Yosemite’s Large Trees See A Decline Of 24%
The number of large-diameter trees in Yosemite National Park have declined 24-percent between the 1930s and 1990s.
The findings are based on a study done by the U.S. Geological Survey and the University of Washington. Scientists compared tree densities from 1932-1936 to those from 1988-1999 where large-diameter trees are those with a diameter greater than three feet.
Along with large-diameter tree loss, they also found a shift to fire-intolerant trees. Amazingly, this shift was experienced in areas that hadn’t seen a wildfire in nearly a century. Trees changed from fire-tolerant ponderosa pines to fire-intolerant white fir and incense cedar. In burned areas, however, the pines remained dominant.
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Since large trees resist fire more than smaller ones, this loss could slow forest regeneration if an uncontrolled fire occurs. It could also lead to a decline in habitat. A reduction in species such as spotted owls, mosses, orchids and fishers is quite likely.
“We should be aware that more frequent and severe wildfires are possible in Yosemite because of the recent shift to fire-intolerant trees in unburned areas and warmer climates bring drier conditions,” said USGS scientist emeritus Jan van Wagtendonk.
But what’s the cause? Climate change is definitely a suspect.
“Although this study did not investigate the causes of decline, climate change is a likely contributor to these events and should be taken into consideration,” said Wagtendonk. “Warmer conditions increase the length of the summer dry season and decrease the snowpack that provides much of the water for the growing season. A longer summer dry season can also reduce tree growth and vigor, and can reduce trees’ ability to resist insects and pathogens.”
These conditions thwart heartier trees like ponderosas and sugar pines from taking root.
“Most of the water that becomes available in the Sierra Nevada comes from the snow pack,” said Jim Lutz, a researcher at the University of Washington who co-wrote the study. “Higher temperatures might increase populations of insects or make fungi more aggressive … which all could increasingly contribute to tree mortality.”
One fix might be a good old fashioned burning. Parts of Yosemite haven’t seen a wildfire for 100 years. This might have allowed other species to compete with the bigger trees.
“What we are really concerned with, is can all of the species that make up the ecosystem continue to persist with characteristic abundance,” Lutz said.
This decline could accelerate as the California climate becomes warmer the report warned.
My mom in 1963 drove through the tree with her dad and her dad’s cousin.
Source: Science Daily | Image: Image-Archeology.com
I think we will see much more of this as time goes on if we don’t all put a step forward to preserving the planet.
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I’m not an ecologist or naturist, or arborist or any other ist that matters here, but I’m pretty sure that ponderosa pines are fire-tolerant because they require the heat to release their seeds, which require ashen soil (aka newly burnt soil) to germinate and grow, hence the decline in ponderosa pines, secondly I’m pretty sure that fires kill NON-fire tolerant trees, thus areas with less fires SHOULD have more fire INtolerant trees. Hate to go all House MD on everyone, but the pines need fires to clear out the competition and reproduce, and humans STOPPING the aforementioned fires is nothing but a death sentence for a species which is rare and impressive. Solution: LET NATURAL FIRES BURN in Ponderosa forests, not LA (I figured if we didn’t get the above, that broad advice could also be misinterpreted)
It’s more than a little strange that a picture from Sequoia National Park is used in an article about Yosemite National Park.
@Jon
The picture is from Yosemite
http://www.image-archeology.com/redwood_tree_ca.htm
Historically the people (indigenous and post-indigenous) up there used to do controlled burns every year until they were forced to stop by the forestry service. The burns would clear the dangerous underbrush, promote pine growth, and provide for food (by way of encouraging bigger pine nut harvests and driving game into the clear). No burns means the fire conditions that now plague the USGS and Park Service could result in much hotter fires killing the entire ecosystem there. Locals have been warning them of this exact possibility for decades. Evidence of tribal burning goes way back, far enough back in the historical record to indicated that yearly fires are a part of the local ecosystem, which can have droughts lasting for hundreds of years.
It is ironic that the Forestry and Parks Services are only just discovering that their plan to “re-establish the forests” was doing just the opposite by restricting the fall burning.
It’s more than a little strange that a picture from Sequoia National Park is used in an article about Yosemite National Park..
Don’t forget attrition… picture 10,000 trees take 1000 years each to grow… we lose 5 a year to storms and wind… then loggers cut down 9,000 of them… that 5 a year looms a lot larger because it takes 1,000 years to replace them… this is exactly what has happened.
It is so interesting!!! I’ve read something of the kind (found at http://filesmixx.com ), but this article made me understand much more!