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In the latest issue of Science scientists reported that changes in water availability between 1930 and the present day drives plant species downhill with an optimum at lower elevations. The study area was about one half of California.

http://www.sciencemag.org/content/331/6015/324.abstract

I am not interested in a general global climate change discussion. I just want to ask whether you have noticed something like that during your years of being in the mountains and foothills. I could not think of a better audience to ask that question than here on SP

Which plant species did they study? (I don't subscribe to Science.)

Here is a non-technical article, for those that are not AAAS members, that talks about the same thing.

http://www.hcn.org/issues/42.17/dancing ... ate-change

SoCalHiker:

If you have a link that non-members can look at I would be interested.

As to noticing these trends. No, I haven't noticed.

MoapaPk wrote:Which plant species did they study? (I don't subscribe to Science.)

A-Lex wrote:If you have a link that non-members can look at I would be interested.

sorry, don't have a link for non-subscribers

anyway, they analyzed over 8,000 vascular plant species and found that the "optimum elevation" for these species on average between 1930 and present day shifted downhill by about 88 meters. Apparently, these species can track regional changes in water balance and adapt by shifting downhill, despite the expected uphill shift given the increase in mean annual temperatures in California by 0.6 degrees Celsius during that time.

Oh wow. I missed the water availability bit in your original post. Interesting. Yeah the Bristlecones were definitely moving uphill per the article I linked. Interesting stuff.

Bristlecones are also moving downhill in some locations.

We still have remnants white fir down to 7000' on the N sides of some desert peaks; it isn't really clear when those became isolated. SP has a dendrochronologist (ScottyS?) who has studied a lot of the mountain trees in Nevada.

There are two tree lines in high deserts area. I don't think they have well-separated the effects of H2O, CO2 and temperature on growth.

Mt Washington in the Snake Range supposedly had live Bristlecones on top 4000 years ago (or at least, 400' higher); there are remnant dead trees with no living cambium. I've always wondered how they can pull trends out for modern bristlecone zone expansion from 40 years of observation, when the trees average about 2000 years old. I'm not doubting they do it, but that would be one of the most interesting parts of the article. I've seen burned bristlecone forests now full of seedlings, but I wonder how long those will last.

Yes, you're right Moapa, the Bristlecones were moving in both directions. I didn't really re-read the article since last reading months ago, but I thought I remembered that the majority were moving uphill. There are definitely a vast number of parameters that define in which direction they migrate over time.

I think that is the interesting aspect of the study. I am certainly not an expert in this area but apparently temperature was considered by most to be the determining factor responsible for plant distribution (altitude). This study now shows some data indicating the factors other than temperature, in this case water availability and balance, is a stronger determinant for vertical distribution.

SoCalHiker wrote:This study now shows some data indicating the factors other than temperature, in this case water availability and balance, is a stronger determinant for vertical distribution.

I'm most certainly not an expert either, but on a recent visit to Valley of Fire State Park, I was taken aback by the water levels at Lake Mead; even though there were several storms during December 2010.

I was just wondering if "water availability" has a profound effect on desert plants. I know that
a plant called "Sticky Buckwheat" is currently endangered in the Valley of Fire area of southern Nevada.

However. some of the Desert Bighorn sheep looked healthy while I was there.
Obviously, they have the ability to find water in the most arid of places, and also find enough
grasses, shrubs, and forbs to keep them well-fed.

Hey Lcarreau (that's gotta be a French name), bighorns do amazingly well in NV. They do without liquid water for a long time, but have the lake as a short jog to the lake.

I wonder how the plants walked to the lower altitudes

MoapaPk wrote:Hey Lcarreau (that's gotta be a French name), bighorns do amazingly well in NV. They do without liquid water for a long time, but have the lake as a short jog to the lake.

Yep, all the sheep I saw were definitely SMILING !!!