Scientists led by Wang and colleagues have conducted a compelling study into the potential for native plant species to defend against invasive plants in aquatic environments. Published in the journal Hydrobiologia, the investigation centres on the interaction of three plant species: the invasive Alternanthera philoxeroides and Myriophyllum aquaticum, and a native Chinese species Ludwigia peploides subsp. stipulacea. This research demonstrates that when harnessed appropriately, local vegetation can be an essential part of managing invasive species.
This research is part of a response to the ongoing ecological crisis of invasive species disrupting local habitats worldwide. Invasive species often spread rapidly in new environments, outcompeting native species for resources and altering ecosystems in potentially devastating ways. The study’s choice of Alternanthera philoxeroides and Myriophyllum aquaticum reflects this crisis, as these plants have spread along the Yangtze River Basin in China, causing significant disruptions.
The research found that the native Ludwigia peploides, a native plant in China (though invasive elsewhere), outperforms both invasive species, showing faster stolon elongation and root recruitment. Stolons, also known as runners, are a form of asexual reproduction where new plants sprout from the main plant’s stems, and root recruitment is the growth and development of new roots. Ludwigia peploides exhibited higher photosynthetic efficiency than Myriophyllum aquaticum due to a greater chlorophyll concentration and leaf nitrogen concentration, leading to the plant’s healthier growth, but outcompeting Alternanthera philoxeroides was more of a surprise.
The invasive A. philoxeroides should have performed better in using the unexploited resource than the native L. peploides. In addition, based on the indication from the trait economic spectrum, the invasive A. philoxeroides should have been situated on the “fast side,” since higher leaf nitrogen concentration and lower leaf C/N ratio and leaf construction cost usually lead to a fast return in investment and thus a rapid growth rate (Montesinos, 2022). However, according to the observation from stolon elongation and root recruitment, the invasive A. philoxeroides obviously showed a slower growth than L. peploides.Wang et al. 2023.
Why was the invader slow? The answer appears that Alternanthera philoxeroides is more conservative in its growth than Ludwigia peploides. Wang and colleagues say that Alternanthera philoxeroides puts resources into non-structural carbohydrates. This acts as a larder that Alternanthera philoxeroides can use if there’s a catastrophic disturbance to regrow and so fill out vacated space. Ludwigia peploides grows faster by skipping these energy stores.
The findings are based on a mesocosm experiment, a controlled outdoor experimental system simulating natural conditions. Wang and colleagues subjected the three plant species to varying combinations of sediment type and flooding conditions. This controlled environment allowed them to measure and analyze plant performance based on morphological traits, biomass allocation, and physiological traits. This is how they found that Ludwigia peploides showed superior performance in space exploitation compared to its invasive counterparts.
The superior performance of the native Ludwigia peploides against invasive species suggests that it has the potential to be used as a biocontrol species, helping to resist and manage the intrusion of exotic plants. This research indicates that turning to nature’s resources could be a viable and effective strategy for combatting invasive species.
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Wang, T., Zhu, Y., Zhang, Z., Chi, X., Huang, X., Zhang, M., Liu, C., Yu, D., Guo, X., Li, M. and Li, H. (2023) “Pervasive native plant has the potential to resist the invasion of exotic species: a trait-based comparison,” Hydrobiologia. Available at: https://doi.org/10.1007/s10750-023-05212-8.