| Popis: |
When considered together, the diversity and abundance of biologically similar organisms (e.g. pollinators) within a community, are more powerful in assessing the effects of disruption than when taken separately. The log-normal model of abundance and diversity is illustrated as a tool in applied ecology. Data were collected from sampling pollinating bees over 8 years in 13 blueberry fields in New Brunswick, Canada. These data were used to test the log-normality of the species diversity and abundance relationships with respect to the disruption of communities by applications of the insecticide fenitrothion to nearby forests. Ecosystemic integrity (health) of the lowbush blueberry fields was assessed by using species diversity and abundance in Sugihara's (1980) sequential breakage model. This model was used to test the log-normality of data sets from fields which were affected and unaffected by fenitrothion. On both spatial and temporal bases, fields unaffected by the pesticide fitted well to the log-normal model of species diversity and abundance, whereas affected fields departed from that pattern. Thus, the relationship is useful because the samples from fields affected by fenitrothion presumably represent compromised integrity and decline in ecosystemic health. Shannon-Wiener's hierarchical diversity indices and Jaccard's indices of similarity were found to have little value in measuring ecosystemic health. For the former, none of the indices calculated showed any difference between communities with a log-normal pattern of species diversity and abundance, and those without it. Jaccard's index of similarity was low and similar in all the cases. In general, ecosystemic health should not be narrowly assessed through biodiversity but must include taxonomic and population changes together. The log-normal relationship linking species diversity and abundance is an objective standard against which applied ecologists can test ecosystemic integrity, disruption, health, ill-health, and reconstitution. |
