Dear Dev and Ecolog colleagues, Good question and great discussion!
I want to mention that if you have details of tree removal data (thinning intensity and density, species, dbh of removed trees, spatial information, thinning from above and low etc.), you can develop a tree removal index. Be cautious with natural mortality as well. You can try this index, climate index and site quality index (for example, derived from yield tables in Austria) as independent variables. If you use location of inventory plots as random effects and want to know whether they are significant, you can do Bayesian GLMM, which is now very easy to perform in R (e.g. package MCMCglmm). You can use DBH, even calculated biomass and mean increment in biomass if you interested on carbon stores issue. For supporting the relevancy of DBH, and biomass derived from DBH-based allometric equation, calculation of removal index from long term periodic forest inventory data, please see the following paper: D’Amato, A.W., J. Bradford, B. Palik, and S. Fraver. 2011. Forest management for mitigation and adaptation to climate change mitigation: insights from long-term silviculture experiments. *Forest Ecology and Management* 262:803-816<http://silviculture.forestry.umn.edu/prod/groups/cfans/@pub/@cfans/@silviculture/documents/asset/cfans_asset_342879.pdf>. DOI:10.1016/j.foreco.2011.05.014 Good luck Cheers Somidh On Sat, Mar 9, 2013 at 7:51 PM, Wayne Tyson <landr...@cox.net> wrote: > 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 > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1430 / Virus Database: 2641/5656 - Release Date: 03/08/13 > -- Dr. Somidh Saha c/o Chair of Silviculture Faculty of Environment and Natural Resources University of Freiburg Tennenbacherstrasse. 4 D-79085 Freiburg i. Br. Germany Homepage<http://www.waldbau.uni-freiburg.de/mitarbeiter-en/Mitarbeiter_sammlung_en/saha-en?set_language=en>
