A new studyout of UC Merced finds that meadows in the Sierra Nevada are slowly disappearing.
“When we looked at the information and looked into the future, using global climate models, what we found is that the average meadow in the subalpine elevations would be converted to forest,” says Lara Kueppers co-author of the study published online in the journal Ecological Applications.
"What we found was that this phenomenon of tree encroachment into meadows was widespread. It's not just local." - Lara Keuppers
The study predicts that by the end of the century meadows just below the timberline in the Sierra Nevada will be gone. The team surveyed 30 meadows over five years and measured the size and age of trees in them.
“What we found was that this phenomenon of tree encroachment into meadows was widespread,” says Keuppers. “It’s not just local, due to the effects of roads or trails. It’s even in these remote locations.”
Researchers found that change in snowpack levels and warming temperatures creates perfect conditions for trees – mostly Lodgepole Pines – to grow in meadows.
“In trying to understand what might drive this pattern over time looking at tree rings and estimating the ages of these trees we found that changes in snowpack, temperature and summer rainfall explain the variation in when trees were coming into the meadow,” says Kueppers.
"If they are being actively managed so that we perceive there are still meadows in the Sierra at this elevation that might be a misperception." - Lara Keuppers
Kueppers biggest worry is that meadows act as mountain aquifers storing water. Her colleague on the study Kaitlin Lubetkin agrees. She says if too many trees move the meadows could become forests draining the stored water underground.
“Think of meadows like a sponge,” Lubetkin told UC Merced inpress release. “After the snow melts, they soak up a lot of water in the landscape. Over time it drains, but drains more slowly, so we have water later into the growing season.”
She also says as the meadows change form species that call them home may have to find new places to live.
The authors note the results of the study bring up a larger issue. Should agencies like the National Park Service actively cut out trees from meadows to preserve them as we know them now?
“If they are being actively managed so that we perceive there are still meadows in the Sierra at this elevation that might be a misperception,” says Lara Keuppers. “Once we get out of our cars and hike into the backcountry where the same maintenance isn’t happening we’d see a pretty different picture.”
