We need to understand kauri dieback and myrtle rust better if we want to protect our ngahere (forest). That’s why the goal of the Risk Assessment & Ecosystem Impacts team is to identify the effects of these diseases and management, as well as which species and ecosystems are most at risk. More detailed information will allow us to better prioritise conservation efforts and management decisions. Our mahi takes a holistic view of both the ecosystem and the pathogens – something that has long been advocated for by affected Māori communities. We look at the pathogen impacts on everything from ecosystem functions to human relationships, considering the effects of not only the pathogens, but also the tools and systems used to manage them. __Theme Co-leads__ - Luitgard Schwendenmann, University of Auckland - Simon Wegner, Scion Research *Unless otherwise specified under individual resources (esp papers), this work is shared CC-BY.*
###Shifting paradigms and creating space for Indigenous leadership in biosecurity management and decision-making### **November 2024** **Godfery T, Keen J, Hikuroa D, Robinson A, Williams N. 2024. [Shifting paradigms and creating space for Indigenous leadership in biosecurity management and decision-making](https://doi.org/10.1111/cobi.14399). Conservation Biology 38(6) 11p.** **ABSTRACT** In New Zealand, awareness regarding protection, enhancement, and regeneration of land-scapes and biodiversity is growing as the relationship between functioning and diverse ecosystems and society’s health is acknowledged. This relationship is especially important for Indigenous people, who hold strong genealogical and familial ties with nature. Signiﬁcant biodiversity loss from anthropogenic factors is exacerbated by climate change, ecosystem degradation, and invasive species. Invasive species and other biological threats,such as native pathogens, are concerning for Māori communities, who hold cultural responsibilities to care for nature. Despite acknowledgment of the value of Indigenous perspectives in environmental management in New Zealand and globally, Indigenous participation still largely occurs within Western non-Indigenous paradigms. We highlight the value of Indigenous participation in biosecurity management and propose a shift from Western-based paradigms to paradigms that reﬂect Indigenous worldviews and relationships with place. Recognizing and including the value of Indigenous participation elevates Indigenous voices to the level of decision-making and leadership in the management of Indigenous lands. Given the genealogical relationships that Māori hold with the natural world and the intertwining of their health and well-being with that of place (land) and nature, biosecurity threats to native species and ecosystems also pose serious risks to community well-being. A holistic biosecurity approach is needed that encompasses cultural,social, economic, and environmental factors at multiple scales. We examined the New Zealand biosecurity context relative to biological threats to native plants and ecosystems and proposed a paradigm shift toward Indigenous place-based biosecurity management. Biosecurity science and science-based tools remain an important component, underscoring the complementary aspects of science and (Indigenous) culture. **KEYWORDS** biosecurity management; contrasting worldviews; Indigenous paradigms; nature relationships
RA2 PAPER: Shifting paradigms in indigenous biosecurity management
###Effect of *Phytophthora agathidicida* infection on kauri leaf litter nutrient content### **December 2022** **Hamilton Murray M, Schwendenmann L, Padamsee M. 2022. [Effect of *Phytophthora agathidicida* infection on kauri leaf litter nutrient content.](https://az659834.vo.msecnd.net/eventsairseasiaprod/production-confer-public/171c47d33fd34874a0ed69300f6f35aa) New Zealand Ecological Society Conference. University of Otago, Dunedin. 28 Nov - 2 Dec 2022., 29/11/2022.** **ABSTRACT** Kauri tree damage by *Phytophthora agathidicida* colonisation of the roots and vascular tissue, consequently restricts water and nutrient transport through the tree. Resulting infection symptoms in the canopy, including foliage discolouration and thinning, suggest biochemical changes are occurring within the leaves. This research aims to understand how *Phytophthora agathidicida* infection impacts the nutrient status of kauri leaves.
RA3 POSTER: Kauri dieback effect on leaf litter nutrients.pdf
###Mapping New Zealanders’ socio-cultural connections to native forests and threatened tree species **March 2024** **Wegner S, Bayne K, Palmer M. 2024. Mapping New Zealanders’ socio-cultural connections to native forests and threatened tree species. A report for New Zealand’s Biological Heritage National Science Challenge: Ngā Rākau Taketake. 41 p. ** **NOTE: ** This report is embargoed until 31/01/2025. For further information please contact [Simon Wegner](mailto:simon.wegner@scionresearch.com) at Scion Research **EXECUTIVE SUMMARY:** __The problem:__ Kauri and native myrtle species are threatened by the plant pathogens kauri dieback (*Phytophthora agathidicida*) and myrtle rust (*Austropuccinia psidii*). As ecological and cultural keystone species, the loss of these trees would have severe impacts on New Zealand’s forest ecosystems, culture and economy. To enable management decisions and research priorities, it is important to understand how these species fit within their wider ecosystems and the risks and impacts associated with the two diseases. Assessing risk and impact requires characterising the critical elements at risk, establishing a baseline and then measuring change. Despite the importance of native kauri and myrtle species in New Zealand forest ecosystems, culture and economy, there is a lack of quantitative or spatial data about their socio-cultural value. To date, our knowledge about the social and cultural value of native species and forests in New Zealand has been qualitative and limited primarily to local case studies. __This project__ This project has sought to: 1. identify the key social, cultural and psychological values or meanings associated with kauri and native myrtle species; 2. develop New Zealand-appropriate quantitative methods to measure people’s socio-cultural attachment to native forests and the affected tree species; and 3. apply these methods to assess and map the current state of socio-cultural connections to native forests across New Zealand. These aims were accomplished by reviewing the existing literature on the meanings of trees, forests and places in New Zealand, working collaboratively with mana whenua representatives to develop quantitative measures for assessing those connections and deploying a participatory GIS survey to measure and map the forest places that New Zealanders value. This was complemented by the mapping of images taken within native forests and uploaded to social media. __Key results__ This research has made valuable progress towards understanding, measuring and spatially assessing the connections that New Zealanders have to native forests and kauri and myrtle species. Representing the input of 2,452 survey participants and incorporating spatial data from 287,400 social media images, the research has produced the national maps illustrating where and how people value native forests. It captures the current state of social, cultural and psychological meanings associated with native forests and the species affected by kauri dieback and myrtle rust, which will enable monitoring of impact over time as the effects of the diseases become more widespread. Moreover, the measures used expand the literature around place attachment by incorporating aspects of place meanings that are both more reflective and inclusive of Māori perspectives and provide a fuller picture of place meanings for all respondents. __Further work__ Although the project made significant progress towards developing assessment methods and providing measurable spatial data illustrating the socio-cultural value of native trees and forests, further work is necessary to improve the accuracy and consistency of the measures used. Additionally, while the present work captures present value, repeat measures will be necessary to assess changes over time.
