Ecological functions of earthworms in soil

W.S. Andriuzzi

Research output: Thesisinternal PhD, WUAcademic

Abstract

Ecological functions of earthworms in soil

Walter S. Andriuzzi

Abstract

Earthworms are known to play an important role in soil structure and fertility, but there are still big knowledge gaps on the functional ecology of distinct earthworm species, on their own and in interaction with other species. This thesis investigated how earthworms affect soil biochemical and biophysical functioning, and other organisms such as plants and smaller soil organisms.

Two field experiments with stable isotope tracers were performed to investigate how anecic earthworms (which feed on organic matter at the soil surface and dig deep burrows) transfer carbon and nitrogen from fresh plant litter into soil, and how this in turn affects soil organic matter composition, protists and nematodes. Another field experiment tested whether the anecic earthworm Lumbricus terrestris can counteract negative effects of intense rainfall on soil and plants (ryegrass). A greenhouse experiment was carried out to study how co-occurring earthworm species – two anecic and one endogeic (smaller, soil-feeding) – affect transfer of nitrogen from dung to soil and plants, nitrogen retention in soil, and plant growth. For the latter experiment, a method to produce herbivore (rabbit) dung triple-labelled with carbon, nitrogen and sulphur stable isotopes was developed.

Overall, the findings highlight important functions of earthworms in carbon and nitrogen cycling, soil biophysical structure maintenance due to burrow formation, and resulting biotic interactions. A novel finding was that the sphere of influence of anecic earthworms in soil (the ‘drilosphere’) is a much larger biochemical and biological hotspot than hitherto assumed. Rapid movement of carbon and nitrogen from surface to soil thanks to anecic earthworm activity resulted in spatial heterogeneity in soil carbon content, organic matter composition, and density of smaller eukaryotes (e.g. bacterial-feeding protists). Evidence was found that distinct earthworm anecic species may have dissimilar effects on soil biochemistry and plant growth, and that both anecic and endogeic earthworms may feed on surface organic matter (dung). This shows that the validity of earthworm ecological groups depends on the function under study, and suggests that, for some research questions, species identity should not be neglected; other approaches to quantify ecological differences between species (e.g. functional traits) are appraised. Finally, L. terrestris was found to ameliorate the disturbance of intense rain on plants, giving evidence to the idea that some components of soil biodiversity may contribute to ecosystem stability in the face of disturbance.

 

 

 

 

 

 

 

 

 

 

 

 

 

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Brussaard, Lijbert, Promotor
  • Bolger, T., Promotor, External person
  • Schmidt, O., Co-promotor, External person
Award date31 Aug 2015
Place of PublicationWageningen
Publisher
Print ISBNs9789462574175
Publication statusPublished - 2015

Fingerprint

ecological function
earthworms
soil
soil organic matter
nitrogen
carbon
Lumbricus terrestris
feces
soil structure
burrows
stable isotopes
soil biochemistry
plant growth
rain
isotope labeling
soil heterogeneity
Lolium
greenhouse experimentation
plant litter
eukaryotic cells

Keywords

  • earthworms
  • oligochaeta
  • soil fauna
  • soil biology
  • soil ecology
  • ecosystems
  • soil structure

Cite this

Andriuzzi, W. S. (2015). Ecological functions of earthworms in soil. Wageningen: Wageningen University.
Andriuzzi, W.S.. / Ecological functions of earthworms in soil. Wageningen : Wageningen University, 2015. 154 p.
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note = "WU-thesis no. 6102",
year = "2015",
language = "English",
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Andriuzzi, WS 2015, 'Ecological functions of earthworms in soil', Doctor of Philosophy, Wageningen University, Wageningen.

Ecological functions of earthworms in soil. / Andriuzzi, W.S.

Wageningen : Wageningen University, 2015. 154 p.

Research output: Thesisinternal PhD, WUAcademic

TY - THES

T1 - Ecological functions of earthworms in soil

AU - Andriuzzi, W.S.

