Responses of decomposition rate and nutrient release of floating-leaved and submerged aquatic macrophytes to vertical locations in an urban lake (Nanhu Lake, China)

ABSTRACT

A leaf-bag field experiment was conducted to investigate the decomposition and release of nutrients from leaves of two aquatic macrophytes (floating-leaved Trapa bispinosa and submerged Vallisneria natans) deposited in the four vertical locations (i.e. air-water interface, AW; sediment-water interface, SW; buried at a depth of 10 cm, B10; buried at a depth of 20 cm, B20) of littoral zone in Nanhu Lake, China, for 60 days from July to August 2015. Leaf initial quality significantly influenced mass loss and nutrient release except TN (total nitrogen) remaining. Compared to V. natans, T. bispinosa leaves decomposed faster under the same treatments. The decomposition was greatly affected by both leaf chemical quality and the location of deposition. With the increasing depth of vertical locations, leaf biomass loss and nutrient release of both T. bispinosa and V. natans decreased. In addition, initial N:P ratio and cellulose were the major determinants for decomposition in AW and SW treatments while total phenol in B10 and B20. Our results suggest that the combined effect of leaf chemical quality and burial could mediate macrophyte mass loss and release of nutrients and carbon, which in turn can influence organic matter accumulation and nutrient cycling in shallow freshwater lakes.

KEYWORDS:

• Macrophyte decomposition
• mass remaining
• nutrient release
• littoral zone
• eutrophic lake

Acknowledgments

We wish to thank anonymous reviewers for their helpful comments on the manuscript, and Dandan Cao, Jinjin Xu and Lingling Song for their help in the field.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Shaojun Chen is a PhD candidate in the School of Life Sciences at the Central China Normal University, China. He majors in wetland ecology, particularly with a focus on aquatic macrophyte decomposition.

Dr. Dong Wang is a professor in the School of Life Sciences at the Central China Normal University, China. His interests are wetland ecology (decomposition), plant-animal interaction (seed dispersal by ants), plant taxonomy and biogeography. Further details about his research profiles can be found at http://sky.ccnu.edu.cn/info/1053/2266.htm.

ORCID

Dong Wang http://orcid.org/0000-0003-1874-7690

Additional information

Funding

The work was supported by the National Natural Science Foundation of China [grant number 31270378], Science and Technology Basic Work [grant number 2013FY112100, 2013FY112300] and the special foundation for the specimen platform of China, teaching specimens sub-platform, Web, http://mnh.scu.edu.cn/ (No. 2005DKA21403-JK).