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Item Open Access National forest owner survey and resource inventory of alternative species. Stage 2b: Mapping alternative species using remote sensing(Forest Growers Research, 2022) Xu, Cong; Manley, BruceThis study provides a proof of concept of using remote sensing to classify species of small-scale plantation at a regional level and achieved high classification accuracies for most species. Douglas-fir and eucalyptus were the two most accurately classified alternative species, with over 90% of producer’s accuracy. The most important input variable selected for the classification was DEM (Digital Elevation Model), suggesting that elevation plays an important role in differentiating plantation species. The accuracy of species classification highly depends on the availability of truthing data. In total, 2151 ha of alternative species were classified for Hawke’s Bay and a majority of them are eucalyptus, cypress and poplar. The transferability of classification derived from one region to another region is low due to regional variations in the topography, climate and species composition. In order to map the national cover of alternative species, truthing data that cover a range of species and ages classes from all regions are required. One limitation with the study is that pre-defining the geographic boundaries of alternative species is required to define the extent of classification, as the current small-scale plantation map developed by the School of Forestry may not pick up all the alternative species. Without the pre-defined boundaries, the classification approach tends to map other land covers as alternative species plantations due to a similar spectral signature.Item Open Access Underground Hydrogen Storage in the Taranaki region, New Zealand(University of Canterbury; commissioned by the Firstgas Group, 2022) Nicol, Andrew; Dempsey, David; Yates, Edward; Higgs, Karen; Beggs, Mac; Adam, LudmilaExecutive summary: Green hydrogen, generated from excess renewable electricity, will be an important component of the future zero-emissions energy system. Hydrogen has a wide range of applications including transport fuel, industrial feedstock, and electricity generation to meet excess demand. Hydrogen is projected to account for at least 10% of the global energy system in 20 years. At current energy demand, this corresponds to 72 PJ (~600,000 tonnes) of hydrogen annually in New Zealand, of which 7 to 18 PJ may need to be held in storage. Storage allows production to take advantage of intermittent renewable surplus at low cost, to accommodate peaks in energy demand, and to provide a strategic reserve. Meeting this storage demand would require up to 200 cryogenic tanks of the most advanced design, or about 500 vertical shafts, which are currently an unproven technology. It could also be met through subsurface storage in a small number (e.g., <10) of porous reservoirs. The large storage volumes of porous reservoirs, which are here referred to as Underground Hydrogen Storage (UHS), will permit larger-scale hydrogen production and provide sufficient capacity for managing out-of-phase supply and demand cycles. Globally, underground storage of pure (>98%) hydrogen has only been achieved in caverns excavated from salt deposits, which are not present in New Zealand. Instead, this report focuses on the potential for UHS in subsurface porous rock formations of Taranaki. Two types of storage systems are considered here, depleted oil and gas reservoirs and saline aquifers. Depleted oil and gas reservoirs are the most attractive of the two options because containment of buoyant fluids over geological time is proven, they are usually associated with extensive subsurface characterization, and have existing infrastructure that could be repurposed (e.g., wells and pipelines). Optimism in the published literature is high for storage in both aquifers and depleted natural gas reservoirs with foundational research and technical trials showing promising results. Effective UHS in porous-media requires the geological system to have sufficient storage capacity, deliverability and security of containment to meet operational specifications. Taranaki UHS systems require three key elements; i) a porous reservoir sandstone to store the hydrogen, ii) an effective geological cap rock (top seal) to prevent hydrogen migrating upwards out of the reservoir, and iii) a suitable geological trap to prevent the hydrogen migrating around the cap rock. The preponderance of hydrocarbon accumulations in the Taranaki region demonstrate that sedimentary strata commonly form effective reservoir-cap rock trap systems. The largest and geologically simplest traps are at the crests of anticlines at depths of <2.5 km. The suitability of five reservoir sandstone formations and three cap rock mudstone formations are considered here. These rocks range in age, mineral composition, physical properties, and burial depths. Reservoir sandstones range in thickness from 10s to 100s of metres, with permeabilities of mainly 10-100 mD. The Tariki Sandstone in the Ahuroa field and McKee Sandstone in the McKee field