Dale,
Not to worry, my friend. All us veterans have special gun totting privileges. Shhh, don't let Jenny know. Bob ----- Original Message ----- From: "Dale Luthringer" <[email protected]> To: [email protected] Sent: Tuesday, January 12, 2010 11:44:36 AM GMT -05:00 US/Canada Eastern Subject: Re: [ENTS] Projected heights and Jenny's wrath That's a tought one, Bob, I've got an itchy trigger finger... On Tue, Jan 12, 2010 at 10:52 AM, < [email protected] > wrote: Gaines, Oh boy, I hope a rift doesn't develop here in ENTS. Those of us obsessed with tree heights will naturally want to limit damage by birds perching in the crowns, especially their highest parts. I'm definitely not suggesting anyone get out his/her youthful slingshot, but in time the temptation could grow. Giving this line of thinking a foothold could prompt Jennifer Dudley to establish a bird safety patrol to keep a close eye on us measurers. Jenny's wrath would be swift and terrible. Resist the temptation Will. Resist the temptation Scott, John, Dale, .......... Resist. Resist. Bob ----- Original Message ----- From: "Gaines McMartin" < [email protected] > To: [email protected] Cc: [email protected] Sent: Tuesday, January 12, 2010 10:07:42 AM GMT -05:00 US/Canada Eastern Subject: Re: [ENTS] Projected heights Jess: I had thought about mentioning it before, but when you say that the growth rate of a pine tree is influenced by its current height, you bring up an important consideration. Strictly speaking it is better to say that growth rate is influenced by age, and it is this relationship that the growth curves are representing. But the growth rate/height relationship is something that is too often ignored. Years ago I read a report of a provenance trial of white oine, that said that the best way to measure results is not the height of the trees after some set period of time, but to measure their growth rate at various specific heights. The idea behind this, if I remember rightly, is that different sites, including microsites (my term) influence the early growth of the seedlings differently, but this influence is minimized in the data if the growth rates of trees are compared when they are at the same heights (comparably established, comparably developed). And this kind of measurement would best predict the trees’ overall growth potential over time. Now the data that prompted me to open the white pine growth topic showed that the growth rate of white pine on the better sites declines more rapidly than that of white pine growing on the poorer sites, so much so that after age 55, the growth rates are the same—one foot per year. I thought this had some application in the discussion of whether or not white pines could, or did grow to 250 feet. Thus if the fastest growing pines maintain their relatively fast growth rate for only 55 years, then the best growing white pines would not grow as much taller than white pines with more ordinary growth rates as we might have thought. White pines 100 feet tall in 50 years is good, but “ordinary.” Growth of 120 feet is excellent, but after gaining 20 feet over the more ordinary trees in 50 years, and maybe a foot or two in the next five, no further advantage will be gained. All that made me think 250 foot white pines, if view of the fact that none exist today, less likely than I might have thought. Sorry—I said all that before. But I wanted to re-establish the context. Now to the height/growth rate relationship: lost is the above data may be the fact that the trees with the most outstanding growth will, in spite of any decline in growth rates down to the level of other white pine trees after age 55, still be growing faster at any specific height. Of course as Will and others have pointed out, there is the risk of storm damage. I would add to that the damage from large bird perch. The bird perch issue is not recognized by all foresters, but I have observed it first hand many, many times. The tallest trees in my pine and spruce stands are the ones usually hit. The new growth is often completely mashed down. If this happens early enough in the growing season, especially with the Norway spruce, a leader can be re-established. I can imagine that slower growing very tall old trees would have some difficulty doing that, and the damage could accumulate. This would be a significant influence on the ability of older, very tall trees to make good further progress upward. This relates to the ability of second growth stands to exceed the growth of trees in the virgin forest. I will take this up in my next response. Enough for one post here already. --Gaines
