ENTS, Please forgive my many missing words and typos. My brain jumps ahead faster than my fingers, and I just can't seem to see the errors when I skim it over before sending.
Basically a tree grows one RING A year, every year. tree species commonly referred to as short living species that live perhaps a hundred years have individuals well over two HUNDRED years in age. These are not the only ones, but the only ones that made their respective sentences unintelligible. Sorry, Ed Frank "The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science." - Albert Einstein ----- Original Message ----- From: Edward Frank To: [email protected] Sent: Wednesday, July 15, 2009 11:16 PM Subject: [ENTS] Re: Tree ring counting Hello, There are many dendrochronology people on the list and they may be able to address the question better. There are a couple of basic assumptions in tree ring dating: basically a tree grows one year, every year. So by counting the number of rings you can determine the age of the tree. The thicker the ring obviously the more the tree grew during that year. This overall is a pretty good assumption. There are some caveats however. In some trees there are locally missing rings - a ring does form every year, but if it has been a really dry year, for example, there may have been little growth between on set of rings and the next. The two adjacent sets of rings formed during this period of little growth in a particular cross-section or core may be impossible to distinguish. What appears to be 1 ring may in fact be two. Then by simply counting rings the age of the tree will be understated because of the "missing" ring. Cross-sections are better for seeing these rings as the amount of growth may vary in different portions of the tree, but still there is a possibility that some rings are missing. If the ring thickness is relatively uniform across the the cross-section, that is one indication that missing rings may be less likely. The other caveat is the phenomena of false or double rings. In this case a dark colored late-wood and appears within the lighter colored early wood of the band. In the false ring both edges of the dark band tend to blend with the lighter wood on either side. In a true ring the transition on the outer edge of the ring is abrupt. This can be seen with a hand lens on a sanded surface. This doesn't always work well with all species. In dendrochronology they use things like skeleton plots and statistical analysis packages to compare a series of rings from different trees in the same area. The missing rings and false rings will not be present in al of the specimens, so through cross-dating between multiple specimens these problem rings can be eliminated from the dataset. When looking at cross-sections from downed trees, likely the best you can do is to simply count the rings present. Without many samples of the same species from the same area you can't really cross-date between specimens and presence of false rings and absence of missing rings will not be distinguishable. I most cases these make up only a small percentage of the total number of rings present in a sample. So basically it is that simple. Just count the rings, and realize that the numbers you are generating may be off by a few years, There are many sites on the internet that discuss these situations and have examples of photos. You can start on a site like the Ultimate Tree Ring Website: Henry writes: The Ultimate Tree Ring Web Pages http://web.utk.edu/~grissino/ Welcome and thank you for visiting the Ultimate Tree-Ring web pages, designed to be the ULTIMATE source for information on the science of Dendrochronology. I've designed these pages to be easily understood by people at all levels of education, from elementary school students to high school students, from first grade teachers to college professors. You won't find anything fancy here - I want these pages to be readable, enjoyable, and (most of all) educational. My goal is to make available as much information about dendrochronology as I can possibly find on the Internet, from the basics of tree-ring dating, to reference and bibliographic information, to products and supplies, to books, and more! My mission was born from an overwhelming need among dendrochronologists for a permanent repository of information that was free to the public, easily understandable, and as comprehensive as humanly possible. Come back and visit from time to time to learn more about new or updated software, new educational tools, new institutions conducting tree-ring research, new publications, and more! You can also search the internet for information via one of the search engines (I like www.metacrawler.com) I have been trying to collect data from such ring counts of trees like you are doing. For many of the trees found in both eastern and western United States there is little actual information on how old these trees may grow. Commonly only the trees know to live the longest are heavily sampled, because the information is being used for archaeological and environmental reconstructions of the past. Trees not know for great age are not routinely or systematically sampled. Many of the tree species commonly referred to as short living species that live perhaps a hundred years have individuals well over two years in age. Only a fraction of the hundreds of species of trees existing in the US have any published ages from cross-dating or ring counts published at all. There is a table on the ENTS website where I am compiling this information. So if you have ring counts to contribute, that information would be appreciated. Ed Frank "The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science." - Albert Einstein --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -~----------~----~----~----~------~----~------~--~---
