is concerned. To be able to fully explore all potentially available management options, the entire ‘source → transport/transformation → impact’ chain needs to be understood. Where, when, and to what extent the root zone losses impact on freshwater bodies depends on the transport and transformation processes occurring in the vadose zone – groundwater – surface water continuum. We will be elucidating these processes using a combination of New Zealand and European examples. Understanding the ‘where’ requires investigation of the relative importance of the various subsurface flow paths (e.g. artificial drainage, interflow, shallow and deeper groundwater). Modelling of the subsurface hydrological system also helps to define the groundwater catchments that contribute water (and the nitrate it carries) to a monitoring site. These groundwater catchments do not necessarily match the topographically defined surface water catchments. Regarding the ‘when’, it is essential to consider the lag times, both in the vadose zone and in the groundwater system. Depending on the relative importance of the various flow paths, not all nitrate lost from the root zone will reach a surface water body at the same time. The resulting distribution of transfer times further complicates establishing the link between an impact observed in a surface water body and the land use activity that has caused it. As for the ‘extent’ to which root zone nitrate losses impact on freshwater bodies, it is critical to account for attenuation processes occurring along the flow paths. The two key nitrate attenuation processes are mixing/dilution and denitrification (occurring below the root zone). While groundwater denitrification has to date received relatively little attention in New Zealand, its potentially substantial role is recognised by many European drinking water supply companies and regulatory authorities. Accordingly, new policy initiatives in Europe have started taking account of the spatially variable nitrate reduction along the flow paths from the source to the impact zones.

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  • Multi-pronged approach to elucidate nitrate attenuation in shallow groundwater

    Stenger, Roland; Clague, Juliet; Woodward, Simon; Morgenstern, U.; Clough, Timothy J.

    Conference Contribution - Published
    Lincoln University

    It is increasingly being recognised in New Zealand that denitrification occurring in the groundwater zone can result in a substantial reduction of the nitrate load leached from agricultural land before this load can reach water supply wells or discharge into groundwater-fed surface water bodies. This natural attenuation process provides an ecosystem service with regard to the protection of the quality of our freshwater resources that to date has not been adequately accounted for. This is largely due to the major challenges involved in trying to understand and quantify the denitrification occurring in a particular water management zone. Based on the example of research conducted at the 'Waihora' site in the Lake Taupo catchment, we demonstrate a multi-pronged approach to elucidate the biogeochemical and hydrological controls on denitrification. The site is unique in New Zealand inasmuch as it has allowed investigating shallow groundwater underlying a pastoral hillslope in great detail using 11 multi-depth well clusters (comprising 26 wells in total). As denitrification is only active under mildly reduced conditions, a systematic approach to characterise redox conditions based on measured concentrations of dissolved oxygen, nitrate, dissolved manganese, dissolved iron, and sulphate provided fundamental initial information on the denitrification potential of the groundwater system. Determining stable isotope signatures of nitrate (δ¹⁵N, δ¹⁸O) and excess N₂ dissolved in the groundwater can help differentiate between denitrification potential and denitrification that has actually occurred in a given groundwater sample. As the interpretation of these data is strongly dependent on the understanding of the temporal and spatial variation of groundwater flows at the site, hydrological understanding proved critical. Tritium, chlorofluorocarbons, and silica were determined on selected groundwater samples to gain insight into the distribution of groundwater mean residence times ('ages') at the field site and slug tests provided estimates of the hydraulic conductivity of the different deposits found in the shallow groundwater system. Given that most biogeochemical and hydrological parameters analysed showed substantial spatial variation, hydrological modelling of the hillslope proved the only promising way to ascertain the overall effect denitrification may have on the groundwater nitrate discharges from this site.

