Introduction

Randomized complete blocks design is probably the most popular experimental design in ecological studies, because it controls in a powerful way the environmental heterogeneity. For a univariate response (e.g. number of species, total biomass) the results of experiments set in randomized complete blocks are evaluated using a two-way ANOVA without interactions. The interaction mean square is used as the error term – the denominator in the calculation of F -statistics. In the following tutorial, you will use the program CANOCO in a similar way to evaluate the community response (i.e. a multivariate response of the species composition of the vegetation). The example is based on an experiment studying the effect of dominant species, plant litter and moss on the composition of a community of vascular plants, with special attention paid to seedling recruitment. In this way, some of the aspects of the importance of regeneration niche for species coexistence were tested. The experiment was established in four randomized complete blocks, the treatment had four levels and the response was measured once. The experiment is described in full by Špa čková et al. (1998). Here is a simplified description of the experiment.

The experiment was established in March 1994, shortly after snowmelt, in four randomized complete blocks. Each block contained four plots, each with a different treatment: (1) a control plot where the vegetation remained undisturbed; (2) a plot with the removal of litter; (3) a plot with removal of the dominant species Nardus stricta; and (4) a plot with removal of litter and mosses. Each plot was 2 m × 2 m square.