Something unusual — but expected — is happening to the conifer forests that blanket large parts of California’s Sierra Nevada. Conifer trees are large, evergreen trees such as spruce, sugar pine, and Douglas fir — all of which typically produce cones.
What’s happening, and why these areas are now being referred to as zombie forests, is that while the older, well-established trees remain strong, few young trees have been able to take root and grow. The climate is now too warm and too dry for them to survive. This is true even though these areas are currently receiving large amounts of precipitation.
A climate mismatch has evolved, and scientists say that based on photographs and survey data, they’ve been expecting this for nearly a century. The situation has been gradually evolving since about the mid-1930s, long before talk of climate change. However, the growth of zombie forests has accelerated in the past two decades, primarily due to climate change.
Today, it is estimated that about 11 percent of the conifer forests are mismatched to their current climate conditions, with another 8 percent “severely” mismatched.
The big concern is what happens should there be a significant disturbance, such as a wildfire, logging disruptions, or mudslides, as is currently happening.
Historically, trees would grow back. Eventually, the forest would return.
But now, instead of trees, we can expect much smaller, shrub-like vegetation that can adapt to warmer and dryer climates.
If we take a broader look at this situation, we see that a mismatch of climate conditions is happening to not only these trees but virtually all living things. Polar bears, for instance, which have inhabited the same areas in the arctic for centuries, are now moving to higher ground to find food. The same movement to new locations is true with other forms of wildlife as well as marine life. The climate these animals initially thrived in is no longer the same, forcing them to literally find greener pastures.
However, even the older conifers that have managed to survive this climate mismatch may need help in the future. With warmer weather comes insects and diseases these trees have never encountered before. How well the trees survive these invasions are still being determined, but some are expected not to make it.
So, what’s the big picture here? Why are zombie forests in California important to all of us?
The first concern is that we may lose one of the main contributions trees make to our planet, absorbing carbon dioxide and greenhouse gases and releasing oxygen through the process of photosynthesis.
A typical mature tree can take in up to about 22 kilograms of CO2 from the atmosphere and convert it into oxygen as well as food, allowing other trees and vegetation in the forests to grow.
Trees also improve water quality in forested areas, slowing rainwater as it falls to the earth so that it can be more thoroughly absorbed. Without this buffer, the rainwater would cause runoff, soil erosion, floods, and pollution in rivers, lakes, and streams.
This would also negatively impact the water we drink. As U.S. Department of Agriculture Secretary Tom Vilsack said, “While most Americans live in urban areas, most of us depend on rural lands, particularly forest lands, for clean water and a healthy climate.”
One of the first things we can do is to start by installing the most water efficient plumbing fixtures possible, such as waterless urinals. Further, whenever a waterless urinal is installed, it reminds restroom users that we must use water responsibly and efficiently.
Zombie forests are created by a planet that is becoming warmer and dryer. Let’s view zombie forests and the installation of waterless urinals as one more heads-up that we need to protect our most precious resource now and for the future.
