Title

Compositional aspects of herbaceous litter decomposition in the freshwater marshes of the Florida Everglades

Authors

Oliva Pisani, Department of Chemistry and Biochemistry and Southeast Environmental Research Center, Florida International University; Southeast Watershed Research LaboratoryUSDA-ARSFollow
Min Gao, Department of Chemistry and Biochemistry and Southeast Environmental Research Center, Florida International University
Nagamitsu Maie, Kitasato University
Daniel L. Childers, Arizona State University
Rudolf Jaffe, Southeast Environmental Research Center, Department of Chemistry and Biochemistry, Florida International University,Follow

Abstract

Aims

Litter decomposition in wetlands is an important component of ecosystem function in these detrital systems. In oligotrophic wetlands, such as the Florida Everglades, litter decomposition processes are dependent on nutrient availability and litter quality. The aim of this study was to assess the differences and changes in chemical composition of above- and belowground plant tissues at different stages of decomposition, and to compare them to organic matter accumulating in wetland surface soils.

Methods

To understand the chemical changes occurring during the early stages of litter decomposition in wetlands, short-term subaqueous decomposition patterns of above- and belowground tissues from Cladium jamaicense and Eleocharis cellulosa were investigated at two freshwater marsh sites in the Florida Everglades. The composition of litter at different stages of decomposition was compared to that of the two end-members, namely fresh plant tissues and soil organic matter (SOM), in an effort to assess both the gradual transformation of this organic matter (OM) and the incorporation of above- vs. belowground biomass to wetland soils. The chemical composition of the litter and of surface soils was assessed using solid-state ¹³C nuclear magnetic resonance spectroscopy.

Results

Decomposition indices (alkyl/O-alkyl ratio, Aromaticity index) of Cladium and Eleocharis leaves varied during incubation likely reflecting physical leaching processes followed by a shift to microbial decomposition. Overall, Eleocharis leaves were more labile compared to Cladium leaves. Relative to aboveground litter, the belowground biomass of both species was more resistant to degradation, and roots were more resistant than rhizomes. Compared to the observed early diagenetic transformations of the plant litter, the SOM is at a more advanced stage of degradation, suggesting that the decomposition of litter and belowground biomass prior to its incorporation into wetland soils requires longer degradation times than those applied in this study.

Conclusions

Litter decomposition in Everglades’ freshwater marshes is driven by a combination of tissue quality and site characteristics such as hydroperiod and nutrient availability, ultimately leading to the accumulation of peat.

Comments

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DEB-1237517, #DBI-0620409, and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Pisani, O., Gao, M., Maie, N. et al. Plant Soil (2017). https://doi.org/10.1007/s11104-017-3495-3