Forests and Biological Invasions

TF Forests and Biological Invasions

Task Force Coordinator:

Andrew Liebhold, United States


Globalization has many benefits, but a harmful consequence of this trend is the movement of organisms among the world’s regions. When species become established in alien environments, they often exhibit explosive population growth resulting in severe impacts on native communities. Forests are currently experiencing invasions by non-native insects, pathogens, plants and other organisms, many of which profoundly alter forest ecosystem properties and sometimes cause massive economic impacts on forest resources. This is a problem that is being experienced worldwide, both in economically developed nations, as well as in developing countries. Given the global nature of the problem, it is unlikely that any single government alone can implement effective solutions. As such, the problem of biological invasions demands international cooperation among researchers, and thus IUFRO represents an ideal instrument organization for addressing the problem.

Below are just a few examples of the devastating impacts of invasions in forests:

  • Emerald ash borer which is in the process of destroying host ash trees across North America and Russia
  • Billygoat-weed which is invading and smothering forest vegetation in Africa, Australia and Southeast Asia
  • Pinewood Nematode that has killed millions of trees in Japan, China and now is poised to heavily impact European forests
  • Maso bamboo encroaching into Asian forest plantations causing economic hardship and altering ecosystem processes
  • Sirex woodwasp that has impacted plantation forestry through out the southern hemisphere
  • The myrtle rust pathogen, jumping from native hosts in Brazil onto Eucalyptus in plantations and then transported to Australia where it is adversely affecting native forests.

There is an urgent need to understand the drivers of biological invasions, characterize their effects on forests and develop strategies for minimizing future invasions and their impacts. Current work on invasions has generally focused within individual disciplines; the lack of synthesis among fields focusing on specific invasive taxa has hindered the development of integrative knowledge and comprehensive management policies. In particular, there is a strong social component to the invasion problem that has largely been neglected. Globalization is inherently driven by social processes and the mechanisms operating that translate globalization into invasions requires elucidation. Information is also lacking on how societies perceive biological invasions in forests. This information is key to the development of solutions to the problem because stakeholders may have conflicting beliefs that either promote or retard invasions. Ultimately, policies that address the problem must be guided by economics but work is needed on how to address the costs and benefits of various strategies.


We are an interdisciplinary team that is synthesizing knowledge among disparate fields studying various aspects of biological invasions in forests. By integrating knowledge among these various fields, we are developing more comprehensive approaches to managing invasions that could be adopted among the worlds’ regions. We also plan to synthesize information to guide development of policies for management of invasions. This information would target a variety of stakeholders as some policies are implemented at a national level (e.g., surveillance and eradication of new species), international levels (e.g. trade agreements on phytosanitary measures) and at local levels (e.g. management of forests for resistance to invasions).

Task Force Members

Andrew LiebholdUS Forest Service, USABiological invasions in forest ecosystems
Alberto SantiniInstitute of Plant Protection, ItalyEcology of Forest Pathogen Invasions
Eckehard BrockerhoffWSL, SwitzerlandEcology of Forest Insect Invasions
Kimiko OkabeForestry & Forest Products Research Institute, JapanForest mite invasions
R.K. KohliPanjab University, IndiaEcology of shrubs and woody plant invasions in forests
David LathamLandcare ResearchEcology of Forest Mammal Invasions
Eric AllenCanadian Forest Service, CanadaWood imports, wood products and phytosanitary treatments
Richard SniezkoUS Forest Service, USABreeding tree resistance to insects and diseases
René EschenCABI Europe-SwitzerlandPlant imports as a pathway for insect and disease invasions
Songlin FeiPurdue University, USAEnvironmental resistance to invasions
David GrayCanadian Forest Service, CanadaRisk analysis for invasion pathway analysis
David WardleSwedish University of Agricultural Sciences (SLU)Ecosystem impacts of biological invasions
Mariella MarzanoForestry Commission, United KingdomSocial Dimensions of tree pest invasions
Rose-Marie MuzikaUniversity of Missouri, USASilviculture and Restoration for Managing Invasions
Rebecca Epanchin-NiellResources for the Future, USABio-economics of forest invasions and their management
Martín NuñezCONICET, ArgentinaEcology and management of invasive trees in plantation forestry
Brett HurleyUniv. Pretoria, South AfricaForest health in exotic forest plantations
Marc KenisCABI Europe, SwitzerlandBiological control of invasive species in forests
Michael OrmsbyMinistry for Primary Industries, New ZealandPhytosanitary policy
Simon ChogeKenyan Forest Research InstittuteForest invasions in countries with developing economies
Mike WingfieldUniv. Pretoria, South AfricaNovel insect / microbial associations
Qiu-fang XuZhejiang A & F University, ChinaInvasions by native plant species
Susan KaliszUniversity of TennesseeEcology of invasions by herbaceous plants


Send comments to Andrew Liebhold (Task Force Coordinator)