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  • Fate of a dairy cow urine pulse in a layered volvanic vadose zone

    Barkle, G. F.; Stenger, Roland; Wöhling, T.; Moorhead, B.; Wall, A.; Clague, Juliet

    Conference Contribution - Published
    Lincoln University

    Nitrate-N leaching from dairy cow urine patches has been identified as one of the major contributors to groundwater contamination and degradation of surface waters in dairying catchments. To investigate the transport and transformations of nitrogen (N) originating from urine, fresh dairy cow urine was collected, amended with the conservative tracer chloride (Cl) and applied onto a loamy sand topsoil, underlain by gritty coarse sands and pumice fragments in the lower part of the vadose zone. The fluxes of the different N components and the conservative tracer leaching from the urine application were measured at five different depths in the vadose zone using three Automated Equilibrium Tension Lysimeters (AETLs) at each depth (max. 5.1 m). The uppermost part of the saturated zone was also monitored for the leached N and Cl fractions from the urine application. Textural changes and hydrophobicity in the vadose zone materials resulted in heterogeneous flow patterns and a high variability in the N and Cl masses captured. All three forms of potentially leachable N from the urine – organic-N (org-N), ammonium-N (NH4-N) and nitrate-N – were measured at the bottom of the root zone at 0.4 m depth. At the 1.0 m depth, effectively all of the captured N was in the mobile nitrate-N form. In the lower part of the vadose zone at 4.2 m, 33% of the applied urine-N was recovered as nitrate-N. This fraction was not significantly different from the corresponding fraction measured at the bottom of the root zone, indicating that no substantial assimilation of the nitrate-N being leached from the root zone was occurring in this vadose zone.

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  • Effects of UV-B radiation on oxalate content of silver beet leaves

    Presswood, Hannah; Hofmann, Rainer; Savage, Geoffrey P.

    Journal article
    Lincoln University

    Silver beet (Beta vulgaricus var. cicla) a common vegetable in New Zealand is known to contain high levels of oxalates in the leaves. Silver beet plants were grown in a field trial under glass and perspex sheets which filtered sunlight reaching the plants. After eight weeks of growth, the plants were harvested and the total, soluble and insoluble oxalate content of the leaves of the plants grown under the two filter treatments and a no-frame control were measured. Perspex allowed the transmission of UV-A, UV-B and photosynthetically active radiation (PAR), whereas glass excluded UV-B radiation. No significant differences between the perspex treatment and the no-frame control were observed when the data was compared on a wet matter (WM) or dry matter (DM) basis. Shielding the growing plants with glass significantly reduced the total oxalate and soluble oxalates to 83 and 84% respectively when compared to the perspex and no-frame treatments.

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  • Management zone delineation in arable crop systems

    Ekanayake, Dinanjana; Roberts, Jessica; Royal, A.; Bennett, L.; Werner, Armin

    Conference Contribution - Published
    Lincoln University

    Management Zone Delineation (MZD) could be of increasing importance for its economic and environmental benefits through varying rates of crop inputs to meet site-specific demands across individual fields. However, research on MZD in arable cropping systems is limited in New Zealand. Previous work from Lincoln Agritech Ltd. presented the benefits of Precision Agriculture for large scale farmers and contractors using yield, soil and aerial images to adopt Variable Rate Application of seeds, fertilizer and agro-chemicals. Furthermore, improved irrigation efficiency in wheat and maize cropping systems and maize zone delineation using Active Light-Nitrogen sensor, NIR camera technology and SPAD chlorophyll meter, were studied. The objective of the presented project is to develop methods and tools to identify optimal N supply rate for maize production with the emphasis on management zones and site adapted plant population densities in New Zealand. Two rain-fed maize fields from Waikato and one irrigated field from Canterbury were selected for field experiments. Yield and elevation data in 2013 and 2014 collected with a John Deer 7050 Series Self-Propelled Forage Harvester. Data analysis and mapping of management zone were done in Esri, ArcGIS 10.2.2. software. VESPER 1.6 free version from Australian Centre for Precision Agriculture was used to interpolate the data. Three management zones with low, medium and high yield potential were derived in the final map. Satellite images from Google Earth Archive of previous years were also used to delineate field boundaries and management zones. A strip-plot experimental design with 3 replicates was allocated to each management zone at each field. Three treatment levels of N fertilizer: farmer’s best N-fertilization practice, +35% and -35% were applied using calculated N-fertilizer demand prescription maps with an 8-row VRA fertilizer spreader. We expect that soil electrical conductivity field survey data, compatibility of yield data and prescription maps between different software packages, and the inclusion of annual yield data would improve the discriminating power of the various approaches.

