Oecologia

, Volume 154, Issue 2, pp 327–338

The effects of tree rhizodeposition on soil exoenzyme activity, dissolved organic carbon, and nutrient availability in a subalpine forest ecosystem

  • Michael N. Weintraub
  • Laura E. Scott-Denton
  • Steven K. Schmidt
  • Russell K. Monson
Ecosystem Ecology

DOI: 10.1007/s00442-007-0804-1

Cite this article as:
Weintraub, M.N., Scott-Denton, L.E., Schmidt, S.K. et al. Oecologia (2007) 154: 327. doi:10.1007/s00442-007-0804-1

Abstract

Previous studies have found that root carbon inputs to the soil can stimulate the mineralization of existing soil carbon (C) pools. It is still uncertain, however, whether this “primed” C is derived from elevated rates of soil organic matter (SOM) decomposition, greater C release from microbial pools, or both. The goal of this research was to determine how the activities of the microbial exoenzymes that control SOM decomposition are affected by root C inputs. This was done by manipulating rhizodeposition with tree girdling in a coniferous subalpine forest in the Rocky Mountains of Colorado, USA, and following changes in the activities of nine exoenzymes involved in decomposition, as well as soil dissolved organic C, dissolved organic and inorganic nitrogen (N), and microbial biomass C and N. We found that rhizodeposition is high in the spring, when the soils are still snow-covered, and that there are large ephemeral populations of microorganisms dependent upon this C. Microbial N acquisition from peptide degradation increased with increases in microbial biomass when rhizodeposition was highest. However, our data indicate that the breakdown of cellulose, lignin, chitin, and organic phosphorus are not affected by springtime increases in soil microbial biomass associated with increases in rhizodeposition. We conclude that the priming of soil C mineralization by rhizodeposition is due to growth of the microbial biomass and an increase in the breakdown of N-rich proteins, but not due to increases in the degradation of plant litter constituents such as cellulose and lignin.

Keywords

Decomposition Pinus contorta Soil carbon cycling Soil nitrogen cycling Ecosystem Carbohydrates Sugars Exudation 

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Michael N. Weintraub
    • 1
  • Laura E. Scott-Denton
    • 2
  • Steven K. Schmidt
    • 2
  • Russell K. Monson
    • 2
    • 3
  1. 1.Department of Environmental SciencesUniversity of ToledoToledoUSA
  2. 2.Department of Ecology and Evolutionary BiologyUniversity of ColoradoBoulderUSA
  3. 3.Cooperative Institute for Research in Environmental SciencesUniversity of ColoradoBoulderUSA

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