Silvia Stanchi, Michele D’Amico, Michele Freppaz THE THIRD WORLD CONFERENCE OF WORLD ASSOCIATION OF SOIL AND WATER CONSERVATION BELGRADE, 22-26 AUGUST 2016 Quantifying the contribution of the root system of alpine vegetation in the soil aggregate stability of moraine Climate change Glacial retreat Contemporary soil Soil reinforcement (mass waisting and erosional processes Pioneer Alpine species, root system A State of the art technique Csilla Hudek, Silvia Stanchi, Michele D’Amico, Michele Freppaz University of Torino, Department of Agriculture Forest and Food Sciences, Italy

Introduction The aim of the study is to quantify the effect of the root system of alpine vegetation on the soil aggregate stability of the forefield of the Lys glacier, (NW-Italian Alps). To study how the root system of ten most dominant pioneer alpine plant species from different succession can contribute to soil development and soil stabilization. Epilobium fleischeri

Gressoney Saint Jean

Mean winter temperature °C Materials and Methods Study site Altitude (m a.s.l.) Soil type Rainfall mm/year Mean winter temperature °C Sample collection Collected samples Method Till deposited 1950-2004 2400  Loamy sand 1200  -4 July-August 2015 60  Modified wet sieving WinRHIZO T. distichopyllum E. fleischeri T. pallescens S. exscapa L. spicata F. halleri Plant species Succession Family Life form Trisetum distichophyllum Early Poaceae Graminoid Epilobium fleischeri Omagraceae Forb Trifolium pallescens Mid Fabaceae Silene exscapa Caryophyllaceae Luzula spicata Juncaceae Festuca halleri Late Minuartia recurva Poa laxa Ubiquitous Leucanthemopsis alpina Asteraceae Salix helvetica Salicaceae Shrub M. recurva P. laxa L. alpina S. helvetica

II. Aggregate stability Sampling Excavated with trowel Placed into plastic container Stored in the lab at 3.5 °C I. Soil analysis soil water content (%) soil pH available phosphorus (mg/g) total nitrogen (g/kg) total organic carbon (g/kg) II. Aggregate stability agg = (m20-mstone)/(mtotal-mstone) [g g-1] Plants at similar stages of growth without neighbouring plants were sampled (6 replicates each species).

III. Root morphology WinRHIZO Statistics average root diameter RLD=average root diameter volume of the soil columne Statistics One-way ANOVA Welch test Tukey post hoc test Robust simple linear regression model WinRHIZO average root diameter total root length 2D root achitecture surface area of roots volume of roots % of diameter classes

Average root diameter (mm) Mean root length density (cm cm-3) Results Measured mean soil and root properties Species n Soil water content % pH P (mg g-1) N (g kg-1) C Average root diameter (mm) Mean soil aggregate stability (g g-1) Mean root length density (cm cm-3) E. fleischeri 3 2.1 6.7 1.3 0.002 0.018 0.17 0.40 9.3 T. distichophyllum 5 6.9 6.1 4.7 0.004 0.053 0.21 0.83* 85* T. pallescens 6 5.6 6.4 2.8 0.009 0.112 0.30 0.80* 33 L. spicata 8.5 0.028 0.16 0.84* 81* S. exscapa 6.5 3.0 0.017 0.192 0.24 0.71 49 M. recurva 4 4.6 4.3 0.006 0.085 0.29 0.68 29 F. halleri 4.4 2.6 0.007 0.072 0.26 0.88* 59* P. laxa 2 5.7 4.1 0.068 0.31 0.93* 47 S. helvetica 9.2 0.043 0.28 0.89* 67* L. alpina 5.8 0.016 0.217 53 *The mean difference is significant at the 0.05 level.

Relationship between aggregate stability and root length density

Conclusion Any degree of aggregate stability in the soil can be mainly attributed to the presence of roots and their mechanical binding of soil particles. It also has to be recognized that due to the quick turnover of very fine roots that supply organic residue and supporting microbial communities as well as discharging polyvalent cations, the stability of soil aggregates increases.

Acknowledgement T2M, Marie Curie Cofunded Fellowship University of Nottingham Craig Sturrok, Larry York University of Torino Michele Lonati Leucanthemopsis alpina

Results

Conclusion Significantly higher value for all studied species (E. fleischeri → forbs→ graminoid and shrub) Driving factors root morphology (dense fibrous root system with more biomass) Root length density (RLD) Root diameter (very fine, fine roots contribute to higher SAS) Symbiotic effect on plant-fungus systems Plant age Neighbouring plant root competition Non related factors measured soil chemical composition (young soil organic matter evolution is limited) successional stages

Future Rhizosphere processes Mycorrhizal fungi interactions Root development ↔ soil development Trisetum distichophyllum Minuartia recurva