Search Search

Level III accreditation is granted to arboreta with a minimum of 500 species or taxa and those that contribute meaningful involvement in scientific research, conservation, or ex situ collections.

These institutions manage extensive and well-documented collections and serve as regional leaders in tree-focused education and conservation.

Level III arboreta are distinguished by professional staff and a demonstrated science and conservation mission.

How to Become Accredited

To become accredited, submit documentation showing your organization meets the Level III criteria below, along with your online application.

Level III Criteria

• An arboretum plan
• A governing group
• Paid management
• A dedicated curator, or curator-equivalent position
• A labeled collection of at least 500 taxa (species, subspecies, cultivars, varieties, etc.) of trees and other woody plants
• Collections policy
• Sharing of plant collections data
• Extensive educational and public programming initiatives
• Collaboration with other institutions
• Tree science, strategic planting, or conservation activities

Download a sample Level III application.

Compare all levels of accreditation.

Explore other resources to help with the application process.

Apply Online

When you’re ready, submit your application online. There is no fee to apply. 

Once your completed application is submitted, ArbNet staff will review your materials. Decisions are typically made within four weeks. 

ArbNet accreditation is free and valid for 5 years. Arboreta can upgrade their accreditation at any time when higher-level requirements are met.

Level III Criteria

The following criteria must be met and supported by documentation to achieve Level III accreditation.

• An arboretum plan
• A governing group
• Paid management
• A dedicated curator or curator-equivalent position
• A labeled collection of at least 500 taxa (species, subspecies, cultivars, varieties, etc.) of trees and other woody plants
• Collections policy
• Sharing of plant collections data
• Substantial educational program related to trees, conservation, and other related topics
• Collaboration with other institutions
• Tree science, strategic planting, or conservation activities

Download a sample Level III application.

Examples of Collections Activities

A collections policy and collections data sharing are required for Level III accreditation through ArbNet. Participation in additional activities beyond that are optional.

This list is meant to provide inspiration and ideas for arboreta wishing to expand and advance their collections management.

• A collections policy (covers records management, accessioning, deaccessioning, etc.)
• Regular collections evaluation
• Conducting or participating in woody plant evaluation trials
• A staffed collections manager or curator
• An herbarium
• A seed bank
• A plant exploration program
• Collections conservation (holding and safeguarding plants of collections or conservation value on behalf of the collective interests of the profession, e.g., rare and endangered plants, legacy cultivars, etc.)
• A woody plant nursery
• A woody plant breeding program
• Any accredited or officially recognized collection(s) 
• A collections strategic plan (develops and plans for the themes and direction of your collections—could be a standalone plan or part of your greater organization-wide strategic plan or expanded collections policy)

Examples of Education and Community Engagement Activities

The following lists include common types of activities, in generally increasing levels of scale and complexity, that arboreta can host to meet accreditation requirements and to use as inspiration to expand event and outreach initiatives to meet higher levels of arboretum accreditation.

On the digital ArbNet accreditation application, you will be asked to check all activities your arboretum participates in.

Open Public Access and Events

• Annual tree events (Arbor Day, International Forestry Day/week)
• Self-guided walking tours
• Giving engagement and outreach presentations for other organizations and groups
• Hosting conferences or similar events
• Exhibitions and/or interpretive signage

Recurring Public Programming

• Guided walking tours or tram tours
• Docent training and opportunities
• Conference (or similar venue) presentations
• Course/class/workshop offerings
• Hosting webinars/ seminars
• Community/citizen science programs
• Children’s garden
• School programs

Extensive / Enhanced Educational Programming

• Articulated engagement philosophy or interpretive plan with intended outcomes and assessment plan
• Plant selection, care, and/or pest/disease consultation and support
• Educational and outreach publications
• Digital content—podcasts, online courses, social media outreach, etc
• Ethnobotanical engagement (Indigenous knowledge content and co-creation with community partners)
• Accredited educational or training programs
• Internship opportunities
• Summer/ seasonal camps

Urban and Community Forestry

• Urban and community agricultural and food forest programs and projects
• Environmental justice and tree equity programs and projects
• Urban and community greening efforts
• Supporting the creation of new accredited arboreta

Examples of Collaborations

Participating in professional, community, and organizational woody-plant related collaborations qualify an arboretum for Level III accreditation through ArbNet.

