A group of college students want the trees in our city to be here for years to come. That’s why they are spending their summer using science to study the health of certain tree species.

“We're able to tell if a tree is showing signs of stress early on. That way, we’re able to do something early on before it becomes too late," said Celine Martinez, an intern with the Nature Conservancy LEAF program.

The Nature Conservancy's Leaders in Environmental Action for the Future, or LEAF, program is a summer internship where students do hands on conservation work.

"They will arrive on site, ready to go. And they basically start out assessing the health of trees, block by block, based on where they're working," said Rachel Holmes, the Healthy Trees Healthy Cities coordinator for the Nature Conservancy.

This summer, the interns are focusing on trees flooded during Hurricane Sandy in Queens. Rich Hallett, a research ecologist with the USDA Forest Service, says Sandy killed about 20,000 trees. Now, this group is taking a closer look at the effects sea water flooding had on specific tree species.

"So in the case of red maple, we saw one year after Sandy, the flooded trees were significantly less healthy. And then, the second growing season, we noticed we lost about 6 percent of the flooded trees," Hallett said.

The data collected by the students will be used by the Parks Department and can help determine what tree species will be planted in flood zone areas in the future.

"A good 40 to 50,000 trees fall within our flood zones. That's a big investment for the city and the trees critical to neighborhoods for their quality of life," said Bram Gunther, the Parks Department Chief of Forestry, Horticulture and Natural Resources.

As for the students, they're learning just how valuable trees are to the city's landscape.

"We need nature in the cities. It's a blend of both. It's integrating nature into the city,” said Esteban Arenas, an intern with the Nature Conservancy LEAF program.