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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.

2011

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Abstract

Field trials at two locations in Norway previously demonstrated differences in winter survival between two Agrostis species used for turf, velvet bentgrass (VB; A. canina L.) and creeping bentgrass (CB; A. stolonifera L.). The objectives of this study were to compare freezing tolerance and crowncarbohydrate composition of VB and CB. We also compared a direct and two indirect methods of measurements of freezing tolerance. Treatments consisted of: (i) nonacclimated (NA); (ii) acclimation at 2°C for 2 wk (A2); (iii) acclimation at 2°C for 4 wk (A4); and (iv) acclimation at 2°C for 4 wk plussubzero acclimation at –2°C for 2 wk (A4+SZA2). Crowns were harvested for determination of carbohydrates and freezing tolerance. Freezing tolerance (lethal temperature for 50% of the test population [LT50]) was based on whole plant survival (WPS), 2,3,5-triphenyltetrazolium chloride (TTC)reduction, and electrolyte leakage (EL). There were no significant difference in freezing tolerance between VB and CB. The LT50 based on WPS was significantly lower for plants exposed to A2 (–12.7°C), A4 (–14.5°C), and A4+SZA2 (–14.6°C) compared to the NA control treatment (–8.4°C). The concentrations of fructans and sucrose were significantly higher in A2 compared to NA plants of both species, but only fructans continued to increase at A4. The LT50 based on TTC reduction showed better correlation with LT50 based on WPS compared to LT50 values based on EL.

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Abstract

Peatlands in the northern hemisphere have accumulated more atmospheric carbon (C) during the Holocene than any other terrestrial ecosystem, making peatlands long-term C sinks of global importance. Projected increases in nitrogen (N) deposition and temperature make future accumulation rates uncertain. •Here, we assessed the impact of N deposition on peatland C sequestration potential by investigating the effects of experimental N addition on Sphagnum moss. We employed meta-regressions to the results of 107 field experiments, accounting for sampling dependence in the data. •We found that high N loading (comprising N application rate, experiment duration, background N deposition) depressed Sphagnum production relative to untreated controls. The interactive effects of presence of competitive vascular plants and high tissue N concentrations indicated intensified biotic interactions and altered nutrient stochiometry as mechanisms underlying the detrimental N effects. Importantly, a higher summer temperature (mean for July) and increasedannual precipitation intensified the negative effects of N. The temperature effect was comparable to an experimental application of almost 4 g N m−2 yr−1 for each 1°C increase. •Our results indicate that current rates of N deposition in a warmer environment will strongly inhibit C sequestration by Sphagnum-dominated vegetation.