Will the Drought Topple California’s Towering Redwoods?
California’s towering redwood trees are dying of thirst.
“They require enormous amounts of water,” said Anthony Ambrose, a tree biologist at the University of California, Berkeley, who has been studying redwoods and giant sequoias for nearly two decades. “For the big, old trees, they can use more than 2,000 liters of water per day during the summer.”
Water, however, is in increasingly short supply in the Golden State. All around drought-stricken California, coast redwoods appear to be suffering. They’re shedding leaves, turning brown, and dropping undersized cones. Some of the state’s younger trees, situated in parks and residential areas hundreds of miles away from their native forests, are even dying.
What does that mean for the state’s ancient redwood forests, where the trees are often centuries old and climb hundreds of feet into the air?
Ambrose and his colleagues Wendy Baxter and Todd Dawson want to answer that question. Last year they started studying the trees at two sites near Santa Cruz, where the redwoods, Douglas firs, and California bay laurel trees all show signs of water stress.
Now they want to take that research to a whole new level to help them understand the long-term effects the drought could have on the redwood forests. Long-term water stress, they fear, could leave the trees susceptible to diseases or insects, make them grow more slowly, reduce their ability to establish seedlings, or even kill them. The trio has launched a crowdfunding campaign to raise the $24,000 necessary for the research.
So, Why Should You Care? “Redwoods are an iconic key species,” Ambrose said. “They’re the tallest, oldest, and largest trees in the world. Everybody around the world knows about them. People love them, even if they’ve never visited them. They’re beautiful forests and beautiful trees.” He called redwoods, Douglas firs, and bay laurel trees the “charismatic mega-flora” of the forests. Beyond that, any impact on the redwoods and other large trees could cascade through the rest of the ecosystem and even into the economy.
Ambrose said if redwood growth suffers, or if the trees start to die back, it could damage the habitat for other plant and animal species in the forests, such as the marbled murrelet, an imperiled and elusive seabird that nests high in the canopy of old-growth redwoods. It could also affect nearby water quality, fish populations, and fisheries. “That will affect tourism in the area as well,” he said.
It’s important to understand that potential impact now, Ambrose said, because future droughts could present more problems as climate change continues to affect the region.
“One of our concerns is that temperatures are definitely going up,” he said. “Regardless of what happens to the rain and the snow in the mountains, the temperature going up will drive more evaporation from the soil and more transpiration from the trees. That’s going to be a bigger, long-term effect that needs to be considered in terms of the water balance in the forest.”
Redwoods have weathered droughts, fires, floods, and other environmental problems before. “They’re incredibly resilient and resistant to disturbance,” Ambrose said. “But every species has a limit. They start to suffer. Now that we are in this drought, it’s really important that we get a better idea of how these trees are responding to these conditions so we can understand how they might respond to future drought.”