Soil microbial response to Rhododendron understory removal in southern Appalachian forests: Effects on extracellular enzymes

Ernest D. Osburn, Katherine J. Elliottt, Jennifer D. Knoepp, Chelcy F. Miniat, J. E. Barrett

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Rhododendron maximum is a native evergreen shrub that has expanded in Appalachian forests following declines of american chestnut (Castanea dentata) and eastern hemlock (Tsuga canadensis). R. maximum is of concern to forest managers because it suppresses hardwood tree establishment by limiting light and soil nutrient availability. We are testing R. maximum removal as a management strategy to promote recovery of Appalachian forests. We hypothesized that R. maximum removal would increase soil nitrogen (N) availability, resulting in increased microbial C-demand (i.e. increased C-acquiring enzyme activity) and a shift towards bacterial-dominated microbial communities. R. maximum removal treatments were applied in a 2 × 2 factorial design, with two R. maximum canopy removal levels (removed vs not) combined with two O-horizon removal levels (burned vs unburned). Following removals, we sampled soils and found that dissolved organic carbon (DOC), N (TDN, NO3, NH4), and microbial biomass all increased with R. maximum canopy + O-horizon removal. Additionally, we observed increases in C-acquisition enzymes involved in degrading cellulose (β-glucosidase) and hemicellulose (β-xylosidase) with canopy + O-horizon removal. We did not see treatment effects on bacterial dominance, though F:B ratios from all treatments increased from spring to summer. Our results show that R. maximum removal stimulates microbial activity by increasing soil C and N availability, which may influence recovery of forests in the Appalachian region.

Original languageEnglish
Pages (from-to)50-59
Number of pages10
JournalSoil Biology and Biochemistry
Volume127
DOIs
StatePublished - Dec 2018

Bibliographical note

Publisher Copyright:
© 2018

Keywords

  • Bacteria
  • Carbon
  • Extracellular enzymes
  • Fungi
  • Nitrogen
  • Rhododendron maximum

ASJC Scopus subject areas

  • Microbiology
  • Soil Science

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