Studies in the Numerical Analysis of Complex Rain-Forest Communities: I. A Comparison of Methods Applicable to Site/Species Data

A set of data relating to eighteen rain-forest sites defined by the presence or absence of 818 vascular species is analysed by four numerical methods, two of which are novel. A Gower ordination proved the single most informative method; but computational considerations suggest that classification should be undertaken first, and ordination invoked only if classification proves unprofitable. Similar considerations apply to the new method of concentration analysis. The analyses reflect known environmental factors with great precision, and have clarified a complex interaction pattern. They recover the original intuitive physiognomic-structural classification only imperfectly, and the cause of this lack of complete correspondence requires further investigation. The results incidentally demonstrate that the basic floristic units which underlie the forest structure are vertically integrated and are not synusial; the wider implications of this observation are discussed.