Effects of microtopography on absorptive and transport fine root biomass, necromass, production, mortality and decomposition in a coastal freshwater forested wetland, southeastern USA

  • Authors: Li, Xuefeng; Minick, Kevan J.; Luff, Jordan; Noormets, Asko; Miao, Guofang; Mitra, Bhaskar; Domec, Jean-Christophe; Sun, Ge; McNulty, Steven; King, John S.
  • Publication Year: 2019
  • Publication Series: Scientific Journal (JRNL)
  • Source: Ecosystems
  • DOI: 10.1007/s10021-019-00470-x

Abstract

Forested wetlands are an important carbon (C) sink. Fine roots (diameter < 2 mm) dominate belowground C cycling and can be functionally defined into absorptive roots (order 1–2) and transport roots (order ‡ 3). However, effects of microtopography on the function-based fine root dynamics in forested wetlands are poorly understood. We studied fine root biomass allocation and biomass, necromass, mass loss rate, production, mortality and decomposition of absorptive and transport roots in hummocks and hollows in a coastal plain freshwater forested wetland (FFW) in the southeastern USA using dynamic-flow method. Biomass ratios of first- to second-order roots and absorptive to transport roots and the biomass and necromass of absorptive and transport roots were significantly higher in top 0–10 cm organic peat layer than in 10–20 cm muck and mineral layer, and were significantly higher in hummocks than in hollows. The mass loss rate, production, mortality and decomposition were significantly higher in hummocks than in hollows. Absorptive roots did not have a lower mass loss rate than transport roots. Microtopography significantly affected the contributions of absorptive and transport roots to the total production, mortality and decomposition. Production, mortality and decomposition of absorptive roots were higher than those of transport roots in hummocks but lower than those of transport roots in hollows. Total (hummocks plus hollows) fine root production, mortality and decomposition were 455 ± 106 g m-2 y-1, 475 ± 79 g m-2 y-1 and 392 ± 60 g m-2 y-1, respectively. Greater mortality than decomposition resulted in net fine root C input to soil. The observed microtopographic controls on fine root dynamics have great implications for soil C cycling. As sea level rises, the relative area of hollows in coastal plain FFWs will increase, causing a decrease in fine root mass loss rate, biomass, production, mortality and decomposition and it is the balance of these processes that will determine future soil C storage and cycling.

  • Citation: Li, Xuefeng; Minick, Kevan J.; Luff, Jordan; Noormets, Asko; Miao, Guofang; Mitra, Bhaskar; Domec, Jean-Christophe; Sun, Ge; McNulty, Steven; King, John S. 2019. Effects of microtopography on absorptive and transport fine root biomass, necromass, production, mortality and decomposition in a coastal freshwater forested wetland, southeastern USA. ecosystems. 65(4): 545-. https://doi.org/10.1007/s10021-019-00470-x.b
  • Keywords: microtopography, fine root, necromass, biomass, production, mortality, decomposition, forested wetland.
  • Posted Date: May 6, 2020
  • Modified Date: May 14, 2020
  • Print Publications Are No Longer Available

    In an ongoing effort to be fiscally responsible, the Southern Research Station (SRS) will no longer produce and distribute hard copies of our publications. Many SRS publications are available at cost via the Government Printing Office (GPO). Electronic versions of publications may be downloaded, printed, and distributed.

    Publication Notes

    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
    • Our online publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact the SRS webmaster if you notice any errors which make this publication unusable.
    • To view this article, download the latest version of Adobe Acrobat Reader.