SPATIAL PATTERN-ANALYSIS OF WEED SEEDS IN THE CULTIVATED SOIL SEED BANK

(1) Spatial pattern of weeds was analysed in an arable-soil seed bank after winter barley. Three hundred samples were taken in a 7.5 x 10m area. Three indices of dispersion (variance-to-mean ratio, Lloyd's mean crowding and Lloyd's patchiness) and the Moran's I statistic of spatial autocorrelation were calculated. (2) The seed bank of the field was almost exclusively composed of annual species, dominated by Thlaspi arvense (43.8%) and a subset of six species (41.7%). (3) For most species with a mean higher than 0.2 seeds per core, the seed pattern was patchy. Only two species. Avena fatua and Chenopodium polyspermum, had random pattern. For the other species, two types of aggregation have been found due to biological and agricultural factors.