Effects of the cultivation of sage and wild camomile on weed communities (a three-year study in Saxony)

In this study we investigated the weed communities of the perennial sage an d the annual wild camomile, exemplarely for cultivation of medicinal and ar omatic plants, in Saxony. This included the examination of the number of sp ecies and individuals, the phenophases, the reproduction rate and the soil seed bank. The weed communities were compared with the vegetation of other typical crops at the same site. Since sage is cultivated in rows with an intensive mechanical weeding, it c ould be shown that the diversity of weeds as regards their current vegetati on and the soil seed bank is reduced in sage fields. The species structure was found to be shifting towards plants with shorter life cycles, unspecifi c requirements on the germination temperature and a suitable camouflage amo ng the sage semishrubs. The soil seed bank varies according to whether it i s situated in the rows or between them, and it diminishes considerably with in the rows. The weed coenosis of camomile fields was found to have many individuals and a rich spectrum of species typical for the site. Species with a germinatio n optimum at lower temperatures, high demands on the light intensity and sh ort life cycles benefit from the camomile culture. To maintain their reprod uction, some weeds require a rotation of crops with cereals with a low cove rage level and a late harvest.