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  • Effects of whole body vibration on glycemic indices and peripheral blood flow in type II diabetic patients

    Manimmanakorn, Nuttaset; Manimmanakorn, Apiwan; Phuttharak, W.; Hamlin, Michael J.

    Journal article
    Lincoln University

    Background: Whole body vibration (WBV) training is a regime of training on a vibration platform that provides oscillatory movement to the body. Vibration training may be a potentially useful therapeutic strategy to control diabetes and its complications. This study aimed to evaluate the effect of WBV on glycemic indices and peripheral blood flow in type II diabetic patients. Methods: A parallel group clinical trial was conducted with 1:1 allocation ratio at Khon Kaen University between February and May 2010. The study included diabetic patients receiving diet or oral medication control over the previous year and excluded patients with serious medical and musculoskeletal disorders. Forty type II diabetic patients [14 males, 26 females, 63.2 (7.7) y, mean (SD)] were randomised into two groups (WBV and control) by computer software using a block of four design. The WBV group was given two sets of six one-minute vibration squats, three times per week for twelve weeks. The control group maintained their normal physical activity levels. The primary outcome was the patients glycemic indices. Results: We found no significant difference in glycosylated haemoglobin (HbA1c), fasting blood sugar, insulin level and insulin sensitivity between WBV and control groups. Compared to the control group, WBV training resulted in a substantial reduction in resting diastolic blood pressure -7.1 mmHg (95% CI: -10.9, -3.3, P = 0.001) and peak systolic velocity -7.3 cm.sec⁻¹ (95% CI: -14.7, -0.03, P = 0.049), but made little difference to resting heart rate, systolic blood pressure, end diastolic velocity, and popliteal artery diameter. Conclusion: Whole body vibration improved resting diastolic blood pressure and peak systolic velocity, however, any beneficial effect of WBV on glycemic indices remains unclear.

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  • An exploratory investigation into human resource practices and employee retention outcome in the Malaysian ICT industry

    Gill, Parveen

    Thesis
    Lincoln University

    Author name as given on title page: Parveen Kaur Sukhdarshan Singh

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  • Combined effects of cotyledon excision and nursery fertilization on root growth, nutrient status and outplanting performance of Quercus variabilis container seedlings

    Shi, W.; Bloomberg, Mark; Li, G.; Su, S.; Jia, L.

    Journal article
    Lincoln University

    Artificial excision of the distal part of acorns in order to promote germination is well researched in oak seedling cultivation studies. However, studies of combined effects of cotyledon excision and nursery fertilization on container seedlings are lacking, especially for seedling root growth and outplanting performance. This study aimed to explore the main effects of cotyledon excision on Quercus variabilis seedling emergence characteristics and demonstrated the combined effects of cotyledon excision and nursery fertilization on seedling quality to improve Quercus variabilis seedling outplanting performance. Four cotyledon excision treatments and two classes of nursery fertilization were implemented. Seedling emergence was noted every week after sowing. Seedling dry mass, morphology, and nutrient status were assessed at the end of the nursery season. After the first outplanting season, the aforementioned measurements along with seedling survival were determined once again. The results showed that cotyledon excision generally induced greater and more rapid seedling emergence, but did not affect shoot emergence synchronicity. The highest total emergence and emergence rate occurred with Intermediate excision (1/2 of the distal end of acorn was excised). Effects of nutrient loss due to cotyledon excision on seedling quality and outplanting performance were somewhat compensated by nursery fertilization. Nursery fertilization promoted dry mass increment (the net increment from T₀ to T₂ for dry mass) for excised seedlings after outplanting, resulting in better performance for Slight (1/3 of the distal end of acorn was excised) and Intermediate excision treatments in the field. Thus we conclude Intermediate excision combined with reasonable nursery fertilization can be recommended for production of nursery grown seedlings for afforestation.

