The main objective of this paper is to reduce the dimensionality of unknown coefficient vectors of finite-element (FE) solutions in two-grid (CN) FE (TGCNFE) format for the nonlinear unsaturated soil water flow problem by using a proper orthogonal decomposition (POD) and to design a new reduced-dimension iteration TGCNFE (RDITGCNFE). For this objective, a new time semi-discrete CN (TSDCN) scheme for the nonlinear unsaturated soil water flow problem is first designed and the existence, stability, and error estimates of TSDCN solutions are demonstrated. Subsequently, a new TGCNFE format for the nonlinear unsaturated soil water flow problem is designed and the existence, unconditional stability, and error estimates of TGCNFE solutions are demonstrated. Next, a new RDITGCNFE format with the same FE basis functions as the TGCNFE format is built by the POD method and the existence, unconditional stability, and error estimates of RDITGCNFE solutions are discussed. Ultimately, the rightness of theory results and the superiority of the RDITGCNFE format are verified by two sets of numerical tests. It is worth noting that the RDITGCNFE format differs completely from all previous reduced-dimension methods, including the authors’ previous works. Therefore, the study of this paper can not only provide a new theoretical method for the dimensionality reduction of numerical models for nonlinear problems but also provide an algorithm implementation technology for the numerical simulation of practical engineering problems.

Although numerous studies have explored the effects of various sounds on plants, a comparative understanding of how long-term exposure to low-intensity sound and rhythmic versus non-rhythmic sound impact on plants is still lacking. In this study, we conducted a field experiment to determine the growth, physiological responses, and allelopathic intensity of an invasive plant Alternanthera philoxeroides under prolonged exposure to different sound rhythms and intensities. The results showed that even at low intensity, long-term sound exposure inhibited the growth of A. philoxeroides while activating its defense mechanisms; these responses intensified with increasing sound intensity. However, the plant could not well distinguish between rhythmic and non-rhythmic sound treatments, although its allelopathic intensity also increased with sound intensity. This study extends the knowledge of plant response to acoustic stimuli, highlights the limited ability of plants to discriminate sound rhythms, and underestimates the negative impacts of prolonged low-intensity sound on plant performance. Therefore, the application of acoustic treatment techniques in future horticulture and agriculture requires a careful trade-off between their potential benefits and adverse effects on plants.

Water-level fluctuation (WLF) is a key factor disturbing aquatic ecosystems, particularly aquatic plants (macrophytes in this review). These organisms are exceptionally sensitive to WLF as it profoundly governs their spatial distribution, productivity, species richness, community composition and successional trajectories. In this review, we synthesized recent advances regarding the impacts of WLF on the growth environment, survival strategies, and the integrated morphological, physiological, and reproductive responses of aquatic macrophytes. While existing research has predominantly focused on flooding-related WLF responses and freshwater macrophytes, the ecological consequences of drawdown and the responses of marine macrophytes remain comparatively underexplored. Despite the adverse alterations in sediment dynamics, light availability, hydrostatic pressure, pollutant concentrations, wind and wave exposure, dissolved oxygen levels and nutrient concentration conditions under WLF, aquatic macrophytes can demonstrate remarkable adaptive plasticity. This resilience was mediated through rapid adjustments in survival strategies, coupled with morphological traits, physiological processes and reproductive modifications. While their adaptive capacities were limited, and varied depending on life-forms, species or the WLF amplitudes, fluctuations in water level often precipitated rapid shifts in dominant species or even community succession over short timeframes. Consequently, while moderate WLF might confer ecological benefits, prolonged or extreme WLF posed substantial threats to aquatic vegetation. Synthesizing these findings, we developed a conceptual model diagram integrating the multifaceted responses of aquatic macrophytes to flooding-induced WLF. Future research should prioritize investigating the ecological consequences of drawdown-induced WLF and the responses of marine macrophytes—areas that remain comparatively underexplored. Furthermore, implementing refined water-level-management regimes could help optimize the good functions and services delivered by aquatic ecosystems.