A technique used in ecological work to relate the composition of different stands of vegetation to each other. It is used by those who consider that no two stands of natural vegetation are ever the same and thus they cannot be classified into distinct associations (compare classification
). Certain properties of each stand, namely data on the species present, are plotted against one or more axes, each axis representing some environmental gradient. The end result should be an arrangement in which the diflerent vegetation stands are ordered in a manner that best reflects their similarities and differences.