Evaluating the impact of an invasive pathogen on tree population decline: An evidence based modelling approach

Abstract

An upsurge of invasive forest pathogens (IFPs) has been causing widespread damage to forest ecosystems worldwide. Modelling future forest loss caused by IFPs is challenging, as it requires a sophisticated understanding of the pathogen-hosts-surrounding interactions. We developed a complexity-appropriate model using an evidence-based approach to predict the decline of the European ash (Fraxinus excelsior L.) population caused by ash dieback (Hymenoscyphus fraxineus) in a British deciduous woodland. Our model predicts that (1) the ash population will decline by ∼26 % in the next 10 year; (2) an ±10 % relative error in mortality survey would cause a ∼8 % bias in 10-year population decline; and (3) a 5 % increase in resistant trees would save ∼3 % population over 10 years. Our research demonstrates the merit of systematic reviews in balancing model complexity against generalisation. By scaling up the methodology to other IFPs, it is possible to forecast forest health with various management scenarios.