Global Change Abstracts The Swiss Contribution - SCNAT

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The daily fluctuations in soil water content suggest
that some root uptake of groundwater was mediated
through the upper soil layers by hydraulic lift.
During the dry season, Q. ilex maintained higher
predawn leaf water potentials, canopy conductances
and transpiration rates than Q. sober: The higher
water status of Q. ilex was likely associated with
their deeper root systems compared with Q. sober.
Whole-tree hydraulic conductance and minimum
midday leaf water potential were lower in Q. ilex,
indicating that Q. ilex was more tolerant to drought
than Q. suber. Overall, Q. ilex seemed to have more
effective drought avoidance and drought tolerance
mechanisms than Q. suber.
Tree Physiology, 2007, V27, N6, JUN, pp 793-803.
08.1-105
Impact of Swiss agricultural policies on nitrate
leaching from arable land
Decrem M, Spiess E, Richner W, Herzog F
Switzerland
Modelling , Agriculture, Soil Sciences , Water Resources
, Toxicology
From 1993 onwards, various policy measures aiming
at reducing nitrogen (N) losses were introduced
in Swiss agriculture. We studied the impact of these
measures on nitrate leaching under arable land in
the Fehraltorf catchment near Zürich. Because of
the well- drained soils, the shallow water table and
the intensive agricultural activity, the groundwater
in this catchment is highly vulnerable to nitrate
pollution. N fluxes and transformations on the
field scale were simulated using the deterministic
model LEACHMN. Following the calibration of the
model with a dataset from a long- term lysimeter
experiment, simulations were run for the period
1998 - 2003. As far as possible, field- specific management
data from farmers’ control sheets were
used as input. Average nitrate leaching in the period
1998 - 2003 was estimated to amount to 39 kg
N ha(-1) year(-1). The conditions before the introduction
of the policy measures were simulated in
three scenarios with a higher use of both mineral
N fertiliser and animal manure and 50% less or no
catch crops. We found that lowering mineral N fertiliser
and manure application by about 25% led to
an average decrease in nitrate leaching of 10 kg N
ha(-1) year(-1). Doubling the catch crop area yielded
a further decrease of 6 kg N ha(-1) year(-1) on average.
Altogether, the implementation of reduced N
fertiliser inputs and increased use of catch crops
proved to be effective and led to a mean reduction
in N leaching of 29% (16 kg ha(-1) year(-1)) for the
arable land in the Fehraltorf catchment.
Agronomy For Sustainable Development, 2007,
V27, N3, JUL-SEP, pp 243-253.
Global Change Abstracts – The Swiss Contribution | Terrestrial Ecosystems
08.1-106
Competition between Lythrum salicaria and a
rare species: combining evidence from experiments
and long-term monitoring
Denoth M, Myers J H
Switzerland, Canada
Plant Sciences , Biodiversity , Ecology
The rare endemic plant Sidalcea hendersonii (Henderson’s
checker- mallow) occurs in tidal marshes
of the Pacific Northwest and may be threatened
by Lythrum salicaria (purple loosestrife), a European
invader plant. We compared the abundances
of Lythrum and Sidalcea in a wetland in British
Columbia (Canada) in 1999 to those measured in
1979 to track changes in both species. Although
the frequency of Sidalcea decreased by more than
50%, and that of Lythrum increased by almost 20%,
there was no significant relationship between the
changes of the two species. We assessed the potential
effects of competition by Lythrum on Sidalcea
in field and patio experiments. In the field, we
measured the response of Sidalcea to the removal
of Lythrum over a two-year period and compared
this to the response of Sidalcea to the removal
of native species and in unmanipulated control
plots. Removal of Lythrum significantly improved
the vegetative performance of Sidalcea compared
to the removal of randomly selected native plants
and the control treatment in the first year. In the
second year, the performance of Sidealcea did not
differ significantly with treatment. Removals did
not influence the reproductive performance of
Sidalcea in either year. A one-year additive experiment,
carried out in pots, compared the competitive
effect of Lythrum on Sidalcea with that of two
native species. Lythrum’s impact on Sidalcea was
not consistently stronger than that of the native
species. Collectively, these results do not indicate
a strong impact of Lythrum on the reproduction
or abundance of Sidalcea.
Plant Ecology, 2007, V191, N2, AUG, pp 153-161.
08.1-107
Effects of landscape structure and land-use
intensity on similarity of plant and animal
communities
Dormann C F, Schweiger O, Augenstein I, Bailey
D, Billeter R, de Blust G, Defilippi R, Frenzel M,
Hendrickx F, Herzog F, Klotz S, Liira J, Maelfait J P,
Schmidt T, Speelmans M, van Wingerden W K R E,
Zobel M
Germany, Switzerland, Belgium, Netherlands,
Estonia
Ecology , Biodiversity , Plant Sciences , Zoology
Aim Species richness in itself is not always sufficient
to evaluate land management strategies