have the greatest potential for UHS. Cap rocks typically comprise fine silt and clay sized particles with porosities of a few percent, permeabilities of <5 mD and thicknesses of >10 m. Reservoir and sealrocks in Taranaki are dominated by silicate minerals (quartz, feldspars, clay) that are unlikely to undergo significant alteration over a typical hydrogen storage cycle. Geochemical modelling of hydrogen-brine-rock systems suggests that reservoir and cap rocks containing sulphates, carbonates (e.g., calcite or dolomite) or pyrite could react with injected hydrogen resulting in mineral dissolution and/or precipitation. Sulphate minerals are generally absent in New Zealand reservoir and seal rocks; many also do not have significant carbonate or pyrite and are considered unlikely to produce adverse reactions. However, carbonate and pyrite content is variable and will need to be assessed for each UHS site. Furthermore, hydrogen-rock reactions are dependent on sub-surface conditions (e.g., temperature, pH, pressure, chemistry) and studies are recommended to predict the degree of rock reactivity and potential resulting changes in rock properties. Preliminary reservoir models were constructed for UHS at three depleted gas fields (Ahuroa, McKee and Rimu) and one saline aquifer (Ahuroa shallow sand). These were characterized using data from well and field reports and published literature. Dynamic (annual) modelling suggests that the depleted reservoirs could have storage capacities up to 850 TJ per well. The McKee scenario has the largest storage due to its high permeability and porosity, thick storage interval and relatively large pressure depletion. Dynamic storage between 55 and 290 TJ at Rimu per well is probably sufficient to accommodate (10 to 15% of) the ~600-770 TJ of hydrogen production estimated for a nearby Waipipi windspill scenario. Static modelling suggests total storage capacity could be 5 PJ at Ahuroa (if converted from natural gas), and 1 PJ at Rimu, which collectively are approaching the estimated requirements of a future hydrogen economy (7 to 18 PJ). These volumes exceed the capacity of other large storage options (cryogenic storage, artificial caverns, linepack). Modelled hydrogen transfer rates are lower at Rimu and McKee (0.45 and 7.0 TJ/d) than Ahuroa (18 to 33 TJ/d). These hydrogen rates are less than the current estimated energy transfer performance for natural gas at Ahuroa (65 TJ/d).Monitoring of UHS is likely to be a regulatory and operational requirement for storage sites. It will ensure that infrastructure (e.g., wells and pipelines) and reservoir performance are within specifications, confirm containment and help manage adverse rock reactions and leakage, which could result in contamination and loss of the recovered hydrogen. Stored hydrogen can be monitored using atmospheric techniques, monitoring wells or geophysical methods. Monitoring wells are widely used in industry and are the most prospective means of confirming stored hydrogen and reservoir-cap rock conditions (pressure, temperature and chemistry). The number of wells will depend on a range of factors including, site conditions, desired resolution and implementation budget. Published studies emphasise the need for case-by-case evaluation using research tailored to a region or reservoir’s particular characteristics. Despite the large datasets available for many depleted oil and gas reservoirsin Taranaki, additional information may be required to support UHS operationalisation by reducing uncertainties. These investigations may include characterisation of 3D geological models, reservoir-cap rock properties, chemical reactions, microbiological activity, reservoir engineering performance and UHS monitoring requirements.Item Open Access New Zealand National Seismic Hazard Model framework plan(2020) Gerstenberger M; Van Houtte C; Abbott E; Van Dissen R; Kaiser A; Bradley, Brendon; Nicol A; Rhoades D; Stirling M; Thingbaijam Kprojects led by USQ which trialled various digital technologies for learning in correctional centres. Most notable of these was the Office for Learning and Teaching-funded project, From Access to Success, which developed a version of USQ’s learning management system, a version of Moodle called USQ StudyDesk, which was installed onto the correctional centre education lab serverItem Open Access Evaluation of empirical ground-motion models for New Zealand application(2022) Lee R; Bradley, Brendon; Manea E; Hutchinson JThis report presents an evaluation of empirical ground-motion models for shallow crustal, subduction interface and subduction slab earthquakes using a recently developed New Zealand ground-motion database.Item Open Access Use of Science-Based Prediction to Characterize Reservoir Behavior as a Function of Injection Characteristics, Geological Variables, and Time(2014) Bromhal, Grant; Arcentales Bastidas , Danilo; Birkholzer , Jens; Cihan , Abdullah; Dempsey, David; Fathi , Ebrahim; King , Seth; Pawar , Rajesh; Richard , Tom; Wainwright , Haruko; Zhang , Yingqi; Guthrie , GeorgeThis report summarizes a detailed study designed to generate a baseline understanding of how pressure plumes and