PARENT SESSION
Symposium 9: Functional Significance of Mountain Biodiversity.
Organized by: WD Bowman
Tuesday, August 3, 1:30 PM to 5:00 PM, Oregon Ballroom 204.

Plant diversity and alpine slope stability.

Koerner, Christian¹, ¹ Institute of Botany, Basel, Switzerland

ABSTRACT- In steep terrain, slopes need engineering forces to stay in place and facilitate sustained ecosystem functioning. A closed plant cover, deep roots, strong rhizomes, and massive root stocks are the tools provided by nature to ensure the persistence of biota in steep alpine terrain. How much variability among plant taxa is needed to fulfill this function in an ever changing environment? How does human land use interfere with these functions? I will present case studies from the European Alps and the Central Caucasus to illustrate the significance of biodiversity and plant cover type for the integrity of alpine ecosystems. For instance, a dwarf shrub cover of >10 % reduces run-off substantially, and water infiltration rates become almost doubled in shrub-dominated plots. Since dwarf shrub cover above 40 % has been shown to increase erosion risk, the observed changes in run-off might explain the high frequency of land slides on abandoned pastures with shrub encroachment. Increasing cover by vascular plants significantly reduced surface run-off. Hence, both cover and plant functional types (biodiversity) affect the stability of steep alpine slopes. Land use can have positive and negative effects on erosion and hydrology, and there is no systematic difference between grazing and mowing with respect to the resultant species diversity in the lower alpine belt. References: Koerner C (2002) Mountain biodiversity, its causes and function: an overview. In: Koerner C, Spehn EM (eds) Mountain biodiversity, a global assessment. The Parthenon Publishing Group, Boca Raton, p 3-20 Koerner C (2003) Alpine plant life. Springer, Berlin, 2nd ed.

Key words: slope integrity, mountain biodiversity, land use, dwarf shrub cover