N1 - WU-thesis no. 6102

PY - 2015

Y1 - 2015

N2 - Ecological functions of earthworms in soil Walter S. Andriuzzi Abstract Earthworms are known to play an important role in soil structure and fertility, but there are still big knowledge gaps on the functional ecology of distinct earthworm species, on their own and in interaction with other species. This thesis investigated how earthworms affect soil biochemical and biophysical functioning, and other organisms such as plants and smaller soil organisms. Two field experiments with stable isotope tracers were performed to investigate how anecic earthworms (which feed on organic matter at the soil surface and dig deep burrows) transfer carbon and nitrogen from fresh plant litter into soil, and how this in turn affects soil organic matter composition, protists and nematodes. Another field experiment tested whether the anecic earthworm Lumbricus terrestris can counteract negative effects of intense rainfall on soil and plants (ryegrass). A greenhouse experiment was carried out to study how co-occurring earthworm species – two anecic and one endogeic (smaller, soil-feeding) – affect transfer of nitrogen from dung to soil and plants, nitrogen retention in soil, and plant growth. For the latter experiment, a method to produce herbivore (rabbit) dung triple-labelled with carbon, nitrogen and sulphur stable isotopes was developed. Overall, the findings highlight important functions of earthworms in carbon and nitrogen cycling, soil biophysical structure maintenance due to burrow formation, and resulting biotic interactions. A novel finding was that the sphere of influence of anecic earthworms in soil (the ‘drilosphere’) is a much larger biochemical and biological hotspot than hitherto assumed. Rapid movement of carbon and nitrogen from surface to soil thanks to anecic earthworm activity resulted in spatial heterogeneity in soil carbon content, organic matter composition, and density of smaller eukaryotes (e.g. bacterial-feeding protists). Evidence was found that distinct earthworm anecic species may have dissimilar effects on soil biochemistry and plant growth, and that both anecic and endogeic earthworms may feed on surface organic matter (dung). This shows that the validity of earthworm ecological groups depends on the function under study, and suggests that, for some research questions, species identity should not be neglected; other approaches to quantify ecological differences between species (e.g. functional traits) are appraised. Finally, L. terrestris was found to ameliorate the disturbance of intense rain on plants, giving evidence to the idea that some components of soil biodiversity may contribute to ecosystem stability in the face of disturbance.                          

AB - Ecological functions of earthworms in soil Walter S. Andriuzzi Abstract Earthworms are known to play an important role in soil structure and fertility, but there are still big knowledge gaps on the functional ecology of distinct earthworm species, on their own and in interaction with other species. This thesis investigated how earthworms affect soil biochemical and biophysical functioning, and other organisms such as plants and smaller soil organisms. Two field experiments with stable isotope tracers were performed to investigate how anecic earthworms (which feed on organic matter at the soil surface and dig deep burrows) transfer carbon and nitrogen from fresh plant litter into soil, and how this in turn affects soil organic matter composition, protists and nematodes. Another field experiment tested whether the anecic earthworm Lumbricus terrestris can counteract negative effects of intense rainfall on soil and plants (ryegrass). A greenhouse experiment was carried out to study how co-occurring earthworm species – two anecic and one endogeic (smaller, soil-feeding) – affect transfer of nitrogen from dung to soil and plants, nitrogen retention in soil, and plant growth. For the latter experiment, a method to produce herbivore (rabbit) dung triple-labelled with carbon, nitrogen and sulphur stable isotopes was developed. Overall, the findings highlight important functions of earthworms in carbon and nitrogen cycling, soil biophysical structure maintenance due to burrow formation, and resulting biotic interactions. A novel finding was that the sphere of influence of anecic earthworms in soil (the ‘drilosphere’) is a much larger biochemical and biological hotspot than hitherto assumed. Rapid movement of carbon and nitrogen from surface to soil thanks to anecic earthworm activity resulted in spatial heterogeneity in soil carbon content, organic matter composition, and density of smaller eukaryotes (e.g. bacterial-feeding protists). Evidence was found that distinct earthworm anecic species may have dissimilar effects on soil biochemistry and plant growth, and that both anecic and endogeic earthworms may feed on surface organic matter (dung). This shows that the validity of earthworm ecological groups depends on the function under study, and suggests that, for some research questions, species identity should not be neglected; other approaches to quantify ecological differences between species (e.g. functional traits) are appraised. Finally, L. terrestris was found to ameliorate the disturbance of intense rain on plants, giving evidence to the idea that some components of soil biodiversity may contribute to ecosystem stability in the face of disturbance.                          

KW - aardwormen

KW - oligochaeta

KW - bodemfauna

KW - bodembiologie

KW - bodemecologie

KW - ecosystemen

KW - bodemstructuur

KW - earthworms

KW - oligochaeta

KW - soil fauna

KW - soil biology

KW - soil ecology

KW - ecosystems

KW - soil structure

M3 - internal PhD, WU

SN - 9789462574175

PB - Wageningen University

CY - Wageningen

ER -

Andriuzzi WS. Ecological functions of earthworms in soil. Wageningen: Wageningen University, 2015. 154 p.