In your online application for Level III accreditation, you will be asked to mark which of the following kinds of organizations your arboretum is engaged with.

• Other arboreta and public gardens
• Botanical garden associations or industry societies
• Seed banks and other germplasm repositories
• Conservation, restoration, ecological, and/or environmental organizations
• Invasive species networks or organizations
• Dendrology and/or forestry associations/societies
• Arborist/arboriculture associations and professional societies
• Indigenous peoples groups and organizations
• Community groups and organizations
• Universities and colleges
• Schools and/or student groups
• Government agencies
• Nongovernmental organizations (NGOs)
• Nature preserves and/or parklands
• Plant, botanical, biological, and/or horticultural societies or associations
• Garden clubs
• Landscape architecture and design societies/ associations
• Businesses (e.g. arborist or landscaping companies)
• Zoos and/or aquariums
• Professional societies or associations for zoos, aquariums, or wildlife
• Museums
• Museum societies/associations
• Other organization types

Examples of Tree Conservation and Science

As part of your application for Level III arboretum accreditation, you will be asked to check activities that your arboretum participates in related to tree conservation and scientific research. 

Links and Acronyms

Global Conservation Consortia (GCC)

International Union for Conservation of Nature (IUCN) Global Tree Specialist Group

Botanic Gardens Conservation International (BGCI)

BGCI Conservation Action Tracker

Public Gardens as Sentinels against Invasive Plants (PGSIP)

General Capacity-Building for Threatened Tree Conservation

• Promote tree conservation through your networks, conferences, presentations, social media, and arboretum website
• Host or share GCC educational content (e.g GCC Species Steward panels and/or taxa information sheets; these are provided by the GCC Coordinators)
• Carry out education/awareness raising and interpretation among your visitors for threatened trees
• Host tree conservation conferences, training workshops, or related meetings (e.g. IUCN Global Tree Specialist Group meeting)
• Contribute content, expertise, or other support to tree conservation training materials, such as guidance briefs, manuals, or reports
• Host employee(s) who is an active member of the IUCN Global Tree Specialist Group
• Report and share information on your tree conservation work using the BGCI Global Tree Portal, including the Conservation Action Tracker

Ex situ Tree Conservation

• Enable researchers or conservationists external to your organization to use your grounds, collections, and/or resources for tree conservation and science work/research
• Formal participation in an ex situ conservation project focused on threatened tree species (provide project name in part 7b below)
• Partner with Indigenous communities to support culturally significant ex situ tree conservation and restoration activities
• Participate in Public Gardens as Sentinels against Invasive Plants (PGSIP) by collecting and sharing data about plants escaping from cultivation in your arboretum
• Share threatened tree germplasm/material with other institutions (e.g. for propagation, living collections, seed banks, herbaria, etc)
• Develop protocols for propagation of threatened tree germplasm
• Host and manage a native or threatened tree nursery
• Undertake planting trials for threatened trees
• Conduct conservation genetics research on ex situ collections of threatened tree species
• Threatened trees included in your collection
• Threatened trees included in your collection with interpretation aimed at conservation awareness
• Conservation of legacy cultivars
• Engage in collections climate change adaptation planning and activities
• Provide support to other arboreta to improve their capacity to participate in threatened tree conservation activities (e.g. provide training, financial support, mentorship, threatened tree germplasm/seeds, etc.)
• Host a metacollection site as a designated Species Steward for one of the GCCs

In situ Tree Conservation

• Formal participation in an in situ conservation project focused on threatened tree species (provide project name in part 7b below)
• Partner with Indigenous communities to support culturally significant in situ tree conservation and restoration activities
• Participate in in situ expeditions and surveys to seek out and monitor threatened tree populations
• Host and manage a native or threatened tree nursery to repopulate threatened tree species in situ
• Conduct conservation genetics research on in situ populations of threatened tree species
• Contribute to red listing initiative for trees within a taxonomic group or region
• Lead red listing initiative for trees within a taxonomic group or region
• Engage in or support in situ habitat restoration or habitat protection in support of priority threatened tree species or ecosystems (e.g. invasive species removal, land protection, reforestation, facilitating sustainable management planning)
• Engage in or support in situ conservation and recovery of threatened tree species in the wild (e.g. population monitoring/surveys, reintroduction of seeds/seedlings, assisted migration)
• Carry out conservation planning for threatened tree species, e.g. individual species recovery plans, or multi-species plans