carbon dioxide (CO2) plumes behave in CO2 storage reservoirs as a function of storage-site properties, injection conditions, and time. The goal of the study was to provide quantitative insight into how operational and geologic factors can impact risk at storage sites both during injection and post injection.Item Open Access A Review of Urban Forest Benefits and Costs(2023) morgenroth, justinEffective urban forest management requires an understanding of tree costs and benefits. Costs can include producing or acquiring trees, site preparation (often including infrastructure requirements), planting, irrigation, inspections and pruning, traffic management, integrated pest management, leaf litter removal, storm cleanup, infrastructure damage, removal, and administration. Benefits, also called ecosystem services, are typically categorised as provisioning, cultural, supporting, or regulating services. The objectives of this report are to provide insight into the economic costs and benefits of urban trees. These objectives were met by thoroughly reviewing existing scientific and grey literature, summarising the reported data, and interpreting the findings. On balance, the benefits of urban trees were found to outweigh the costs. For studies with roughly comparable methods, annual tree benefits ranged from $110.16–$490.06, while annual costs, per tree, generally ranged between roughly $68–$99. Excluding outliers, the studies that reported both costs and benefits of urban trees showed that the benefit-to-cost ratio (BCR) of urban trees ranged between 1.35 and 6.69, with an average of 3.39. This means that for every $1 invested on trees, trees returned $3.39 worth of benefits. Tree size and lifespan, both related to species, had an influence on tree BCR. Generally speaking, the larger a tree and the longer it lives, the greater the tree’s benefit-to-cost ratio. Modelled values show that, on average, large trees (BCR = 3.93) have a BCR 2.8 times greater than small trees (BCR = 1.4). Costs were known with greater certainty than estimates of the economic value of benefits. Costs are relatively accurately quantified in budgets. In contrast, many benefits remain unquantified or under-quantified with most studies focusing on a small number of benefits. This under-quantification of urban forest benefits suggests that the BCRs reported in many studies are conservative and that the benefits of investments in urban trees are likely greater than the average BCR of 3.39 presented in this report. No New Zealand-based studies exist from which to draw knowledge. To gain a local accurate estimate of urban tree benefits and costs, Auckland Council should consider undertaking its own assessment using the newly available i-Tree NZ. This proposed local study would give Auckland Council greater certainty over the benefits and costs associated with the urban trees they manage, rather than having to rely on overseas studies.Item Open Access New Zealand National Seismic Hazard Model 2022 revision: model, hazard and process overview(2022) Gerstenberger M; Bora S; Bradley, Brendon; DiCaprio, C.; Van Dissen, R.J.; Atkinson, G.M.; Chamberlain, C.; Christophersen, A.; Clark, K.J.; Coffey, G.L.; de la Torre, Christopher; Ellis, S.M.; Fraser, J.; Graham, K.; Griffin, J.The New Zealand National Seismic Hazard Model (NSHM) 2022 revision has involved significant revision of al datasets and model components. In this report we present a subset of the many results from the model, as well as an overview of the governance, scientific and review processes followed by the NSHM team.Item Open Access 2021 New Zealand Ground-Motion Database(2022) Hutchinson J; Bradley, Brendon; Lee, Robin; Wotherspoon L; Dupuis M; Schill C; Motha J; Kaiser, A.E.; Manea EThis report summarises the development of the 2021 New Zealand ground-motion database.Item Open Access Summary of the ground-motion characterisation model for the 2022 New Zealand National Seismic Hazard Model(2022) Bradley, Brendon; Bora, S.; Lee, Robin; Manea, E.F.; Gerstenberger, M.C.; Stafford, P.J.; Atkinson, G.M.; Weatherill, G.; Hutchinson, J.; de la Torre, Christopher; Hulsey, A.; Kaiser, A.E.; Van Dissen, R.J.Item Open Access Combining observed linear basin amplification factors with 1D nonlinear site-response analyses to predict site response for strong ground motions: application to Wellington, New Zealand(2022) de la Torre, Christopher; Bradley, Brendon; Kuncar F; Lee, Robin; Wotherspoon, L.M.; Kaiser, A.E.Item Open Access 3D geological modelling of Wellington Quaternary sediments and basin geometry(2022) Hill, M.P.; Kaiser, A.E.; Wotherspoon, L.M.; Manea, E.F.; Lee, Robin; de la Torre, Christopher; Bradley, BrendonItem Open Access 2022 Revision of the National Seismic Hazard Model for New Zealand: overview of site/basin effects, including a case study of the Wellington Basin(2022) Kaiser, A.E.; Manea, E.F.; Wotherspoon, L.M.; Hill, M.P.; Lee, Robin; de la Torre, Christopher; Stolte, A.C.; Bora, S.; Bradley, Brendon; Hulsey, A.; Gerstenberger, M.C.This paper tells the story of a collaborative trial project between the University of Southern Queensland (USQ) and Queensland Corrective