1. Silvia Stanchi, Michele D’Amico, Michele Freppaz
THE THIRD WORLD CONFERENCE OF WORLD ASSOCIATION OF SOIL AND WATER CONSERVATION BELGRADE, 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

2. 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

5. Gressoney Saint Jean

6. 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
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

7. 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).

8. 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

9. 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.

10. Relationship between aggregate stability and root length density

11. 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.

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

13. Results

14. 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

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