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  • Deprecated function: Return type of DatabaseStatementBase::execute($args = [], $options = []) should either be compatible with PDOStatement::execute(?array $params = null): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2244 of /mnt/www/html/mgrieblerdev/docroot/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseStatementEmpty::current() should either be compatible with Iterator::current(): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2346 of /mnt/www/html/mgrieblerdev/docroot/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseStatementEmpty::next() should either be compatible with Iterator::next(): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2346 of /mnt/www/html/mgrieblerdev/docroot/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseStatementEmpty::key() should either be compatible with Iterator::key(): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2346 of /mnt/www/html/mgrieblerdev/docroot/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseStatementEmpty::valid() should either be compatible with Iterator::valid(): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2346 of /mnt/www/html/mgrieblerdev/docroot/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseStatementEmpty::rewind() should either be compatible with Iterator::rewind(): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 2346 of /mnt/www/html/mgrieblerdev/docroot/includes/database/database.inc).
  • Deprecated function: Return type of DatabaseCondition::count() should either be compatible with Countable::count(): int, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in require_once() (line 1652 of /mnt/www/html/mgrieblerdev/docroot/includes/database/query.inc).
  • Deprecated function: Creation of dynamic property MergeQuery::$condition is deprecated in MergeQuery->__construct() (line 1344 of /mnt/www/html/mgrieblerdev/docroot/includes/database/query.inc).
  • Deprecated function: Creation of dynamic property DatabaseCondition::$stringVersion is deprecated in DatabaseCondition->compile() (line 1865 of /mnt/www/html/mgrieblerdev/docroot/includes/database/query.inc).
  • Deprecated function: Creation of dynamic property DatabaseCondition::$stringVersion is deprecated in DatabaseCondition->compile() (line 1865 of /mnt/www/html/mgrieblerdev/docroot/includes/database/query.inc).
  • Deprecated function: Creation of dynamic property DatabaseCondition::$stringVersion is deprecated in DatabaseCondition->compile() (line 1865 of /mnt/www/html/mgrieblerdev/docroot/includes/database/query.inc).
  • Deprecated function: Creation of dynamic property DatabaseCondition::$stringVersion is deprecated in DatabaseCondition->compile() (line 1865 of /mnt/www/html/mgrieblerdev/docroot/includes/database/query.inc).

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Levels of Accreditation

The four levels of accreditation recognize arboreta at various degrees of development, capacity, and professionalism. Accredited arboreta are encouraged to seek and achieve higher professional standards and move up through the levels.

Level I

Level I arboreta are generally smaller publicly accessible sites with at least 25 species of woody plants, one or a few employees or volunteers, a governing body, and an arboretum plan. Examples of arboreta at this level may include golf courses, college arboreta, cemeteries, zoos, private estates, or towns with an organized tree collection. 

View Level I Accredited Arboreta

Level II

Level II arboreta have at least 100 species of woody plants, employ paid staff, and have enhanced public education programs and a documented collections policy. 

View Level II Accredited Arboreta

Level III

Level III arboreta have at least 500 species of woody plants, employ a collections curator, have substantial educational programming, collaborate with other arboreta, publicize their collections, and actively participate in tree science and conservation. 

View Level III Accredited Arboreta

Level IV

At the highest level of accreditation, Level IV arboreta employ well-qualified tree scientists engaged in publishing sophisticated research, manage living tree collections for the purpose of conservation, and take an active role in supporting tree conservation through the Global Trees Campaign. Level IV arboreta are world-renowned tree-focused institutions.

View Level IV Accredited Arboreta

 

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