Water depth rather than substrate heterogeneity affects the clonal performance of the stoloniferous submerged plant, Vallisneria spiralis L

Abstract

Environmental heterogeneity profoundly influences the performance of clonal plants. To evaluate the effects of substrate patchiness and different water depths on clonal performance, we subjected the stoloniferous submerged plant Vallisneria spiralis L. to different patchy substrates and water depths. We measured several growth traits. We found that ramet number, leaf number, and stolon length decreased, and ramet height, spacer thickness, and biomass increased with increasing water depth. We saw no significant trait variations across different substrates. Furthermore, the trait allocation – the distribution of trait values in different patches of heterogeneous substrates – was consistent in most treatments. Clonal integration homogenized the effects of substrate patchiness via resource exchange through interconnected ramets. The ability to use water nutrients may enable submerged plants to alleviate the uneven distribution of soil nutrients in patchy substrates. Additionally, the simple root structure and weak root functions curtail submerged plants in obtaining sufficient nutrients from soil. Water depth rather than substrate heterogeneity determined the plant performance of V. spiralis.