Global Change Abstracts The Swiss Contribution - SCNAT

Global Change Abstracts – The Swiss Contribution | Terrestrial Ecosystems 77
for nature conservation. The exchange of species
between local communities may be affected by
landscape structure and land-use intensity. Thus,
species turnover, and its inverse, community
similarity, may be useful measures of landscape
integrity from a diversity perspective. Location A
European transect from France to Estonia. Methods
We measured the similarity of plant, bird,
wild bee, true bug, carabid beetle, hoverfly and
spider communities sampled along gradients in
landscape composition (e.g. total availability of
semi- natural habitat), landscape configuration
(e.g. fragmentation) and land-use intensity (e.g.
pesticide loads). Results Total availability of seminatural
habitats had little effect on community
similarity, except for bird communities, which
were more homogeneous in more natural landscapes.
Bee communities, in contrast, were less
similar in landscapes with higher percentages
of semi- natural habitats. Increased landscape
fragmentation decreased similarity of true bug
communities, while plant communities showed a
nonlinear, U-shaped response. More intense land
use, specifically increased pesticide burden, led
to a homogenization of bee, bug and spider communities
within sites. In these cases, habitat fragmentation
interacted with pesticide load. Hoverfly
and carabid beetle community similarity was
differentially affected by higher pesticide levels:
for carabid beetles similarity decreased, while for
hoverflies we observed a U-shaped relationship.
Main conclusions Our study demonstrates the effects
of landscape composition, configuration and
land-use intensity on the similarity of communities.
It indicates reduced exchange of species between
communities in landscapes dominated by
agricultural activities. Taxonomic groups differed
in their responses to environmental drivers and
using but one group as an indicator for ‘biodiversity’
as such would thus not be advisable.
Global Ecology and Biogeography, 2007, V16, N6,
NOV, pp 774-787.
08.1-108
Weak and variable relationships between
environmental severity and small-scale cooccurrence
in alpine plant communities
Dullinger S, Kleinbauer I, Pauli H, Gottfried M,
Brooker R, Nagy L, Theurillat J P, Holten J I, Abdaladze
O, Benito J L, Borel J L, Coldea G, Ghosn D,
Kanka R, Merzouki A, Klettner C, Moiseev P, Molau
U, Reiter K, Rossi G, Stanisci A, Tomaselli M, Unterlugauer
P, Vittoz P, Grabherr G
Austria, Scotland, Switzerland, Norway, Rep Of
Georgia, France, Romania, Greece, Slovakia, Spain,
Russia, Sweden, Italy
Plant Sciences , Modelling , Ecology
1. The stress gradient hypothesis suggests a shift
from predominant competition to facilitation
along gradients of increasing environmental
severity. This shift is proposed to cause parallel
changes from prevailing spatial segregation to aggregation
among the species within a community.
2. We used 904 1-m(2) plots, each subdivided into
100 10 x 10 cm, or 25 20 x 20 cm cells, respectively,
from 67 European mountain summits grouped
into 18 regional altitudinal transects, to test this
hypothesized correlation between fine-scale spatial
patterns and environmental severity. 3. The
data were analysed by first calculating standardized
differences between observed and simulated
random co-occurrence patterns for each plot.
These standardized effect sizes were correlated to
indicators of environmental severity by means of
linear mixed models. In a factorial design, separate
analyses were made for four different indicators
of environmental severity (the mean temperature
of the coldest month, the temperature sum
of the growing season, the altitude above tree
line, and the percentage cover of vascular plants
in the whole plot), four different species groups
(all species, graminoids, herbs, and all growth
forms considered as pseudospecies) and at the 10
x 10 cm and 20 x 20 cm grain sizes. 4. The hypothesized
trends were generally weak and could only
be detected by using the mean temperature of the
coldest month or the percentage cover of vascular
plants as the indicator of environmental severity.
The spatial arrangement of the full species
set proved more responsive to changes in severity
than that of herbs or graminoids. The expected
trends were more pronounced at a grain size of 10
x 10 cm than at 20 x 20 cm. 5. Synthesis. In European
alpine plant communities the relationships
between small-scale co-occurrence patterns of vascular
plants and environmental severity are weak
and variable. This variation indicates that shifts
in net interactions with environmental severity
may differ among indicators of severity, growth
forms and scales. Recognition of such variation
may help to resolve some of the current debate
surrounding the stress gradient hypothesis.
Journal of Ecology, 2007, V95, N6, NOV, pp
1284-1295.
08.1-109
Minor changes in soil organic carbon and charcoal
concentrations detected in a temperate
deciduous forest a year after an experimental
slash-and-burn
Eckmeier E, Gerlach R, Skjemstad J O, Ehrmann O,
Schmidt M W I