Dear friends,
I am dealing with a particular relativization issue in a microhabitat
analysis and would like to hear your opinion about it, would it be possible?
Here follows a resume:
Hypothesis:
The Southern dominant conifer Araucaria angustifolia occurs more often than not
on higher microtopographic sites, and avoids the lower ones.
Data:
XY positions of 600 young individuals in 10 separate plots. Each plot has 1 ha
(100 m x 100 m) and is subdivided in 100 10 x 10 m subplots. The area is a
mountainous terrain at ca. 850 m elevation.
Altitude has been measured on the corners of each subplot, and at the locations
of each individual.
Analysis:
Simply, the comparison of the background altitude distribution of the subplot
corners with the individuals altitude distribution, through a
Kolmogorov-Smirnov test.
The expectation is that the distribution of individuals will be different from
that of the local microtopography because they lack individuals at the lower
altitudes
The focus is not at the altitude in itself, but in the lower parts of the
plots, which correspond to local depressions, which are more humid.
Problem:
Each one of the 10 areas is located at a distinct altitude. Although these are
not too much different (amplitude ~100 m), it precludes me to pool the altitude
data of the areas, that form multimodal distributions.
My Current Doubt:
I am thinking of considering the relative altitude of each corner and each
individual, instead of the real altitude. This relativization would be carried
out by transforming each altitude datum in its relative "distance" from the
average altitude of its plot (xi - averageX).
I guess this would allow me to pool all altitude measures and focus on what is
the question of the research.
What do you think? Should I standardize the data, dividing the relativized
measures by the standard deviation? Why?
Any thoughts are well come.
Sincerely,
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
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