RA4 REPORT: Mapping socio-cultural connections
###Assessing the effect of phosphite treatment on arbuscular mycorrhizal fungal colonisation in kauri (*Agathis australis*) **2022** **Patterson HR. 2022. Assessing the effect of phosphite treatment on arbuscular mycorrhizal fungal colonisation in kauri (*Agathis australis*). Unpublished Honours thesis, University of Auckland. ** **NOTE:** This thesis is not publicly available online. For further information please contact supervisor, Dr. Luitgard Schwendenmann at the University of Auckland (l.schwendenmann@auckland.ac.nz) A poster presented at the New Zealand Ecological Society Conference, University of Otago, November 2022 has been provided. **ABSTRACT** Kauri (*Agathis australis*) is a keystone New Zealand tree species. Kauri are also a taonga species with an integral place in Māori culture. Kauri are threatened by *Phytophthora agathidicida*, an oomycete that causes kauri dieback. Currently, phosphite is the treatment used to manage the disease, and although it is an effective short-term treatment, it is not a cure. There is little research on the effect of phosphite on the arbuscular mycorrhizal fungi (AMF), which exist in a symbiotic relationship with kauri roots. AMF are integral for kauri survival in low-nutrient soil. This study investigates the effect of phosphite on AMF in the root nodules of kauri trees.
RA3 THESIS: Effect of phosphite on arbuscular mycorrhizal fungal
###Carbon stocks and fluxes in New Zealand Myrtaceae### **December 2021** **Easdale T, McCarthy J, Bellingham P, Jo I, Richardson S, Wiser S. 2021. Carbon stocks and fluxes in New Zealand Myrtaceae. 39 p.** **ABSTRACT** Understanding the potential impacts of myrtle rust on the integrity of natural forest ecosystems thus hinges on understanding the contribution of the Myrtaceae to the structure and dynamics of natural forests. Comprehensive assessments of tree-mediated contribution to wood production in the context of changing climates (Coomes et al. 2014) and stand-level forest biomass stock and growth (Holdaway et al. 2017) provide valuable initial background. However, understanding the specific role of Myrtaceae requires a new assessment, which we undertake here. To this end we provide an analytical stocktake of Myrtaceae’s contribution to national forest biomass stocks and fluxes.
###Phyllosphere of *Agathis australis* Leaves and the Impact of the Soil-Borne Pathogen *Phytophthora agathidicida*### **October 2024** **Hamilton Murray ML, Dopheide A, Leonard J, Padamsee M, Schwendenmann L. 2024. [Phyllosphere of *Agathis australis* Leaves and the Impact of the Soil-Borne Pathogen *Phytophthora agathidicida*](https://doi.org/10.1007/s00248-024-02441-9). Microbial Ecology: 87(125) 10p.** **ABSTRACT** Leaf surface microbial communities play an important role in forest ecosystems and are known to be affected by environmental and host conditions, including diseases impacting the host. *Phytophthora agathidicida* is a soil-borne pathogen that causes severe disease (kauri dieback) in one of New Zealand’s endemic trees, *Agathis australis* (kauri). This research characterised the microbial communities of the *A. australis* phyllosphere (i.e. leaf surface) using modern molecular techniques and explored the effects of *P. agathidicida* on those communities. Fresh leaves were collected from trees where *P. agathidicida* was and was not detected in the soil and characterisation of the leaf surface microbial community was carried out via high-throughput amplicon sequencing of the internal transcribed spacer (ITS) and 16S ribosomal RNA regions. Nutrients in leaf leachates were also measured to identify other possible drivers of microbial diversity. The dominant phyllosphere microbial phylum was Proteobacteria followed by Acidobacteria. The phyllosphere microbial richness of A. agathis associated with *P. agathidicida*-infected soils was found to be generally lower than where the pathogen was not detected for both prokaryote (bacterial) and fungal phyla. Leaf leachate pH as well as boron and silicon had significant associations with bacterial and fungal community structure. These findings contribute to the development of a comprehensive understanding of *A. australis* leaf surface microbial communities and the effects of the soil pathogen *P. agathidicida* on those communities. **KEYWORDS** fungi; kauri; leaf leachate; microbiota; oomycota; phylloplane
RA3 PAPER: Phyllosphere of Agathis australis Leaves
###Soil invertebrate communities in kauri-dominated forests and the impact of tree pathogens### **March 2023** **Struijk M, Stavert J, Barnes A. 2023. Soil invertebrate communities in kauri-dominated forests and the impact of tree pathogens. The 3rd Global Soil Biodiversity Conference. Dublin, Ireland, 14/03/2023.** **ABSTRACT** New Zealand kauri (*Agathis australis*) are ecologically dominant and culturally significant endemic conifers that likely exert great influence on belowground food webs. Kauri are threatened by the soil-borne root pathogen *Phytophthora agathidicida* (PA). Onset of visible symptoms –base bleeds, chlorosis, defoliation, dieback, and eventually, tree death– can take up to a decade. We are interested in characterising the ecological significance of kauri and identifying beyond-the-host impacts of PA on the soil food web.