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  • Grapevine phenology in France: from past observations to future evolutions in the context of climate change

    García de Cortázar-Atauri, I.; Duchêne, E.; Destrac-Irvine, A.; Barbeau, G.; De Rességuier, L.; Lacombe, T.; Parker, Amber; Saurin, N.; Van Leeuwen, C.

    Journal article
    Lincoln University

    Aim: Phenology is a key factor in explaining the distribution and diversity of current vineyards in France. This work has the objective to summarize the different studies developed in France to analyze grapevine phenology. Methods and results: Several topics are presented: a general description of all historical databases and observatory networks developed in France during the last 70 years; an overview of the different models developed to calculate the main phenological stages; an analysis of the main results obtained using these models in the context of studies of climate change impacts on viticulture in France; and finally a general discussion about the main strategies to adapt the phenological cycle to future climate conditions. Conclusion: This review emphasizes that even if phenology is not the only trait to be considered for adapting grapevine to climate change, it plays a major role in the distribution of the current variety x vineyard associations. Significance and impact of the study: It is therefore critical to continue to study phenology in order to better understand its physiological and genetic basis and to define the best strategies to adapt to future climatic conditions.

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  • The Brandenburg Coppice

    Brandenburg, Bill

    Book
    Lincoln University

    Before discussing the rationale behind planting and managing a coppice, the term itself should be more closely defined. In various locations and amongst various groups of English speaking people a "coppice" or “copse" may mean undergrowth in a forest or a small group of trees and shrubs but also trees that are to be used for coppicing. The verb "to coppice'0 is however generally taken to mean the harvesting of trees by cutting them off near ground level and allowing them to regrow. In the context of this booklet I propose to attach this latter meaning to the words "coppice" and "coppicing”. This is not to exclude other functions such a coppice may have in the landscape or ecologically, as, for instance, provision of shelter, sanctuary for biological pest control organisms, supply of pollen and nectar for bees, beautification, etc. There is a wide range of uses available for trees harvested by coppicing and amongst these are drought fodder for livestock, fuelwood, canes for basketry, poles for fencing and fruitgrowing trellises and, last but not least, high quality timber for artwork, furniture making, parts of implements including wheels and so on. Some of the uses listed for coppicewood are also fulfilled by timber from various forms of plantation forestry. This tends to be carried out under commercial conditions favouring high outputs per unit area. To achieve this, accepting high establishment costs and - as a consequence of this - seeking high market returns quickly without much consideration for maintaining future production, is the rule. Purposes outside the immediate commercial target such as ecological or recreation ones are seldom considered.

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  • Developing a framework for growth modelling in a managed southern black beech forest

    Ganivet, E.; Moltchanova, E.; Bloomberg, Mark

    Journal article
    Lincoln University

    Background: A model of individual tree growth using simple predictors in a managed black beech (Fuscospora solandri (Hook.f.) Heenan & Smissen) forest could provide a useful tool for predicting future stand characteristics. Methods: Data from permanent sample plots were used to develop a framework for modelling individual tree growth in Woodside forest, a managed black beech forest in north Canterbury (New Zealand). We tested three mixed-effect models to identify effects of sites, treatment (thinnings), individual tree size and competition on tree growth rates. Results: A power function amended with variables specifying stand basal area and thinning treatment was best suited for black beech, explaining about 55% of the variation in growth rates. Treatment history (thinnings), as well as the individual tree size and the stand basal area, strongly affected tree diameter growth. Only 3% of the variation in diameter growth rates was explained by plot-specific effect which was less than observed in earlier studies. Conclusions: All predictor variables (management history, individual tree diameter and stand basal area) are quite simple to measure in the field and could be easily used to predict diameter increments in managed or unmanaged forests. A limitation of our study was that available growth data in Woodside were from small plots, focused on a small number of trees and a narrow range of diameters. However, our results are a good starting point, providing a promising framework for further modelling of tree growth in Woodside forest from new permanent plot data.

