Trees. A focal point for any ecosystem, an important component to a community, and the prime player in combating climate change.
“Trees are really good at sequestering carbon, so they take carbon from the atmosphere and hold it in their leaves and in their bark and especially in their roots,” Brian Metcalf from the Rotary Club of San Luis Obispo de Tolosa said. “You also don’t get the benefit of insects and birds and the entire food web and pollinators when there are no trees around.”
The Rotary Club of San Luis Obispo de Tolosa is committed to planting 1,000 trees in SLO County to help improve quality of life.
The group has a focus on planting California live oak trees, native to the Central Coast, which Metcalf said have a lifespan of up to 600 years and will hold onto carbon until they die. Adding these to a community will help provide shade, a cooling effect, and a better aesthetic.
“We actually collect our own acorns from around town and stratify them and germinate them, and then we plant them when they’re only like 3 or 4 inches tall,” he said.
In fact, Metcalf said California live oak does more than just sequester carbon—its acorns have been used as a food source for local indigenous cultures for thousands of years.
“We’ve gotten away from it, and I think it’s probably because it’s just a lot of processing,” he said. “But it’s a full-on food source, and the culture survived on it forever, for 15,000 years. So it’s a super important tree in not only California but lots of places.”
The Rotary Club isn’t the only organization in SLO County focused on increasing the number of trees in the community.
Grant Helete, program coordinator of the Environmental Center of San Luis Obispo (ECOSLO) said they’re committed to planting 10,000 trees in the county through volunteer support.
“They bring a lot of benefits to a community like San Luis Obispo. There’s core benefits like carbon sequestration, but trees have other benefits,” he said. “They act like insulators, so they reduce a lot of urban noise, which is great for noise pollution. They help with wildlife, especially in urban communities.”
With communities experiencing record-breaking temperatures year after year, Helete said one of the most important things trees provide is a cooling effect on urban areas.
“It gets hot here in the summer, and it’s only getting hotter,” he said. “Urban trees can go a long way to breaking up a lot of hard pavement environments and reducing what’s called the heat island effect. That’s when you have a lot of paved area that just really radiates the heat. Trees suck in that heat and hold it, so it can go a long way with reducing temperatures and reducing energy usage.”
Helete said ECOSLO partnered with the Cal Poly Urban Forest Ecosystems Institute (UFEI) to help address the increasing need for improved management of urban forests in California.
The institute is taking the push to plant trees further by collaborating with Cal Fire to help boost the state’s tree canopy by 10 percent by 2035.
Cal Poly biology sciences professor Jenn Yost said this will help some of the most disadvantaged communities in the state, which experience the largest burden of climate change and heat-related problems.
“Trees provide people with all kinds of epic ecosystem services,” she said. “They do stormwater mitigation, they protect cities from flooding and massive events like that, they provide clean air, they provide habitats for animals.”
Using AI remote sensing, UFEI can pinpoint every tree in every California city to help locate the areas that need more tree canopy through the help of Cal Poly economics, computer science, geography, biology, environmental management, and forestry students.
UFEI also has tools available to the public that explain what trees are school friendly, talk about the trees that are good for planting in your yard, and categorize every public tree that has been inventoried in California, Yost said.
To learn more about California trees, visit ufei.calpoly.edu.
This article appears in Get Outside – Winter/Spring 2025.