RA3 POSTER: Impact of pathogens on soil mesofauna
###The role of frost tolerance in defining the kauri line floristic boundary### **September 2024** **Elliott TAW, Burns BR, Perry GLW, Macinnis-Ng C. [The role of frost tolerance in defining the kauri line floristic boundary](https://doi.org/10.20417/nzjecol.48.3568). New Zealand Journal of Ecology 48(1): 3568** **ABSTRACT** Floristic boundaries, where the range limits of multiple species coincide, are frequently recognised ecological phenomena for which underlying mechanisms are often unclear. Plant species range limits are often determined by their tolerance to climatic conditions. Therefore, the positions of floristic boundaries are also likely related to climatic conditions. Seedlings are a vulnerable life stage and are often highly susceptible to adverse climatic events such as frosts, and frost susceptibility varies among plant species. Few studies have focussed on the relationship between measured frost tolerances of different plant species and their distributions relative to a floristic boundary. Our study looked at interspecific variation in frost tolerance in a suite of native tree species relative to the kauri line, a floristic boundary recognised at approximately 38°S in Aotearoa New Zealand. We exposed seedlings of four species with range limits near the kauri line and three species with more widespread distributions to one-off simulated frost events and monitored their health for eight weeks after the event. We also excised, froze, and conducted electrolyte leakage tests on leaf samples from each species. The frost tolerances of the kauri line species were similar to each other and were generally lower than those of the widespread species. The outcomes of the electrolyte leakage tests were broadly consistent with the whole seedling frost tests, although the frost tolerance of *Pseudopanax lessonii*, a kauri line species, was under-estimated. Our study highlights that frosts could play a role in the ranges of kauri line species, especially species whose seedlings are common in early successional habitats, such as *Agathis australis*. The convergence of the frost tolerance of *A. australis* with those of other kauri line species is not consistent with the Pleistocene ratchet hypothesis, which suggests a decoupling of plant species current and potential ranges due to rapid climatic changes. Climate change is likely to reduce the incidence of frosts in New Zealand and may facilitate the southward shift of kauri line species, changing the nature of this boundary. **KEYWORDS** *Agathis australis*, electrolyte leakage, leaf traits, seedlings, species ranges
RA3 PAPER: Frost tolerance role in kauri line boundary
###Flower visitation of *Leptospermum scoparium* and the nationally critical plant genus *Lophomyrtus* spp.### **March 2024 ** **Pugh A, Trower M, Mercier C, Bartlett M, Sutherland R, Cridge A. 2024. Flower visitation of *Leptospermum scoparium* and the nationally critical plant genus *Lophomyrtus* spp. Scion Research. p15** **NOTE:** This report is embargoed until 31/03/2025. For further information please contact Andrew Cridge at Scion Research [andrew.cridge@scionresearch.com](mailto:andrew.cridge@scionresearch.com) **ABSTRACT** Environmental DNA (eDNA) is an established technique for studying plant-arthropod interactions, that has so far had very limited use in exploring flower visiting insect communities. This study provides important evidence of the efficacy of eDNA for studying these flower visiting arthropod communities, proving its ability to provide a comprehensive overview of pollinator communities beyond traditional observational methods. Our data revealed a surprising diversity of flower visiting insects, including both expected pollinators and possible non-pollinating species utilising pollen and/or nectar as a nutritional resource. Notably, native bees, such as *Leioproctus* spp., and various flies, including those with uncertain roles in pollination, were detected. This study also shed light on the underexplored area of nocturnal pollination, providing evidence of native moth involvement in pollinating plant species. While there was no definitive evidence of rare insects visiting mānuka (*Leptospermum scoparium*) or *Lophomyrtus* spp., this study did reveal the importance of these plant species and the resources the flowers provide not just to pollinators, but arthropods with other key roles in the ecosystem.
###Physicochemical Characterisation of Soil from Dieback Kauri Forest **March 2024** **Mohini T. 2024. [Physicochemical Characterisation of Soil from Dieback Kauri Forest](https://openrepository.aut.ac.nz/bitstreams/d0acd094-bb7a-45fe-9fd2-caa5e73b1847/download). Unpublished Masters thesis, Auckland University of Technology. 200 p. ** **ABSTRACT** Kauri (*Agathis australis*) is an ecologically and culturally significant conifer, endemic to the northern North Island of Aotearoa New Zealand. Kauri trees are designated as foundation species due to their substantial effect on the configuration of distinct surrounding plant communities and significant impact on overall species diversity in kauri forests. Kauri greatly influence the soil conditions underneath their crowns by lowering soil pH, impeding nitrogen cycle, and occasionally creating podzols. In kauri forests, soil has significant influence on the health of the ecosystem by anchoring roots, storing water and nutrients, and providing a habitat for a variety of invertebrates and microorganisms. However, these ancient and iconic kauri trees are threatened with extinction as a result of dieback disease caused by the highly pathogenic and intrusive oomycetes, *Phytophthora agathidicida*. This novel soil and waterborne pathogen has the ability to disturb above and below ground species composition and biogeochemical processes. This study utilised soil samples from kauri forests located in the Waitākere Ranges Regional Park in Auckland, and Tairua and Whangapoua in Coromandel, to investigate physical and chemical characteristics of soil from beneath healthy kauri trees as well as kauri trees that display dieback disease symptoms. These soil characteristics were compared using two-sample unpaired t-tests and Wilcoxon tests to investigate whether there are differences in the physicochemical characteristics of kauri soil within and between healthy and unhealthy trees. In both the Auckland and Coromandel regions, unhealthy kauri soil demonstrated significantly higher moisture factor (p = 0.0481 in Waitākere and p = 0.00239 in Coromandel) and water holding capacity (p = 0.0224, p = 0.0347) than healthy soil, which may indicate that wetter soil provides more favourable conditions for growth and proliferation of *Phytophthora agathidicida*. Moreover, unhealthy kauri soil in both regions also exhibited significantly higher total carbon (p = 0.000559, p = 0.0235), total nitrogen (p = 4.621×10-5, p = 0.0318), and total hydrogen (p = 0.00953, p = 0.0265) in comparison to healthy kauri soil. The root cause of the elevated content of these elements is likely to be thinning of kauri canopies and defoliation, both symptoms of dieback which add to the acidic, tannin-rich litter. The association with litter was confirmed by using Kendall rank coefficient test to find significant negative correlations between pH and total carbon (p = 2.58×10-5) as well as total nitrogen (p = 0.00762) in unhealthy kauri soil. Hence, these elements may be useful indicators of the presence of dieback, and thus could help map the spread of the disease. The findings of this study contribute towards presenting more comprehensive insight into the link between soil physicochemical characteristics and kauri dieback in the Auckland and Coromandel regions. The current study also contributes to the ongoing research into the detection and prevention of dieback disease, and ultimately in the preservation of the remaining kauri stands in Aotearoa New Zealand.
