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
Abstract
Nitrogen-limited ecosystems are threatened by extensive spread of broom (Cytisus scoparius (L.) Link), a European leguminous shrub that is invasive in several countries. The establishment of invading species may, however, be suppressed by competition from native vegetation. The neighbor impact of the grass Festuca rubra subsp. commutata Gaudin on the performance of C. scoparius was studied in a greenhouse experiment with different arrival order, under low and high nitrogen supply, and with or without inoculation of nitrogen-fixing bacteria. Aboveground biomass of both species was measured after a six-months establishment period, and after a five-months regrowth period. In both periods, presence of F. rubra reduced the performance of C. scoparius as indicated by negative neighbor-effect intensity indices (NIntA). During the establishment period the competitive impact of F. rubra was highest, when planted before C. scoparius, followed by synchronous and late planting. Inoculation with rhizobia and low fertilization decreased the competitive impact of F. rubra. After cutting and regrowth priority effects of F. rubra were still visible. Interaction between the two study species was not affected anymore by inoculation, but strongly by fertilization, with highest competitive impact of F. rubra on C. scoparius under high nitrogen fertilization. In both study periods biomass of C. scoparius was negatively correlated with biomass of F. rubra. Our study provides knowledge about competition processes, which help to improve conservation and restoration measures regarding the spread of C. scoparius. Early sowing of a native grass can help to suppress the invasive species at an early stage. Competitive impact of the grass might be strengthened by high nitrogen availability.
Authors
Tatsiana EspevigAbstract
No abstract has been registered
Authors
Tatsiana EspevigAbstract
No abstract has been registered
Authors
Tatsiana EspevigAbstract
No abstract has been registered
Abstract
To predict how the function of urban vegetation and the provision of ecosystem services respond to combinations of natural and anthropogenic drivers, a better understanding of multiple stress interactions is required. This study tested combined effects of moderate levels of drought, soil salinity and exposure to diesel exhaust on parameters of physiology, metabolism, morphology and growth of Pinus sylvestris L. saplings. We found that plant responses were primarily dominated by single stressors and a few two-way interactions. Stressor combinations did not have considerable additional negative effects on plant performance compared to single stressors. Hence, synergistic and antagonistic interactions were rare and additive effects frequent. Drought cycles caused most negative effects, from chlorophyll a fluorescence and epicuticular wax content to growth responses, while soil salinity caused fewer negative effects but contributed to reduction in fine root growth and fluorescence parameters at low air contamination. Interestingly, the air contamination alone had only marginal effects on plant morphology and growth, but contributed an antagonistic effect, dampening the negative effect of drought and salinity on the maximum quantum efficiency of PSII photochemistry (Fv/Fm) and fine root biomass. Although, these effects were moderate, it appears that exhaust exposure had a cross-acclimation effect on plant responses to drought and salinity. We also found that salinity had a negative effect on the accumulation of particulate matter on shoots, illustrating that the plant stress situation can affect the provisioning of certain ecosystem services like pollution attenuation. These findings have implications for the understanding of the complex natural and anthropogenic stress situation of urban, and how to maintain the ecological functions and delivery of ecosystem services.
Authors
Trygve S. AamlidAbstract
No abstract has been registered
Abstract
Seed crops of white clover (Trifolium repens L.) are usually established with a cover crop. Provided sufficient light, white clover may compensate for low plant density by stoloniferous growth. Our objectives were (1) to compare spring barley or spring wheat used as cover crops for white clover and (2) to find the optimal seeding rate/row distance for white clover. Seven field trials were conducted in Southeast Norway from 2000 to 2003. Barley was seeded at 360 and 240 seeds m−2 and wheat at 525 and 350 seeds m−2. White clover was seeded perpendicularly to the cover crop at 400 seeds m−2/13 cm row distance or 200 seeds m−2/26 cm. Results showed that light penetration in spring and early summer was better in wheat than in barley. On average for seven trials, this resulted in 11% higher seed yield after establishment in wheat than in barley. The 33% reduction in cover crop seeding rate had no effect on white clover seed yield for any of the cover crops. Reducing the seeding rate/doubling the row distance of white clover had no effect on seed yield but resulted in slightly earlier maturation of the seed crop.
Authors
Trygve S. AamlidAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered