Silicon in aquatic vegetation

Abstract

Summary1. Silicon (Si) use by plants has not always received the research attention of other elements. Yet today, the importance of Si for plant functioning is slowly becoming better understood. Si is a crucial element for many terrestrial plant species (especially grasses), yet a recent surge of research has shown that some species of aquatic plants contain significant amounts of Si too. 2. We argue that degree of Si accumulation is a functional trait in aquatic vegetation, with plants adapting to environmental conditions. Aquatic vegetation can show apparent plasticity regarding Si uptake, adaptive to water and wind dynamics, light interception, herbivory and nutrient stress. Beyond a plant physiological viewpoint, high Si uptake results in high BSi in plant litter, which can impact on aquatic decomposition processes. Si content in aquatic vegetation shows intriguing relations with other strength components such as cellulose and lignin. Si content has also been linked to fungal and microbial community, litter stoichiometry and invertebrate shredders: all factors that potentially influence organic turnover in aquatic sediments. 3. Uptake of Si by aquatic vegetation is thus not only an important transient sink for Si in the global biogeochemical Si cycle, it can also affect carbon turnover in aquatic ecosystems. Experimental and field studies should be conducted to elucidate controls on aquatic plant Si uptake, especially focusing on interactive effects of multiple biotic and abiotic factors. This review provides an overview of the state-of-the-art knowledge on silicon in aquatic vegetation.

Coping with waves: Plasticity in tidal marsh plants as self‐adapting coastal ecosystem engineers

“…Plant BSi correlated well with flexural stiffness and tensile strength and also (to a lesser extent) with Young's modulus and breaking force of the shoots (Table ), which are typically correlated to the presence of strengthening compounds such as cellulose, lignin and BSi (Mullarney and Henderson ; Rupprecht et al ; Schoelynck and Struyf ). While lignin and cellulose concentrations were similar between plants from different sites (Fig.…”

The functional ecology of plant silicon: geoscience to genes

“…Cornelis & Delvaux (, this issue ) examine the relationship between soil development and plant Si cycling, while Hartley & DeGabriel (, this issue ) review how Si uptake mediates the interactions between plants and their herbivores, focussing on natural ecological systems. Schoelynck & Struyf (, this issue ) interpret the findings from wetland studies, where structural function is best understood and Si accumulation varies with functional type. Finally, Carey & Fulweiler (, this issue ) assess the implications of Si uptake in agriculture and therefore global Si cycling, and Cooke & Leishman (, this issue ) synthesize many studies to show how plants consistently use Si in abiotic stress alleviation despite between‐family Si variation.…”

“…Schoelynck & Struyf (, this issue ) contend that Si accumulation in wetland species has adaptive capacity for environmental conditions. Many macrophytes are high Si accumulators, in part because abundant water allows high transpiration rates.…”

“…Si has long been suggested to have a structural and biomechanical role in plants (Raven ; Epstein ), but we still have relatively little hard evidence quantifying this (but see Dakora & Nelwamondo ; Schaller, Brackhage & Dudel ). Relationships between Si, lignin and cellulose remain unclear (Schoelynck & Struyf , this issue ), but there is increasing interest in the idea that Si could replace carbon‐based structural components in plants (Raven ; Cooke & Leishman ,b). There is some evidence of negative correlations between Si‐based and C‐based defences in plants (Frew et al .…”

Association of leaf silicon content with chronic wind exposure across and within herbaceous plant species

“…However, some empirical and experimental evidence has shown that application of Si could enhance the strength of the rice cell wall, consequently improving the lodging resistance of stems and yield (Dakora & Nelwamondo, ; Isa et al, ; Kashiwagi & Ishimaru, ; Liang et al, ; Ma, ; Ma & Takahashi, ; Ma & Yamaji, ; Savant, Snyder, & Datnoff, ) or mechanical strength of leaves (e.g., erectness; Epstein, ; Ma & Takahashi, ; Ma & Yamaji, ; Yoshida, Navasero, & Ramirez, ) of some crops (e.g., rice) in managed ecosystems. A possible role of leaf Si for protection against wind or wave stress was mentioned for emergent macrophytes (Schoelynck & Struyf, ) and tidal wetland plants (Sloey & Hester, ), but this link with wind has, to our knowledge, not been tested outside agricultural systems and certainly not in natural ecosystems on a large scale. Given that chronic wind stress can affect plant growth, morphology and physiology within the lifetime of a plant (Gardiner, Berry, & Moulia, ; Grace, ; Vogel, ) or on an evolutionary time‐scale (Niklas, ), we predict selection for high tissue [Si] associated with windy environments, that is, well above a minimum concentration needed for physiological function in the absence of wind.…”