Forest health and protection, mycology, entomology and biotechnology
Invasions in Forest, Forest entomology
Invasive species, intersection of biology, ecology and the social sciences
Forest health and plant pathology, particularly the biology, ecology and genetics of microorganisms affecting natural ecosystems and plantation forests
Invasive trees and shrubs. The role of biotic interactions in invasions
Management of invasive plants, human and social dimensions of biological invasions
Growth of plant species is often higher outside their native range compared to when they grow in the native range and similarly non-native plants often grow faster that native plants growing within the same community (Van Kleunen et al 2010, Leishman et al. 2014). Several mechanisms have been proposed to explain high growth rates in non-native plant populations; these include climatic niche expansion, novel interactions with competitors, different abiotic conditions, and release from herbivory and plant pathogens (Colautti et al 2004, Gioria et al. 2023).
The exceptional growth of non-native plants is often exploited in both agriculture and commercial forestry enterprises. Worldwide, planted forests extend over an area of almost 300 million hectares and are steadily expanding (Payn et al 2015). These forests are increasingly important, both for the provisioning of wood products, but also their role in sequestering atmospheric carbon (Baral et al. 2016). In many regions, especially the global south, extremely high rates of forest productivity are achieved by planting non-native tree species (Waring et al. 2008, Pötzelsberger et al. 2020). This practice is exemplified by widespread plantations of North American and European Pinus spp. in South America, Africa and Australasia (Burgess and Wingfield 2001). The tree genus most widely grown outside of its range is Eucalyptus which is planted across 25 million hectares of South America, Africa, Asia, and Europe.
Though much of the exceptional growth of non-native trees used in plantation forestry can be attributed to the absence of herbivores and tree pathogens, this enemy release typically diminishes over time (Hawkes 2007, Schulte et al. 2025). Native herbivores and pathogens can sometimes expand their host use onto non-native trees, thereby reducing the benefit these plants otherwise gain from enemy release (Crous et al. 2016). The ability of herbivores and pathogens to expand their host range onto non-native plants is closely linked to the phylogenetic similarity of the non-native plant with native hosts; plant parasites are generally more successful at attacking closely related species, while more distantly related plant species are usually less susceptible (Hill et al. 2009, Pearse and Andermatt 2013). For example, Zhao et al. (2025) found higher levels of foliar pathogens in a North American pine species growing in Europe, where it coexists with European pine species, than in the same pine species grown in South America where native pines are absent.
Enemy release experienced by non-native trees also diminishes over time as specialist insects and pathogens from these trees’ native ranges invade and are re-united with their hosts (Crous et al. 2016). For example, Eucalyptus species have been widely planted in forest plantations worldwide due their exceptional growth which can be partially attributed to enemy release; but over the last few decades, insects and diseases from the Eucalyptus native range have accidentally been transported to these regions and this accumulation of insects and herbivores have diminished their productivity (Hurley et al. 2016, Burgess and Wingfield 2017). Another example is provided by Douglas-fir which is native to North America but widely planted in New Zealand from ca. 1940 to 1990 due to its fast growth and high wood quality (Lavender and Hermann 2014, Waring et al. 2008). However, the pathogenic fungus Phaeocryptopus gaeumannii, the causal agent of Swiss needle cast, was accidentally introduced from North America and by the time it spread throughout the planted range (~ 1990) it caused extensive reduction in tree growth, greatly diminishing the profitability of the forest enterprise (Kimberly et al. 2011).
Another problem facing the use of non-native tree species in plantation forestry is the escape and spread of trees into adjoining areas (Richardson et al. 2014). While not all tree species exhibit such invasive tendencies, many of the same traits for which species are selected for use in plantation forestry (e.g. fast growth rates, rapid reproduction, etc) may also lead to these species exhibiting invasive tendencies. Impacts of tree invasions can be substantial but are often related to the ability of invasive trees to outcompete and thereby displace native plant species. Not all tree species exhibit invasiveness and tree invasions are often limited to specific environmental conditions. Based on this information, guidelines have been developed to inform the selection of tree species for planting in forestry in order to avoid tree invasions (Brundu et al. 2020). However, these guidelines have not been consistently adopted by practicing foresters in all world regions, so the problem of tree invasions continues to grow.
This working group aims to synthesize existing knowledge about the use of non-native trees in forestry worldwide and explore how concepts from the field of invasion biology can help guide future practices. The intent is that by assembling an interdisciplinary team of scientists, it will be possible to draw new insights into these problems and apply that knowledge to provide improved guidance for the use of non-native trees in plantation forestry.
Objectives:
Anticipated deliverables:
References
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Brundu, G., Pauchard, A., Pyšek, P., Pergl, J., Bindewald, A. M., Brunori, A., … & Richardson, D. M. (2020). Global guidelines for the sustainable use of non-native trees to prevent tree invasions and mitigate their negative impacts. NeoBiota, 61, 65-116.
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Zhao R, Nuske SJ, Nuñez MA, Fajardo A, Moyano J, McIntosh ACS, et al. 2025. Distinct foliar fungal communities in Pinus contorta across native and introduced ranges: evidence for context dependency of pathogen release. Sci. Rep.;15:7273
Project HIVE 101187384. Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Executive Agency. Neither the European Union nor the granting authority can be held responsible for them.
