Global Tree Assessment

The Global Tree Assessment (GTA) aims to assess the conservation status of every known tree species by the year 2020.

  • Status of project

  • Region

  • Topic

    Conservation Prioritisation
  • Donor

    Franklinia Foundation and others (see below)


The Global Tree Assessment was launched in 2015 in recognition of the poor understanding of the conservation status of the world’s tree species, limiting the conservation action that can be taken towards saving threatened species. The initiative is coordinated by BGCI and the IUCN Species Survival Commission Global Tree Specialist Group (IUCN-SSC GTSG) and acts as a continuation and expansion of the red list activities undertaken by the two groups over the last 20 years.

Before the Global Tree Assessment was established, the total number of global tree species was not known, nor did we know where these tree species occur. Also, less than 10,000 species of tree were assessed for the IUCN Red List. With over 60,000 known tree species, the GTA is the largest biodiversity assessment ever undertaken at a species level.


Since the Global Tree Assessment began, we have launched GlobalTreeSearch which identified all the world’s trees (approximately 60,000 species) and their country level distributions. We also launched ThreatSearch, which consists of all currently available conservation assessments for trees at national, regional and global level. These two databases are useful tools to look up tree species, their distribution and any conservation assessment they may have. They are also used as tracking tools for the Global Tree Assessment, monitoring progress towards the 2020 goal by showing which tree species do or do not have a global conservation assessment.

As of March 2019, 45% of tree species have a global conservation assessment and 12,587 of these tree species are also listed on the IUCN Red List. Some groups have been comprehensively assessed on the IUCN Red List, these include all tree species in Europe, as well as taxonomic groups of Betulaceae, Magnoliaceae, Theaceae, Fraxinus, Zelkova, Tovomita and Nothofagus.

The Global Tree Assessment has also designed and implemented a rapid assessment methodology for trees of low conservation concern (Least Concern) which are widespread, occurring in multiple countries and well known in botanical collections. Efficiently producing assessments for these trees allows more time to complete assessments for threatened species.


The Global Tree Assessment is a collaborative process. We are working with a variety of botanical institutions, national red listing programmes and tree specialists across the globe to produce conservation assessments for trees. We have established partnerships with government agencies and NGOs in Madagascar, Papua New Guinea, Malaysia, Indonesia, Brazil, Colombia and Bolivia to produce conservation assessments for endemic trees in these highly diverse regions. We are supporting taxonomic experts producing assessments for large tree families such as Lauraceae, Lamiaceae and Annonaceae. We have prioritised the assessment of commercially utilised timber species, in collaboration with the IUCN Red List Unit. We are also working with other IUCN Red List specialist groups and plant authorities to increase their output of tree assessments.

The Global Tree Assessment is essential in the wake of our current biodiversity crisis. Producing conservation assessments for all the world’s tree species will enable the identification of the world’s most threatened tree species prioritising them for greater conservation action. It will also inform national, regional and international conservation planning. Conservation assessments raise awareness of the need to protect tree species and forests for their ecological, cultural and economic benefit.


The Global Tree Assessment has been funded by a wide range of donors, including Fondation Franklinia, The Critical Ecosystem Partnership Fund (CEPF), Toyota/IUCN, Japanese Biodiversity Fund/CBD, Keidandren Nature Conservation Fund, The Mohamed bin Zayed Species Conservation Fund, EU-Life, St Andrews University, Rothschild Foundation and The Rufford Foundation.