Linking soil biodiversity to ecosystem functioning Influence of

Linking soil biodiversity to ecosystem functioning Influence of soil macrofauna on soil structure & erosion Pascal JOUQUET IRD / France - pascal. jouquet@ird. fr

A large number of unknown species Decaëns et al. 2006. EJSB

A large number of unknown species performing a large number of functions Trophic functions Bioturbation functions

THE KEY SOIL BIOTURBATORS

Bioturbation by soil engineers Formation of biostructures: Biopores & Biogenic aggregates (galeries) (casts, mounds…) Modification of soil structure Hydrodynamic, SOM decomposition, nutrient cycling Ecosystem services Water infiltration, retention & quality Flood & erosion control Fertility & productivity Greenhouse gas emission

Some examples of Biogenic structures

Some examples to convince you of the importance o « SOIL ENGINEERS »

1 - Effect on soil properties More SOM cast control C & N content Protection of fresh OM Hong et al. 2011. SBB

1 - Effect on soil properties Jouquet et al. 2002. EJSS Clay content & quality Jouquet et al. 2005. BFS

1 - Effect on soil properties vs Soil porosity Soil aggregate scale Soil matrix scale Jouquet et al. 2008. Geoderma Bottinelli et al. 2010. Geoderma

2 - Effect on soil erosion Soil, N and P loss Jouquet et al. , 2012. Appl. Soil Ecol.

2 - Effect on soil erosion Loss of C Jouquet et al. , 2010. Catena

3 - Effect on plants Plant growth & diversity Jouquet et al. 2004. Appl. Soil Ecol.

3 - Effect on soil macrofauna diversity Soil macrofauna diversity Choosai et al. , 2009. Env. Conserv.

Some examples to convince you of the importance o « SOIL ENGINEERS » Convinced?

And now? New research questions in soil ecology?

Are soil engineers all the same? Earthworms Link between soil fauna strategy and ecosystem functioning

Are soil engineers all the same? SOIL STOCK FLUX « Organizing processes » S- Exergie ( « E » ) SOM protection Aggregation of ressources Water diffusion Resistance to erosion « Dissipating processes » sol (1) SSOM & nutrient protection (2) S+ Respiration Dispersion of ressources Mineralisation Erosion, runoff (3) S+ SOM mineralisation Can these differences be explained by The ecology of soil engineers?

Improving ecosystem eco-efficiency through 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.

METHODS: - Direct inoculation and/or indirect stimulation. - Externalization (vermicompost) 25 y. after Longer but much more impressive… Lepage, pers. com.

METHODS: - Direct inoculation and/or indirect stimulation. - Externalization (vermicompost) An alternative to the composting method: The vermicomposting technology A Boom of knowledge ! N=789 articles since 1989

METHODS: - Direct inoculation and/or indirect stimulation. - Externalization (vermicompost) An expl of Ecological Engineering Externalization and Intensification of ecological processes A new fate for OM: more available N, stabilization, PGPM producing phytohormones

Very different substrate… Ngo et al. 2011. Ecol Engineering And therefore, very different SOM dynamic Ngo et al. 2012. SBB

Plant development Jouquet et al. 2010. Compost Sci. Util. Long term effect of this amendment?

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

Corn yield 9 2 nd year 1 st year Ton. ha -1 A AB Ab 6 Ee 3 th year a d DE CD e G G BD C Hh h Ff Gg BCc c f 3 0 M BD C V More a trend than a generality Doan Thu, in prep.

Flow of bacteria and viruses g-1 (× 106) 16 (a) A 12 8 4 a c C Bb B Cc 0 bacteria g-1 (× 106) 3 (b) A 2 b 1 Aa a B Cc D 0 Soil To M BM C V Doan Thu, in prep.

Bacterial diversity In Water In soil V- T 0 BM V+ C V- V+ C M+ BM M- M- Ct M+ T 0 Fertilization > biochar Biochar > Fertilization Doan Thu, in prep.

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