Services, from its inception to the present stage of near completion. The project involved the use of internet-independent ICT for prisoner education. A major aim was to enable prisoners to greatly enhance their employment and further education prospects by developing their e-literacy/learning skills. The project involved the development of an internet-independent form of a USQ course Moodle site that could be placed on a correctional centre server intra-netted to computer labs for educational use by prisoners. Additionally, participating prisoners were individually supplied with internet-independent e-readers containing the course study materials. The trial commenced at the start of semester 2, 2012. Student support in the use of the Moodle site and the e-readers was provided by correctional centre staff and through regular visits by USQ Tertiary Preparation Program (TPP) teachers. The evaluation plan for the trial included gathering weekly feedback from the students via an evaluation instrument in the Moodle site, and from the correctional centre staff. The paper provides an account of the numerous challenges encountered and overcome by the project team, and a summary evaluation of the trial project.Item Open Access Best practices for reducing harvest residues and mitigating mobilisation of harvest residues in steepland plantation forests.(2018) Spinelli R; Brown K; Visser, RienSummary: Plantation forestry in New Zealand covers approximately 7% of NZ’s total land area with 28 million m3 of timber expected to be harvested in 2018. The majority of timber harvest is from Pinus radiata (‘radiata’) plantation forests grown 25-30 years. Approximately 40% of the plantation estate is on steeper and or erodible terrain, driven mainly by the lower land values for forest conversion but also the benefits of stabilising erosion prone land with trees. The current preferred harvesting practice in New Zealand is larger scale clear-cutting, based on logistical and economic benefits, but also on planting regimes whereby whole catchment areas are planted in a short time-frame. Although certainly not new, recent larger scale debris flow events with entrained harvesting residues has caused significant damage to downstream land use. This includes inundation of land with sediment and slash, damage to infrastructure including roads, bridges and homes, or the deposition of woody debris on beaches. A number of events have occurred in the Gisborne Region resulting in significant flooding, but also large scale deposition and damage from harvest residues on the regions’ rivers and beaches, coinciding with recent extensive harvesting within the catchments. Similar events have also occurred in Northland, Coromandel, Bay of Plenty and Nelson-Marlborough. These events are prompting Regional and District Councils to review the acceptability of current forestry practices and to identify opportunities for improvement. The report focusses on the relationship between harvesting, harvest residues, and the best practices that help mitigate debris flow events and or the delivery of harvest residue.Item Open Access Horizontal and vertical integration of biomass production: a case study of Azwood Ltd, Nelson(Forest Growers Research, 2020) Spinelli R; Visser, RienSummary: Commercial recovery of harvest residues from logging operations is not well established in New Zealand. What is well known is that the harvesting of pine plantations creates large volumes of residues and presents a clear opportunity for meeting renewable energy goals and making forestry more sustainable. This report backgrounds the concepts of horizontal and vertical integration in woody biomass production and highlights aspects of the business model, products, and supply chain in Europe to improve our understanding from the perspective of successfully managing a biomass recovery business. One example of a company that is recovering and processing harvest residues in New Zealand is AZWood Energy Ltd., a well-established and large-scale energy company based in Nelson. They are developing strong relationships with local forestry companies to facilitate the recovery of harvesting residues, and the development and production of multiple product lines.Item Open Access Using Data Envelopment Analysis to explore productivity benchmarking in the New Zealand harvesting sector(2019) Obi F; Visser, RienExecutive Summary: A benchmarking system developed by Forest Growers Research Ltd., and managed by the University of Canterbury, School of Forestry has been recording cost and productivity for plantation forest harvesting operations in New Zealand over 10 years (2009 – 2018) with over 1500 unique entries. This report details a study using the benchmarking database, whereby the pattern and sources of productivity changes are investigated using the Data Envelopment Analysis (DEA) method. This is known as the DEA-based Malmquist non-parametric frontier technique. The study measures productivity changes in the forest harvesting sector in New Zealand. Productivity growth reflects how well an industry has been able to increase its output, while minimising or keeping inputs constant. This