Sorting seed by hydrochory

Vegetation along rivers is an important feature affecting the functioning of the entire riverine ecosystem. The structure of riparian vegetation is shaped to a considerable degree by the dispersal of seeds by water, also known as hydrochory. Mostly buoyant seeds are transported by hydrochory, but non-buoyant seeds are also transported. A series of laboratory experiments were conducted on 8 different types of non-buoyant seeds to see if the theory used for sediment could apply to seeds. This study suggests that in water, seeds respond in a similar way to sediment and the tools used for sediment can be extended to seeds also. The key factor in the sorting of buoyant seeds by hydrochory (leading to spatial species differentiation) is usually considered to be the effect of potential duration of buoyancy, which has received much interest. The way seeds are distributed in rivers is strongly influenced, however, by their hydrodynamic properties, such as size, shape and density. A series of laboratory experiments were conducted to investigate qualitatively how 5 different types of buoyant seeds wit