A local organization is making an effort to bring back one of Lake Tahoe’s threatened trees.

Sugar pines, once prosperous in the area, have dwindled since fungi, logging, fire suppression and environmental factors have diminished their population.

The Sugar Pine Foundation seeks to help bring back the population by planting seedlings around the region. The foundation also integrates its efforts into educational programs and hosts “plant days” open to the public.

On Saturday and Sunday the group will host plant days in South Lake Tahoe.

“Sugar pines are the biggest pines in the world, and they have the longest cones,” Foundation Executive Director Maria Mircheva said. “They used to be about 25 percent of the forest around here, but now they are about 5 percent.”

Blister rust is the fungus that kills off the white pine subgenus, which sugar pines belong to, and Mircheva said about 95 percent of all white pines that become infected die within a short period of time.

“Scientists have found they have a gene that makes them immune to the fungus,” Mircheva said. “So what we did is run around the Tahoe Basin and got pine cones off of 500 healthy sugar pines. We just gave them to a nursery in Placerville, and they got infected.”

The lots that survived proved some of the mother trees can resist the fungus, so the foundation is trying to breed the seedlings that, in theory, will not be harmed by infection.

It takes about 30 years for a white pine to mature, but the importance of the trees is interconnected with the ecosystem in that they provide food for small animals, Mircheva said.

“They have really big nutritious seeds the birds and chipmunks feed on,” Mircheva said. “They don’t have spikes on their cones, which prevent rodents for getting in and getting the seed.”

Mircheva said restoring the species will help with forest resilience to fires, distress from climate change and more.

“The more diversity in a forest, the more resilience,” she said.

On Monday, the group brought out environmental science and ecology classes from Lake Tahoe Community College to help with the planting effort. The group has planted sugar pines near the college for three or four years, and Mircheva said they intend to plant thousands throughout the Lake Tahoe Basin.

The students placed “Hydrosource,” a gelatinous substance that holds water and releases it slowly within the soil, around the base of the seedlings. The substance captures rain or irrigated water and releases it over a period of time, Mircheva said.

Elaine Olson said she decided to take the ecology class, “Just for general knowledge, especially for the local environment and ecosystems around the lake.”

Olson said she has been taking random classes at LTCC for five years.

“I just like to keep myself educated and learning knew things,” she said. “It’s great at any age, whether you’re trying to get a degree or just for fun.”

LTCC Ecology Professor Sue Kloss said she implements the plant day project into her curriculum by showing how human influence and auxiliary factors affect different species.

“We’re talking about how organisms have specific physical characteristics that are adaptations for particular environments,” Kloss said, “and the sugar pines are really well adapted for our mountain environment. They were primarily logged out as their value as a timber species.”