TY  - JOUR
A1  - Rūsiņa, Solvita
A1  - Pušpure, Ilze
A1  - Gustiņa, Lauma
T1  - Diversity patterns in transitional grassland areas in floodplain landscapes with different heterogeneity
T1  - Diversitätsmuster in Graslandkomplexen von Auen mit unterschiedlicher Landschaftsheterogenität
T2  - Tuexenia : Mitteilungen der Floristisch-Soziologischen Arbeitsgemeinschaft
N2  - The complex topography of floodplains provides conditions for high diversity and density of transitional areas between different grassland plant communities. Nevertheless, transitions have been almost completely neglected in previous studies of diversity patterns in semi-natural floodplain grasslands. We analyzed α-, β- and γ-components of plant species diversity in transitional areas between neighbouring wet and dry grassland communities in two landscapes of the Gauja River floodplain (Latvia) differing in landscape heterogeneity created by land use history and current management type (grazing versus mowing). In total 9 transition areas and their adjacent vegetation were sampled in 1 m wide and 8 to 28 m long belt transects gridded into 0.5 m × 1 m plots. Cluster analysis was used to analyze varia-tion in species composition of transitional areas and adjacent vegetation. Indicator species analysis was used to determine species specific to transitional areas (ecotonal species). Transitional areas of the homogeneous site had a more distinct species composition (clear division in clusters by cluster analysis) and significantly lower β-diversity than those of the heterogeneous site. α-Diversity was significantly higher in transitions than in wet grasslands and lower than in dry grasslands in both sites. Comparing the two sites, α-diversity was significantly higher in wet grasslands of the heterogeneous site, but no differences were found between transitions and dry grasslands in the two sites. Higher β-diversity of transitional areas in the heterogeneous site could be attributed to a higher density of different habitats per unit area in combination with grazing. No species were restricted to transitions, and no differences were apparent in the number of generalist species (indifferent species sensu Ellenberg indicator values for edaphic factors) between transitions and adjacent grasslands. Nevertheless, the total number of generalist species was considerably higher in the investigated flood-plain grasslands than usually reported for respective vegetation types in Latvia. It was concluded that transitions of neighboring floodplain grassland plant communities were more important in shaping β-diversity compared to α- and γ-diversity. Our results suggest that destroying transitional areas between dry and wet grasslands by leveling the ground or by abandonment of the management practices will decrease habitat heterogeneity and lead to less pronounced ecotonal pro-cesses in the whole riverine landscape. Thus further studies about the role of fine-scale transitional areas for biodiversity of floodplains are important for ecological restoration of floodplain grasslands.
N2  - Die vielschichtige Topographie von Flussauen ist Vorrausetzung für eine hohe Diversität und Dichte an Ökotonen und damit auch für zahlreiche Übergänge zwischen verschiedenen Graslandgesellschaften. Ökotone sind ein wichtiges Landschaftselement da sie erheblich zur floristischen Diversität sowohl auf Habitats- wie auch auf Landschaftsebene beitragen. Wir untersuchten den Ökoton zwischen Buckeln/Wällen und Senken im Grasland von Flussauen. Auf den Buckeln/Wällen wuchs trockenes Grasland der Verbände Filipendulo vulgaris-Helictotrichion pratensis (Brachypodietalia, Festuco-Brometea) und Arrhenatherion und in den Senken feuchtes Grasland des Calthion und Magno-caricion. Nach unserem Wissen liegen für solche Ökotone bislang keine Biodiversitätsdaten vor. Das Ziel der Untersuchung war die Einschätzung der Diversität des halbnatürlichen Graslands im Übergangsbereich von trockenen zu feuchten Auenstandorten in Beziehung zur Landschaftsheterogenität. Wir vermuteten, dass sich die Übergangsbereiche durch spezifische Arten sowie eine höhere Beta-Diversität und auch eine höhere Anzahl an Generalisten als die angrenzenden, entweder trockenen oder feuchten Bereiche, auszeichneten. Gleichzeitig erwarteten wir in einer heterogen strukturierten Landschaft mit hoher Dichte an Ökotonen eine höhere Pflanzenartendiversität als in einer homogen strukturierten Landschaft mit geringer Dichte an Ökotonen.
KW  - boundary
KW  - diversity
KW  - ecotone
KW  - generalists
KW  - grazing
KW  - mowing
Y1  - 2013
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/35516
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-355161
SN  - 0722-494X
VL  - 33
SP  - 347
EP  - 369
ER  -