Oecologia

, Volume 172, Issue 1, pp 231–243

Herbivore trampling as an alternative pathway for explaining differences in nitrogen mineralization in moist grasslands

  • Maarten Schrama
  • Pieter Heijning
  • Jan P. Bakker
  • Harm J. van Wijnen
  • Matty P. Berg
  • Han Olff
Community ecology - Original research

DOI: 10.1007/s00442-012-2484-8

Cite this article as:
Schrama, M., Heijning, P., Bakker, J.P. et al. Oecologia (2013) 172: 231. doi:10.1007/s00442-012-2484-8

Abstract

Studies addressing the role of large herbivores on nitrogen cycling in grasslands have suggested that the direction of effects depends on soil fertility. Via selection for high quality plant species and input of dung and urine, large herbivores have been shown to speed up nitrogen cycling in fertile grassland soils while slowing down nitrogen cycling in unfertile soils. However, recent studies show that large herbivores can reduce nitrogen mineralization in some temperate fertile soils, but not in others. To explain this, we hypothesize that large herbivores can reduce nitrogen mineralization in loamy or clay soils through soil compaction, but not in sandy soils. Especially under wet conditions, strong compaction in clay soils can lead to periods of soil anoxia, which reduces decomposition of soil organic matter and, hence, N mineralization. In this study, we use a long-term (37-year) field experiment on a salt marsh to investigate the hypothesis that the effect of large herbivores on nitrogen mineralization depends on soil texture. Our results confirm that the presence of large herbivores decreased nitrogen mineralization rate in a clay soil, but not in a sandy soil. By comparing a hand-mown treatment with a herbivore-grazed treatment, we show that these differences can be attributed to herbivore-induced changes in soil physical properties rather than to above-ground biomass removal. On clay soil, we find that large herbivores increase the soil water-filled porosity, induce more negative soil redox potentials, reduce soil macrofauna abundance, and reduce decomposition activity. On sandy soil, we observe no changes in these variables in response to grazing. We conclude that effects of large herbivores on nitrogen mineralization cannot be understood without taking soil texture, soil moisture, and feedbacks through soil macrofauna into account.

Keywords

Large herbivores N cycling Soil compaction Soil fauna Soil texture Soil moisture 

Supplementary material

442_2012_2484_MOESM1_ESM.doc (5.7 mb)
Supplementary material 1 (DOC 5834 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Maarten Schrama
    • 1
    • 2
  • Pieter Heijning
    • 1
  • Jan P. Bakker
    • 1
  • Harm J. van Wijnen
    • 3
  • Matty P. Berg
    • 4
  • Han Olff
    • 1
  1. 1.Community and Conservation EcologyUniversity of GroningenGroningenThe Netherlands
  2. 2.Department of Terrestrial EcologyNetherlands Institute of EcologyWageningenThe Netherlands
  3. 3.National Institute for Public Health and the Environment (RIVM)BilthovenThe Netherlands
  4. 4.Department of Ecological ScienceVU UniversityAmsterdamThe Netherlands

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