RA3 THESIS: Physicochemical Characterisation of Soil
###Risk Assessment and Ecosystem Impacts: Data Description **June 2023** **Dowling L, Mattea S. 2023. Risk Assessment and Ecosystem Impacts: Data Description. M.E Research. 31 p. ** **ABSTRACT** This progress report provides an update on the Risk Assessment and Ecosystem Impacts project, under Research Area 4, Social, Cultural and Economic Characterisation. The objective is to assess the impacts of Myrtle Rust caused by the pathogen *Austropuccinia psidii* and Kauri Dieback caused by a microscopic water mould called *Phytophthora agathidicida*. To achieve this, we will use cost-benefit analysis and build on previous research. This progress report described the collection of data to support future analysis and presents key findings to date.
RA4 REPORT: Economic Impacts - Data Description
###Effect of kauri dieback on organic layer biomass and proportion of kauri components### **2021** **Hua W. 2021. Effect of kauri dieback on organic layer biomass and proportion of kauri components. Unpublished Masters thesis, University of Auckland.** **NOTE:** This thesis is not publicly available online. For further information please contact supervisor, [Dr. Luitgard Schwendenmann](mailto:l.schwendenmann@auckland.ac.nz) at the University of Auckland **ABSTRACT** Kauri (*Agathis australis*) is one of the largest and longest-lived conifer species in the world. Kauri is endemic to New Zealand and is now listed as threatened because of the decline caused by the oomycete pathogen *Phytophthora agathidicida*. In this study, organic litter layer (litter (Litter) and partially decomposed (OF) layer) biomass was measured under kauri trees differing in health status. The material was also sorted into its major components (leaves, twigs, pollen cones, seeds, bark, roots). It was further tested if Litter and OF layer depth is related to the biomass of these layers. The study selected two locations, Cascades and Piha, in the Waitakere Ranges Regional Park in Auckland, New Zealand, and selected symptomatic plots and control plots respectively. The samples were collected between May and July 2021. The Litter and OF biomass in the Cascades plots was higher than in the Piha plots. This may be the effect of the size of the trees, or it may be the effect of the duration of the disease. The proportion of reproductive material in the control plot was higher than that in the symptomatic plot, which will lead to fewer and fewer kauri in the symptomatic plots in the future. No relationship between biomass and forest floor depth has been found. This study discussed the impact of kauri dieback on biomass and litter fractions and proposed the idea that the smell can be used to distinguish whether kauri is diseased.
RA3 THESIS: Effect on organic layer biomass
###Probabilistic economic analysis of a weather-based adaptive disease management strategy-the case of myrtle rust in New Zealand nurseries### **August 2024** **Dowling L, Monge J. & Beresford R. 2024. Probabilistic economic analysis of a weather-based adaptive disease management strategy - the case of myrtle rust in New Zealand nurseries. Biological Invasions.** **ABSTRACT** In agricultural systems, responsive management can mitigate the effects of risk and uncertainty by facilitating adaptation to changing conditions. A tool for evaluating management systems while accounting for risk and uncertainty is Probabilistic Cost Benefit Analysis (PCBA). This study used PCBA to contrast a new responsive disease management strategy against an existing prescriptive strategy. Fungicide application to prevent myrtle rust (MR) in NZ plant nurseries was used as a case study to test if the expected benefits of a responsive strategy such as avoided incursions, justified the investment in potentially more frequent and costlier control. A stochastic MR risk generator was developed and used to simulate disease incursion reflecting variable weather. Using the stochastic generator, empirical distribution functions of net benefits were estimated and compared across scenarios highlighting the potential impact of infrequent but substantial disease impacts. Our results showed that the risk-based strategy was more effective at controlling the disease, especially for myrtle plant species that are highly susceptible in high-risk locations. The findings highlighted the essential role of fungicides in the cultivation of highly MR-susceptible species, and that disease management that is responsive to risk enhanced the efficiency of fungicide use. Responsive fungicide strategies are discussed as an effective management option for nursery managers, and the wider implications of responsive management for maintaining the robustness of agricultural systems are considered. **KEYWORDS** myrtle rust; plant nurseries; probabilistic cost benefit analysis; fungicide; responsive management
PAPER: Weather-based economic analysis: myrtle rust
###Capturing forest structure with high density laser scanning### **May 2023** **Cordes M. 2023. Capturing forest structure with high density laser scanning. YouTube, BioHeritage Challenge.** Presented at the Kaurilands Summit. Whangārei, New Zealand, 9 - 12 May 2023, hosted by Ngā Rākau Taketake.
RA3 PRESENTATION: Forest structure using laser scanning
###Effects of the soil-borne pathogen *Phytophthora agathidicida* on the kauri (*Agathis australis*) phyllosphere### **July 2023** **Hamilton Murray M. 2023. [Effects of the soil-borne pathogen *Phytophthora agathidicida* on the kauri (*Agathis australis*) phyllosphere](https://researchspace.auckland.ac.nz/bitstream/handle/2292/64513/HamiltonMurray-2023-thesis?sequence=1&isAllowed=y). Unpublished Masterate thesis, University of Auckland.** **ABSTRACT** Kauri tree damage by *Phytophthora agathidicida* (PA) colonisation of the roots and vascular tissue, consequently restricts water and nutrient transport through the tree. Resulting infection symptoms in the canopy, including foliage discolouration and thinning, suggest biochemical changes are occurring within the leaves. This research aims to understand how PA infection impacts the nutrient status of kauri leaves.
RA3 THESIS: Effect of kauri dieback on kauri phyllosphere
###ABSTRACT **May 2023** **ABSTRACT** Developing standardised measures to quantify the impact both kauri dieback and myrtle rust are having on the wider ecosystem. Poster presented at the Kaurilands Summit. Whangārei, New Zealand, 9 - 12 May 2023.
POSTER: Risk Assessment and Ecosystem Impacts
###Effect of kauri dieback on soil characteristics and decomposition in kauri dominated forest **September 2022** **Yang S. 2022. [Effect of kauri dieback on soil characteristics and decomposition in kauri dominated forest](https://researchspace.auckland.ac.nz/bitstream/handle/2292/61024/Yang-2022-thesis.pdf?sequence=1&isAllowed=y). A thesis submitted in fulfilment of the requirements for the degree of Master of Environmental Science, University of Auckland. 113 p. ** **ABSTRACT** Kauri dieback is a disease caused by an oomycete called *Phytophthora agathidicida*, a soil-borne pathogen that infects kauri roots. Kauri dieback results in yellowing of leaves, thinning of the canopy, dieback and mortality. This study investigated (1) soil characteristics and decomposition rates in kauri dominated forests affected by *Phytophthora agathidicida*, (2) the difference in soil characteristics and decomposition between kauri and non kauri trees, (3) the relationships between soil characteristics and decomposition.
