While in general I concur with Wayne's view that "all kinds" of site variables can affect tree height and dbh - most meaningfully, asymptotic tree height - I disagree with the flip statement that "mean annual anything as independent variables are next to worthless". My colleagues and I have a paper we are about to submit that predicts max tree height from two "mean anything" environmental variables over a 600-km transect with an r2 = 0.88. That is NOT "next to worthless".
Thomas J. Givnish Henry Allan Gleason Professor of Botany University of Wisconsin [email protected] http://botany.wisc.edu/givnish/Givnish/Welcome.html On 03/08/13, Wayne Tyson wrote: > Dev (and Ecolog): > > Climate is highly variable from place-to-place, even in the "same" location, > and "all kinds" of site variables can affect tree height and dbh (not to > mention age). Mean annual anything as independent variables are next to > worthless (or worse, misleading) unless you have years, decades, to devote to > the project (and even then they are very questionable), largely because such > variable can vary too much from year to year. DBH is a very crude measure, > and cores are also crude (except for the single tree being cored). > > I must be missing something if this is the way "most contemporary studies" > are done. I hope someone can point out the errors of my thinking. > > WT > > ----- Original Message ----- From: "D Chakraborty" <[email protected]> > To: <[email protected]> > Sent: Friday, March 08, 2013 5:51 AM > Subject: [ECOLOG-L] need help > > > Dear Colleagues > I am working on developing growth response functions to investigate the > effects of climate on growth performance of Douglas fir provenances. Most > of the contemporary studies use multivariate models with tree height at > specific age as dependent variable and climate parameters(eg. Mean annual > temperature, degree days , Annual heat mositure index etc) as independent > variable. > > We all know that tree height is least influenced by management and > therefore its most logical to use tree height as the dependent variable. > However in my case I have very little tree height data. > > In this circumstance I am looking for your valuable opinion that can > justify the use of DBH as a dependent variable. > > Looking forward to hearing from you. > best regards > Dev > > > > -- > 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: [email protected], [email protected] > 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 --
