A GEOSTATISTICAL ANALYSIS OF THE SPATIAL-DISTRIBUTION OF ABAX-PARALLELEPIPEDUS (COLEOPTERA, CARABIDAE) IN A WOODLOT

In order to examine the small-scale distribution and population densit y of Abax parallelepipedus and to assess the carrying capacity of wood lots, we ran a capture/recapture study in a small woodlot (0.45 ha) at Saint Marcan, Brittany, in the French 'bocage' (hedgerow network land scape). We used a grid of 160 pitfall traps between June 23(rd) and Se ptember 1(st), 1996, which was checked every 2 days. Each Abax paralle lepipedus caught was individually marked with a micro-drill and releas ed. The whole capture-recapture history was used to estimate the popul ation density using the Jolly-Seber method. The density was of 0.1 ind /m(2). Frequency distributions are approximately lognormal. Geostatist ical analysis was used to display the spatial pattern of activity amon g the traps. The variogram suggests that 75% of the sample variance wa s related to spatial autocorrelation over a range of 50 m. Moreover, w e used a block kriging to obtain a complete map of activity within the study area. This activity appeared patterned at this scale, with two fundamental well-defined patches. A one way ANOVA did not reveal any s tatistical significance between the total catches and the structure of the litter and the presence of rotten tree stumps. We propose that cl uster or interaction groups of individuals could be used as basic unit s to model populations in woodlots, at an intermediate ecological leve l between individual and population. (C) Elsevier, Paris.