Litter Controls Earthworm-Mediated Carbon and Nitrogen Transformations in Soil from Temperate Riparian Buffers

Maria Kernecker,Robert L. Bradley,Joann K. Whalen

doi:10.1155/2014/329031

Maria Kernecker, Robert L. Bradley + Show 1 more

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https://doi.org/10.1155/2014/329031

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Abstract

Nutrient cycling in riparian buffers is partly influenced by decomposition of crop, grass, and native tree species litter. Nonnative earthworms in riparian soils in southern Quebec are expected to speed the processes of litter decomposition and nitrogen (N) mineralization, increasing carbon (C) and N losses in gaseous forms or via leachate. A 5-month microcosm experiment evaluated the effect ofAporrectodea turgidaon the decomposition of 3 litter types (deciduous leaves, reed canarygrass, and soybean stem residue). Earthworms increased CO2and N2O losses from microcosms with soybean residue, by 112% and 670%, respectively, but reduced CO2and N2O fluxes from microcosms with reed canarygrass by 120% and 220%, respectively. Litter type controlled the CO2flux (soybean ≥ deciduous-mix litter = reed canarygrass > no litter) and the N2O flux (soybean ≥ no litter ≥ reed canarygrass > deciduous-mix litter). However, in the presence of earthworms, there was a slight increase in C and N gaseous losses of C and N relative to their losses via leachate, across litter treatments. We conclude that litter type determines the earthworm-mediated decomposition effect, highlighting the importance of vegetation management in controlling C and N losses from riparian buffers to the environment.

Highlights

Plant litter quality is known to affect several soil properties and ecosystem functions such as nutrient cycling [1], net primary productivity [2], and ecosystem carbon storage [3]
There was no difference in the LFC content in microcosms with and without earthworms, leading us to assume that earthworms initially accelerate decomposition of soybean residue but that, otherwise, they may not increase the total amount of organic matter that is decomposed and mineralized in the long term (Figure 1)
Higher light fraction (LF)-C in microcosms amended with reed canarygrass coincided with lower mean CO2 emissions, compared to microcosms amended with soybean, which had lower LF-C remaining, most likely due to greater overall decomposition

Summary

Introduction

Plant litter quality is known to affect several soil properties and ecosystem functions such as nutrient cycling [1], net primary productivity [2], and ecosystem carbon storage [3]. The effect of litter quality on soil greenhouse gas (GHG) emissions is a growing concern that requires more empirical data-driven research. It has been long known that litter quality (i.e., lignin concentration) is related to short-term soil CO2 emissions, but the rate of these emissions may vary according to both biotic [4] and abiotic [5] factors. The long-term effects of litter quality on CO2 release are less obvious [6]. It could be assumed that plants producing litter that is palatable for soil fauna might favor the production of certain While some studies have looked at peat quality on the release of gases other than CO2 [7], surprisingly few studies have looked at the effects of litter quality from trees and agronomic crops on gases such as N2O or CH4.

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