Paul Barber

Perth, the capital city of Western Australia, is situated on a river with numerous bays. The peri‐urban environment extends along the coast for 100 km north and south of the city. Within the region is a fragmented landscape of suburbs, parks and remnant woodlands. The Eucalyptus gomphocephala woodland south of Perth is classified within the peri‐urban environment. Numerous Phytophthora species have been isolated from dead and dying endemic trees. The most frequently isolated species is P. multivora (65%), followed by P. aff. arenaria (21%); P. palmivora, P. syringae, P. inundata, P. aff. humicola, P. nicotianae and P. sp. ohioensis have also been isolated, although rarely. P. multivora and P. aff. arenaria have both been isolated from dying E. marginata (jarrah), E. gomphocephala (tuart), Corymbia calophylla (marri), C. ficifolia (red flowering gum) and Agonis flexuosa (WA peppermint). While P. multivora is commonly encountered in less impacted ecosystems, the other species found in the periurban environment (P. inundata and P. nicotianae) are rarely or never isolated. In the riparian ecosystem, P. aff. humicola has been isolated from dying Casuarina obesa. The knowledge about the impact of these species on our remnant trees is lacking. Further research is required on the origin, pathogenicity and control of these species to deliver effective management strategies.

Stem injections with phosphite liquid protect B. grandis and E. marginata from P. cinnamomi for at least four years . However, stem injection of phosphite is labour intensive and requires training, specialised equipment, and the mixing of chemicals. The recent development of soluble phosphite implants which can be quickly inserted into stems, overcomes the need for training and the use of specialised equipment. Systemic nutrient implants and injections have been effectively used to correct nutrient deficiencies in ornamental and horticultural plants and can help increase tree vigour to pests and pathogen attack. However, soluble implants of phosphite and nutrients have never been trialled for the control of Phytophthora. This study aimed to determine if liquid phosphite, soluble implants of phosphite alone, or combinations of macro and micro nutrients within implants inserted into the trunks of the trees could control lesion development caused by P. cinnamomi. In B. grandis and E. marginata, phosphite liquid and soluble phosphite implants significantly reduced lesion length compared to the control and application of nutrient implants. In B. grandis and E. marginata, nutrient implants reduced significantly the average lesion length compared to the control. Results show that both phosphite liquid and implants are effective at controlling lesion extension in B. grandis and E. marginata, caused by P. cinnamomi. Stem treatment with soluble phosphite implants will facilitate the rapid treatment of trees, and control of P. cinnamomi, in diseased areas. In addition, the uptake is passive, there is likely less damage to internal stem tissues, and less risk from phytotoxicity due to slow release of the phosphite compared to the liquid treatments.

In Western Australia there are a number of substantial declines and deaths across a number of forest and woodland tree species. These include Eucalyptus marginata, E. gomphocephela (tuart), E. wandoo (wandoo), E. rudis (swamp gum), Agonis flexuosa (peppermint) and Corymbia calophylla (marri). There are many theories put forward as to the reasons for these declines including: (i) global climate change; (ii) habitat loss and fragmentation; (iii) changes in land management, e.g. the absence of planned fire, damage from wildfires, and past timber harvesting and grazing; (iv) weeds, pests and diseases; (v) salinity; (vi) changes in hydrology; (vii) poorly developed links between research and management; and (viii) sub‐optimal management policies and strategies at Local and State Government levels. The Centre is made up of three core research organisations, 27 collaborating industry partners and seven collaborating international and national institutions. An overview of these declines, the possible causes, their implications to ecosystem function and health and the different research and adaptive management approaches that are in place to understand and mitigate these declines will be discussed.

Corymbia ficifolia is a widely planted amenity tree worldwide. Recently, the species has been observed to be in decline in urban environments. This study investigated the causes of the decline in 246 trees in roadsides/median islands, parks, streets within residential areas in five urban areas in the City of Melville, 77 trees on the Murdoch University campus, and 82 trees in other urban areas and in its natural habitat in south‐western Australia. Tree diameter, height, and canopy/crown densities ranged from 5.5‐104.1 cm, 2.4‐18 m and 5‐100%, respectively. Most adult trees in urban areas suffered from canker disease caused by Quambalaria coyrecup which was commonly associated with branch flagging and dieback. No canker symptoms were found in natural stands of C. ficifolia. Occurrence of canker, dieback, flagging, and foliar diseases across all sites ranged from 0‐80%; 26.6‐80%; 4.7‐57.1%; and 29.2‐100%, respectively. Foliar symptoms caused by biotic and abiotic causal agents were also present. Whilst leaf disease is widespread, stem cankers are of major concern in larger trees. The health and structural condition of trees were scored and correlation among tree parameters with disease presence was assessed. Some diseases were common on C. ficifolia at a particular plant growth stage or in particular areas. The research indicates that disease problems in urban C. ficifolia trees are common and that more than one causal agent is responsible.

