Progressive effects of shading on experimental wetland communities over three years

To investigate how the composition of wetland communities changes over time in response to altered light regimes, experimental communities of five Carex and four grass species were subjected to artificial shading (continuous or seasonal) in a three-year field experiment. Shoot number and size was measured after six weeks, and shoot biomass was harvested five times during the experiment. Communities were initially dominated by three grass species in all treatments, but subsequently, the Carex species increased and reached dominance in the control plots, whereas grasses remained dominant in the shaded plots. Shading had no effect on the biomass of communities or of single species in the first year. In the second year, community biomass was still unaffected, but shading reduced the biomass of three Carex species and also reduced species diversity. In the third year, shading reduced community biomass and all Carex species, but not species diversity. The greater shade tolerance of the grasses could not be explained by differences in morphological plasticity: after six weeks of growth all species had increased shoot height in response to shade by 40-70%. Grasses were hardly more plastic than Carex species. We propose that the long-term success of the Carex species in full light was due to a high allocation of biomass to belowground parts, which may have reduced losses caused by repeated harvesting of shoots (a simulation of management in productive wet meadows). Shading probably caused the Carex plants to change their allocation pattern, and thus prevented their progressive increas

Herausforderung alpiner Renaturierungen : markante Unterschiede in Vegetation, Bakterien und Boden

Die Schweiz weist mit ihrer abwechslungsreichen Topografie eine hohe Artenvielfalt auf. Die heterogene Landschaft und insbesondere die mächtigen Gebirgszüge tragen dabei zur besonderen Verantwortung gegenüber dem Schutz und Erhalt der Biodiversität bei. Bautätigkeiten und Eingriffe in die Landschaft ausserhalb der Bauzonen werden daher häufig von Renaturierungsmassnahmen begleitet. Jonathan Blank-Pachlatko untersuchte in seiner Masterarbeit am Corvatsch im Engadin, welche ökologischen Unterschiede sich dabei kurz nach der Ausführung im Vergleich zu unberührten Flächen feststellen liessen

Progressive effects of shading on experimental wetland communities over three years

ISSN:1385-0237ISSN:1573-505

Differences in vegetation composition, bacterial community and soil properties after restoration of construction sites on alpine grasslands

Vegetation surveys and soil samples were taken within two former construction sites and near them in undisturbed areas at 2500 m, above the tree line in circular 10 m2 plots at the Curtinella ski lift on the Corvatsch mountain range (Canton Graubünden, Switzerland) in 2021. The sites were re-vegetated in 2015 (seeding and turf) and 2020 (turf). The areas from 2015 are used as ski slopes with artificial snow. Vegetation cover per species recorded as well as ground cover (stones, gravel, fine soil) was estimated and the soil depth, pH and electrical conductivity were measured. The nutrient content (C, H, N) as well as the content of active microorganisms of the soil samples were analysed. In addition, the bacterial community was analysed via 16S rRNA-sequencing. The plots of the sown construction site from 2015 show a decrease in the number of species and Shannon Index compared to the undisturbed plots, the plots of the construction site with turf from 2020 show a decrease in the vegetation cover and Shannon Index. Both former construction sites show a significant decrease in soil depth and nutrients and an increase of pH. In addition, a significant decrease in soil microbial activity could be detected. The bacterial communities differ between the former construction sites and the undisturbed area. Despite the successful revegetation for this altitude, the results show a considerable loss of topsoil and species diversity of the investigated species groups and speak for a considerate approach for future construction sites in alpine regions

Herausforderung alpiner Renaturierungen : markante Unterschiede in Vegetation, Bakterien und Boden

Die Schweiz weist mit ihrer abwechslungsreichen Topografie eine hohe Artenvielfalt auf. Die heterogene Landschaft und insbesondere die mächtigen Gebirgszüge tragen dabei zur besonderen Verantwortung gegenüber dem Schutz und Erhalt der Biodiversität bei. Bautätigkeiten und Eingriffe in die Landschaft ausserhalb der Bauzonen werden daher häufig von Renaturierungsmassnahmen begleitet. Jonathan Blank-Pachlatko untersuchte in seiner Masterarbeit am Corvatsch im Engadin, welche ökologischen Unterschiede sich dabei kurz nach der Ausführung im Vergleich zu unberührten Flächen feststellen liessen