Andrew,
I'm sure that you'll get kudos and credits in Jenny's avian
sensitivity rating system. But Gaines and I may be in trouble.
We'll mend our ways. At 68 1/2 I can still change. Really I can. I
think I can. Maybe I can.
Bob
----- Original Message -----
From: "Andrew Joslin" <[email protected]>
To: [email protected]
Sent: Tuesday, January 12, 2010 11:15:28 AM GMT -05:00 US/Canada
Eastern
Subject: Re: [ENTS] Projected heights and Jenny's wrath
That's funny! I've been a birder for more than 20 years. As a
climber I
frequently visit the tops of white pine. In my area in eastern
Massachusetts I can very confidently say that damage to tops is
primarily from weather. Over the years I've seen many large raptors
perched in white pine and have never seen them break anything. I've
even
seen a pair of Red-tailed Hawks mating in the top of a white pine,
you'd
think this rambunctious activity would do some damage but no. I can
imagine perching birds breaking delicate tops on smaller conifers
but on
mature white pine for example any branch thicker than an inch is
going
to support Red-tailed Hawk (our largest common raptor). I have seen
red-tails intentionally breaking small branches off of red oak for
nest
material but they don't seem to go for the uppermost branches when
they're doing this. They need a secure perch on a thicker branch to
get
into position to break a small branch. I can imagine a bald eagle
easily
breaking out some top branches but their population densities are not
enough in the east to make a difference for our tall white pines.
-Andrew
[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 foo
t 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
