Effects of plant species on nitrogen mineralization in grassland ecosystems

A.J. van der Krift

Research output: Thesisinternal PhD, WU

Abstract

<p>In many ecosystems, the nutrient supply is an important factor that determines plant species composition. Plant species have developed different characteristics, which make them successful competitors in either nutrient-poor or more fertile environments. These plant characteristics could, in turn, have important consequences for soil fertility. The research described in this thesis set out to investigate different plant characteristics of species from habitats that differ in nitrogen availability, to assess their possible consequences for soil nitrogen mineralization. Compared to species from nutrient-poor habitats, species from fertile habitats were expected to stimulate the N mineralization because they produce larger quantities of rhizodeposits and litter, which decompose better.</p><p>Overall, the results described in this thesis support this hypothesis. Plant species from high fertility habitats increased soil N mineralization more than species from low fertility habitats. Living plants of species from high fertility habitats produced more root biomass and consequently more rhizodeposits. Moreover, species from high fertility habitats had a shorter root lifespan than low fertility species. As a result, they added greater amounts of dead roots to the soil, but the decomposability of these dead roots was not related to the fertility of the habitat that they preferred. The effect of N availability on the plant characteristics studied was striking. When N supply decreased, root biomass declined, especially for the species from high fertility habitats, and as a result the rhizodeposition decreased. Moreover, for all species lower N supplies had a negative effect on rhizodeposit and dead root decomposition. Living plants stimulated dead root decomposition but the degree of stimulation depended on the C:N ratio of the decomposing roots. Overall, the differences in stimulation or inhibition of the N mineralization as a result of different levels of soil fertility seemed to be greater in species from high fertility habitats than in species from low fertility habitats.</p><p><strong>Keywords:</strong> decomposition, nitrogen mineralization, perennial grasses, rhizodeposition, root lifespan, soil fertility.</p>
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
Supervisors/Advisors
  • Berendse, Frank, Promotor
  • Kuikman, P.J., Promotor, External person
Award date1 Dec 2000
Place of PublicationS.l.
Publisher
Print ISBNs9789058083203
Publication statusPublished - 2000

Keywords

  • nitrogen
  • mineralization
  • soil fertility
  • nutrients
  • decomposition
  • nutrient availability
  • grasslands
  • grasses
  • roots
  • root exudates
  • species differences

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