Drought, extreme heat kill thousands of trees in Santa Monica Mountains

SANTA MONICA MOUNTAINS (KABC) -- Topanga State Park is one of the largest urban parks in the U.S. The view along the hiking trails has changed dramatically in the last few years there and throughout the Santa Monica Mountains.

Rosi Dagit, a senior conservation biologist for the Resource Conservation District of the Santa Monica Mountains, said at least 9,000 oaks and about 114,000 sycamores, alders and willows have died due to the drought.

She and her colleagues began monitoring the trees in 2015 after noticing the die off. Last year with the help of NASA's remote sensing imagery, scientists were able to see how massive the die off was from 2013 to 2016. During that time there was an increase in the number of days with temperatures above 95 degrees.

"The combination of both the lack of rain and then you add on top of it these extreme heat days probably is what made this drought such as killer," Dagit said.

The loss of the oaks means not only less shade, it greatly impacts the survival of other species.

"There are over 5,000 species of insects, 150 species of birds, 105 species of mammals, 58 species of reptiles and amphibians that need oaks for some or all of their lifecycle," Dagit said.

Since 2012, L.A. County has not been out of the drought despite last year's rainfall. Oak trees have experienced the lack of rain in their lifetime, but the hotter temperatures on record have taken a measurable toll.

Dagit said climate change is real. Where the oaks trees have died, biologists will need to plant other trees that can withstand hotter weather in the future.