Yosemite trees in decline; climate change is lead suspect

Yosemite National Park has fewer large trees than it did 70 years ago. Researchers believe climate change is behind the decline.

From the 1930s to the 1990s, Yosemite's large-diameter tree density decreased 24%, according to a study by researchers at the U.S. Geological Survey and the University of Washington. Scientists compared the park's earliest records (1932-1936) with records from 1988-99. The study was published in the journal Forest Ecology and Management.

"Climate change is a likely contributor to these events and should be taken into consideration," said USGS scientist emeritus Jan van 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."

Scientists also believe Yosemite may now be more vulnerable to major wildfires, since areas that have not experienced fires in almost 100 years have shifted from fire-tolerant ponderosa pines to fire-intolerant trees, such as white fir and incense cedar.

The study comes on the heels of recent findings by a team of UC Davis scientists that a decline in winter chilling hours due to global warming is having a dramatic effect on trees in the Central Valley, where much of the nation's fruit and nut crops grow.

-- Amy Littlefield

Photo: Yosemite National Park's Merced River. Credit: Brian Vander Brug / Los Angeles Times

Comments

[Yosemite-Mono Lake Paiutes]

The original Indians of Yosemite were Yosemite-Mono Lake Paiute people and we have a close special tie with the trees of Yosemite. Here are some short stories about that;

http://www.indiancountrytoday.com/yourict/52071242.html

http://www.indiancountrytoday.com/yourict/52313777.html

Hopefully the trees will come back stronger. Chief Tenaya was the founder of the Paiute colony of Ahwahnee.

[aaron]

About five years ago i visit yosemite valley and i did notice a change from the mid 70's, many of the pine trees seemed to have more brown pine needles than green ones, although there was plenty of green pine trees it was quite evident to me that there were many with brown pine needles. It was just something that i noticed, at the time i thought perhaps its just nature way, perhaps it is, perhaps it global warming. who knows? i dont, but i have noticed a change.

[michael norman Bayes]

Look at the decline of the San Bernardino Forest, out here in Joshua Tree the vast and growing amount of daily air pollution is obvious. The natural environment is being steadily degraded, we are running roughshod over what was pristine beauty a few short years ago.

[Cat]

The Earth is always changing its the NATURE of things. Yes we humans infterfere but truly how do we know that climate change just isn't a phase that the earth is going through? Have we made it worse??? I recall when it was called global warming and now its climate change, my question is why? Because some of the glaciers that were melting are growing so how do you justify global warming? Oh wait, I know call it climate change. I was in Yosemite a couple of years ago and I can tell you what has ruined it is the commercialization of a once beautiful pristine place. What do you expect when there are millions of people visiting usually in a car that pollutes the air. Those same people walk allll over the place not using trails and throwing trash wherever they feel like it. If you camp you are packed in like sardines in the campground. If yo stay in a cabin you're lucky if you have even 12 inches between cabins its a sad, sad situation. Yosemite has been abused by us and we should close it down for 50 years not allow anyone in and then check it out an see if its healed itself.

[JP]

Many of the trees of Yosemite were planted, as part of a designed park, by Frederick Law Olmsted in the 1860s. He consciously designed many of the vistas that we have always called "natural".

The bulk of the trees may simply have reached the end of their lifespan, and if replanting hadn't been done en-masse with a succession plan in mind, then a dieback is to be expected within the natural order of things.

[Steph]

I grew up in the Fresno/Madera area..so I consider Yosemite my home. And over the past 30 years Yosemite has definitely gotten more commercial and increasingly crowded. Festival and holiday times are now unbearable. My friends and I used to be able to have some room at our campground during the busy season time..and now its seemingly out of control at times...with cars parking outside the park because its so full..and traffic spilling out down onto highway 41. Most importantly, i have noticed a change in the wildlife. Over the past recent years..the bear activity has become more and more frequent at unusually early evening times. I remember seeing tourists take pictures of a poor bear on the side of the road, in the middle of the park, like it was in a zoo or a deer crossing. We usually don't see the bears in the middle of the day..in plain sight and on our campsite during dinner!!! I believe it is because of a combination of climate change, less food resources and more tourist activity. Fresno has majorly increased in population..so why not consider that for Yosemite? Close Yosemite down for a few years! Let the animals and plantation have peace for a while to recover from the chaos of human wreckage. I often wonder why that has not been an action seriously planned and talked about..well the dollar speaks louder than life and nature i guess..sad.