Sequoia Tree ring data confirms Medieval Warm Period

This is an excellent project carried out primarily by the excellent tree-ring lab at the University of Arizona. They have laboriously prepared slabs from stumps cut from this western Sierra forest during the logging era there. A lot of additional information is going to be derived from this record in the future.

Dr. Swetnam edited the entire issue on "Fire History in California" and it appears to be in the clear for anyone to read:

Volume 5, Issue 3-The Association for Fire Ecology

(the article is the last one listed there)

My excuse for not bringing it to your attention here (two weeks ago when I picked it up) is that the authors were at pains to make clear that results from their site cannot be applied elsewhere. They note that while there is evidence other of "Medieval droughts" in several western US studies, long chronologies in the Great Basin do not show them.

The timing presented for the sequoia droughts/fires does not match the Soon/Singer MWP very well, but the authors do not discuss that. For the possible global extent of MWP, they refer to Hughes and Diaz 1994. In case you haven't read it, the short story is "not global". They don't refer to Thompson et al 2006 (also not global) but that is appropriate because it's all glaciology.

They also leave open the question whether the fire increase could have been human caused, which is fascinating at this site because the archaeologists have pretty good data.

In short, I think I'd have chosen a different title for the thread. A great study, and more useful things will flow from it in the future. There are pockets of big (though not 3000-yr) trees scattered around the globe, and if we had about 20 more groups like this, chain sawing and belt sanding, we'd know quite a bit more about paleoclimates.

 

Swetnam has been involved in Anasazi 'dendro' as well:

Anasazi, Droughts, and Forest Fires: Cautionary Tales that Tree-Rings Tell | UANews.org

Again, the UA group is great and I wish there were more like them elsewhere in the world.

At the risk of hijacking, I'll mention that southwestern China is in quite a deep drought at present. Two years ago nobody cared when I set up a water manipulation experiment; sort of a mini-Nepstad (2005) which has received a lot attention about Amazon drought sensitivity lately. But now I have a lot of soil respiration data from the experiment (still to be analyzed) and everybody's my friend.

The big droughts around here seem to be associated with multi-year failures of the monsoon. Happened circa 1790, and before that 1430 (which may have contributed to collapse of Angkor Wat civilization; that just published in PNAS). For earlier than that, additional dendro studies are needed!

 

Does this mean anything when the rise and heydays of the Anasazi in the region also occurred during this MWP?

 

The ages of the canyons exceeds the ages of the human artifacts in them by several decimal points.

From the estimates I've seen, it would seem that the Anasazi flourished at these sites during the height of the so-called MWP. Then they died out or left as MWP was closing.

 

Drop a tree in a peat bog and its records are preserved for longer. A new study on Kauri trees in New Zealand

Scientists to unearth Ice Age secrets from preserved tree rings

will certainly bear watching.

 

But how can you trust anything funded by Natural Environment Research council?? They obviously have a hidden agenda...

 

Any talk about sequoia rings showing signs of (what some have called) the 'mini ice age' ?

 

hill, Swetnam's Figure 8c indicates lower summer temperatures in LIA, but they were relying on

Graumlich, L.J. 1993. A 1000-year record of temperature and precipitation in the Sierra Nevada. Quaternary Research 39: 249-255.

Not their own new analysis, which so far focused on burn scars.

 

thanks!
this info tracks perfectly with many other studies on MWP as well as the LIA.

I'm in the middle of an excellent book on the subject

Unstoppable Global Warming Every 1,500 Years
S. Fred Singer and Dennis T. Avery
expanded/updated 2008 edition

 

Interestingly, I just attended a forestry management tour at Blodgett Forest Research Station (UC Berkeley) in the Sierra Nevada. I learned about about quite a few experiments they are conducting. One of which was a fire scar study. They are purposefully fire wounding small portions of bark on Douglas-fir (pseudotsuga menziesii) and then observing how the tree grows around that area during different seasons. If I heard correctly this would help us to calibrate our methods for determining time of fire with regards to age of the tree as well as the specific conditions the tree was subject to at the time, or prior to the time, of the fire. The project has just started and when I find more information on the study I'll post it up in here.

Dr. Robert York, one of the Forestry Professionals at the station, regularly posts reviews of the studies and papers that relate to forestry, fire, and management. These papers and reviews can be found at ForestSteward.com.

 

There is a small Bristle cone grove up on the west slope of Ward Mt next to Florence Lk. The hike is a bear but well worth it. There are a couple trees there with bases in the 8' diameter range...and maybe 20' in height.

 

I've been up to Schulman and Patriarch Grove and the White Mountain Research Station a few times and I agree that such massive yet not massive trees are well worth the drive/hike!

Pics are from one of my trips there...




I had to throw in a pic of a krumholtzing white bark pine because it's so cool!

 

wow. Nice pics, F8L. The middle one looks like a dead Ent!

 

He's not dead, just naked. F8L caught him fresh out of the bath.

Tom

 

I'm not comfortable with the idea of photographing naked hard wood.