Biodiversity and Soil Stability

How does plant diversity affect soil aggregate stability and surface erosion in disturbed alpine ecosystems?

Machine-graded ski pistes are often subject to erosion in steep terrain above treeline, and a species-rich vegetation may play a key role in preventing erosion. A research project of the WSL and the University of Basel investigates therefore the relationship between plant diversity and soil stability parameters (aggregate stability and surface erosion) at disturbed high alpine sites.

Research questions

Sampling of soil cores

Cartoon of determination of soil aggregate stability in the lab, Fig.: Martin Frei

Tests of surface erosion with rainfall experiments on machine-graded ski pistes

Below-ground parts of alpine plant show a remarkable diversity in growth forms, Fig. partly Eggenberger und Möhl (Flora Vegetativa)

1. Is soil aggregate stability positively correlated with plant species richness?
2. Is surface erosion decreased with higher plant functional diversity?
3. What are potential root properties that could explain mechanisms for the positive effect of plant diversity on soil properties?

Methods

• aggregate stability tests of soil from ski slopes and analyses of relationships between aggregate stability, root traits and plant diversity,
• rainfall experiments on a machine-graded ski piste and analyses of the influence of vegetation cover and plant functional diversity on surface erosion and
• analyses of root traits of 13 alpine pioneer species from a ski piste.

Results

1. Soil aggregate stability was positively correlated with plant species richness.
2. Surface erosion was decreased with higher plant functional diversity. Graminoids were the most efficient group.
3. A high diversity of belowground growth forms is the most likely mechanism for the positive effect of plant diversity on soil properties.
4. Diese Untersuchungen unterstreichen, wie wichtig eine hohe Pflanzendiversität für den Erosionsschutz von gestörten alpinen Flächen ist.

Literatur

Roux-Fouillet P, Wipf S, and Rixen C (2011). Long-term impacts of ski piste management on alpine vegetation and soils. Journal of Applied Ecology, 48, 906–915.

Pohl M, Stroude R, Buttler A, and Rixen C  (2011). Functional traits in root systems of alpine plants Annals of Botany, 108, 537–545.

Martin C, Pohl M, Alewell C, Körner C and Rixen C (2010). Interrill erosion at disturbed alpine sites: Effects of plant diversity and vegetation cover. Basic And Applied Ecology 11:619-626.

Pohl M (2010). How does plant diversity affect soil aggregate stability and surface erosion in disturbed alpine ecosystems? PhD thesis, University of Basel, Basel.

Pohl M, Alig D, Körner C, and Rixen C (2009). Higher plant diversity enhances soil stability in disturbed alpine ecosystems. Plant and Soil 324:91-102.

Krautzer B, Wittmann H, Peratoner G, Graiss W, Partl C, Parente G, Venerus S,  Rixen C, and Streit M (2006). Site-specific high zone restoration in the alpine region - the current technological development. Federal Research and Education Centre (HBLFA) Raumberg-Gumpenstein, Irdning.

Further references and projects

http://www.wsl.ch/personal_homepages/rixen/index_EN

Further links

Verein Ingenieurbiologie

Arbeitsgruppe Hochlagenbegrünung

Contact

• Christian Rixen