Graduate student John Harre was in an online class at Temple University’s Ambler campus when the internet went out. Then the power. He heard what sounded like trees banging, rain pounding, and hail hitting.

Harre, a resident adviser, directed more than a dozen students to shelter in a downstairs hallway. When the storm subsided, he walked outside.

“Broke my heart,” he said.

A tornado had ripped through the heart of the 187-acre Montgomery County campus, also an arboretum. And two weeks later, the scope of the damage and what it might take to repair it is still becoming evident.

For decades, the campus has doubled as an outdoor learning laboratory for more than half of its 1,000 students, those enrolled in horticulture, landscape architecture, and engineering classes. Thousands of plants and trees, some more than 100 years old, were twisted at the base, felled, or so heavily damaged they had to be taken down. Two parallel rows of pecan and walnut trees were flattened. Shaded canopies were blown away, shade gardens turned to sun gardens, roofs ripped off or damaged on 17 of 19 campus buildings, and 50 light poles lost.

The tornado even plucked the “L” off the campus library. (An employee just found that L tucked inside a tree on Thursday.)

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Campus walkways were virtually impassable after the Sept. 1 storm, remnants of Hurricane Ida. Some buildings couldn’t even be accessed because so many trees had fallen down around them, said Vicki Lewis McGarvey, vice provost and campus director. She estimated damage in the tens of millions.

Elsewhere in the region, damage was extensive and many were displaced from their homes. One woman who was only minutes away in Fort Washington died when a tree crashed into her home. Others died in floodwaters. Reps. Shelby Labs (R., Bucks) and Todd Stephens (R., Montgomery), who toured damaged areas of their counties, said Thursday they were introducing legislation to extend Gov. Tom Wolf’s State of Emergency declaration.

But at Temple Ambler — founded in 1911 as the Pennsylvania School of Horticulture for Women and one of the first of its kind in the United States, teaching women to garden and farm — what survived is perhaps just as remarkable.

The campus’ state-champion Turkish filbert tree, which also made it through Hurricane Sandy, was virtually untouched. A prodigious weeping beech that creates a shaded tunnel over a walkway was relatively unscathed, though a tree just behind it had fallen on a building. The greenhouse lost some glass panes, but all 1,600 plant species were undisturbed and three beehives left intact.

Kathy Salisbury, director of the arboretum, was able to locate most of the 305 woody plant species she teaches in her classes.

“There’s only six I can’t find on campus anymore,” she said.

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A fountain in the shape of a girl pouring a water pitcher was unharmed, though all the trees around it had fallen and a historic pavilion next to it was crushed.

“When the electric came back on, the water [in the fountain] started running again,” Salisbury said. “For us, it was this sign of hope.”

On Wednesday, the day the campus reopened for in-person classes, a red-tail hawk perched on a branch that used to be part of a full tree, another sign of hope for Salisbury, who had been worried about the impact on wildlife.

“It’s really encouraging to see we’re still a place for them,” she said.

For two weeks, dozens of tree and roofing companies have been working long days to make repairs and ready the campus for reopening, McGarvey said.

And now, campus leaders and educators are not focused on what was lost but what can be gained. They see their outdoor learning space as a “disturbance” lab where students for months, years — even decades — to come will study the lasting effects of nature’s fury, including the impact of climate change.

“It’s a research opportunity,” said Amy Freestone, director of Temple Ambler Field Station and an associate professor of biology.

That morning, Freestone and a team of researchers, all in hard hats, entered the campus’ Old Growth Forest, an area that the school has never cut or altered. It almost looked like a field of matchsticks, with the few trees still standing devoid of foliage and most branches. The entire forest canopy had fallen. A stream that runs through it was no longer visible.

They began planning their research and that of their students. They will evaluate “how the forest recovers through time,” she said. “We’ll try to understand the resilience of some of those species to this type of disturbance. What survived? Why? What’s going to come back quickly? Are we going to have a lot of some species? What does this mean for the animals? This is one of those changes our students get to experience firsthand.”

It’s the one area of campus where none of the fallen trees or brush will be removed or cleaned up.

“Our intent is to let it lie and study it,” Freestone said.

Other areas will be replanted and reimagined, Salisbury said. Next to the forest, piled high, were logs from the trees that didn’t survive. The campus plans to use them in the rebuilding, she said.

In one of her classes, students will learn how to do a lawn renovation from start to finish.

“We didn’t have lawns that needed to be renovated before,” she said. “Now we do. If anything, we have a lot more to teach.”

This week, companies were still hard at work, clearing debris and repairing damage. There was a steady hum of saws and other machinery. Employees were tagging tree stumps and assessing the size of those lost and the impact on the ecosystem. Student workers gathered and bagged broken branches.

“It feels like a bad dream,” said Emilia Zabegay, 29, a senior horticulture major from Fishtown.

Michael Hitchings, 32, also a senior horticulture major, from Bethlehem, said he’ll miss the tree-filled backdrops that will take generations to replace.

“It’s just unfortunate that students won’t have the opportunity to fall in love with this place the same way I did,” he said.

The campus, which became affiliated with Temple in 1958 and has a mix of historical buildings from its founding to a learning center that opened in 2006, has a broad and loyal following. Donations and calls offering support have been pouring in, campus leaders said, and a relief fund has been established. Neighbors and people who have gotten married or engaged on the campus or have other connections have been calling or stopping by to check on their favorite trees, Salisbury said.

She was gratified to tell the parents of a late student that her memorial tree had survived.

“Many people are connected to this space,” Salisbury said. “They are grieving with us.”