Browsing by Subject "plant community"

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  • Räsänen, Aleksi; Juutinen, Sari; Tuittila, Eeva-Stiina; Aurela, Mika; Virtanen, Tarmo (2019)
  • Andersen, Line Holm; Nummi, Petri; Bahrndorff, Simon; Pertoldi, Cino; Trojelsgaard, Kristian; Lauridsen, Torben Linding; Rafn, Jeppe; Frederiksen, Cecilie Majgaard Skak; Kristjansen, Mads Prengel; Bruhn, Dan (2021)
    Question Reed beds, dominated by common reed (Phragmites australis), have high ecological value. Several studies have examined the differences between managed and unmanaged reed beds without taking into account the time passed since the last management. In this paper, we seek to answer the question: how does the time passed since last management and the management method itself affect the plant community and the habitat structure of reed beds? Location "De ostlige Vejler," Northern Jutland, Denmark. Methods We examined four reed bed treatments - beds either cut or harvested during the year of the study (0-year-old reed beds) and reed beds harvested 3 and 25 years ago, respectively. The reed bed plant communities and the reed bed habitat structure were determined in May and August. We tested the data for overall between-treatment differences (multivariate analysis of variance [MANOVA] and principal components analysis [PCA]) and specific differences in the plant community and habitat structure (Kruskal-Wallis). Results The plant community differed significantly between the four reed beds according to treatment, and each reed bed exhibited unique species. Species richness was significantly higher in the recently harvested reed beds (0 and 3 years since harvest) compared with the 25-year-old reed beds. Harvest sparked reed rejuvenation and increased the growth of new reeds. The 3-year-old reed bed had a habitat structure that equally resembled that of the newly harvested (e.g., similar green reed shoot density) and the 25-year-old reed beds (e.g., similar height). Cutting, as opposed to harvesting, created a plant community adapted to less light availability. Conclusions To secure most plant species and most variation in habitat structure, reed beds should contain a mosaic of differently aged and differently managed patches. Previous studies have disagreed on the effect of management on plant species diversity, which could be explained either by different reed bed age or different sampling periods.
  • Maliniemi, Tuija; Happonen, Konsta; Virtanen, Risto (2019)
    Experimental evidence shows that site fertility is a key modulator underlying plant community changes under climate change. Communities on fertile sites, with species having fast dynamics, have been found to react more strongly to climate change than communities on infertile sites with slow dynamics. However, it is still unclear whether this generally applies to high-latitude plant communities in natural environments at broad spatial scales. We tested a hypothesis that vegetation of fertile sites experiences greater changes over several decades and thus would be more responsive under contemporary climate change compared to infertile sites that are expected to show more resistance. We resurveyed understorey communities (vascular plants, bryophytes, and lichens) of four infertile and four fertile forest sites along a latitudinal bioclimatic gradient. Sites had remained outside direct human disturbance. We analyzed the magnitude of temporal community turnover, changes in the abundances of plant morphological groups and strategy classes, and changes in species diversity. In agreement with our hypothesis, temporal turnover of communities was consistently greater on fertile sites compared to infertile sites. However, our results suggest that the larger turnover of fertile communities is not primarily related to the direct effects of climatic warming. Furthermore, community changes in both fertile and infertile sites showed remarkable variation in terms of shares of plant functional groups and strategy classes and measures of species diversity. This further emphasizes the essential role of baseline environmental conditions and nonclimatic drivers underlying vegetation changes. Our results show that site fertility is a key determinant of the overall rate of high-latitude vegetation changes but the composition of plant communities in different ecological contexts is variously impacted by nonclimatic drivers over time.