GREG GERRITT showed me the pond in early May. It was one of the last water bodies left in a river valley of once-vast wetlands, a former cradle of the American Industrial Revolution now primarily pavement. An environmental organizer and consultant, Gerritt lived up the hill from the pond. He told me about a campaign, “2008 Year of the Frog,” launched to increase awareness and understanding of the threats to half of the world’s 6,000 species of amphibians from disease, pollution and climate change.

Worldwide, zoos were monitoring and/or collecting thousands of threatened species of amphibians to protect them from the deadly disease-causing chytrid fungus. Plans called for breeding and raising the frogs in captivity until the fungus could be stopped.

Gerritt dubbed the water body “Frog Pond.” Amphibians had become “a rare commodity, especially in the city, yet so many bullfrogs lived here,” he said. The frogs bred in the pond’s relatively still waters, said Gerritt, who had also seen up to nine painted turtles sharing one of the logs.

This summer Gerritt will host visitors from Zoo Camp 2008, a conservation and exploration program of Roger Williams Park Zoo. They will meet at the pond to observe the wildlife and discuss the rapid loss of frogs, toads, salamanders, newts and other amphibians.

I re-visited Frog Pond in mid May. To get to the water, I entered through an ancient gate of iron set into stone columns, and stepped down an elegant, curving, double-sided stone staircase, where the valley unfolded before me. As I strolled past the pondweed, cattails, ferns and other shoreline vegetation, bullfrogs splashed into the pond in amphibian synchronicity. Looking like commuters clustered beneath green shells instead of umbrellas, five painted turtles stood bunched on a log.

In the water I saw minnows, large tadpoles, and a selection of striding, skimming insects. Several orioles, draped in brilliant orange and black, chased each other overhead.

As I stood between two flowering dogwoods, I noticed a secretive and solitary green heron motionless in a leafing red maple. When the bird arose, it unleashed an explosive “keow” sound before landing on the far shore. Through binoculars I studied the creature’s outstretched, velvety brown neck, which the heron typically kept tucked in tightly to the body.

Leaving the pond felt akin to exiting the Harry Potter “Wizarding World” for the non-magical land of “Muggles.” Outside the gate a lone guardsman stood in the road, directing a line of artillery trucks out of the Headquarters of the First Battalion of the 103rd Field Artillery Brigade, Rhode Island Army National Guard. The air was thick with diesel fumes.

The pond was a three-minute walk into North Burial Ground from the gate on North Main Street across from the Armory. The trek was an urban expedition to tranquility, to a sacred site that harbored species becoming rarer by the day. Here was a wedge of nature that had remained true to its place in a world where most else had changed.

Scott Turner, a weekly contributor, is a Providence-based nature writer ( scottturnerster@gmail.com).