Shade tolerance as a key trait in invasion success of submerged macrophyte Cabomba caroliniana over Myriophyllum spicatum

Abstract

The synergy between climate change, eutrophication, and biological invasion is threatening for native submerged plants in many ways. The response of submerged plants to these changes is a key factor that determines the outcome of biological invasion. In order to explain the invasion successes, we investigated the combined effects of climate change and eutrophication‐related environmental factors (temperature, light, and nutrients) on the trait responses of a native (Myriophyllum spicatum) and an alien (Cabomba caroliniana) submerged species. In a factorial design, we cultivated the two species in aquaria containing low (0.5 mg N L−1, 0.05 mg P L−1) and high (2 mg N L−1, 0.2 mg P L−1) nutrient concentrations, incubated at four light intensities (average 25, 67, 230, and 295 μmol m−2 s−1 PAR photon flux density) under two temperature levels (21.5 and 27.5 ± 0.5°C). We used four invasion‐related functional traits (relative growth rate (RGR), specific leaf area (SLA), leaf dry matter content (LDMC), and nitrogen to carbon ratio (N:C molar ratio)) to measure the environmental response of the species. We calculated plasticity indexes to express the trait differences between species. Cabomba caroliniana showed significantly higher RGR and SLA than M. spicatum especially under low light intensity indicating that Cabomba is much more shade tolerant. Elevated temperature resulted in higher SLA and reduced LDMC for C. caroliniana indicating that Cabomba may have higher invasion success. Myriophyllum showed higher LDMC than C. caroliniana. Chemical analyses of the plant tissue revealed that although M. spicatum showed significantly higher N:C molar ratio, nonetheless, the daily nitrogen uptake of C. caroliniana was more than three times faster than that of M. spicatum. Results supported the idea that due to its higher shade tolerance and nitrogen uptake capacity, Cabomba likely has greater invasion success with increasing temperature combined with low light levels.

How Eutrophication Promotes Exotic Aquatic Plant Invasion in the Lake Littoral Zone?

“…Furthermore, the native species combination in this study did not significantly affect the biomass, ramet number, and RGR of the invasive species A. philoxeroides and M. aquaticum and the effect of mixed species ratios on invasive plant traits was almost 84 This is because increased availability of resources induced by eutrophication enhances dominance of exotic species over native species as exotic species tend to have a high resource acquisition capacity. 16,85 Our PTN analysis indicated that A. philoxeroides had high connectivity between traits, supporting its high resource uptake and assimilation efficiency as well as its high RGR, which is consistent with the high invasiveness of this species. Furthermore, eutrophication led to a significant increase in leaf SOD activity for A. philoxeroides, demonstrating that eutrophication caused physiological stress to the plants.…”

“…philoxeroides and, in general, aquatic plant invasion is more likely to occur following intensified eutrophication of water bodies caused by human activities . This is because increased availability of resources induced by eutrophication enhances dominance of exotic species over native species as exotic species tend to have a high resource acquisition capacity. , Our PTN analysis indicated that A. philoxeroides had high connectivity between traits, supporting its high resource uptake and assimilation efficiency as well as its high RGR, which is consistent with the high invasiveness of this species.…”

Do Tree Size and Tree Shade Tolerance Affect the Photosynthetic Capacity of Broad-Leaved Tree Species?

“…Shade tolerance is one of the factors affecting the interspecific variation of leaf traits. The difference of shade tolerance among species reflects the response of species to different light environments [ 38 ], determines whether species can grow and reproduce in new habitats [ 39 ], and has an important influence on the formation of stand structure in the process of natural forest succession [ 40 , 41 ]. There is evidence that shade-tolerant species tend to have wider crowns and more fixed branching patterns than shade-intolerant species, reducing their self-occlusion and helping them better capture light in low light conditions [ 42 ].…”

How does trait variance partitioning help us to understand plant community assembly? The example of pond communities in the Kerguelen Islands

“…Most plant morphological traits are key for coping with environmental filters (see, e.g., Lavorel & Garnier, 2002). Responses to both biotic and abiotic filters have been evidenced extensively in macrophyte traits involved in growth or resource acquisition (i.e., the specific leaf area [SLA], height, and root and internode lengths; Pilon & Santamaría, 2002; Wolfer & Straile, 2004; Fu et al., 2013; Gao et al., 2021) and in resource conservation (i.e., the leaf dry matter content [LDMC] and specific connection mass; Pilon & Santamaría, 2002; Elger & Willby, 2003; Gao et al., 2021; Koleszár et al., 2022). How traits respond to simultaneously varying biotic and abiotic conditions, however, remains unclear (Chalmandrier et al., 2022).…”