There was recently (May 13-17) a conference at the LTRR in Tucson AZ, called “AmeriDendro 2013“, the second in a series focusing on tree ring research primarily in the Americas. I did not attend it and have only read some of the available abstracts. It was not solely a dendroclimatology conference, but rather covered all aspects of tree ring research, including fire history reconstructions, proxy and methods development, and so forth; there were 231 presentations in all. Nevertheless, there was a heavy focus on ring/climate relationships, including sessions titled “Dendroclimatology”, “Climate-Growth Relations”, and “Climate of Recent Millennia”. As at any conference, there were a number of (apparently) interesting presentations, although of course, it’s hard to gauge that fully from the abstracts alone.
There were a few presentations that stood out to me as of (potentially) fundamental importance. The first was titled “A mixed-effects modeling approach for describing climate-growth relationships with applications to climate change research” by David Peterson. A second was titled “A Modified Negative Exponential Curve For Estimating Growth Trends in Closed-Canopy Forests”, by Daniel Druckenbrod. A third was titled “Mixed signals, mixed messages and lessons from bristlecone pine”, by Malcolm Hughes. And a couple of very interesting looking presentations were titled “A comparison of tree-ring inferred climate reconstructions from central Minnesota, USA, to 19th century US military fort climate data and high-resolution pollen-inferred climate data”, by Jeannine-Marie St. Jacques, and “Widespread absent rings have not occurred in boreal and temperate trees outside the American Southwest” by Scott St. George.
There were also several talks looking at the mechanistic basis for ring initiation and development, a topic area that is absolutely essential to improving the understanding of the relationship between climate and ring response. Examples included Greg King’s talk titled “Elevational gradients reveal tree growth response to a warming climate” and a talk by Chris Crawford on the likely causes of frost ring formation in Douglas-Fir in Idaho.
There were no presentations that I could see discussing the problems of accurately accounting for, and removing, trends imparted by changing tree age/size, a topic which remains a serious issue with respect to estimating long term trends, a number of which were presented involving both temperature and precipitation reconstructions in various locations. There were also apparently no presentations on the many issues involved in calibration, an enormous (and enormously important) topic by itself. I really hope people will stop attempting to estimate such long term variability until these issues are thoroughly examined and any necessary methodological changes made, because they are just not useful. The conference itself however, most certainly was, from all appearances.