RA3 THESIS: Effect of kauri dieback on soil characteristics
###The effect of kauri dieback on a diverse beetle community **March 2024** **Wardhaugh C, Black H. 2024. The effect of kauri dieback on a diverse beetle community. A report for New Zealand’s Biological Heritage National Science Challenge: Ngā Rākau Taketake. 38 p. ** **NOTE:** This report is embargoed until 31/01/2025 or until a paper is published. For further information please contact [Carl Wardhaugh](mailto:carl.wardhaugh@scionresearch.com) at Scion Research ###EXECUTIVE SUMMARY### __The problem__ Kauri dieback, caused by the soil-borne fungal pathogen *Phytophthora agathidicida*, has spread through much of New Zealand’s kauri forests, killing thousands of trees. The impact of the loss of numerous canopy trees on the wider biological communities in kauri forests is largely unknown. Here we undertake an initial survey of the beetle fauna in symptomatic forest with widespread dieback of kauri trees, and asymptomatic forest with little or no dieback, to ascertain whether the loss of kauri trees is having any noticeable impact on this diverse community. __Key results__ Overall, we collected 1,696 individual beetles from 228 species. Diversity did not differ between asymptomatic and symptomatic sites, but beetle abundance was much higher in asymptomatic areas. This pattern was driven by higher abundances of fungivorous, predatory, and herbivorous species in asymptomatic sites. Conversely, the abundances and diversity of species we expected to benefit from the widespread deaths of kauri trees (e.g., xylophages) did not differ among sites. The broad range of species with lower abundances in areas with kauri dieback that are not directly reliant on kauri trees suggests that abundance patterns are being influenced by changes to abiotic conditions caused by the loss of dominant canopy trees, rather than the loss of kauri per se. __Implications of results for the client__ While these communities may recover somewhat with the replacement of kauri by other tree species as the dominant canopy species at these sites, beetle communities will likely be forever changed by the loss of kauri trees. __Further work__ Continued monitoring of insect communities, either continuously or at regular intervals, is recommended to track how these ecologically vital assemblages change as the forest changes due to kauri dieback disease.
RA3 REPORT: Kauri dieback impact on beetles
###Does kauri dieback disease change soil bacterial community structure?### **February 2023** **King Z, Buckley H, Lear G, Seale B, Lacap-Bugler D. 2023. Does kauri dieback disease change soil bacterial community structure? First Australian & New Zealand Environmental DNA (eDNA) Conference - Innovation and Application. Hobart & Online, 14-17 Feb 2023. **
RA3 POSTER: Soil bacterial community structure
###Assessment of Forest Structural Complexity in Kauri (*Agathis australis*) Dominated Stands affected by Kauri Dieback using Mobile Terrestrial Laser Scanning **2023** **Cordes M. 2023. Assessment of Forest Structural Complexity in Kauri (*Agathis australis*) Dominated Stands affected by Kauri Dieback using Mobile Terrestrial Laser Scanning. Unpublished Masters thesis, Georg-August-University Göttingen. ** **NOTE:** This thesis is not publicly available online. For further information please contact supervisor, [Dr. Luitgard Schwendenmann](mailto:l.schwendenmann@auckland.ac.nz) at the University of Auckland **ABSTRACT** Forest development is determined by various biotic and abiotic factors over time, resulting in distinctive spatial patterns of vegetation. Forest Structural Complexity (FSC) metrics, derived from laser-scanning-generated point clouds, are increasingly used to analyse these patterns and to describe and investigate related ecosystem functions, such as light availability. Furthermore, FSC is influenced by species composition, their traits, and potential complementarity effects in tree canopy architecture and is expected to show recognisable variations by different disturbance agents. The endemic tree species of New Zealand, kauri (*Agathis australis*), faces a significant threat from the soil-borne pathogen Phytophthora agathidicida. This pathogen affects the water and nutrient transport of the keystone species, leading to the lethal disease known as kauri dieback. This study aimed to assess the current structural complexity of 6 long-term monitoring plots of a kauri-dominated forest ecosystem in northern New Zealand and to develop a standardised method to investigate the effects of *P. agathidicida* on kauri demography by mobile terrestrial laser scanning. A set of 16 structural metrics, across four distinct dimensional foci, were selected to investigate a variety of structural characteristic groups. Furthermore, a progressive symptomatic defoliation simulation was performed to identify the most suitable metrics of this approach for following research. The FSC metrics indicate distinct variations between old growth and secondary forest plots, with greater consistency and structural complexity observed within old growth forest plots in contrast to more pronounced differences among secondary forest plots. Besides basic statistical measures, arrangement and heterogeneity metrics are promising to detect changes in FSC. Nevertheless, the non-uniform distribution of laser points, typically for the used scanning system, leads to bias sources for individual structural metrics. The findings of this thesis create the baseline for following research on structural change of kauri-dominated ecosystems and contribute to the development of a comprehensive understanding of the effects of *P. agathidicida*.
RA3 THESIS: Assessing kauri stands with Laser Scanning
###Fine root characteristics in kauri-dominated forests affected by *Phytophthora agathidicida* **2022** **Yang J. 2022. [Fine root characteristics in kauri-dominated forests affected by *Phytophthora agathidicida*.](https://hdl.handle.net/2292/62582) A thesis submitted in fulfilment of the requirements for the degree of Master of Environmental Science, University of Auckland. 77 p.** **ABSTRACT** Fine roots (≤ 2 mm diameter) are a small but functionally important portion of belowground biomass in forest ecosystems, contributing to net primary productivity, carbon transfer, and nutrient cycling. Yet, fine roots are poorly quantified in Southern Hemisphere forests. Kauri (*Agathis australis*), an ecologically and culturally significant species, is threatened by the pathogen *Phytophthora agathidicida* (PA) which causes kauri dieback. Considering infection begins within living tissue of the fine roots, knowledge on fine roots is crucial to understanding tree responses to PA.
