Joe: I will make a guess based on my experience. Increasing rainfall and ring width relationships in northern hardwood forests are probably almost proportional to rainfall amount when the growing season rainfall goes from 10 to 20 inches (double ring width for 20 inches versus 10), but probably less than proportional when comparing 20 inches to 40 inches (perhaps 1.3 or 1.5 times for 40 versus 20). Increasing rainfall beyond 40 inches would probably result in even less increase in growth, because water limitations could become less than other limitations to growth, such as competition from other trees, and inability to obtain enough nitrogen to make use of all the extra water.
Some trees might actually grow less in extremely rainy summers if they are at the edge of a wetland and the roots are flooded by rising water tables. Also, the more evenly distributed the extra rain is over time, the more increase in growth might be expected. During August 2007, some parts of MN had 17 inches of rain in one day, and needless to say the trees could use no more than an inch of it and the rest ran off to cause a flood. If the 17 inches had fallen at a rate of 0.5 inches per day for 34 days, it would have increased tree growth rates more than it did (the 17 inches was preceded by am extreme drought). We have had only 5 inches of rain this growing season in Minneapolis--and a lot of trees are shedding leaves, have dying branches on the top of their crown, or might die entirely if we don't get significant rain soon. Trees here will have a tiny ring width this year. Lee Joseph Zorzin wrote: > Now that this is year is one of the wettest on record, at least in the > northeast, just how much can we expect tree growth rings to reflect > this fact? That is- if it rains twice as much as typical, during the > growing season, will that result in a ring twice as wide? Probably > not, but I wonder what sort of relationship there is between these 2 > variables. > > I started thinking about this as I notice the trees in my backyard > showing what appear to be greater growth at the top than previous > years- especially noticeable on white and pitch pine leaders. > > Joe > > > --~--~---------~--~----~------------~-------~--~----~ 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] -~----------~----~----~----~------~----~------~--~---
