INFERENCE ABOUT DISPERSAL PATTERNS

Statistical methods are discussed, which are used in the analysis of point patterns. Special attention has been paid to their application in ecological research. Some new procedures are presented, which seem to be better compatible with the needs of the ecologist. It is pointed out that patterns can usually be described in terms of an appropriate trend surface as well as in terms of mutual interactions. This circumstance restricts the value of the analysis of point patterns for ecological research in tracing the mechanisms which are connected with the distribution of individuals. After having discussed the current sampling designs with respect to point patterns, the, estimation of the local intensity is treated. Although the so-called distance-method has got considerable attention in this respect, it is stated that this method is not very appropriate for this purpose. For two sampling designs, it is illustrated how to estimate functions, which describe density variation in the field. Further, a procedure is proposed which estimates the covariance curve, as well as the total amount of interaction in the pattern. The relation of the statistic with the covariance curve has been pointed out. An improvement has been proposed of the well-known Greigh-Smith method, i.e. the estimation of the variance curve. The estimation procedures proposed have been illustrated by three examples from the field, i.e. dispersal patterns of barnacles, anemones and glassworts, all belonging to low structured communities. They are presented in the Appendix. Monte Carlo-methods are used to study the properties of some statistical procedures. © 1979 Leiden University Press.