RA3 THESIS: The effect of Phytophthora agathidicida on fine roots
###Relationships between landscape and soil characteristics in a diseased kauri forest – soil carbon modelling case study from Waitākere Ranges Regional Park, New Zealand### **June 2023** **McElvein A. 2023. [Relationships between landscape and soil characteristics in a diseased kauri forest – soil carbon modelling case study from Waitākere Ranges Regional Park, New Zealand](https://researchspace.auckland.ac.nz/bitstream/handle/2292/64425/McElvein-2023-thesis.pdf?sequence=1&isAllowed=y). Unpublished Masterate thesis, University of Auckland.** **ABSTRACT** This research aimed to investigate the geospatial distribution and drivers of soil characteristics in diseased kauri forests, using samples from Waitākere Ranges Regional Park. Measurements included various soil characteristics, such as carbon, nitrogen, carbon-to-nitrogen ratio, pH, and bulk density, and considered 31 environmental variables, including tree-related factors, distance from important features, remote sensing imagery indices, topography, and observation location. The analysis revealed significant correlations between soil characteristics and tree-related variables, with soil carbon showing strong connections with variables from all categories.
###Using soundscapes to assess avian response to the presence of kauri dieback### **May 2023** **Turner-Steele J. 2023. Using soundscapes to assess avian response to the presence of kauri dieback. Kaurilands Summit 2023. Whangarei, 10/05/2023.** **ABSTRACT** This project seeks to grow our understanding of how the avian communities in kauri forests are affected by dieback and whether there is potential to use birds as an early detection system.
RA3 POSTER: Soundscapes to assess kauri dieback presence
###Morphological measurements to facilitate new species descriptions of three fungal isolates from *Austropuccinia psidii* in New Zealand### **March 2024** **Cu D, Dobbie K, Fraser S, Bartlett M. 2024. Morphological measurements to facilitate new species descriptions of three fungal isolates from *Austropuccinia psidii* in New Zealand. A report for New Zealand’s Biological Heritage National Science Challenge: Ngā Rākau Taketake and Beyond Myrtle Rust: Towards Ecosystem Resilience. 10 p.** **NOTE:** This report is embargoed until 30/06/2026 or until a paper is published. For further information please contact Michael Bartlett at Scion Research: [michael.bartlett@scionresearch.com](mailto:michael.bartlett@scionresearch.com) **ABSTRACT** This report describes three previously unknown (new to science) fungal species. These are potential fungal mycoparasites isolated from rust pustules of *Austropuccinia psidii* collected from Northern Taranaki in February 2023.
RA3 REPORT: Three new fungal species descriptions
###Developing standardised measures to quantify the impact both kauri dieback and myrtle rust are having on the wider ecosystem. To view website [CLICK ON THIS LINK](https://bioheritage.nz/research/risk-assessment-ecosystem-impacts/) **NOTE:** This website will cease in 2027.
WEBPAGE: Risk Assessment and Ecosystem Impacts
###Ecosystem impacts of tree pathogens### **May 2023** **Struijk M. 2023. Ecosystem impacts of tree pathogens [video]. YouTube, BioHeritage Challenge. ** Presented at the Kaurilands Summit. Whangārei, New Zealand, 9 - 12 May 2023, hosted by Ngā Rākau Taketake.
RA3 PRESENTATION: Ecosystem impacts of tree pathogens
###Monitoring myrtle rust disease effects on *Lophomyrtus* spp. reproductive capability in the natural environment Aotearoa New Zealand### **January 2024** **Zhulanov M, Soewarto J, Bartlett M, Sen D, Sutherland R, Gillard K, Miller E, Fraser S. 2022. Monitoring myrtle rust disease effects on *Lophomyrtus* spp. reproductive capability in the natural environment Aotearoa New Zealand. A report for New Zealand’s Biological Heritage National Science Challenge: Ngā Rākau Taketake. 27 p.** **NOTE** This report is embargoed until 31/01/2025 or until a paper is published. For further information please contact Stuart Fraser at Scion Research [stuart.fraser@scionresearch.com](mailto:stuart.fraser@scionresearch.com) **EXECUTIVE SUMMARY** **The problem** *Lophomyrtus* species are some of the most susceptible native host species under threat from myrtle rust in New Zealand. Previous studies have shown that all the reproductive structures of *Lophomyrtus* spp. are vulnerable to the disease, including flower buds, flowers, and fruits. While myrtle rust has the potential to kill mature *Lophomyrtus* trees (e.g. East Cape), it could also be interfering with the regeneration of *Lophomyrtus* species populations in the natural environment. Little is known about how myrtle rust impacts floral reproductive potential and seed germination. Quantitative characterisation of the impact of myrtle rust on *Lophomyrtus* species reproduction will directly inform conservation activities. __Client initiatives__ New Zealand’s BioHeritage National Science Challenge Ngā Rākau Taketake-Saving our Iconic Trees provided essential funding to monitor the impact of myrtle rust on the reproductive potential of *Lophomyrtus* spp. over the 2019-2020, 2020-2021 and 2021-2022 summer seasons. __This project__ This study aimed to investigate whether myrtle rust could impact the reproductive capacity of *Lophomyrtus* spp. in the natural forest environment. The development of flowers and fruits and the incidence of myrtle rust on these were assessed at three sites in the Bay of Plenty region. __Key results__ - *Lophomyrtus* spp. reproductive phenology overlapped with the myrtle rust seasonal epidemic. - Symptoms and signs of disease can develop on all reproductive stages, (from flower buds to developing fruit), but predominantly on developing fruits. - Regularly infected *Lophomyrtus* spp. trees had a lower rate of fruit production, likely due to the indirect effect of repeated myrtle rust infections on plant health rather than direct infection of flower buds and flowers. - Along with the increase of myrtle rust incidence on developing fruits, the production of fruits per tree during the fruiting peak declined at each site. Between 2021 and 2022, fruit production decreased 73-93% at the three locations assessed. __Further work__ - Statistical analysis is required to confirm the impact of fruit infection severity on seed germination rate. - Continuing the current monitoring and extending it to other regions in New Zealand with different climatic conditions and forest composition would determine how variation in environmental conditions impacts host susceptibility or tolerance over consecutive years. - Extending the seed germination test would enable the evaluation of the longer-term impacts of fruit infection on seedling fitness. - Active conservation practices such as encouragement of reproduction and identification of resistant phenotypes of *Lophomyrtus* spp. will support a long-term disease resistance breeding programme.
