New London — As director of the Connecticut College Arboretum, Glenn Dreyer has planted and inventoried trees, led wildflower walks and autumn-color tours, tracked birds, established volunteer programs, ushered in the Music in the Meadow series and assisted numerous professors of botany, environmental studies and anthropology.

He worked on building the four-acre conifer collection after trees died from red pine scale infestation in the mid-1980s, launched a project in 1992 that trains college students to give tours to children and has overseen the electronic mapping of all the plants in the collection.

"I would say the biggest thing that I think he's been able to do is to really have a strong vision for the arboretum as something that is beneficial in a variety of areas, from research to teaching to public access and public programming," said Chad Jones, chairman of the botany department at Connecticut College.

Dreyer, who has served as director of the 750-acre arboretum since 1988, is retiring at the end of the month. The college held a retirement party for him on Friday, and the bog at the arboretum has been named in his honor.

In a June 8 letter to arboretum members and friends, Dreyer wrote that he decided to retire because of both family obligations and a voluntary retirement offer.

Dreyer's ecological causes over the years have included managing invasive species and expanding meadows.

"There's an awful lot of species that are really not adapted to forests," he said, commenting that some that started showing up on rare-species lists need to be in fields and meadows.

Dreyer came to the arboretum in 1981 as a graduate student of Professor Bill Niering, the third director of the arboretum, and participated in the arboretum's 50th anniversary at the end of his first semester.

Dreyer, who has been instrumental in the Connecticut Notable Trees Project, which collects information on the largest and most historic trees in the state, previously also served as director of the Goodwin-Niering Center for the Environment.

Along with Niering, Dreyer got to know the arboretum's first two directors, Dr. George Avery and Dr. Richard Goodwin.

"He knew the first three directors of the Connecticut College Arboretum, so he's carried on this tradition, and for me, a major connection to the history of the arboretum," said Maggie Redfern, assistant director of the arboretum. "He's living history."

Redfern will be taking on the role of interim director. She said the college will spend the summer thinking about what it is looking for in a new director and likely will start advertising for a new director in the fall.

"He also has helped to facilitate using the arboretum as ... a living laboratory for students to go to," Redfern said of Dreyer. "He works closely with the professors that have classes or courses that are run in the arboretum."

One such professor is Anthony Graesch, an archaeological anthropologist who is chairman of the anthropology department. His work includes preserving cultural resources in the arboretum, such as stone walls and the foundations of colonial farmsteads.

Graesch said he is about halfway done with the process of inventorying these cultural resources, and that Dreyer has been good about making sure the mission of the arboretum includes their protection.

"One thing that impressed me about Glenn, right from the outset, is his ability to look at the big picture and to think holistically," Graesch said. "He wasn't just focused on our tree inventory, he wasn't just focused on looking at particular invasive species, he wasn't just focused on a particular ecology."

Peter Siver, director of the environmental studies program, commended Dreyer for his fundraising efforts over the years, whether it was raising money to increase the height of fencing to keep out deer or for improvements to Buck Lodge, where classes and small conferences are held.

Siver recalls that when he considered joining Connecticut College nearly 30 years ago, Dreyer showed him around the arboretum despite a recent snowstorm.

e.moser@theday.com