Global Change Abstracts The Swiss Contribution - SCNAT

Global Change Abstracts – The Swiss Contribution | Terrestrial Ecosystems 107
tivity variations, we developed a tree-ring width
chronology (1464-2003). For the period 1804-2003
separate chronologies for the earlywood and latewood
were built, and resin duct density was assessed
on total ring, earlywood and latewood. Age
structure of saplings was also determined. After
1950 a steep decline in tree-ring width was followed
by a recovery since 1981. During the 20th
century radial growth response to climate was not
strong and not stable. In the period 19532000 P.
leucadermis radial growth seemed to take advantage
of high temperatures and low precipitation.
Resin duct density chronologies were not a reliable
dendroecological variable, but they documented
a metabolic trade-off between growth and differentiation
processes. The gap in the age structure
between long- lived trees (over 200 years old) and
saplings around 40 years old, which mainly grow
in protected microsites between rocks, could indicate
a negative influence of grazing and related
human activities. We suggest that the protection
strategies introduced by the National Park could
play a positive role in the recruitment of new saplings
and in the ring growth recovery of old trees
of P. leucodermis.
Biological Conservation, 2007, V137, N4, JUL, pp
507-519.
08.1-182
Regional assessment of climate change impacts
on maize productivity and associated
production risk in Switzerland
Torriani D S, Calanca P, Lips M, Ammann H, Beniston
M, Fuhrer J
Switzerland
Agriculture, Soil Sciences , Modelling , Ecology ,
Plant Sciences
A simple model of yield was used along with climate
scenarios to assess the impact of climate
change on grain maize productivity and associated
economic risk in Switzerland. In a first application,
changes in the precipitation regime
alone were shown to affect the distribution of
yield considerably, with shifts not only in the
mean but also in the standard deviation and the
skewness. Production risk was found to respond
more markedly to changes in the long-term mean
than in the inter-annual variability of seasonal
precipitation amounts. In a further application,
yield projections were generated with respect to a
full climate scenario, with the emission pathway
as specified in the IPCC A2 scenario. Anticipation
of the sowing date was found to reduce the negative
impact of climate change on yield stability,
but was not sufficient to ensure average productivity
levels comparable to those observed at pres-
ent. We argued that this was caused by the reduction
in the duration of the growing season, which
had a stronger impact than suggested by previous
studies. Assuming no change in price relations,
the results also revealed a strong increase in production
risk with climate change, with more than
a doubling in the probability of yield falling short
of a critical threshold as compared to today’s situation.
Regional Environmental Change, 2007, V7, N4,
DEC, pp 209-221.
08.1-183
Potential effects of changes in mean climate
and climate variability on the yield of winter
and spring crops in Switzerland
Torriani D S, Calanca P, Schmid S, Beniston M,
Fuhrer J
Switzerland
Modelling , Meteorology & Atmospheric Sciences ,
Agriculture, Soil Sciences , Ecology , Biodiversity
Climate change is expected to affect both the average
level and the variability of crop yields. In
this modelling study, we quantified mean and
inter-annual variability of grain yield for maize
Zea mays L., winter wheat Triticum spp. L. and
winter canola Brassica napus L. for climatic conditions
corresponding to current and doubled atmospheric
CO 2 concentrations. Climate scenarios
with and without taking into account changes
in the inter-annual variability of climate were
developed from the output of a regional climate
model for the time window 2071 to 2100. Climate
change effects on the mean yield of maize and
canola were consistently negative, but a positive
impact was simulated for mean yield of winter
wheat for elevated CO 2 concentration. The coefficient
of yield variation increased in the scenarios
for maize and canola, but decreased for wheat.
Higher thermal time requirements increased
mean yield and reduced yield variability for all
crops. Shifts in the sowing dates had a beneficial
impact on the yield of maize, but not on the yield
of canola and wheat. It is concluded that in the Alpine
region, the potential effect of climate change
is crop-specific. However, the introduction of new
cultivars may provide means by which to maintain
or even increase current productivity levels
for most of the crops.
Climate Research, 2007, V34, N1, JUN 14, pp
59-69.