Q: As a regular user of the Kern River Bike Path, I have noticed over the last several months that many of the larger trees along the river bed appear to be quite dead, with many fallen tree trunks and large branches. Is there some disease affecting these trees?  I know that some trees are in winter dormancy, but many appear to truly be dead. What’s up?
— Bob Smith

A: It’s true, some trees along the bike path are dead but there’s several explanations for why.
Disease is not one of them; however, a lack of water in the river is.
“Because of the droughts, and because of the hesitance of the water agencies to allow a minimum flow down the river, the river has been dry all summer long,” said Rich O’Neil, a co-founders of Kern River Parkway Foundation, a group that has planted trees and advocated for parks and trails to be built along the Kern River since the mid-1980s. “The water table is so low now that the trees’ roots can’t tap into it. If there's no water for the riparian habitat, trees will die.”
It’s been three years since there’s been a substantive water flow in the river through Bakersfield, said city Water Resources Manager Florn Core.
The type of tree is also contributing to the deaths. Many along the bike path, particularly in the Truxtun Lake area, are hybrid, non-native cottonwoods. O’Neil said he and other volunteers planted this type of tree in the 1970s to comply with a city ordinance that prohibited native female cottonwoods, which produce a fluffy white seed that can blow off and jam air conditioning units.
Unfortunately, O’Neil said, the non-native, hybrids have turned out to have very weak root systems and only have about a 20-year lifespan. As a result, many now have brittle roots and limbs. Since then, the group has switched to planting native cottonwoods that are certified males, which don’t produce the pesky seeds and will live longer, O’Neil said. They are also planting native sycamores and oaks that have deeper root systems to better withstand drought.
“As volunteers we’re learning and trying to do a better job,” he said.
The Parkway Foundation also has an agreement with the city that trees other than those immediately lining the bike path won’t be maintained by the city Recreation and Parks Department. Trees on the periphery are to be left in their natural state so any dead ones will remain there until fully decomposed.
“We wanted those areas left natural so the parkway would be low-maintenance and a lower cost to the taxpayer, O’Neil said.
Still, O’Neil said, his group hopes to replace some of the dead trees in the future with new plantings that will have a longer lifespan. And like many others, they’re also hoping for more water in the river, too.