RA3 REPORT: Lophomyrtus spp reproductive capability
###Exploring the impacts of *Phytophthora agathidicida* on soil bacterial communities associated with kauri (*Agathis australis*) **March 2023** **Michael I. 2023. [Exploring the impacts of *Phytophthora agathidicida* on soil bacterial communities associated with kauri (*Agathis australis*)](https://researchspace.auckland.ac.nz/bitstream/handle/2292/67546/Michael-2023-thesis.pdf). Unpublished Masters Thesis, University of Auckland. 162 p. https://hdl.handle.net/2292/67546** **ABSTRACT** Kauri trees (*Agathis australis*) are iconic giants in Aotearoa, New Zealand, renowned for their immense size and longevity. They are endemic to Aotearoa and hold immense ecological, cultural, and social significance as a keystone species. Kauri were once prolific across the North Island, but extensive logging by early European settlers drastically reduced their mature forested areas to a mere 7500 hectares. This alarming decline spurred efforts to safeguard these precious species. In contemporary times, kauri face a new threat, *Phytophthora agathidicida*, the causal agent of kauri dieback. This soil-borne oomycete pathogen causes yellowing of leaves, canopy dieback, and gum lesions on the base of the tree trunk, eventually leading to tree death. Infection of kauri by *P. agathidicida* occurs through colonisation of the host’s roots and vascular tissue, leading to changes in the flow of nutrients and water throughout the tree and within the surrounding soil. Research efforts have unveiled the consequences of kauri dieback disease on kauri health, many of which have broader ecological implications for forest health. However, few studies have considered how *P. agathidicida* influences the soil microbial communities that maintain forest ecosystem and plant health, e.g., through carbon and nutrient cycling and pathogen protection. It is essential to consider the implications that *P. agathidicida* has on the soil bacterial communities beneath infected kauri, as this could directly impact kauri health, as well as kauri forest ecosystem health and functioning. My study used 16S rRNA gene sequencing to examine the impact of *P. agathidicida* on the soil bacteria of ~700 kauri trees in the Waitākere Ranges, an area severely affected by dieback disease. I found that healthy and infected kauri trees possess significantly different core soil bacterial communities that are deterministically selected by the environment of infected trees. The roles of environmental, climatic and soil physicochemical variables on soil bacterial composition were explored to determine which caused or are related to the differences in soil bacterial communities I observed between healthy and infected trees. Soil pH was the most important predictor of soil bacterial structure and composition, with infection being more common in soils with higher pH. I employed random forest models to determine whether soil bacterial communities could be harnessed as bioindicators for *P. agathidicida* presence. Key environmental attributes such as soil pH could be predicted from the analysis of the bacterial community data, and *P. agathidicida* could be predicted also, though with less accuracy. Future investigations should explore fungal or metagenomic data to enhance predictive models, assisting in detecting *P. agathidicida* in the environment and related biological interactions. My thesis greatly advances our understanding of the broader ecological impacts of *P. agathidicida* infection on soil bacterial communities and contributes to efforts to conserve these vital kauri forests.
RA3 THESIS: Phytophthora agathidicida impact on soil bacteria
###The threat of a major tree pathogen to forest soil mesofauna food webs and ecosystem functioning### **March 2024** *Struijk M, Stavert J, Le Grice R, Schwendenmann L, Romera J, Mitchell G, Yang J, Hjelm F. 2024. [The threat of a major tree pathogen to forest soil mesofauna food webs and ecosystem functioning](https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2024.1338109/pdf?isPublishedV2=false). Frontiers in Ecology and Evolution 12.** **ABSTRACT** This research focuses on the impact of *Phytophthora agathidicida* on the soil mesofauna community structure, functional feeding groups and energy fluxes in kauri forests, for kauri and adjacent broadleaf trees. Soil mesofauna communities were sampled from kauri and adjacent broadleaf trees. Analysis accounted for factors including kauri canopy health scores, tree diameter, slope, forest floor depth, and soil carbon dioxide efflux. Soil samples were analysed for the presence of *P. agathidicida*, total carbon, and total nitrogen. Soil mesofauna food webs were constructed for kauri and broadleaf trees and analysed for uniqueness associated with kauri and the impact of the presence of *P. agathidicida* on key foodweb characteristics. **KEYWORDS** soil food web, trophic group, foundation species, kauri dieback, Agathis australis, Phytophthora agathidicida, energy flux, soil fauna
###A Functional Assessment of Community Vulnerability to the Loss of Myrtaceae From Myrtle Rust### **October 2024** **McCarthy J, Richardson S, Jo I, Wiser S, Easdale T, Shepherd J. & Bellingham P. 2024. [A Functional Assessment of Community Vulnerability to the Loss of Myrtaceae From Myrtle Rust](https://doi.org/10.1111/ddi.13928). Divers Distrib e13928.** **ABSTRACT** Woody ecosystems provide critical ecosystem functions and services but are increasingly threatened as invasive pathogens spread globally. Myrtle rust, caused by *Austropuccinia psidi*i, arrived in New Zealand in 2017 and infects at least 12 of 18 species in the susceptible Myrtaceae plant family. Among these are species of structural, successional and cultural importance. We aim to assess whether the functional consequences of Myrtaceae loss could be mitigated if co-occurring species with shared functional attributes are able to replace them. **KEYWORDS** *Austropuccinia psidii*, functional redundancy, functional similarity, invasive pathogens. *Kunzea, Leptospermum, Metrosideros,* New Zealand, tree diseases
RA3 PAPER: Assessing community vulnerability to myrtle rust.
###Risk Assessment & Ecosystem Impacts 2021 **June 2021** **Akariro Films. 2021. Risk Assessment and Ecosystem Impact - Video for Kaurilands Summit 2022. YouTube, BioHeritage Challenge.** **ABSTRACT** We need to understand kauri dieback and myrtle rust better if we want to protect our ngahere. That’s why the goal of the ‘Risk Assessment & Ecosystem Impacts’ team is to identify the effects of these diseases and management, as well as which species and ecosystems are most at risk. More detailed information will allow us to better prioritise conservation efforts and management decisions. If we get really good data now, we will be better informed in 10, 50 and 100 years’ time about the changes in the forest ecosystems. Click ‘play’ to view what they’ve been up to in the first three years of the programme. This video was screened at the online Kaurilands Summit 2021. This research programme is funded by Ngā Rākau Taketake, which is administered by New Zealand's Biological Heritage National Science Challenge | Ngā Koiora Tuku Iho.
