When a new irrigation system was installed in Comstock Park this summer, some of the digging got too close to old trees, damaging their root systems. An old Siberian elm at the Northwest corner of the park, facing 29th Avenue, was the first one to be cut down, and more may follow. “The urban forestry staff is spread pretty thin these days, and we weren’t monitoring the project closely enough,” said Steve Nittolo, the city’s horticulture supervisor. “Also, the irrigation contract wasn’t as specific in some areas as I would have liked for it to be. Obviously, this is something we don’t intend to have happen again.”