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.
2007
Authors
Håkan Broman Mikael Frisk Mikael RönnqvistAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
O. Janne Kjønaas Richard Frederic WrightAbstract
To determine the source of dissolved inorganic nitrogen (N) in runoff, approx. 35 kg N enriched with the stable isotope 15N (2110‰ δ15N) was added to a mature coniferous forested catchment for one whole year. The total N input was approx. 50 kg ha-1 year-1. The enrichment study was part of a long-term whole-catchment ammonium nitrate addition experiment at Gårdsjön, Sweden. The 15N concentrations in precipitation, throughfall, runoff and upper forest floor were measured prior to, during, and 3-9 years following the 15N addition. During the year of the 15N addition the δ15N level in runoff largely reflected the level in incoming N, indicating that the leached NO3- came predominantly from precipitation. Only 1.1% of the incoming N was lost during the year of the tracer addition. The cumulative loss of tracer N over a 10-year period was only 3.9% as DIN and 1.1% as DON.
Authors
Arne Oddvar Skjelvåg Ole Einar Tveito Inge BjørdalAbstract
An example is given from a pilot project on a coherent application of soil and weather data to produce crop security estimates of barley. GIS was used to interpolate daily weather elements from a network of weather stations to individually mapped soil type units, oil average less than 1 ha, of arable land. Other model tools are: a soil moisture model to estimate soil drying from the day of snow thaw until sowing date, temperature Run functions to estimate daily advance in phenological development to emergence, heading, and yellow ripeness, and thereafter, a grain moisture model for logging of combine harvesting days, taking also daily precipitation into account. The outcome is probability estimates of getting at least a given number of combining options within a given calendar day.
Abstract
The relationships between measures of forest structure as derived from airborne laser scanner data and the variation in quantity of young trees established by natural regeneration in a size-diverse spruce forest were analyzed. A regeneration success rate (RSR) was regressed against 27 different laser-derived explanatory variables. The 27 different models were ranked according to their Akaike information criterion score. Each laser variable was then associated with two categories. These were return and type. Within the return and type categories, the variables were grouped according to if they originated from first or last return echoes and if they were canopy height or canopy density metrics. The results show that the laser variables strongest correlated to the quantity of small trees could be attributed to last return and density metrics.
Authors
Ole Martin Bollandsås Kjersti Holt Hanssen Solfrid Marthiniussen Erik NæssetAbstract
The relationships between measures of forest structure as derived from airborne laser scanner data and the variation in quantity of young trees established by natural regeneration in a size-diverse spruce forest were analyzed. A regeneration success rate (RSR) was regressed against 27 different laser-derived explanatory variables. The 27 different models were ranked according to their Akaike information criterion score. Each laser variable was then associated with two categories. These were return and type. Within the return and type categories, the variables were grouped according to if they originated from first or last return echoes and if they were canopy height or canopy density metrics. The results show that the laser variables strongest correlated to the quantity of small trees could be attributed to last return and density metrics.
Authors
Mikael Frisk Mikael Rönnqvist Mikael RönnqvistAbstract
No abstract has been registered
Authors
Sigrun H. Kværnø Lars Egil Haugen Trond BørresenAbstract
The ability to predict the timing of optimum soil workability depends on knowledge of the extent and structure of variability in main physical characteristics of the soil. Our objectives were to quantify the variability in texture and carbon content within soil map units in a small agriculture-dominated catchment in South-east Norway and to assess implications of variability in texture and carbon content on land management operations, using the predicted maximum water content for optimum workability as an example. Information from three different sources were used: a soil map (1:5000), a large sample grid (100 m spacing, 270 ha extent), and a small sample grid (10 m spacing, 2.25 ha extent). Readily available information on texture and organic matter content from the soil map was found to be of limited use for soil management due to broad textural classes together with deviations from the mapped main textural classes. There were significant differences in clay, silt and sand content between the different soil textural classes on the soil map. Statistical distributions within soil map units were generally either positively or negatively skewed and the coefficient of variation was intermediate, 15-50%. Most of the variation in both grids was spatially correlated. The large grid was dominated by a patchy structure, whilst the small grid showed a systematic trend with a gradual transition indicating fuzzy boundaries between map units in this catchment. The effective range for texture was 16 times larger in the large grid. Implications of variability in texture and carbon content on land management operations were assessed for the maximum water content for optimum workability (Wopt), predicted using pedotransfer functions. Wopt was usually in the same range as the water content at-100 kPa matric potential, indicating that considerable evaporation in addition to drainage is required for obtaining workable conditions in the field. The time required for obtaining the water content was estimated to about 5 days, which is longer than an average length of periods without precipitation in the area, median 3.7 days. Wopt predicted from the soil map deviated strongly from Wopt predicted from the sample grids. Comparing estimates of Wopt from the large grid with measurements in the small grid showed differences corresponding to +/-2-3 days of evaporation. (C) 2007 Elsevier B.V. All rights reserved.
Authors
Lena Finér Helja-Sisko Helmisaari Krista Lohmus Hooshang Majdi Ivano Brunner Isabella Børja Toril Drabløs Eldhuset Douglas L. Godbold Tine Grebenc Bohdan Konôpka Hojka Kraigher Merja Möttönen Mizue Ohashi J Oleksyn Ivika Ostonen V Uri Elena VanguelovaAbstract
Fine roots (2 mm) are very dynamic and play a key role in forest ecosystem carbon and nutrient cycling and accumulation. We reviewed root biomass data of three main European tree species European beech, (Fagus sylvatica L.), Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.), in order to identify the differences between species, and within and between vegetation zones, and to show the relationships between root biomass and the climatic, site and stand factors.The collected literature consisted of data from 36 beech, 71 spruce and 43 pine stands. The mean fine root biomass of beech was 389 g m-2, and that of spruce and pine 297 g m-2 and 277 g m-2, respectively. Data from pine stands supported the hypothesis that root biomass is higher in the temperate than in the boreal zone.The results indicated that the root biomass of deciduous trees is higher than that of conifers. The correlations between root biomass and site fertility characteristics seemed to be species specific. There was no correlation between soil acidity and root biomass. Beech fine root biomass decreased with stand age whereas pine root biomass increased with stand age. Fine root biomass at tree level correlated better than stand level root biomass with stand characteristics. The results showed that there exists a strong relationship between the fine root biomass and the above-ground biomass.
Authors
Leena Finér Heljä-Sisko Helmisaari Krista Lõhmus Hooshang Majdi Ivano Brunner Isabella Børja Toril Drabløs Eldhuset Douglas Lawrence Godbold Tine Grebenc Bohdan Konôpka Hojka Kraigher M.-R. Möttönen J. Oleksyn Ivika Ostonen V. Uri Elena Iordanova VanguelovaAbstract
No abstract has been registered