Invasive and introduced tree species database

The database provides summarized information about those forest tree species that have been reported naturalized or invasive in at least one country or territory..

Data sources

Data was collated by CAB International in 2003 and updated by US Forest Service, Pacific Northwest Research Station in 2008 as a collaborative venture with FAO. Data is the combined results of literature reviews, electronic searches of Web resources, and correspondence with forestry professionals and invasive species specialists.



Species are defined as "forestry trees" if they are:
  • listed in the FAO Ecocrop (FAO, 1999) list of 760 species that were returned in a search using the terms "life form: tree" and "category: forest or wood";
  • returned by the species selection module of the Forestry Compendium Global Module (CAB International, 2000) as a species planted for fuelwood, round wood, sawn or hewn building timber, wood-based materials or pulp or
  • referred to as a forestry species by an author, correspondent or electronic source.

Each species is linked to country(-ies) in which it has been reported naturalized or invasive and to a supporting reference source. Species reported to be naturalized or invasive but for which no supporting information on the locality of this behaviour was available, may not be accessed from this Web site.

The definitions used to assign status to trees in this database are as follows:
  • Naturalized - a species reported to occur in the wild (self-sustaining), but not reported as spreading.
  • Invasive - a species undergoing unassisted spread in the wild, or described as an alien species in need of a control strategy.


Species behaving invasively within their native range are not included in the dataset, which focuses purely on species naturalizing or becoming invasive following introduction to a country or territory outside their native range.

The wide range of information sources used in the compilation of data is vulnerable to the incorporation of errors, such as misidentification of a species.

Data on invasive behaviour reported at genus level or at a wide region level are not accessible, and some species may be naturalized or invasive across a wider geographical range than is reported.

Status terms used by authors and correspondents (naturalized, invasive) have been accepted, as in most cases agreed upon definitions are not available. Variation in the use of these terms among authors places a caveat on the extent to which ¿naturalized¿ and ¿invasive¿ species are consistently distinguished.

The large number of invasive species associated with particular countries and territories may be a reflection of the research effort that has been directed at reporting occurrence and impacts. The comparative absence of naturalized or invasive species in other countries may actually be due to under-reporting, rather than the absence of invasive species.


The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

Data searches should be interpreted cautiously. Results are for users' information only and have no legal value.


Haysom, K.A. & Murphy, S.T. 2003. The status of invasiveness of forest tree species outside their natural habitat: a global review and discussion paper. Forest Health and Biosecurity Working Paper FBS/3E. Forestry Department, FAO, Rome.
last updated:  Tuesday, April 21, 2009