Subordinate plant species and Mycorrhizal Fungi: Preferential symbiosis association? P. Mariotte, C. Meugnier, C. Vandenberghe, E. Mitchell, A. Buttler 7ème SER European Conference on Ecological Restoration – 26 August 2010 – Avignon

Landscape of woody-pastures: Semi-natural ecosystem with high biodiversity but a fragile equilibrium Commentaires vérifiés le 20.01.04 Biodiversité – C. Vandenberghe

Introduction Subordinate species: co-occur with dominants 1 Subordinate and dominant species selection for a sample of herbaceous vegetation (Field site of Amburnex, CH) Subordinate species: co-occur with dominants important for biodiversity high frequency low relative cover greater risk of extinction According to: J. P. GRIME, Benefits of plant diversity to ecosystems: immediate, filter and founder effects, Journal of Ecology, 1998.

Introduction Arbuscular Mycorrhizal Fungi (AMF) : 2 Arbuscular Mycorrhizal Fungi (AMF) : 80% of plant species are colonised by AMF Parasitism and/or symbiosis Increase surface exchange of roots with soil and enhance N and P acquisition of plant Increase resistance to stress (drought, pathogens) Influence the structure, productivity and diversity of plant communities Subordinate species seems to be more mycorrhizal dependent and profit from AMF

Introduction Preliminary results of a field experiment: 15 plots 3 Dominants (65,3 to 85,3) and subordinate species (2,8 to 16) in percents per plot x value = 29% p = 0,018 y value= 3.6% Preliminary results of a field experiment: 15 plots Vegetation relevees AMF community profiles by T-RFLP analysis (DNA) AMF communities are differentiated by percentage of subordinate and dominant species

Methods Site: Swiss Jura Species-rich pasture Species selection: 4 Site: Swiss Jura Species-rich pasture Species selection: 7 Subordinates 7 Dominants Previous competition experiment: 3 subordinate species 5 dominant species Prunella vulgaris / Achillea millefolium Agrostis capillaris / Taraxacum officinale Are subordinate species more competitive in presence of AMF?

Methods 5 GREENHOUSE EXPERIMENT collaborations : D. Johnson and M. Van der Heijden Competition + AMF treatments 11 plant interactions x 2 AMF treatments in 6 blocks (132 pots) Sterilized sandy soil + AMF inoculum Sterilized sandy soil 11 plant interactions: 4 monocultures 6 mixculture of 2 species 1 mixculture of 4 species AMF inoculum: Glomus intraradices Obligate symbiont

Methods Pots design 6 Sterilized seeds in bleach 5% 3 months Spe 1 Spe 2 Sterilized seeds in bleach 5% 3 months Germination on sterilized Agar-agar 1,6 % 2 individuals by species Transplantation and assembly

Methods Measures AMF effect 7 - Above-ground biomass - Root biomass (collected by washing)  Dried at 60°C for 72h and weighted AMF effect Biomass i growing with j with AMF Biomass i growing with j without AMF AMF effect = 0 : no effects of fungi AMF effect > 0 : Increasing biomass with fungi AMF effect < 0 : Decreasing biomass with fungi AMF effect ij = ln

Methods Competitive effect 8 Relative Yield per Plant (RYP) Biomass of species i in mixculture Biomass of species i in monoculture Competitive effect = Mean RYPi with each neighbour RYPi = Good competitor = high competitive effect / Mean RYP > 1(i.e dominants) Bad competitor = low competitive effect / Mean RYP < 1 (i.e subordinates)

Results 9 Mixculture of 4 species - 2 Dominant and 2 subordinate species Negative effect on dominant species No effects on subordinate species Dominants: decrease of CE Subordinates : increase of CE Parasitism on dominants

Results 10 AMF effect in subordinates and/or dominants interactions Negative effects on all species in each combination More parasitism than symbiosis Subordinates less affected in subordinate/dominant interactions Beginning of symbiosis with subordinate ?

Results 11 Competitive effect in subordinates and/or dominants interactions Without AMF Dominants Good competitors Subordinates Bad competitors Dominants Decrease of CE Loss of competitiveness Subordinates Increasing of CE Grow as in monoculture With AMF Without root competition (NRC)

Conclusion 12 Arbuscular Mycorrhizal Fungi : Preliminary results Lead a differential response of subordinate and dominant species in mixculture of each species and in pairwise interactions between them Null/low effects on subordinates and very negative on dominants in term of biomass Reduce competitiveness of dominants species removing negative effects on subordinates which increase their competitive effect Promote the competitiveness of subordinate against dominant species Might be a important factor for persistence of subordinates in plant communities maintaining high plant diversity

Perspectives for new research 13 Perspectives for new research Longer experiment to favour symbiosis instead of parasitism More dominant and subordinate species involved in polyculture Different species of arbuscular mycorrhizal fungi Acknowledgements Claire Meugnier (University of Neuchâtel, Switzerland) David Johnson (University of Aberdeen, UK) Marcel Van der Heijden (Agroscope Reckenholz-Tänikon ART, Switzerland

Total biomass in mg Prunella vulgaris Achillea millefolium Taraxacum officinale Agrostis capillaris