Clonal integration in homogeneous environments increases performance of Alternanthera philoxeroides

Abstract

Physiological integration between connected ramets can increase the performance of clonal plants when ramets experience contrasting levels of resource availabilities in heterogeneous environments. It has generally been shown or assumed that clonal integration has little effect on clonal performance in homogeneous environments. However, a conceptual model suggests that integration could increase performance in a homogeneous environment when connected ramets differ in uptake ability and external resource supply is high. We tested this hypothesis in a greenhouse experiment with the amphibious plant Alternanthera philoxeroides. Ramets in clonal fragments containing three rooted and two unrooted ramets were either left connected or divided into a basal part with two rooted ramets and an apical part with the other ramets. To simulate realistic, homogeneous environments of the species with different levels of resource supply, plants were grown at 0, 20, or 40 cm of water depth. Water depth had a positive effect on most measures of growth, indicating that resource supply increased with depth. Connection had negative to neutral effects on total growth of fragments at a water depth of 0 cm, and neutral to positive effects at 20- and 40-cm depths; effects on the apical part were generally positive and larger at greater depth; effects on the basal part were generally negative and smaller at greater depth. Results largely supported the hypothesis and further suggest that clonal integration of allocation and reproduction may modify benefits of resource sharing in homogeneous environments.

The invasive stoloniferous clonal plant Alternanthera philoxeroides outperforms its co-occurring non-invasive functional counterparts in heterogeneous soil environments – invasion implications

“…Moreover, a long-term experimental study by Fransen and de Kroon50 showed that the extent to which environmental heterogeneity favours clonal plants weakens over time. Recently, Dong et al 51. showed that the performance of A. philoxeroides can be enhanced by clonal integration in homogeneous environments.…”

Physiological Integration Affects Expansion of an Amphibious Clonal Plant from Terrestrial to Cu-Polluted Aquatic Environments

“…There is a large ecological span from the terrestrial to the aquatic environments. In that case, the organ structures of the amphibious plants should possess both terrestrial and aquatic traits to accommodate the heterogeneity11213. Furthermore, the different traits should be interchanged between different water conditions.…”

“…For clonal plants, the well-established ramets can support the growth of physiological connected apical sections and facilitate the broader occupation of space in heterogeneous habitats via physiological integration11213. Elongation of stolons and sprouting of new ramets from the perennial roots or stems are two strategies for A. philoxeroides to extend populations in the heterogeneous habitats.…”

“…Griseb (Amaranthaceae) is an amphibious perennial herb originating from Parana River region in South America12326. As one of the most detrimental invaders in China, it is widely distributed in aquatic (e.g., rivers, lakes, canals) and terrestrial habitats (e.g., crop lands, lawn) and the junctions (e.g., river banks,) in tropic and subtropical area.…”

“…Many exotic invasive plants are also amphiphytes, which span a broad habitat niche ranging from terrestrial to aquatic habitats or vice versa 12. Furthermore, certain invasive amphiphytes exhibit clonal growth characteristics, such as physiological integration345.…”