Global Tree Conservation

Conservation Gap Analysis of Native U.S. Oaks

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Many native oaks are threatened with extinction in the wild. These trees are critical to the health and function of forest and shrubland ecosystems in the United States and provide essential habitat and food for many species. Conservation efforts exist, but more can be done by coordinating efforts and setting priorities. Working together to conserve oaks becomes more important as threats increase.

With the goal of coordinated action in mind, The Morton Arboretum conducted a comprehensive analysis of the achievements and most urgent needs for in situ (in the native habitat) and ex situ (in managed botanical collections) conservation of oak species in the United States. These efforts were undertaken in partnership with Botanic Gardens Conservation International U.S., the USDA Forest Service, Fauna & Flora International, and the Global Trees Campaign.

The final report presents a summary of the analysis, including patterns in threats and conservation efforts for the most at-risk species and recommendations for the most urgently needed conservation activities. Of the 91 native U.S. oak species, the study identified 28 species of conservation concern. Each of these at-risk species is analyzed in a detailed species profile, providing specific recommendations for in situ and ex situ conservation actions and a listing of stakeholders currently engaged in conservation efforts. The results and guidelines provided in this study are a catalyst to encourage collaboration across disciplines, and to support efficient and effective biodiversity conservation, preserving our native oaks for generations to come.

For more information on the conservation gap analysis projects and to see the final reports for the Conservation Gap Analysis of U.S. Trees in Nine Priority Genera published in 2021, see the Conservation Recommendations for Trees Under Threat project page.



Major Findings of the Report

Species of conservation concern
  • Overall, 28 of 91 native U.S. oaks have a high need for conservation action, based on threats, such as climate change and habitat destruction, and a lack of representation in conservation collections (e.g., botanic gardens).
  • These species are concentrated in California, Texas, and the southeastern United States. 
Threats to wild populations
  • The most common threat is climate change, affecting 80 percent of the 28 species of concern.
  • The second and third greatest threats are human modification of natural systems (e.g., fire suppression) and human use of the landscape (e.g., development, mining, roads), each affecting 75 percent of the 28 species of concern. 
Results of an ex situ survey
  • In 2017, 162 botanical institutions from 26 countries provided accessions-level data on their living collections of oaks.
  • Forty-four percent of plants are documented as wild-origin; approximately 7 percent of these have no locality data.
  • Nine species of concern are represented by fewer than 15 plants in ex situ collections.
  • Four species of concern aren’t held in any collections in North America.
Results of a Conservation Action Questionnaire
  • In 2017, 255 organizations reported oak conservation activity within a range of sectors: botanic gardens and arboreta, private companies, NGOs, governing bodies (city, county, state, national), and universities.
  • Conservation activities most commonly reported included population surveys and collecting and propagating wild germplasm.
  • Activities least reported included conservation genetics research,  reintroduction, and translocation.
  • Species with lower vulnerability were more frequently reported as the target of conservation efforts, compared to those with higher vulnerability.
Conservation Recommendations
  • Occurrence surveys, population monitoring, and research are recommended for every species of concern.
  • Wild collecting is the third most common conservation need, with 26 of 28 species of concern requiring this activity.
  • Further sustainable management of land and land protection are also recommended for the majority of species of concern.
  • Collaboration and coordination across institutions and public and private sectors are essential for effective species conservation.
  • The main challenges to cross-sector collaboration include clear communication of activities and efficient data sharing.
  • There is no one-size-fits-all strategy for conserving at-risk oak species; data-driven conservation recommendations that directly address the threats to each species are critical for success.

Funding Sources

USDA Forest Service

Fauna and Flora International

Global Trees Campaign


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