Dev and Ecolog:
Thanks for clarifying your objectives. ("My issue is... I want to explain
the variations in growth that are caused by climate. The data that I have
is a time series on DBH and *some *heights for 40 years for around 65 trial
locations covering entire Asutria. Usually DBH
strongly respond to management operation like thinning , felling etc . So
How can I be sure that the variations in growth (if i take DBH as a
indicator) is due to climate and not due to management.") Please excuse me
for changing the order of your statements--I did that or organize my own
thoughts.
[Note to all: My comments regarding the value of means being "next to
worthless" was meant to convey my concerns with those generalizations that
don't prove anything (or what they are sometimes claimed to prove) and to
imply that they have limitations that should be taken into account when
reaching conclusions--particularly when they are used to make policy or are
disseminated to non-specialists. I meant that to imply great caution in
their use, not to insult everybody/anybody who uses means in their work. I
trust that good judgments will be made in each case. However, I see
generalizations as traps for the unwary, and am concerned that their
limitations will not be recognized and relevant variations within
generalizations can become errors that can accumulate and distort
conclusions. My apologies to all who were hurt by the statement--it was not
my intent to gore any particular ox; I was generalizing. I, in fact, often
go much farther than generalizing; I often go beyond the data into
intuition. But I make no claims that my intuitions are anything but
provisional. No, sometimes I DO claim that provisional conclusions are
likely more true than untrue based on as solid a scientific foundation as
possible.]
I will venture the guess that your basic question is answered by the
well-known connection between climate and growth (deserts and rainforests),
but if you are attempting to demonstrate (I'm guessing here) that climate
change will affect DBH and height, you will need good records on past
climatic conditions with which to correlate those (I'm tempted to be flip
and say "variable," but I shall forego such an impertinence) variables. But
teasing out the effects of climate change upon growth from all the other
factors and variations is indeed challenging, to say the least.
My guess is that the data on the results of thinning, felling, etc. should
stand out clearly unless the damage is severe (as in the USA), in which case
it might not (possibly due to erosion and increased Q (stream-gauge data?)
for example.
I hope you will post the research design that you decide upon--I'm sure I
will learn a lot from it.
WT
----- Original Message -----
From: "D Chakraborty" <dev.vi...@gmail.com>
To: <ECOLOG-L@LISTSERV.UMD.EDU>
Sent: Saturday, March 09, 2013 12:27 AM
Subject: Re: [ECOLOG-L] need help
Thank you all for the comments. It will definitively help me
The data that I have is a time series on DBH and *some *heights for >40
years for around 65 trial locations covering entire Asutria. I am aware
that DBH and height are very strongly correlated. My issue is... I want to
explain the variations in growth that are caused by climate. Usually DBH
strongly respond to management operation like thinning , felling etc . So
How can I be sure that the variations in growth (if i take DBH as a
indicator) is due to climate and not due to management.
The issue raised on examining the residuals seems interesting and useful,
also on Dendrochronology. The issues raised on micro
climate is definitely worth examining but I also agree with Thomas J.
Givnish on his views on "mean annual anything". Its definitely not
worthless because many of us tend to forget that modelling aims
at simplifying things to an extent that we have just adequate set
of information.
Thanks and have a nice weekend
best regards
Dev
On Sat, Mar 9, 2013 at 6:39 AM, Journals <fbjourn...@gmail.com> wrote:
If stands are fully stocked basal area of a stand (m2 ha-1) is a
relatively good measure of productivity. If your stands are not fully
stocked it may be possible to play around with stand density and diameter
(which would not be trivial).
Frank
--
Debojyoti Chakraborty
Wissenschaftlicher Mitarbeiter
Department of forest and soil sciences, Universität für Bodenkultur Wien
Ph: Vienna +43 6764871296 (m)
Lecturer, Amity Institute of Global Warming and Ecological Studies
Amity University campus, Block D, II floor,Sector 125, NOIDA
India www.amity.edu/aigwes
India +919868001750 (M India), 01204392562 (O) 0120-4392606 (Fax)
alternate email id: dchakrabo...@amity.edu, dev_...@rediffmail.com
skype: d-chakraborty
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