THE PROBLEM OF NON-LINEARITY IN ORDINATION: EXPERIMENTS WITH TWO-GRADIENT MODELS.

The article presents an experiment with two-gradient models for the problem of non-linearity in ordination. This paper focuses on the environmental factors in relation to the species performance. Information on the optimum and decline to zero for high and low levels are discussed. An ecological assumption implication for ordination methods assuming monotonicity and frequent linearity is presented. Models representing environmental space in two factors are given. The experiment's results is briefly discussed.