VIDEO: Risk Assessment & Ecosystem Impacts 2021
###Soil microbial functional gene dataset associated with *Agathis australis*### **December 2023** **Lawrence P, Padamsee M, Lee K, Lacap-Bugler DC. 2023. [Soil microbial functional gene dataset associated with *Agathis australis*.](https://www.sciencedirect.com/science/article/pii/S2352340923008533/pdfft?md5=88c56dae98d9a00d0666d14c1199a30a&pid=1-s2.0-S2352340923008533-main.pdf) Data in Brief: 109791.** **ABSTRACT** *Agathis australis* (kauri), is currently facing a threat from *Phytophthora agathidicida*, causing kauri dieback disease and reducing the kauri tree population. Only 1% of the original New Zealand virgin kauri forest remains. Recent studies have shown that soil-borne microorganisms can enhance the trees' defense mechanisms by competing with pathogens for nutrients, preventing pathogen colonisation, and modulating plant immunity. This study characterises the functional gene profile in relation to soil microbial diversity of the kauri trees in three distinct environments (Native Forest, Kauri Grove, and Rose Garden) at Auckland Botanic Gardens. **KEYWORDS** Soil microbiome; *Agathis australis*, Kauri dieback; Geochip 5 **NOTE:** The research team acknowledges the mana whenua groups of the rohe where Auckland Botanic Gardens is located, and the support of the Kauri Ora Community (Ngā Rākau Taketake) for our research on kauri, a taonga species in Aotearoa.
RA3 PAPER: Soil microbial functional gene dataset
###Effect of kauri dieback on leaf litter nutrient concentrations### **2022** **Sharma I. 2022. Effect of kauri dieback on leaf litter nutrient concentrations. Unpublished Honours thesis, University of Auckland.** **NOTE:** This thesis is not publicly available online. For further information please contact supervisor, [Dr. Luitgard Schwendenmann](mailto:l.schwendenmann@auckland.ac.nz) at the University of Auckland **ABSTRACT** Kauri dieback, caused by *Phytophthora agathidicida*, is threatening the survival of the iconic kauri (*Agathis australis*) species. Kauri has been found to modify their environment through significant effects on soil processes. Leaf litter is the primary nutrient input to soil, with litter analysis being widely used to assess overall plant and soil health. The extent of how kauri dieback impacts these processes is largely unknown. This study seeks to identify whether leaf litter nutrient concentrations are impacted through *P. agathidicida* infection. Three sites in the Waitākere Ranges Regional Park have been selected for this study. Macro- and micronutrients have been selected for analysis, along with litter biomass and tree size. A comparison of kauri leaf litter to broadleaf litter is also presented, to understand whether nutrient concentrations differ between species of the same forest ecosystem. A significantly higher litter biomass in the site characterized by large trees was observed. Some effects of sample type on nutrient concentrations was also observed. Kauri leaf litter nutrient concentrations were significantly higher for carbon, calcium, and the C:N ratio, whilst broadleaf litter was significantly higher for boron and copper concentrations. Primarily, *P. agathidicida* infection did not have a significant effect on leaf litter nutrient concentrations when sites were grouped. However, differences were seen when sites were separated. This indicates that the effects of *P. agathidicida* infection on leaf litter nutrient concentrations was site specific. Most kauri leaf litter macro- and micronutrients concentrations tended to be lower underneath trees showing kauri dieback symptoms. Lower leaf litter nutrient input may result in long term changes to species compositions and biogeochemical processes in kauri dieback affected forests.
RA3 THESIS: Leaf litter nutrient concentrations
###Seasonal progression of myrtle rust on *Lophomyrtus* trees in New Zealand leading to declining health and reproductive potential### **June 2023** **Bartlett M, Soewarto J, Beresford R, Zhulanov M, Todoroki C, Sutherland R, Gillard K, Balfour N, Smallman T, Pugh A, Fraser S. 2023. Seasonal progression of myrtle rust on *Lophomyrtus* trees in New Zealand leading to declining health and reproductive potential. Australasian Myrtle Rust Conference, Sydney, Australia, 21 - 23 June 2023.**
RA3 PRESENTATION: Seasonal progression of myrtle rust
###Risk Assessment & Ecosystem Impacts 2022 **June 2022** **Akariro Films. 2022. Risk Assessment and Ecosystem Impact - Video for Kaurilands Summit 2022. YouTube, BioHeritage Challenge.** **ABSTRACT** We need to understand kauri dieback and myrtle rust better if we want to protect our ngahere. That’s why the goal of the ‘Risk Assessment & Ecosystem Impacts’ team is to identify the effects of these diseases and management, as well as which species and ecosystems are most at risk. More detailed information will allow us to better prioritise conservation efforts and management decisions. If we get really good data now, we will be better informed in 10, 50 and 100 years’ time about the changes in the forest ecosystems. Click ‘play’ to view what they’ve been up to in the first three years of the programme. This video was screened at the online Kaurilands Summit 2022. This research programme is funded by Ngā Rākau Taketake, which is administered by New Zealand's Biological Heritage National Science Challenge | Ngā Koiora Tuku Iho.
VIDEO: Risk Assessment & Ecosystem Impacts 2022
###Assessing the Effect of Phosphite Treatment on Arbuscular Mycorrhizal Fungi in Kauri (*Agathis australis*)### **December 2022** **Patterson HR, Padamsee M, Schwendenmann L. 2022. Assessing the Effect of Phosphite Treatment on Arbuscular Mycorrhizal Fungi in Kauri (*Agathis australis*). New Zealand Ecological Society Conference. University of Otago, Dunedin. 28 Nov - 2 Dec 2022.** **ABSTRACT** Arbuscular mycorrhizal fungi (AMF) inhabit the roots of kauri and aid in nutrient uptake, water retention and possibly pathogen resistance. The effect of phosphite treatment on AMF inhabiting kauri roots is unclear. This research aims to: 1. Trial and optimise the measurement of AMF colonisation in kauri roots. 2. Confirm the presence of, and measure, AMF colonisation in selected phosphite-treated trees. 3. Investigate the relationship between soil properties and AMF species diversity and colonisation at each site.
RA3 POSTER: Phosphite effects on mycorrhizal fungi