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.
2009
Authors
Kjersti Holt HanssenAbstract
We studied the growth of Norway spruce and Scots pine seedlings in the understory, using three sites with selective cutting and group fellings in SE Norway. Seedlings were planted in plots with and without trenching in gaps of four different sizes, ranging from 20 m2 to 500 m2 and giving light levels from around 20 to 75 % of open sky. After tree years seedlings were dug up and measured. Vegetation cover was also registered. Growth of both species was positively and significantly correlated with increasing gap size. This applied for height, diameter, shoot volume, needle length and needle number as well as total dry weight. However, trenching also had a clear and significant positive effect on the same growth parameters. The growth of some weed species, especially wavy hair-grass (Deschampsia flexuosa) also increased significantly with both gap size and trenching. The results show that competition for both light and below-ground resources matters for understory seedling growth under the studied conditions.
Authors
Stig Strandli GezeliusAbstract
No abstract has been registered
Authors
Knut Anders Hovstad Mikael OhlsonAbstract
Plant litter is an important determinant of seed germination and seedling establishment. Positive effects of litter have received considerable attention, but few studies have explicitly tested whether seedlings are more facilitated by conspecific litter compared to heterospecific litter. In order to contrast conspecific and heterospecific facilitative effects on seedling establishment, we used Anthriscus sylvestris, Angelica sylvestris, Pimpinella saxifraga and different combinations of their seeds and litter seedbeds as a model system. Although litter had a significant species-specific effect on seedling emergence, we found no evidence of strictly conspecific facilitation. Anthriscus sylvestris displayed a positive response to all types of litter. In contrast, there was a clear negative effect of conspecific litter in Pimpinella saxifraga. Activated carbon did not modify the negative effect, indicating that chemical compounds were not the cause. Our study suggests a high level of idiosyncrasy in response to litter at the species level.
Abstract
In high-latitude areas, landscapes with flat or moderate relief areas usually contain lakes and mires. The identification of flowpaths in such areas is a difficult issue. The increasing availability of high resolution topography from airborne Lidar measurements offers new opportunities for automatic or semi-automatic channel extraction from DEMs in small watersheds, substantially outperforming the hydrographic network in conventional digital maps....
Abstract
No abstract has been registered
Authors
Tor MykingAbstract
No abstract has been registered
Abstract
Control of dock species are a true bottleneck in the development of grassland based organic forage production in Norway. Rumex obtusifolius, Rumex crispus and Rumex longifolius are among the most important perennial weeds in grassland areas throughout the world. These dock- species are undesired in grasslands because they decrease yields and reduce forage feeding value. The experiment in our study is carried out as a full-factorial design, including key-factors, which may influence dock behaviour significantly. The first factor, (i) date of grassland establishment, may be important for preventing /decreasing the flush of seedlings from seeds as well as shoots from root fragments. The purpose of the second factor, (ii) black fallow, is both false seedbed preparation and decreasing food reserves in underground plant parts. The third factor, (iii) is the use of equipment for cutting the taproot either (a) before ploughing by using a tractor propelled rotovator, or (b) cutting the dock taproot in the same operation as ploughing by using a prototype ¿two layer dockplough¿. The biological background for cutting the taproot before ploughing is that many studies have shown that new shoots only come from the 5 upper cm of the taproot. Furthermore, our hypothesis is that shoots from highly fragmented regenerative parts (the neck) of the taproot placed deep will not reach the soil surface before their reserves are depleted. Experiments were carried out at 3 and 4 locations in 2007 and 2008, respectively. Weed development were assessed as number of emerging seedlings as well as number of sprouting plants from root fragments, both in the year when the treatments were carried out and the following year. The results are yet not completely analyzed, but preliminary results indicate that plants from seeds frequently are more numerous than plants from roots. At least at some locations and years both the use of rotovator and the ¿dock plough¿, has reduced the number of plants from root fragments with approx. 50%. However, our experiments have shown that ¿dock plough¿ prototype has to be improved, especially because it did not cut the taproot near the open furrow, and did not bury the green parts well enough.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Fruit samples of seven sweet cherry cultivars grouped into three different groups of fruit flesh firmness (soft-fruited: 'Ranna Ljaskovska', 'Vista' and 'Sunburst', medium firm: 'Ulster' and 'Sylvia' and firm cultivars: 'Van' and 'Lapins') were harvested over a three week period with 3-4 d intervals prior to, during and after normal harvest time in 1997 and 1998 in Ullensvang, western Norway. Fruit firmness was measured at each harvest date along with measurements of soluble solids content (SSC), air temperature, precipitation and estimation of fruit colour. Corresponding samples picked at normal harvest date were stored in normal air atmosphere at temperatures 2 degrees C and 8 degrees C, respectively, and firmness was measured during storage with 3-5 d intervals. All the tested cultivars reached normal firmness, colour and SSC at harvest both years. Fruit were generally darker in 1998 than in 1997. All cultivars showed a more or less distinct reduction in firmness over the period prior to and slightly after normal harvest. Exceptions were 'Sunburst' in the 1998-season, that increased in firmness after normal harvest date, and the two firmest cultivars that increased in firmness over the ripening period in 1997. Generally, firmness increased during the first part of storage followed by a decrease after 1-2 weeks, the decrease being usually earlier and more distinct at 8 degrees C than at 2 degrees C. 'Van' in 1998 showed no change in firmness development throughout the storage period but a small increase in the last part. 'Lapins' in 1997 had however, a pronounced drop in firmness in the middle of the storage period followed by an increase. All the tested cultivars were more firm at normal harvest time in 1998 than in 1997, except the two firm-fleshed cultivars 'Van' and 'Lapins'. The warm and sunny 1997-summer produced softer fruits than the cold and rainy 1998-season, except for the firm-fleshed cultivars. It was anticipated that the many contradictory results of sweet cherry fruit firmness reported by other authors may be caused by differences in weather conditions as demonstrated.