Dear friends, Some days ago I wrote to you asking for some ideas about the estimation of altitude at unsampled plants.
Basically, I received the suggestion to avoid simply averaging nearby values when assigning altitude values to individual plants. This was very useful, because since then I estimated these altitudes by distance weighted averaging, a procedure simpler than kriging, but robust enough to be safe in simple cases like this. My question is: do Araucaria angustifolia young plants avoid microtopographic depressions? Now I would like to ask you how would you calculate standardized scores for poles and plants in inclined planes. Since some 1 ha plots I have are not horizontal, I fitted plane equations (XYZ) through multiple regression to these areas (Z is altitude and XY are xy coordinates). Now I need to standardize the altitude values of both poles and plants in relation to this plane, and not to a single average of the whole area. This will, I believe, rule out the inclination of the area, and give me deviations that represent microsite/microtopographic elevations and depressions. I am planning to calculate these standardized scores as: each altitude value minus the plane equation predicted value for that point (instead of the grand average, and note that this represents the equation's residuals), and divide by the standard deviation of the points IN RELATION TO THE PLANE. And here is where I am not secure. This standard deviation should use the equations predicted value instead of the average, also. Do you think is this all ok? My other optin is just to exclude the inclined plots from the analysis, and use only the horizontal ones. This would be an ugly optin, wouldn't it? Thank you very much in advance for any contributions and ideas. All the best, Alexandre Dr. Alexandre F. Souza Programa de Pós-Graduação em Biologia: Diversidade e Manejo da Vida Silvestre Universidade do Vale do Rio dos Sinos (UNISINOS) Av. UNISINOS 950 - C.P. 275, São Leopoldo 93022-000, RS - Brasil Telefone: (051)3590-8477 ramal 1263 Skype: alexfadigas [EMAIL PROTECTED] http://www.unisinos.br/laboratorios/lecopop -- Esta mensagem foi verificada pelo sistema de antivírus e acredita-se estar livre de perigo.
