Jack: I agree with your general ideas about the limitations of the study and the limitations of its implications. I want to make it clear that the only point I was referring to was this part:
By age 55, the rate of annual growth is about equal on all sites (9). For example, in stands with a site index of 36.6 m (120 ft), maximum growth of 1.0 m (3.4 ft) per year occurred at age 14; whereas, with a site index of 18.3 m (60 ft), maximum growth of 0.5 m (1.5 ft) per year did not occur until age 23. By age 55, however, annual growth for all sites was about 0.3 m (1.0 ft) per year. And I have to admit I did not make myself clear on the other point: You say: Also, according to that chart, the height difference between trees growing on the poorest sites to those on the best is 60 feet, not 20. I did not mean to imply that the difference between the growth on all sites was only 20 feet. I was using the more limited range of site indices only because it is only sites rated at 100 to 120that are likely to produce the tallest pines. Of course those pines growing on sites rated at only 60 feet will be 60 feet shorter than those growing on a site rated at 120 feet after 50 years. I accept your point that there are sites that include some special factors not covered by this study. In my answer to the point made by surfbum, I pointed out that most if not all of the stands considered in this study were probably stands grown on sites that had some soil disturbance, perhaps from farming, as with “old field” sites. Your points here I think expand our understanding of other limitations that the kinds of sites included in the study might involve. But on the other side, I AM using the phrase “might include.” I do think that this study has some broad implications about the future growth of white pines and the possibility that white pines may in the future, and/or did in the past, achieve the very great heights attributed to them. Before I read the summary of this study, I had assumed that the very best sites would continue to produce superior growth of white pines throughout the life of the trees. I had read about the growth curves that have been determined for other species. What is commonly the case is that trees growing on the best sites will continue to grow faster than trees growing on the poorer sites, but over time the difference diminishes because the drop off in growth rates of trees growing on the poorer sites is slower than it is for trees growing on the better sites. What really surprised me about this study of white pine is that after only 55 years the drop off in the growth rates of white pines on the best sites is so great, that in fact all the difference in growth rates completely disappears after 55 years. This is completely counterintuitive. To my mind, it simply doesn’t make sense! But this is not the first time my sense of how things work or should work has been shown false by research. Now for me the bottom line is that this study would “seem” to suggest that the idea that some absolutely superior sites may not, as we might think, produce trees of absolutely superior heights, something like 30 to 50 feet greater. This study suggests that the difference may be only 10 or 20 feet. Now this has really surprised me, to say the least! Yes, we need more research. But this study, while not eliminating the possibility that there may be certain kinds of sites that will support the continuation of fast growth rates well beyond the age of 55, it does, I think, raise very serious questions about the assumptions that I and others may have had about the sustainability of especially fast growth rates of white pines on superior sites. This does make me think that the possibility of 250 foot tall white pines less likely than I had previously thought. If the growth rates of white pines on the best sties are not sustained, then trees would have to live a very, very long time undisturbed to reach 250 feet. You can draw different conclusions about whether 250 foot pines existed in the past or will exist in the future. All I am trying to say is that the information produced by this study does bear on the question, and would seem to suggest that the possibility is less than it would be if some sites, even if only the potentially limited variety of sites covered in this study, could continue to support very superior growth rates for white pines over a period of time much longer than 55 years. Is this a fair interpretation? Personally, I would like to believe that white pines did/could grow to 250 feet. That is a thought I could cherish. Eastern white pine is a truly noble species. I think it is the most beautiful of all the pines I have seen, and that includes the magnificent sugar pines growing in the Sierra Nevada Mountains. I am just finding it harder, after reading about this study, to maintain that cherished thought. --Gaines --------------------------------------------------------------------------------------------------- On 1/5/10, JACK SOBON <[email protected]> wrote: > Dear Gaines, > Thanks for keeping the White pine height debate alive. > I read the white pine info at the link you referenced but didn't glean the > same information that you did. First off, nowhere was there indicated a > maximum height potential, regardless of site index. Second, the > charts showing growth increments are for sites in the Southern Appalachians, > the Southern extreme of White pine's range. The historic reports of 250+ > trees are all in New England, at the center of its range. Third, site index > does not take into account the micro climate and topography. We've all seen > those damp, sheltered hollows and ravines where nutrients collect, the > ground stays wet all through the growing season, and mosses cover > everything, where trees are protected from wind and are substantially taller > and healthier than those outside the area though of similar age. That's > where the tallest trees are now and would have been historically. Not a lot > of trees in the 250' class, just a handful scattered across the > Northeast but certainly thousands of trees over 180' (our current Northeast > tallest pine). > Also, according to that chart, the height difference between trees growing > on the poorest sites to those on the best is 60 feet, not 20. > As for annual growth after 55 years being about a foot, I've felled trees > in the 55-80 year old class where I've measured the annual height growth for > the last three years over 30" per year. A chart for the Southern > Appalachians won't necessarily apply to New England. > Though the account of a 300 foot pine in Charlemont, Massachusetts may be > stretched, surely some of the other 250'+ accounts must be true. They had > accurate measuring devices then. Though they lacked the techno-gizmo's of > today, they were not primitive. There were surveyors, builders, and others > skilled in measuring then. When I measure old structures from the 1700's, > they are typically within a quarter inch on a sixty foot length. A modern > steel measuring tape can vary that much from winter to summer with thermal > expansion. Just because we don't have them today, doesn't mean there > weren't 250 footers then. Nowhere in New England are there now pines > growing in an ideal spot (like that I mentioned above) where they have > been undisturbed for 400 years! > Jack Sobon > > >
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