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  • The Forgotten Islands: Monitoring tourist numbers and managing tourism impacts on New Zealand's Subantarctic Islands

    Stewart, Emma; Espiner, Stephen R.; Liggett, D.; Taylor, Z.

    Journal article
    Lincoln University

    Situated to the south of New Zealand in the Southern Ocean are the New Zealand Subantarctic Islands, comprising the Auckland, Campbell, Antipodes, Snares and Bounty Islands. Sometimes referred to as the ‘Forgotten Islands’, these island groups are among the most remote and hostile within New Zealand waters. Yet, as they harbour some of the country’s most unique biodiversity and contain some of the world’s least modified landforms, they were recognized in 1998 with the designation of World Heritage Area status. It is not surprising therefore that the Islands have long appealed to visitors wishing to explore and understand the Islands’ rich natural and cultural environments. Typically, fare-paying tourists arrive by sea in small- to medium-sized expedition-style cruise vessels, although in recent years, the number of small vessels, such as yachts and sail boats, has increased. The most recent Conservation Management Strategy (2016) proposes developing and implementing a visitor monitoring programme to determine the effects of visitors on the natural and cultural environment, as well as on the visitor experience itself. However, there is only piecemeal data published on visitor numbers (especially since the mid-1990s) upon which to base visitor monitoring, and there is only limited evidence regarding the range of possible impacts visitors may have, including direct and indirect impact on wildlife, soils, and vegetation. In order to address this gap in knowledge, this case study draws on stakeholder interviews (n = 4), and a range of secondary sources (including visitor statistics from the Department of Conservation, tour operators and other published works) to provide an overview and update on visitation to the Islands, including site-specific data, an assessment of tourist impacts, and how impacts are currently monitored and managed.

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  • Heavy metals in suburban gardens and the implications of land-use change following a major earthquake

    Ashrafzadeh, S.; Lehto, Niklas; Oddy, G.; McLaren, Ronald G.; Kang, L.; Dickinson, Nicholas; Welsch, J.; Robinson, Brett

    Journal article
    Lincoln University

    Numerous studies have shown that urban soils can contain elevated concentrations of heavy metals (HMs). Christchurch, New Zealand, is a relatively young city (150 years old) with a population of 390,000. Most soils in Christchurch are sub-urban, with food production in residential gardens a popular activity. Earthquakes in 2010 and 2011 have resulted in the re-zoning of 630 ha of Christchurch, with suggestions that some of this land could be used for community gardens. We aimed to determine the HM concentrations in a selection of suburban gardens in Christchurch as well as in soils identified as being at risk of HM contamination due to hazardous former land uses or nearby activities. Heavy metal concentrations in suburban Christchurch garden soils were higher than normal background soil concentrations. Some 46% of the urban garden samples had Pb concentrations higher than the residential land use national standard of 210 mg kg⁻¹, with the most contaminated soil containing 2615 mg kg⁻¹ Pb. Concentrations of As and Zn exceeded the residential land use national standards (20 mg kg⁻¹ As and 400 mg kg⁻¹ Zn) in 20% of the soils. Older neighbourhoods had significantly higher soil HM concentrations than younger neighbourhoods. Neighbourhoods developed pre-1950s had a mean Pb concentration of 282 mg kg⁻¹ in their garden soils. Soil HM concentrations should be key criteria when determining the future land use of former residential areas that have been demolished because of the earthquakes in 2010 and 2011. Redeveloping these areas as parklands or forests would result in less human HM exposure than agriculture or community gardens where food is produced and bare soil is exposed.

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