STUDY ON THE EFFECT OF THE SEED DISPERSAL AND THE GERMINATION AND GROWTH OF ACTIVE RIVER CHANNEL

Abstract

Vegetation in a river plays critical role in the river ecosystem. Factors for successful colonization of plants can be divided into two factors: hydraulic seed dispersal and “germination and growth” condition. Here, we carried out a field survey and germination experiment to elucidate a dominant factor of vegetation colonization. The field survey was conducted at the pointbar clearly divided into two part, i.e. sandy and silty segment. Invasive Noogoora burr (Xanthium occidentale) covered over the silty segment, on the other hand almost no plant over the sandy segment. Both silty and sandy sediment at the pointbar were used for germination experiment. Germination was observed at silty segment’s sediment; however, no germination was detected in the sandy sediment though conditioned to enhance the germination from seedbank. These results indicate that the colonization success of river vegetation is dominantly subject to not “germination and growth”, but hydraulic seed dispersal properties.