Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2017
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Abstract
Successional dynamics in plant community assembly may result from both deterministic and stochastic ecological processes. The relative importance of different ecological processes is expected to vary over the successional sequence, between different plant functional groups, and with the disturbance levels and land-use management regimes of the successional systems. We evaluate the relative importance of stochastic and deterministic processes in bryophyte and vascular plant community assembly after fire in grazed and ungrazed anthropogenic coastal heathlands in Northern Europe. A replicated series of post-fire successions (n = 12) were initiated under grazed and ungrazed conditions, and vegetation data were recorded in permanent plots over 13 years. We used redundancy analysis (RDA) to test for deterministic successional patterns in species composition repeated across the replicate successional series and analyses of co-occurrence to evaluate to what extent species respond synchronously along the successional gradient. Change in species co-occurrences over succession indicates stochastic successional dynamics at the species level (i.e., species equivalence), whereas constancy in co-occurrence indicates deterministic dynamics (successional niche differentiation). The RDA shows high and deterministic vascular plant community compositional change, especially early in succession. Co-occurrence analyses indicate stochastic species-level dynamics the first two years, which then give way to more deterministic replacements. Grazed and ungrazed successions are similar, but the early stage stochasticity is higher in ungrazed areas. Bryophyte communities in ungrazed successions resemble vascular plant communities. In contrast, bryophytes in grazed successions showed consistently high stochasticity and low determinism in both community composition and species co-occurrence. In conclusion, stochastic and individualistic species responses early in succession give way to more niche-driven dynamics in later successional stages. Grazing reduces predictability in both successional trends and species-level dynamics, especially in plant functional groups that are not well adapted to disturbance. bryophytes; burning; Calluna vulgaris; coexistence; conservation management; determinism; disturbance; grazing; heathland; randomization test; stochasticity; vascular plants.
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Authors
Patryk Czortek Jutta Kapfer Halina Ratynska Amy Eycott Anna Delimat Antoni Zieba Anna Orczewska John-Arvid Grytnes Bogdan JaroszewiczAbstract
No abstract has been registered
Abstract
Habitat loss is one of the primary environmental causes of biodiversity decline across scales; locally to globally. Ecological restoration is acknowledged as an important tool to counteract this negative trend. The semi-natural calcareous sand dune meadows in south-western Norway are known for their high species diversity, much like similar habitats of high conservation value across Europe today. The recent cessation of grazing has caused a decline in several endangered species associated with these habitats due to the advancement of secondary succession. We conducted a long-term restoration experiment in semi-natural dune meadows over 16 years to examine if current trends in biodiversity loss could be reversed and at what time-scale restoration measures take effect. Three treatments were applied; mowing annually, mowing bi-annually, and a control (no mowing). In fields mown annually species richness increased significantly over time. However, the response was slow and significant effects were first seen after year 10. Fields mown bi-annually also showed a similar trend but the response was more variable. Several characteristic meadow species were favoured by annual mowing while they declined in the control fields. Principal component analysis (PCA) revealed a compositional shift, indicating the re-arrangement/-establishment of typical meadow vegetation in the mown sites, contrasting the further successional development in the control. Our results demonstrate the importance of long-term data in supporting good evidence-based management. Annual mowing is effectively restoring this unique habitat, but restoration efforts need to be sustained over many years to show positive effects.
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The composition of plant secondary metabolites (PSMs) extensively impacts ecosystem functioning. It is vital that we understand temporal patterns in the plants’ allocation of resources to PSMs, particularly those influenced by human activity. Existing data are insufficient in the long-term perspective of perennial plants (age or ontogeny). We analysed phenolic concentrations in foliage from birch (Betula pubescens Ehr.) considered to be undamaged and growing on 5, 10 and 15 years old clear-cuts in two boreal forest landscapes in Norway, sampled at the peak of the growing season. In sum, low molecular weight phenolic concentrations decreased with age. Apart from one apigenin glycoside, the low molecular weight phenolics co-varied similarly at all ages, suggesting a lack of temporal compound-specific prioritisation of this group. In contrast, the concentration of MeOH-soluble condensed tannins increased with age. The compositional shift fits well with several hypotheses that may provide proximate explanations for age patterns in PSM allocations, including both resource constraints and external pressures. Regardless of these explanations, our study adds an important perennial perspective (plant age) to temporal PSM patterns already well-known in boreal plant phenology (foliage age).
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Abstract
No abstract has been registered