CLAYTON — The river community will miss Aaron R. Vogel.

"I can't think of Aaron without a smile," said Jay Nash, a good friend of Mr. Vogel.

Mr. Vogel, 39, executive director of the Thousand Islands Land Trust, died unexpectedly Wednesday afternoon at Crouse Hospital, Syracuse, during an MRI scan. Cause of death has not been determined.

Mr. Nash, a singer-songwriter from Syracuse, said he almost canceled his concert Friday night at the Clayton Opera House after he heard the devastating news.

"He was a great man," he said. "I'll miss him and I think everyone will."

Scott M. Smith, who said he knew Mr. Vogel "from the very first day he came to Clayton," said he remembered his friend as an active and energetic person. He said Mr. Vogel was a car enthusiast, a boat lover and a hard worker. Mr. Vogel and his wife, Robin, have been remodeling a house for many years, he said.

Kenneth R. Deedy, a trustee of the land trust, said Mr. Vogel worked for the trust since 1996. Mr. Vogel started as an intern who designed the Grindstone Island Nature Trail that connects Canoe and Picnic Point state parks. He was soon a full-time land steward and was promoted to executive director in 2005.

Mr. Deedy said Mr. Vogel always seemed energetic and healthy and was planning an ATV trip to Grindstone Island. Mr. Smith said Mr. Vogel had "been having issues of vertigo for about two weeks," but the condition certainly didn't seem life-threatening.

Erin McCarthy Brick, another trustee of the land trust, said Mr. Vogel was an excellent leader of the land trust and was an "exuberant" man who did not hide his excitement and love of working to preserve the natural beauty of the region.

Ms. Brick said Mr. Vogel played an essential role in expanding the Zenda Farm Preserve at the edge of the village to 190 acres and expanded outreach programs such as the annual Community Picnic at Zenda Farm.

"The Zenda Farm picnic grew under his guidance and became a summer kickoff event," Ms. Brick said.

Under Mr. Vogel's leadership, the land trust expanded the Crooked Creek Preserve in the towns of Alexandria and Hammond to more than 1,600 acres and raised hundreds of thousands of dollars for habitat restoration and natural space preservation in the north country. Ms. Brick said Mr. Vogel worked closely with many organizations including the state Department of Environmental Conservation, the U.S. Fish and Wildlife Service, the office of Parks, Recreation and Historic Preservation, the municipalities of Clayton and environmental advocacy groups such as Save the River and Ducks Unlimited.

"He worked with other organizations so well. He had a knack for reaching out to other organizations in the region and in securing grants," she said.

Mr. Vogel was a member of the New York State Region 6 Department of Environmental Conservation Open Space Advisory Committee, the Land Trust Alliance's New York Advisory Committee and the Clayton Local Development Corp.

Born in Rochester, Mr. Vogel was a graduate of Bishop Carney High School, Rochester, and earned a bachelor's degree in landscape architecture at the State University of New York College of Environmental Science and Forestry in Syracuse.

Mr. Vogel's funeral was Saturday at Rest Haven Cemetery in Phelps.

Besides his wife, Robin Hoffman Vogel, he is survived by his mother, Nancy Vogel, his father, Charles Vogel of Fairbanks, Alaska, and his grandmother Anna Snyder of Waterloo.

Calling hours will be from 1 to 5 p.m. today at the land trust office on John Street.

A memorial service will be held here next summer.

Donations may be made to the Thousand Islands Land Trust, P.O. Box 235, Clayton, N.Y. 13624 or to the American Heart Association.