Constrained Ordination: Tutorial with R and vegan
نویسنده
چکیده
Constrained ordination methods include constrained (or canonical) correspondence analysis (CCA), redundancy analysis (RDA) and distancebased redundancy analysis (db-RDA). Constraining means that ordination only shows the community variation that can be explained by external environmental variables or constraints. This document describes the following basic concepts (1) usage of constrained ordination, (2) construction of model formulae, (3) updating of the model and choice of the constraining variables, (4) statistical significance of the overall model, single model terms or axes with permutation tests, and (5) partial ordination where the effects of some variables are removed before main ordination. The document also describes basic R concepts of inspecting data, and indexing, selecting and subsetting data.
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