Global Change Abstracts The Swiss Contribution - SCNAT

Global Change Abstracts – The Swiss Contribution | Terrestrial Ecosystems 111
a few decades). To do so, we examined soil characteristics
including the dithionite-, oxalate- and
pyrophosphate-extractable forms of Fe, Al and
Si as well as the phyllosilicate mineralogy of the
clay fraction with a pair- wise comparison procedure.
On L-type patches, short-term changes
resulted in higher contents of secondary, poorly
crystalline Fe. The accumulation of pedogenetic
Fe probably results from a lower availability of
organic complexing moieties under L-type vegetation
and thus leading to a reduced removal. As
soil acidity did not change with the vegetation
types, a strong effect of organic compounds on Fe
and At chemistry must be assumed. A correlation
analysis confirmed that metal binding to organic
matter was different between L-type stands (correlation
of Fe and Al with organic matter was less
significant) and C-type stands. The differences in
clay phyllosilicate assemblage between the different
vegetation sites were rather small. There
was, however, a trend towards higher contents of
hydroxy-interlayered vermiculite (HIV) under Ltype
vegetation when compared to C-type sites. It
seems that Al-polymers fixation in interlayers of
2:1 clay minerals was increased or their removal
hindered at sites having L-type vegetation. Changes
in the long-term (response to C-type vegetation)
were only measurable for the pyrophosphateextractable
Si content (formation of phytolithe?).
The colonisation of laurophyllous species led in
the short-term to significant alterations of the soil
system that were even more pronounced than the
long-term effect of chestnut on soil quality.
Geoderma, 2007, V141, N1-2, SEP 15, pp
119-129.
08.1-193
Importance of dispersal for the expansion of a
Eurasian lynx Lynx lynx population in a fragmented
landscape
Zimmermann F, Breitenmoser Wursten C, Breitenmoser
U
Switzerland
Zoology , Ecology , Biodiversity
Dispersal allows recolonization of previous areas
of habitat following severe depression of a population
but the significance of this is not clear in
felids. There is little evidence to support the general
belief that subadult felids will colonize new
areas, although this is a crucial assumption in reintroduction
or recovery projects. Eurasian lynx
Lynx lynx were reintroduced into the Swiss Alps
and have subsequently spread over part of their
potential range but the expansion halted in the
mid 1980s. We postulated that high lynx densities
would lead to an expansion of the population,
and to assess the potential of this population to
expand we compared the dispersal characteristics
of 22 subadults from the northwest Swiss Alps,
where an increase in lynx abundance occurred
from 1995 onwards, to 17 individuals from the
Jura Mountains, an area with a lower lynx density.
Dispersal data came mainly from radio-telemetry.
Dispersal rates and distances for subadults that
completed dispersal were lower in the north-west
Swiss Alps than in the Jura Mountains. In general,
subadults exhibited little ability to cross major
barriers such as highways. The hypothesis that
high density alone will foster the expansion of
the population was therefore not confirmed. This
has consequences for the reintroduction and recovery
of carnivores in fragmented landscapes. To
establish only one strong source population may
not be an optimal strategy, and population nuclei
should therefore be founded in several neighbouring
patches.
Oryx, 2007, V41, N3, JUL, pp 358-368.
08.1-194
Remote sensing-based predictors improve
distribution models of rare, early successional
and broadleaf tree species in Utah
Zimmermann N E, Edwards T C, Moisen G G,
Frescino T S, Blackard J A
Switzerland, USA
Ecology , Remote Sensing , Modelling , Plant Sciences
, Forestry
1. Compared to bioclimatic variables, remote
sensing predictors are rarely used for predictive
species modelling. When used, the predictors represent
typically habitat classifications or filters
rather than gradual spectral, surface or biophysical
properties. Consequently, the full potential
of remotely sensed predictors for modelling the
spatial distribution of species remains unexplored.
Here we analysed the partial contributions
of remotely sensed and climatic predictor
sets to explain and predict the distribution of 19
tree species in Utah. We also tested how these partial
contributions were related to characteristics
such as successional types or species traits. 2. We
developed two spatial predictor sets of remotely
sensed and topo-climatic variables to explain the
distribution of tree species. We used variation partitioning
techniques applied to generalized linear
models to explore the combined and partial
predictive powers of the two predictor sets. Nonparametric
tests were used to explore the relationships
between the partial model contributions of
both predictor sets and species characteristics. 3.
More than 60% of the variation explained by the
models represented contributions by one of the