consequently increases the competitiveness of the sector. Using the Malmquist Total Factor Productivity (TFP) index that measures productivity (the ratio of output to input), the study shows that productivity growth in New Zealand harvesting was positive, growing at an average rate of 1.7% per annum over the study period. The index is decomposed into two other productivity change measures, an efficiency change index and a technology change index, in order to better understand the causes of change in relative performance. Efficiency change relates to how well a business or organisation has been able to efficiently manage its inputs to produce outputs. A technology change (or frontier shift) is where the business or organisation has adopted or utilised improved technologies, and therefore the best practice frontier moves upwards. Productivity is driven by two components; (1) the technology deployed and (2) the efficiency of the technology. The study indicates that the sector experienced productivity growth over the 10-year period primarily as a result of technological progress rather than efficiency growth. The contribution to the overall output (system productivity) growth from technology change ranged from 1.4 to 26%, while that from efficiency gain ranged from 7.3 to 19%. Technological gain was therefore the most important driver of TFP growth in the sector rather than efficiency improvement. The results of the study show that the productivity growth in the industry was mainly as a result of improved technologies, however, efficiency of the technologies lag. There is potential for increasing efficiency of existing technologies, increasing output while using or reducing current input levels, which should be the focus of the industry in order to achieve sustainable growth in productivity.Item Open Access Assessment of Winch-Assist Skidder in Gisborne, New Zealand(2020) Pedofsky M; Visser, RienExecutive Summary: Winch-assist systems are commonly used to expand ground-based operations onto steeper terrain. Skidders tethered to winch-assist machines are becoming popular in New Zealand as a method of extraction, however little is known about the productivity and soil disturbance effects from this system. The aim of this research was to improve the industry’s knowledge of winch-assisted skidder systems. An investigation was carried out in Emerald Forest, about 30km south-west of Gisborne, of an operation using a Falcon Winch Assist machine and a six-wheeled Tigercat 635G grapple skidder over a period of three days. Objectives were to determine the productivity of the winch-assisted skidder operation, to carry out a soil disturbance assessment on the slopes, and to evaluate the benefits of utilising this system. Productivity was assessed by measuring 121 skidder cycles over two different skidder paths using standard time study methods. The skidder paths followed the same main trail from the landing for 150m before diverging down different sides of a ridge. Bunches were extracted from different distances along the paths. Skidder Path 1 had a maximum slope of 33 degrees (65%) and was 300m long. Skidder Path 2 had a maximum slope of 30 degrees (58%) and was 315m long. As expected, as the extraction distance increased, the cycle time of the skidder increased and productivity decreased. The average skidder productivity over the study period was 65.0 cubic metres per productive machine hour (m3 /PMH). The average productivity per scheduled machine hour (SMH) was 48.7 m3 /SMH. Machine utilisation was 75%. This was largely attributed to a significant mechanical delay which stopped the skidder from working for half of the second day of the study. The soil disturbance assessment was carried out post-harvest using a line transect method collecting 902 data points over three different sites. The assessment combined the effect on site of the winchassist skidder, the tracked felling machine and the shovel logger. The three sites resulted in deep disturbance across 17%, 11% and 10% of the sites measured, where deep disturbance was defined as exposure of subsoil. Shallow disturbance, defined as mixing of litter and topsoil, occurred in 27%, 20% and 21% of the three sites respectively. In this particular setting, the use of the winch-assisted skidder contributed to saving the construction of 720m of road, a large culvert crossing and two skid sites that were originally planned. A forest area of 19.3 hectares which was planned to be harvested by cable yarder was scheduled for this winch-assisted skidder system, with significant savings in logging cost. Other benefits of using this system included increasing the utilisation of the winch machine by tethering both the felling machine and skidder. By enabling more days logging due to the ability to work in poor weather conditions, overall system productivity was improved. The ability to extract stems away from waterways resulted in the riparian strips being left intact, reducing the impact of harvesting on the waterways. It was evident that maintaining a mix of extraction distances throughout the day was necessary to ensure that the processor on the landing had adequate