Vegetation Dynamics and Neighbour Associations in Pasture-Community Evolution

(1) This paper reports analyses of vegetation patterns and species associations conducted over 3 years in three different-aged pasture communities with similar management histories. (2) Relative abundances of species differed among the three pastures but there were no significant differences in species diversity or composition. Ordination of percentage-cover data from all surveys, however, established a trend of increasing community stability, or constancy, with increasing pasture age. (3) Soil analyses showed little correlation with species-cover and no trends with pasture-age. (4) Patterns of association in time between species were investigated with contact sampling. Four different patterns were identified. Between-species associations in younger communities were predominantly temporary, while older communities had more associations which were persistent over the study period. (5) These data form the basis of a qualitative model of pasture-community evolution which attributes within-community changes in time to biotic interactions between neighbours. The model serves as a hypothesis for experimental studies to be reported later.