Earthworms Increase Soil Microbial Biomass Carrying Capacity And Nitrogen Retention In Northern Hardwood Forests

Keywords

Carbon; Earthworms; Isotopes; Microbial biomass; Nitrification; Nitrogen

Abstract

Earthworms have been shown to produce contrasting effects on soil carbon (C) and nitrogen (N) pools and dynamics. We measured soil C and N pools and processes and traced the flow of 13C and 15N from sugar maple (Acer saccharum Marsh.) litter into soil microbial biomass and respirable C and mineralizable and inorganic N pools in mature northern hardwood forest plots with variable earthworm communities. Previous studies have shown that plots dominated by either Lumbricus rubellus or Lumbricus terrestris have markedly lower total soil C than uncolonized plots. Here we show that total soil N pools in earthworm colonized plots were reduced much less than C, but significantly so in plots dominated by contain L.rubellus. Pools of microbial biomass C and N were higher in earthworm-colonized (especially those dominated by L.rubellus) plots and more 13C and 15N were recovered in microbial biomass and less was recovered in mineralizable and inorganic N pools in these plots. These plots also had lower rates of potential net N mineralization and nitrification than uncolonized reference plots. These results suggest that earthworm stimulation of microbial biomass and activity underlie depletion of soil C and retention and maintenance of soil N pools, at least in northern hardwood forests. Earthworms increase the carrying capacity of soil for microbial biomass and facilitate the flow of N from litter into stable soil organic matter. However, declines in soil C and C:N ratio may increase the potential for hydrologic and gaseous losses in earthworm-colonized sites under changing environmental conditions.

Publication Date

8-1-2015

Publication Title

Soil Biology and Biochemistry

Volume

87

Number of Pages

51-58

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.soilbio.2015.03.025

Socpus ID

84929458800 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84929458800

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