Tahoe's Dead Trees Double In One Year
The amount of dead trees around Lake Tahoe has doubled in just one year and that's why researchers are collecting pine cones.
Severe drought is taking its toll on the trees in the Sierra, killing more than 100 million trees. In the Lake Tahoe Basin, the amount of dead trees jumped from 35,000 in 2015 to 72,000 in 2016.
"Dead trees are a huge problem for Tahoe," Amy Berry, CEO of the Tahoe Fund said. "The most obvious one would be wildfire risk but also you want a healthy forest for our environment, for our habitat, and for our people who are enjoying the forest."
Four years of drought, followed by an average 2015-2016 winter, left many trees vulnerable to disease and bark beetles.
"Mountain Pine Beetle does well in these periods because the trees kind of lose their vigor, their ability to defend themselves," Camille Jensen, Research Biologist at UC Davis said. "They quickly move to a live tree, infest it and kill it."
The Tahoe Fund and UC Davis are teaming up to plant new trees. Thomas Burt is a Forest Specialist. He helps with the process by using the Big Shot Launcher. He shoots a weight, connected to a string, up to 50 feet in the air. The string hangs over a branch, allowing him to shake the pine cones out of the sugar pines.
"You can climb the tree, climb out and take the cones off the end," Burt said. "While it's a lot more dangerous, I tend to like to stay on the ground."
The goal is to collect cones from 100 trees. Each cone has about 100 seeds.
"When you replant, you only get a percentage that actually live," Burt said. "So, that's why you plant so many."
The plan is to grow 10,000 seedlings, which are expected to be mature enough to plant.
"6,000 of those will be distributed to our public agency partners to replant in the hardest hit areas, and then I think this is really neat, 4,000 of those will be available to the private community," Berry said.
Last winter brought record amounts of precipitation to the Sierra, but even more trees are still expected to die this year, simply because it takes awhile for trees to recover from long droughts.
"These trees have long roots," Berry said. "They have long memories and they know that for five years, they were starved of the hydration they need to survive. We need a couple more seasons to really give them the hydration and nourishment they need to fend off bark beetles and other things."
Planting the new trees will also give researchers an opportunity to look at each tree's genetics to see why some are more resilient than others. Throughout Tahoe, you can find four sugar pines within 50 yards or so, yet only one of the three survived. The research can help them understand why some live and others die. Sugar Pines are a big part of the overall health of the forests.
"It's great for long-term carbon storage, just simply for biodiversity, it's good to stabilize our soils, which in turn is very important for long-term water quality."
It will take more than two years before the seedlings are ready to plant. That is expected to happen in 2020.