Figure 4. Canonical correspondence analysis (CCA) ordination graphic. Arrows = quantitative environmental variables. Solid circles = nominal environmental variables. Only the variables significantly associated with axes 1 and 2 were plotted. A: Annual. Samples corresponding to the autumn (stars), winter (squares), spring (open circles) and summer (triangles). B: autumn, C: winter, D: spring (samples = circles, species = stars, numbers indicate the taxa enumerated in the appendix).