Clonal integration affects growth and sediment properties of the first ramet generation,but not later ramet generations under severe light stress

Clonal integration benefits clonal plants by buffering environmental stress and increasing resource extraction efficiency.However,the number of connected ramet generations that benefit from clonal integration in a clonal system has received relatively little attention.A pot experiment was conducted to evaluate the extent of physiological integration within the clonal system of Vallisneria natans consisting of a mother ramet and three sequentially connected offspring ramets.Mother ramets were grown in full sunlight,and offspring ramets were heavily shaded with limited light availability.Stolons between mother ramets and offspring ramets were severed or connected,but connection among the three offspring ramets remained.The photosynthetic ability of unshaded mother ramets of V.natans was significantly enhanced,but their biomass accumulation was greatly reduced when connected to shaded offspring ramets.Clonal integration significantly increased biomass accumulation,C and N availabilities,extracellular enzyme activities and microbial biomass of the first ramet generation(adjacent ramet),but not later ramet generations.Our results indicate that support from the mother ramet of V.natans may be limited to the adjacent offspring ramet in a clonal system under severe light stress,implying an effect of ramet generation.Our results contribute to a better understanding of the hierarchy and segmentation of clonal plants.These findings suggest that the extent of clonal integration plays a vital role in ecological interactions of the ramet population.

Clonal performance of Scirpus yagara in multiple levels of substrate heterogeneity and submergence

Aims Environmental heterogeneity affects the performance of clonal aquatic plants.Few researchers integrated two aspects of heterogeneity into the study of clonal plant ecology.The aims of the present study are to(i)test whether different substrate heterogeneity and submergence exert similar effects on plant performance and(ii)explore the foraging behaviour.Methods In this study,Scirpus yagara was subjected to multiple levels of substrate heterogeneity and submergence.Substrate treatments included one homogeneous substrate and three heterogeneous substrates(two-patch,four-patch and eight-patch).Water level treatments included 0,10 and 30 cm.Traits including ramet number,generation number,leaf number,bulb number,ramet height,culm length,rhizome length,clonal radius,spacer length,spacer thickness,total biomass,biomass of bulbs and biomass per bulb were measured.Important Findings Deeper water levels significantly reduced variables associated with growth such as ramet number,generation number,leaf number and bulb number,while substrate patchiness induced significant variations in traits such as spacer length and spacer thickness.Significant interactive effects of the two factors were found for ramet number,leaf number and spacer length.Scirpus yagara showed colonization towards the lake sediment patch in two-patch and four-patch substrates,and more structures were placed in the lake sediment patch.Especially for the two-patch substrate,all structures occupied the lake sediment patch.Two-sided intrusion was observed in the eight-patch substrate,which induced an even allocation of structures in different patches.The foraging behaviour was correlated with the patch size.