Monitoring sentinel trees for identifying harmful alien pests before they arrive to new area – improvement of sampling design

Alien pests and pathogens of trees are one of the major threats to forest ecosystem health and biodiversity. The number of introduced alien pests and pathogens of trees has been increasing due to accelerating trade in live plants and reproductive plant material, causing significant economic and ecological damage worldwide.

The monitoring of sentinel trees is a novel and promising tool which enables the detection of potentially harmful organisms before they arrive in a country. Monitored trees may belong to vulnerable or valuable species for the importing country and present species in botanical gardens, arboreta or sentinel plantations in the exporting country. It is unknown, however, how many samples need to be taken from a tree species to capture a relevant proportion of the potentially harmful insect and fungal species that are associated with it.

To obtain data needed for the improvement of sampling methodology we designed a study that will use data collected from botanical gardens, arboreta and other plantations on three continents (North America, Europe and Asia). Samples of trees of twelve economically important species from each continent will be collected from botanical gardens and arboreta to assess the presence of pests and pathogens of leaves, bark and seeds. The results will provide information for prioritization of harmful species for risk assessment and for development of measures to reduce the risk of their introduction.