Linking soil biodiversity to ecosystem functioning Influence of soil macrofauna on soil structure & erosion Pascal JOUQUET IRD / France -

Decaëns et al 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…) Water infiltration, retention & quality Flood & erosion control Fertility & productivity Greenhouse gas emission Modification of soil structure Hydrodynamic, SOM decomposition, nutrient cycling Ecosystem services

Some examples of Biogenic structures

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

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

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

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

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

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

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

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

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.

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 of Ecological Engineering

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

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

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

M BDCV st year 2 nd year3th year Ton.ha -1 MBDCVM CV Ab A BCc AB CDDE Ee FfGg G G Hh a c d e f h Corn yield More a trend than a generality Doan Thu, in prep.

Cc A Aa D B b a M Soil To BM V C A B c C a Cc Bb (a)(a) (b)(b) bacteria g -1 (× 10 6 ) viruses g -1 (× 10 6 ) Flow of bacteria and viruses Doan Thu, in prep.

Bacterial diversity T0T0 V+ V- C BM M- M+ In soil Fertilization > biochar V- BM C V+ M- Ct T0T0 M+ In Water Biochar > Fertilization Doan Thu, in prep.

Thank you for your attention Convinced? Join the Soil Ecology! I WANT YOU!