Invasive pathogens in Austrian forests - public awareness and strategies (RESIPATH)

The aim of the proposed research project is to study how European forests are affected by and respond to invasive pathogens, as well as to develop means to mitigate their impact. This will be perfomed in a coordinated way by altogether 13 European researchers within the frame of five work packages: WP1: Long term sustainability of tree species affected by invasive pathogens and framework for impact assessment. WP2: Understanding the mechanisms involved in adaptation of forest tree populations to new pathogens. WP3: Mechanisms of hybridisation in Europe. WP4: Detection and early warning of fungal and oomycete pathogens. WP5: Public perception on impact of invasive pathogens. The Austrian project part will focus on the following tree species threatened by pathogens: Ophiostoma novo-ulmi , elms (Ulmus spp.); Chalara fraxinea (ash dieback), ash (Fraxinus spp.); Phytophthora alni, alder (Alnus spp.) and Erysiphe alphitoides, oak (Quercus spp). These invasive pathogens have not yet damaged the entire tree populations in Europe. The Austrian project part will contribute to impact studies on both host and pathogen population demographics and evolution, to the development of detection systems and thus to a better understanding of the public perception. WP1 addresses the concept of base-rate mortality to understand if mortality due to invaders can impair the long term sustainability of the selected tree populations. Here we will evaluate the long-term sustainability of ash and alder populations affected by invasive pathogens. In selected monitoring plots of declining and non declining ashes as well as comparative plots with alders, which have been assessed for disease development annually during the past 5 years (ashes) and 15 years (alders), mortality and climatic data will be provided for calculating the difference between base-rate mortality. For the calculation of the base-rate mortality, data from the Austrian Forest Inventory will be taken for ashes and alders and, in addition, for oaks and elms to be included in the calculation by partner 6 (INRA France). Numerous forest diseases caused by fungal or oomycete pathogens are currently spreading in Europe, due to human activities (trade) and the natural dissemination of airborne fungal propagules. Here we aim at providing a validated early detection system of potentially harmful and invasive pathogens (WP4). For the monitoring of invasive airborne pathogens we will use spore traps enabling detection of low concentrations of spores in the air. We will combine spore trapping and PCR for the specific detection of airborne spores using C. fraxinea as a model system. DNA extraction methods will be optimized for different spore traps and the outcome of different passive spore traps and active Burkard spore samplers will be compared in different forest and nursery environments. The information gathered will be compiled in a detailed guideline for practitioners as well as plant protection services how to use spore traps for air-borne pathogens. Furthermore, we will test state of the art technology to detect invasive Phytophthora pathogens in nurseries, forests and riparian plantings of alders, as well as in rivers by baiting, filtering and direct isolation methods. Water from fish hatcheries which import fish stock from overseas will be tested for contamination with Phytophthora spp.. In addition, the gravel from forest roads will be tested for infestation by Phytophthora spp. In WP5, the project is aimed to evaluate the inter-correlations between impact of invasive pathogens, mass media coverage and public awareness. Standardized methodology will be employed including public opinion surveys, mass media analysis and workshops with identified stakeholders. Understanding of important information pathways will be used to develop improved means to communicate within society. Public opinion surveys will be conducted by phone interviews of citizens. Mass media analysis will be done systematically studying the content of communication messages for invasive forest pathogens related messages in the two biggest newspapers of Austria. Automatic internet searches will be conducted in order to find key words in the related news of the lasts 10 years. The information provided will allow a better means of communicating the importance of this issue to public and policy makers. After this stage the results will be presented in a workshop with experts and selected stakeholders, who are asked about their perceptions, opinions, beliefs, and attitudes towards invasive pathogens. Experts and stakeholders will analyse the results of the citizen opinions and mass media coverage. The WP will deliver information, from the expert point of view, and considering the public opinion and the media content, what messages are missing or should be emphasized and what messages should be corrected.

This project was targeted at a calculation of consequences of invasive fungal or fungi-like pathogens of trees for the European forests and at the development of measures to reduce the impact, thus it contributed to a long-term sustainment of endangered tree species. Early detection of invasive tree pathogens was a primary aim. Special emphasis was placed on the adaption of tree populations to new tree diseases as well as on fundamentals for early warning systems. The public awareness of invasive pathogens was assessed as well. The Austrian project part contribted to the collar rot of alders by various species of the oomycete genus Phytophthora, to the actual ash-dieback by the fungus Hymenscyphus fraxineus as well as to the assessment of the awareness of the public. Fungal cultures and leaf samples were delivered to project partners dealing with population studies of Dutch elm disease (Ophiostoma novo-ulmi) and oak mildew species of the genus Erysiphe. Regarding ashes and alders data from long-term damage monitoring as well as climate data were analysed in order to identify, whether the mortality endangers the stands over the years. In order to assess the Phytophthora species in diseased alders, in the soil and in river water 11 Austrian river systems were investigated in all federal provinces of Austria. In total seven species of Phytophthora were widespread in riparian alder stands. P. polonica was recorded for the first time from alders in Austria and identified as an aggressive pathogen in roots. In some river systems disease intensity is related to human activities as river management (regulation, canalisation, disturbances as road construction work near the river banks, water abstraction). The common presence of Phytophthora in roots indicates a possible spread via plant stock: analyses of alders, beech, oaks, firs and ashes from in total 6 nurseries revealed numerous Phytophthora-species present in plant stock. Long-term monitoring plots showed a decrease in the disease-course over the years, which significantly was intensified in dry years. Contrary winters with hard frost increase mortality. An infection trial however indicated the presence of some tolerance of the alders to Phytophthora. In some river systems, Phytophthora-decline of Grey alders recorded from the 1990ies on caused a massive spread of secondary pests and pathogens (Buprestids and Armillaria) endangering the stands substantially, since they prevent natural regeneration of the alders. Monitoring of ash-dieback from 2008 and 2016 revealed a chronic disease-development in older trees with a low mortality in 10 years (<5%). Considerable annual fluctuation of the mean disease % might be explained by changing infection conditions under climatic influence, however they also show the high regeneration capacity of ashes. Intensity of spore dispersal showed a distinct relation to relative air humidity: following precipitation the spore intensity enormously increased and dropped to minimal value in dry periods. In 9 states a broad group of people was telefonically confronted with questions to invasive pathogens. In total the awareness of the problem was quite high, however the risk by the pathogens was regarded as a future problem rather than an existing one. Public acceptance of political measures was high: information was regarded as the main and initial need, followed by legal measures including even trade limitation. The lowest acceptance concerned limitation of access to forest stands deserving protection.