buffer stock and was not waiting for wood throughout the day.Item Open Access Biomass recovery operations in New Zealand: a review of the literature(2020) Harrill H; Baek K; Visser, RienExecutive Summary; Plantation forests in New Zealand generate a considerable amount of woody residues at the time of harvesting. These residues comprise branches, tree tops, and offcuts from log manufacturing on the landing, but also lower value merchantable material left in the cutover that is not economic to extract. Harvest residues can impede harvesting, processing and forest re-establishment operations and, if mobilised during a storm, can affect the downstream environment. Conversely, converting residues into woody biomass products create new market opportunities. The current FGR harvesting and logistics programme focusses on automation of forest operations, including developing more effective, efficient and safe methods of processing on the log landing. As these processes focus on maximising value recovery from the forest resource, such systems cannot be successful without efficient residue management systems to support them. Concurrently, increasing concerns about environmental risk, and the role of renewable forestry resources in mitigating climate change, has resulted in increased interest in efficient and cost-effective biomass recovery operations. There is a lack of information about the technologies used to recover harvest residues, the types of merchantable products produced, and who uses these products in New Zealand. This report introduces forest biomass operations and reviews previous literature that has studied biomass harvesting systems, both in New Zealand and overseas. Biomass recovery technologies and systems, their efficiency and costs, as well as variables affecting the supply chain have been summarised. Examples of forest biomass end-users and markets in New Zealand currently being operated in New Zealand are also provided.Item Open Access Design of a Prototype Autonomous Forestry Extraction Machine(2018) Treanor J; Hartley A; Bell T; Chen X; Visser, RienExecutive Summary: The purpose of this project was to design and build a prototype autonomous forestry extraction vehicle and demonstrate the feasibility of integrating an autonomous control system on a forestry forwarder. Forestry in Australasia is a multi-billion-dollar industry and provides opportunities for autonomous vehicles with the potential to improve efficiency, productivity and worker safety and health. The use of autonomous vehicles to support industry processes is not a new concept. For over 10 years they have been successfully used in the mining industry carrying ore from the mining site to the processing area. The process of transporting material from an extraction site to a sorting and distribution area following a consistent route is common throughout many industries, including forestry. Log extraction from the tree felling area to a loading site and returning for another load is a typically repetitive task and has been identified as well suited for early adoption of autonomous vehicles. Technology integration and semi-automation in forestry equipment is becoming commonplace (such as integration of hydraulics, cameras and remote control in a motorised grapple carriage for cable logging). This project focussed on opportunities to develop equipment with autonomous control; that is without direct control of a human operator. Introducing autonomous forwarders has the potential to improve safety and worker health, extend working hours and providing all year round wood supply, increasing annual production and reducing operating costs in the forest industry. In addition, less experienced operators can help manage autonomous forwarders providing a solution to the present shortage of skilled machine operators. As a first step to achieving these goals, a small prototype wheeled vehicle was built to provide a platform for testing the electrical componentry necessary to achieve autonomous functionality. Construction of the prototype began by modifying a low cost wheeled trolley to serve as a mobile platform and installing a chain drive system. This provided drive and differential skid steering functionality. The integrated sensor system included GPS for guidance and LiDAR for obstacle detection. The GPS unit provided location and compass direction, which gave the prototype a heading and approximate distance from a predefined waypoint. The electrical system was designed to include an electrical board to mount a microcontroller to interface with the obstacle detection sensors. A primary scope change removed the requirement for the prototype to self-navigate around detected obstacles. Instead, the prototype would simply stop movement and provide live video feedback using of an optical camera. A remote operator would then move around the prototype obstacle and subsequently then continue its autonomous travel. The present functionality of the prototype includes remote control operation of the motors, and basic collision avoidance. GPS guidance is provided by inputting a path through waypoints and wireless camera feedback to a smart phone