Zum Einfluss von Landnutzungsänderungen, Stickstoffanreicherung und Erwärmung auf die Interaktionen von Xerothermrasenarten

Content Provider	Semantic Scholar
Author	Partzsch, Monika
Copyright Year	2015
Abstract	Effects of land use change, nitrogen addition and warming on the interactions of dry grassland species Currently a major global environment change as a result of traditional land use change and different processes like warming and nitrogen deposition takes place and leads to a change in plant-plant-interactions. These interactions are key drivers of regulating species composition, productivity, structure and dynamic in plant communities and ecosystems. The interactions are manifold between the co-existing species and depend on the environmental conditions and the particular plant traits. They can be positive in terms of facilitation and negative in terms of competition. Several studies showed that the decrease in biodiversity is a result of global environmental change. In order to investigate the effect on plant-plant-interactions in dry grasslands two competition experiments were carried out, where the total number of individuals in the pots kept constantly but the number of individuals of the co-existing species varied. As study species the expanding grass Festuca rupicola and the dicot Dianthus carthusianorum, which is protected by law, were chosen. In a two-years-pot-experiment in the open field, the effect of land use change was tested by simulating grazing/mowing or abandonment. In a growth chamber experiment the effects of eutrophication and warming were tested, both under nutrient-poor (simulating natural habitat conditions) and under nutrientrich conditions (simulating eutrophication). One growth chamber simulated current temperature conditions during vegetation period with 20 °C per day and 10 °C per night and the other chamber simulated predicated conditions with 22 °C during day and 15 °C during night. The plant parameters biomass, number and length of leaves, number of flowers and length of panicles were measured and the positive and negative interactions were calculated by Relative Interaction Index. The results of the first experiment show that land use change has only a minor effect on the performance of D. carthusianorum in the second year, but the biomass and the length of panicles of F. rupicola significantly increased in unclipped treatments (simulating abandonment). The interactions suggested facilitation of F. rupicola in neighborhood of the dicot and neutral till competitive interactions of D. carthusianorum by the co-existing grass. In generally the abandonment of traditional land use (grazing or mowing) leads to the expansion of F. rupicola, which can caused the decline of the co-existing dicotyledonous species. The results of the second experiment showed that the performance of the plant parameters and the interactions were species-dependent: under nutrient poor conditions the performance of both species was low and the interactions were minor, but after nutrient addition, both species grew better and interacted much stronger. Under both nutrient levels, D. carthusianorum was significantly promoted, but biomass and leaf length of F. rupicola did not differ and leaf number significantly decreased after warming. As such, the dicot became competed against and the grass facilitated under current conditions, while under warmed conditions the competitive ability of the grass declined and that of the dicot increased, indicating that interactions between both species reverses with warming climate. This suggests, that under predicted climate conditions, the current dominance of the grass will become reduced and the dicot will be promoted, which can have positive effects on biodiversity of dry grasslands. As a consequence, further investigations are needed for a better understanding of the plant dynamics and interactions under the ongoing global environmental change.
Starting Page	301
Ending Page	320
Page Count	20
File Format	PDF HTM / HTML
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Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article