Global Change Abstracts The Swiss Contribution - SCNAT

Global Change Abstracts – The Swiss Contribution | Soil and Lithosphere 119
important it can be in identifying the origin of
soil pollution not only to look into areal distribution
patterns of suspected contaminants, but also
to investigate their depth profiles as well as that
of other elements and to account for pedological
factors and their variability.
Geoderma, 2007, V140, N1-2, JUN 15, pp 52-61.
08.1-214
Slip rates variability and sediment mobilization
on a shallow landslide in the northern
Swiss Alps
Schwab M, Läderach C, Rieke Zapp D,
Schlunegger F
Switzerland
Geology , Geomorphology
Geomorphic and morphometric data imply that
process rates of the Schimbrig landslide, located
in the Entle watershed (Central Switzerland), are
still limited by the elevation of the LGM base level.
At present, the Entle watershed is in a stage of adjusting
to the lowered post-glacial base level as indicated
by knick zones in the trunk stream. Some
thousands of years later when these knick zones
will reach the Schimbrig site, we anticipate a substantial
increase in process rates and sediment
flux for the landslide. The pattern of slip rates
was measured on the Schimbrig landslide over
a 14-months period. We propose that a Bingham
plastic model explains much of how measured
slip rates are linked to the observed topography,
climatic variations and thickness variability of
the landslide mass. This model explains why slip
rates have been highest where the thickness of the
material is substantially higher. It also explains
why slip rates are highest in late summer/autumn
and early spring. It appears then that snow melt
in spring and decreasing temperatures in late
summer/autumn potentially result in a high retention
of the pore water and thus in a low viscosity
of the material, which, in turns, promotes
slip rates. Interestingly, an extreme rainstorm like
the one of August 2005 only had a local impact
on the landslide mass by triggering small scale
earth flows and debris flows. This implies that the
earth slide material does not directly respond to
an episodic pattern of rainfall. Such precipitation
events, however, superimpose a smaller-scale imprint
on the landslide relief.
Swiss Journal of Geosciences, 2007, V100, N2, SEP,
pp 281-292.
08.1-215
Dry-end surface soil moisture variability during
NAFE’06
Teuling A J, Uijlenhoet R, Hurkmans R, Merlin O,
Panciera R, Walker J P, Troch P A
Switzerland, Netherlands, Australia, USA
Hydrology , Agriculture, Soil Sciences
Characterization of the space-time variability of
soil moisture is important for land surface and
climate studies. Here we develop an analytical
model to investigate how, at the dry-end of the
soil moisture range, the main characteristics of
the soil moisture field (spatial mean and variability,
steady state distribution) depend on the intermittent
character of low intensity rain storms.
Our model is in good agreement with data from
the recent National Airborne Field Experiment
(NAFE’06) held in the semiarid Australian Murrumbidgee
catchment. We find a positive linear
relationship between mean soil moisture and its
associated variability, and a strong dependency
of the temporal soil moisture distribution to the
amount and structure of precipitation.
Geophysical Research Letters, 2007, V34, N17, SEP
13 ARTN: L17402.
08.1-216
Dynamics of soil organic matter turnover and
soil respired CO 2 in a temperate grassland
labelled with C-13
Theis D E, Jäggi M, Aeschlimann D, Blum H,
Frossard E, Siegwolf R T W
Switzerland
Plant Sciences , Ecology , Agriculture, Soil Sciences
, Geochemistry & Geophysics
The fate of carbon (C) in grassland soils is of particular
interest since the vast majority in grassland
ecosystems is stored below ground and respiratory
C-release from soils is a major component of the
global C balance. The use of C-13-depleted CO 2 in a
10-year free- air carbon dioxide enrichment (FACE)
experiment, gave a unique opportunity to study
the turnover of the C sequestered during this experiment.
Soil organic matter (SOM), soil air and
plant material were analysed for delta C-13 and C
contents in the last year of the FACE experiment
(2002) and in the two following growing seasons.
After 10 years of exposure to CO 2 enrichment at
600 ppmv, no significant differences in SOM C
content could be detected between fumigated
and non-fumigated plots. A C-13 depletion of 3.4
parts per thousand was found in SOM (0-12 cm) of
the fumigated soils in comparison with the control
soils and a rapid decrease of this difference
was observed after the end of fumigation. Within
2 years, 49% of the C in this SOM (0-12 cm) was