screen has been achieved. While further testing and refinement would be required to consider the project a success, overall the project has demonstrated that basic autonomous movement of extraction machines such as forwarders can be readily achieved with relatively low-cost existing technology.Item Open Access Design of Debris Slash Traps: Considerations for NZ Plantation Forestry Operating on Steep Terrain(2020) Harvey C; Visser, RienItem Open Access Comparative phenology of Paropsisterna cloelia and Paropsis charybdis in Marlborough(2022) Weser C; Pawson, StephenExecutive Summary: Paropsine leaf beetles (referred to as paropsines) are the most damaging group of eucalypt foliar pests in Australian plantations and elsewhere where eucalypts are grown. Six eucalypt-feeding paropsine leaf beetles from Australia have established in New Zealand (NZ) to date. Paropsis charybdis has historically been the most damaging defoliator of eucalypt species throughout NZ and is currently regarded as the number one eucalypt pest. Paropsisterna cloelia was first detected in March 2016 in New Zealand, in Hawke’s Bay. The current known range of Pst. cloelia in NZ spans the central North Island to the upper South Island, including the districts of Gisborne, Taupo, Hawke’s Bay, Manawatu-Wanganui, Wellington, Marlborough, Nelson, and North Canterbury. The Australian distributions of P. charybdis and Pst. cloelia largely overlap and extend from subtropical Queensland to cool temperate Tasmania. This suggests a similar climate tolerance of the two species. Paropsis charybdis generally produces two generations per year in NZ, however, no systematic study of Pst. cloelia phenology (i.e., seasonal presence and abundance of life stages) has been completed. In Australia, Pst. cloelia produces two to five generations depending on climatic region. This project aims to understand Pst. cloelia phenology in NZ. This contributes to our understanding of the potential risks posed by Pst. cloelia compared to P. charybdis. Moreover, knowledge of a pest species’ phenology informs the development and implementation of more effective and efficient control methods, such as integrated pest management and biological control. A total of 15 assessments were made at regular two-week intervals between September 2021 and March 2022 on Eucalyptus bosistoana at the NZDFI Dillon site in Marlborough. Immature life stages (egg batches and four larval stages) and adults beetles of Pst. cloelia and P. charybdis were counted. Defoliation and the production of new leaves was measure using the Crown Damage Index (CDI) and New Leaf Score (NLS), respectively. The southern distribution of Pst. cloelia along the eastern coast of the South Island was quantified in an ad hoc, opportunistic assessment. Paropsisterna cloelia clearly dominated P. charybdis on E. bosistoana and accounted for 96% of all immature stages and 88% of all adult beetles counted throughout the sampling season. Both species produced two generations with simultaneous peaks of immature life stages in November and January for the first and second generation, respectively, and the start of a third generation with egg batches again being found in March. The total time that immature stages were discovered in the field differed between species: first Pst. cloelia egg batches were observed on 28 September and first P. charybdis batches on 26 October. At the end of the season, however, immature life stages of both species were still found on the last sampling date on 29 March. The second larval generation was smaller for both species with second-generation last-instar larvae being 35 and 4% of the first generation for Pst. cloelia and P. charybdis, respectively. Additionally, survival rate of last-instar larvae in the first generation was 46% and 88% for Pst. cloelia and P. charybdis, respectively, but only 20% for both species in the second generation. New Leaf Score declined severely from an average of 2 to 0.1 from beginning to end of the first larval generation (November/December), but showed the highest seasonal peak of 2.5 in the middle of the second larval generation (January/February). Hence, food limitation is an unlikely driver of the higher larval mortality. We tentatively attributed low larval survival in the second generation to an increase in predation. Since its first discovery in the South Island in Nelson/Marlborough in 2019, Pst. cloelia has spread by at least 120 km in a direct line southward to North Canterbury. We conclude that it is likely that Pst. cloelia will establish throughout NZ where preferred eucalypts occur and will dominate or potentially even outcompete P. charybdis. Paropsisterna cloelia has the potential to become a damaging pest to its preferred eucalypt hosts, but it remains unknown whether its abundance and impact on the trees will exceed that previously observed by P. charybdis. The threat that Pst. cloelia may pose to eucalypt plantings in the warm northern regions will depend on a complex interaction between climate, the ability of trees to produce new leaves in response to herbivory, and the strength of top-down control by natural enemies on populations.