Differences in biomass and silica content in typical plant communities with ecotones in the Min River estuary of southeast China.

Silica (Si) is a basic nutrient requirement for many aquatic organisms and its biogeochemical cycle plays an important role in estuarine coastal ecosystems. However, little is known about the role Si plays during plant-plant interactive processes in the marsh ecosystems. Here, variations in biomass, biogenic silica (BSi) content, and available Si content of -dominated marshes, -dominated marshes, and their ecotonal marshes were studied in the Shanyutan marsh in the Min River estuary, China. Results showed that and biomass in ecotones was lower than those in typical communities by 46.4% and 46.3%, respectively. BSi content in aboveground organs of and culms and roots of was lower in ecotones than in typical communities, whereas BSi content in other organs showed the opposite trend. Biomass allocation in and roots in ecotones was higher by 56.9% and 19.5%, respectively, and BSi stock in and roots was higher than that in typical communities by 120.9% and 18.9%, respectively. Available Si content in ecotonal marsh soils was 12.6% greater than that in typical communities. Thus, the two plant species may use different strategies for Si accumulation and allocation in ecotones to adapt to the competitive environment. may expand primarily via occupation of wider aboveground space, thereby increasing the Si accumulation capacity in aboveground organs. Meanwhile, may increase the Si allocation capacity of its roots to withstand the pressure from . This study will provide new insights into marsh plant competition from the perspective of Si, which can also benefit plant management in marsh ecosystems.