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

Hui Gao,Chuan Tong,Zhigao Sun,Shuijing Zhai,Juan Liu

doi:10.7717/peerj.7218

Abstract

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 Cyperus malaccensis-dominated marshes, Phragmites australis-dominated marshes, and their ecotonal marshes were studied in the Shanyutan marsh in the Min River estuary, China. Results showed that C. malaccensis and P. australis biomass in ecotones was lower than those in typical communities by 46.4% and 46.3%, respectively. BSi content in aboveground organs of C. malaccensis and culms and roots of P. australis was lower in ecotones than in typical communities, whereas BSi content in other organs showed the opposite trend. Biomass allocation in C. malaccensis and P. australis roots in ecotones was higher by 56.9% and 19.5%, respectively, and BSi stock in C. malaccensis and P. australis 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. P. australis may expand primarily via occupation of wider aboveground space, thereby increasing the Si accumulation capacity in aboveground organs. Meanwhile, C. malaccensis may increase the Si allocation capacity of its roots to withstand the pressure from P. australis. This study will provide new insights into marsh plant competition from the perspective of Si, which can also benefit plant management in marsh ecosystems.

Highlights

Silica (Si) is considered as a beneficial element for plants (Ma & Yamaji, 2015; Klotzbücher et al, 2018; Coskun et al, 2019)
In the western Shanyutan marsh, there are five typical plant communities distributed in a belt-like pattern from land to sea (Fig. 1): C. malaccensis community, P. australis community, C. malaccensis community, S. alterniflora community, and C. compressus community, with the latter two communities excluded from the present study
Variation of biomass allocation of marsh plants in typical communities and ecotones Biomass allocation was widely different in typical communities compared to ecotones for the same plant species (Fig. 2A; Table 2A)

Summary

Introduction

Silica (Si) is considered as a beneficial element for plants (Ma & Yamaji, 2015; Klotzbücher et al, 2018; Coskun et al, 2019). Si has received increased attention in natural ecosystems owing to its importance in plant growth, nutrient content (Schaller et al, 2012b, 2013; Brackhage et al, 2013; Coskun et al, 2016), stoichiometry (Schaller & Struyf, 2013; Schaller et al, 2016; Schaller, Hines & Brackhage, 2017), providing rigidity to plant structures, and enhancing resistance to abiotic and biotic stresses (Epstein, 1994, 2009; Querné, Ragueneau & Poupart, 2012; Schoelynck et al, 2014). Si could play a significant role in vegetation dynamics, and the processing and functioning of ecosystems (Struyf & Conley, 2009; Schaller et al, 2012b; Schoelynck et al, 2014; Struyf et al, 2015; Carey et al, 2017; Coskun et al, 2019)

Methods

Results

Discussion

Conclusion