The Ludlow Tuart Forest is the only remaining tall tuart forest in the world and one of the rarest ecosystems on earth. Tuart forests are of immense value for conserving biodiversity and protecting ecosystem function, as well as providing important cultural, social and economic values. However, these areas have been impacted upon by various disturbances including logging, grazing, clearing and weed and pathogen invasion, which have resulted in changes in vegetation structure and composition. This is concerning to scientists, land managers and the public and has resulted in a growing desire to develop techniques to restore these forests. This study investigated techniques for establishing tuart forest species in degraded tuart forests, including: the creation of ashbeds; and the addition of nutrients, chelating agents and water sources. Restoration trials were undertaken with the assistance from a number of community-based programs aimed to facilitate participation in a number of phases of the restoration process. These included provenance seed collection, planting and monitoring. Trials indicated that creation of conditions that mimic natural disturbances has a positive influence on seedling survival and growth. Significant levels of survival and growth can also be produced through the use of plant treatments such as specific types of fertilisers and chelating agents. This study has shown that together with a range of plant and site treatments community engagement can be successfully captured to assist in the establishment and on-going monitoring of restoration trials. These types of trials will drive continued improvement of restoration techniques for degraded forests.

Forest, woodland and shrubland declines are widespread and in many cases severe in Western Australia and elsewhere in temperate Australia. The causes are often complex, poorly understood and include: declining rainfall, changes in groundwater levels and quality, pathogens and pests, excess nutrients, salinity, changing fire regimes, and weed competition to name a few. This presentation reviews current projects by members of the State Centre of Excellence on Climate Change Woodland and Forest Health and other researchers based at Murdoch University. The Centre, a co-operative venture with the University of Western Australia, the Department of Environment and Conservation and approximately 26 other partners, has four key Research Programs: Climate Change, forest and woodland declines; Decline Ecology; Restoring Biodiversity Values, and Education, Training, Communication and Policy. The aim of the Centre is to bring together multi-disciplinary teams of research scientists to (a) determine the factors that contribute to declines, (b) determine how they interact with climate change, (c) develop adaptive management strategies to mitigate the declines and to restore ecosystem function and health, and (d) work with agencies, industry and the wider community to ensure research findings are rapidly and effectively implemented through policy, legislation and community engagement. Keywords: Climate Change; Remote Sensing, Restoration, Fauna, Flora

Since the early 1990's there has been a significant decline of Eucalyptus gomphocephala and more recently E. marginata, in the tuart forest in Yalgorup National Park SW Western Australia, although no satisfactory aetiology has been established to explain the decline. Characteristics of the canopy dieback and decline distribution are reminiscent of other forest declines known to involve Phytophthora soil pathogens and indicate that a Phytophthora species may be involved in the decline. In 2007 isolates of a Phytophthora species were recovered from rhizosphere soil of declining or dead trees of E. gomphocephala and E. marginata, and were described as P. multivora. For E. gomphocephala and E. marginata, the pathogenicity of P. multivora was tested: ex situ on seedlings using a soil infestation method; and in situ on stems using an under bark inoculation method. Trials suggest that P. multivora can be significantly aggressive to both E. gomphocephala and E. marginata, although further research is needed. The soil infestation trial indicates that P. multivora is a pathogen of E. gomphocephala and may be a significant soil pathogen in the field, although there is variation in the pathogenicity between P. multivora isolates. The under bark inoculation trial confirms that P. multivora is a pathogen to E. gomphocephala, and especially pathogenic to E. marginata, where it is able to colonize the vascular tissue in the field.

Tuart (Eucalyptus gomphocephala) is an iconic woodland tree, endemic to Western Australia, and is one of the few eucalypts able to dominate on calcareous soils. Unfortunately, less than one third of the original extent of the E. gomphocephala woodland ecosystem remains in existence today, largely as a result of clearing for urbanisation, agriculture and industry. Equally disturbing is the extensive decline of the E. gomphocephala ecosystem within the Yalgorup region, south of Mandurah, from unknown but probably complex abiotic andlor biotic causes. The recently described species Phytophthora multivora was isolated from the rhizosphere of declining tuart and may be contributing to this decline. A large collaborative, integrated research effort is focused on finding the cause(s) of this decline. Intensive ground-based studies are being used in conjunction with digital remotely sensed imagery and other spatially explicit datasets to aid establishment of research sites, map the spatial and temporal pattern of the decline with the major objective to find strong correlations with abiotic andlor biotic factors. The historical trend in canopy cover of areas of E. gomphocepha/a woodland can be accurately determined across the landscape using medium resolution (25m) LandsatTM-derived satellite data. Areas of particular interest were 'ground-truthed' in the present study to enable establishment of field sites according to changes in canopy cover over a 17 year period. High resolution (0.5 - 1m) Digital Multi-Spectral Imagery (DMSI) was then acquired for these sites and trees and shrubs of interest located using a differential GPS system. Detailed canopy assessments, foliar analysis, soil analysis and injection treatments have been completed for each site. Correlations between indicators of canopy health and a range of established spectral indices were examined. Annual DMSI has been acquired to detect changes in E. gomphocepha/a canopy and patterns of decline within the landscape. Results from this study will be presented.