Linking soil biodiversity to ecosystem functioningInfluence of soil

macrofauna onsoil structure & erosion

Pascal JOUQUETIRD / France - pascal.jouquet@ird.fr

Decaëns et al. 2006. EJSB

A large number of unknown speciesA large number of unknown species

A large number of unknown speciesA large number of unknown speciesperforming a large number of functionsperforming a large number of functions

Trophic functions Trophic functions

Trophic functions Trophic functions

Bioturbation functionsBioturbation functions

THE KEY SOIL BIOTURBATORSTHE KEY SOIL BIOTURBATORS

Bioturbation by soil engineers

Formation of biostructures: Biopores & Biogenic aggregates (galeries) (casts, mounds…)

Water infiltration, retention& quality Flood & erosion control

Fertility & productivityGreenhouse gas emission

Modification of soil structureHydrodynamic, SOM decomposition, nutrient cycling

Ecosystem services

Some examples of Biogenic structuresBiogenic structures

Some examples to convince you of the importance of

« SOIL ENGINEERS »

1- Effect on soil properties

C & N content

Hong et al. 2011. SBB

cast

control

Protection of fresh OM

More SOM

Clay content & quality

Jouquet et al. 2002. EJSS

Jouquet et al. 2005. BFS

1- Effect on soil properties

Soil porosity

Bottinelli et al. 2010. Geoderma

1- Effect on soil properties

Jouquet et al. 2008. Geoderma

Soil aggregate scale

Soil matrix scale

vs

Jouquet et al., 2012. Appl. Soil Ecol.

Soil, N and P loss

2- Effect on soil erosion

Jouquet et al., 2010. Catena

Loss of C

2- Effect on soil erosion

Jouquet et al. 2004. Appl. Soil Ecol.

Plant growth & diversity

3- Effect on plants

Choosai et al., 2009. Env. Conserv.

Soil macrofauna diversity

3- Effect on soil macrofauna diversity

Some examples to convince you of the importance of

« SOIL ENGINEERS »

Convinced?

And now?And now?

New research questions in soil ecology?New research questions in soil ecology?

Are soil engineers all the same?

Link between soil fauna strategy and ecosystem functioning?

Earthworms

Are soil engineers all the same?

« Dissipating processes »

RespirationDispersion of ressourcesMineralisationErosion, runoff

solS- S+

FLUXSOIL

« Organizing processes »

SOM protectionAggregation of ressourcesWater diffusionResistance to erosion

STOCK

Can these differences be explained byThe ecology of soil engineers?

Exe

rgie

(« 

E »

)

(1) (2) (3)

S+

SOM mineralisationS-

SOM & nutrient protection

Improving ecosystem eco-efficiencythrough soil macrofauna stimulation?

METHODS:- Direct inoculation and/or indirect stimulation.- Externalization (vermicompost)

METHODS:- Direct inoculation and/or indirect stimulation.- Externalization (vermicompost)

Not always an easy job…

METHODS:- Direct inoculation and/or indirect stimulation.- Externalization (vermicompost)

Control Mulch + Dieldrin Mulch

Productivity+ 25 termite sp.

Mando et al., 1999, Rest. Ecol.

25 y. after

METHODS:- Direct inoculation and/or indirect stimulation.- Externalization (vermicompost)

Lepage, pers. com.

Longer but much more impressive…

METHODS:- Direct inoculation and/or indirect stimulation.- Externalization (vermicompost)

A Boom of knowledge !

An alternative to the composting method: The vermicomposting technology

N=789 articles since 1989

METHODS:- Direct inoculation and/or indirect stimulation.- Externalization (vermicompost)

Externalization and Intensification of ecological processes

A new fate for OM:more available N, stabilization, PGPM producing phytohormones

An expl ofEcological Engineering

Very different substrate…

Ngo et al. 2012. SBB

And therefore, very different SOM dynamic

Ngo et al. 2011. Ecol Engineering

Long term effect of this amendment?

Plant development

Jouquet et al. 2010. Compost Sci. Util.

Influence of vermicompost (and biochar) on:(i) Soil fertility,(ii) Exportation of N and microorganisms,(iii) Water quality

M BD C V

0

3

6

9 1st year 2nd year 3th year T

on.h

a -1

M BD C VM BD C V

AbA BCcAB

CDDEEe

Ff GgG GHh

a

cd

e f

h

Corn yield

More a trend than a generality

Doan Thu, in prep.

0

1

2

3

Cc

A Aa

D

Bb

a

M Soil To BM VC

0

4

8

12

16

A

Bc

C

a

Cc

Bb

(a)

(b)

bact

eria

g-1

(× 1

06 )vi

ruse

s g-1

(× 1

06 )

Flow of bacteria and viruses

Doan Thu, in prep.

Bacterial diversity

T0

V+

V-

C

BM

M-

M+

In soil

Fertilization > biochar

V-

BM

C

V+

M-

Ct

T0

M+

In Water

Biochar > Fertilization

Doan Thu, in prep.

Thank you for your attention

Convinced?Convinced?

Join the Soil Ecology!

I WANT YOU!