Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2006
Sammendrag
Toxic effects of aluminium (Al) on Picea abies (L.) Karst. (Norway spruce) trees are well documented in laboratory-scale experiments, but field-based evidence is scarce. This paper presents results on fine root growth and chemistry from a field manipulation experiment in a P. abies stand that was 45 years old when the experiment started in 1996. Different amounts of dissolved aluminium were added as AlCl3 by means of periodic irrigation during the growing season in the period 19972002. Potentially toxic concentrations of Al in the soil solution were obtained. Fine roots were studied from direct cores (1996) and sequential root ingrowth cores (1999, 2001, 2002) in the mineral soil (040 cm). We tested two hypotheses: (1) elevated concentration of Al in the root zone leads to significant changes in root biomass, partitioning into fine, coarse, living or dead fractions, and distribution with depth; (2) elevated Al concentration leads to a noticeable uptake of Al and reduced uptake of Ca and Mg; this results in Ca and Mg depletion in roots. Hypothesis 1 was only marginally supported, as just a few significant treatment effects on biomass were found. Hypothesis 2 was supported in part; Al addition led to increased root concentrations of Al in 1999 and 2002 and reduced Mg/Al in 1999. Comparison of roots from subsequent root samplings showed a decrease in Al and S over time. The results illustrated that 7 years of elevated Altot concentrations in the soil solution up to 200 M are not likely to affect root growth. We also discuss possible improvements of the experimental approach.
Forfattere
T. Larssen E. Lydersen D. Tang Yi He Jixi Gao H. Liu Lei Duan H.M. Seip R.D. Vogt Jan Mulder M. Shao Yan-Hui Wang H. Shang X. Zhang Svein Solberg Wenche Aas Tonje Økland O. Eilertsen V. Angell Quanru Liu D. Zhao Renjun Xiang J. Xiao J. LuoSammendrag
Acid rain emerged as an important environmental problem in China in the late 1970s. Many years of record economic growth have been accompanied by increased energy demand, greater coal combustion, and larger emissions of pollutants. As a result of significant emissions and subsequent deposition of sulfur, widespread acid rain is observed in southern and southwestern China. In fact, the deposition of sulfur is in some places higher than what was reported from the ?black triangle? in central Europe in the early 1980s. In addition, nitrogen is emitted from agriculture, power production, and a rapidly increasing number of cars. As a result, considerable deposition of pollutants occurs in forested areas previously thought to be pristine. Little is known about the effects of acid deposition on terrestrial and aquatic ecosystems in China. In this article, we present the current situation and what to expect in the future, largely on the basis of results from a five-year Chinese?Norwegian cooperative project. In the years ahead, new environmental challenges must be expected if proper countermeasures are not put into place.
Forfattere
Svein SolbergSammendrag
Det er ikke registrert sammendrag
Forfattere
Svein SolbergSammendrag
Remote sensing is a promising tool for monitoring forest health. Foliar mass, or correspondingly leaf area index (LAI), together with chlorophyll concentration in the foliage, are two suitable measures of forest health. So far, airborne laser scanning has proven to be very suitable for measuring LAI. The work is in progress, and still in an early phase.
Sammendrag
In this study, we present a new method for single tree segmentation and characterization from a canopy surface model (CSM), and its corresponding point cloud, based on airborne laser scanning. The method comprises new algorithms for controlling the shape of crown segments, and for residual adjustment of the canopy surface model (CSM). We present a new criterion that measures the success of locating trees, and demonstrate how this criterion can be used for optimizing the degree of CSM smoothing. From the adjusted CSM segments, we derived tree height and crown diameter, and based on all first laser pulse measurements within the segments we derived crown-base height. The method was applied and validated in a Norway spruce dominated forest reserve having a heterogeneous structure. The number of trees automatically detected varied with social status of the trees, from 93 percent of the dominant trees to 19 percent of the suppressed trees. The RMSE values for tree height, crown diameter, and crown-base height were around 1.2 m, 1.1 m, and 3.5 m, respectively. The method overestimated crown diameter (0.8 m) and crown base height (3.0 m).
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Inger HansenSammendrag
Det er ikke registrert sammendrag
Forfattere
Inger HansenSammendrag
Det er ikke registrert sammendrag
Forfattere
Inger HansenSammendrag
Det er ikke registrert sammendrag
Forfattere
Inger HansenSammendrag
Tradisjonelt bruk av vokterhunder har hatt god tapsforebyggende effekt i utlandet, men et effektivt predatorvern forutsetter at sauene går i flokk. Dersom vokterhund skal bli et effektivt tiltak under norske forhold må sauene samles bedre. Alternativt kan nye bruksmåter tilpasset utmarksbasert beitedrift utvikles. Patruljeringsmetoden er en ny bruksmåte som kan være aktuell på utmarksbeiter i Norge.