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Effects of control of the invasive plant, Phragmites australis, on microbes and invertebrates in detritus

Kennedy, Emmalisa

Abstract Details

2008, MS, Kent State University, College of Arts and Sciences / Department of Biological Sciences.
Emergent plant litter is a major source of energy and carbon in wetland food webs. Detritus and the associated microbes are eaten by invertebrates, thereby transferring the carbon and energy to higher trophic levels. Monocultures of an invasive common reed, Phragmites australis, can alter wetland food webs and decrease native plant diversity. Therefore, stands are often controlled by cutting and/or herbiciding. The processes of decomposition were studied using leaves of herbicided and non-herbicided Phragmites and non-herbicided native wool grass, Scirpus cyperinus, using litterbags in wetland mesocosms. Leaf mass loss, percent organic content, C:N ratios, fungal biomass, bacterial numbers and biomass, and invertebrate community composition (total numbers, abundance of functional feeding groups and dominant taxa, richness) were examined on ten dates over the course of 293 days. There were no differences in invertebrate communities or most chemical characteristics between herbicided and non-herbicided Phragmites leaf litter, and both litter types decayed at similar rates (0.0047 k-1 and 0.0051 k-1, respectively). However, herbicided Phragmites litter had higher fungal and bacterial biomass than non-herbicided Phragmites litter. In contrast, Scirpus litter decayed much more slowly (0.0029 k-1) and had higher organic content remaining than either Phragmites litter. At the end of the study, over 44% of the Scirpus litter remained but only 13 - 14% of Phragmites litter remained. Significant differences were found in microbial communities between Scirpus and Phragmites litter, where Phragmites litter generally had higher fungal and bacterial biomass. Invertebrate richness was also higher on Phragmites than Scirpus litter. Furthermore, there were non-significant trends that total invertebrates, detritivores and collector-gatherers were higher on Phragmites than Scirpus litter by the last sampling date (25 May 2007). Principle components analysis also showed high positive correlation between fungal biomass and invertebrate richness. Collectively, these results indicate that the use of herbicide to control Phragmites may not significantly alter decomposition processes or the associated invertebrate community compared to non-herbicided Phragmites stands. Furthermore, although dense stands of the invasive Phragmites can decrease overall wetland plant diversity, numbers and diversity of detritivorous invertebrates on the litter, invertebrates on Phragmites leaf litter may be as high as those occurring on native plants that have slow decay rates.
Laura Leff, PhD (Advisor)
Ferenc de Szalay, PhD (Advisor)
Oscar Rocha, PhD (Committee Member)
107 p.

Recommended Citations

Citations

  • Kennedy, E. (2008). Effects of control of the invasive plant, Phragmites australis, on microbes and invertebrates in detritus [Master's thesis, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1216395163

    APA Style (7th edition)

  • Kennedy, Emmalisa. Effects of control of the invasive plant, Phragmites australis, on microbes and invertebrates in detritus. 2008. Kent State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1216395163.

    MLA Style (8th edition)

  • Kennedy, Emmalisa. "Effects of control of the invasive plant, Phragmites australis, on microbes and invertebrates in detritus." Master's thesis, Kent State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=kent1216395163

    Chicago Manual of Style (17th edition)