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

Abstract

Environmental heterogeneity is considered to play a defining role in promoting invasion success, and it favours clonal plants. Although clonality has been demonstrated to be correlated with the invasion success of several species of clonal invasive plants in heterogeneous environments, little is known about how the spatial scale of heterogeneity affects their performance. In addition, the factors that distinguish invasive from non-invasive clonal species and that enhance the invasive potential of clonal exotic invaders in heterogeneous environments remain unclear. In this study, we compared several traits of a noxious clonal invasive species, Alternanthera philoxeroides, with its co-occurring non-invasive functional counterparts, the native congener Alternanthera sessilis, the exotic Myriophyllum aquaticum and the native Jussiaea repens, in three manipulative substrates with different soil distribution patterns. We found that the invasive performance of A. philoxeroides was not enhanced by heterogeneity and that it was generally scale independent. However, A. philoxeroides showed some advantages over the three non-invasives with respect to trait values and phenotypic variation. These advantages may enhance the competitive capacity of A. philoxeroides and thus promote its invasion success in heterogeneous environments.

Influence of Soil Nutrient Heterogeneity and Competition on Sprouting and Ramets Growth of Alternanthera philoxeroides

“…Density‐dependent effects have different influences on germination. For example, high densities restricted the subsequent seed germination of desert annuals, ramet establishment increased with seed density, or density did not affect the seed germination or ramet establishment . The results showed that higher fleshy root densities significantly restricted the sprouting and growth of A. philoxeroides , which was consistent with previous studies on propagules of other species .…”

“…On the other hand, compared with non‐clonal plants, clonal plants generally show positive responses to heterogeneity in terms of overall growth, and they display a greater number of morphological features, tend to efficiently capture resources and further increase their local growth in heterogeneous environments . However, ramet growth traits were not affected by soil heterogeneity, and this result was consistent with a previous study showing that the growth of fragments of A. philoxeroides benefited less from soil heterogeneity . The results were inconsistent with a previous study that soil heterogeneity can increase the growth performance of fragments of A. philoxeroides .…”

“…A. philoxeroides may have derived from a single clone, as molecular data have indicated its genetic diversity is extremely low in China . Though intraspecific competition significantly restricts the growth rates of A. philoxeroides , resource heterogeneity significantly increases the invasiveness of A. philoxeroides , likely because A. philoxeroides can easily utilize heterogeneous resources through clonal integration . In addition, those experiments were focused on the stolon growth of this species.…”

Effects of Temporal Heterogeneity of Water Supply and Spatial Heterogeneity of Soil Nutrients on the Growth and Intraspecific Competition of Bolboschoenus yagara Depend on Plant Density

“…Therefore, B. yagara was more sensitive to soil nutrient heterogeneity than to heterogeneity of water supply. Spatial or temporal heterogeneity in soil nutrient distribution and water supply patterns may be highly important with respect to the growth performance and population structure of clonal plants (Hutchings et al, 2003; Wang T. et al, 2016; Wang Y.J. et al, 2016; You et al, 2016).…”

Does Soil Nutrient Heterogeneity Improve the Growth Performance and Intraspecific Competition of the Invasive Plant Myriophyllum aquaticum?

“…Furthermore, the long-term response of Holcus lanatus was to produce far less shoot biomass in the heterogeneous treatment than expected under the homogeneity treatment (Fransen and Kroon, 2001). In addition, the growth performance of clonal plants in heterogeneous soil conditions may be correlated with the spatial scale of heterogeneity (Wijesinghe and Hutchings, 1997; Wang et al, 2016). For example, the growth of Glechoma hederacea was dependent on the spatial scale of soil nutrient heterogeneity (Wijesinghe and Hutchings, 1997), but Alternanthera philoxeroides displayed generally similar, scale-independent performance in most traits under different scales of soil nutrient heterogeneity (Wang et al, 2016).…”