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.
2001
Authors
Halvor TorgersenAbstract
No abstract has been registered
Authors
Oddvar SkreAbstract
Småplanter av tre bjørkepopulasjonar (Betula pubescens) blei dyrka i veksttorv ved to ulike gjødselnivå, tilsvarande 1 og 10 g N m-2 yr-1 ved 50 og 450 m høgd i det sørlege Noreg. Det var ei sterk opphoping av karbohydrat i røter frå det høgaste feltet, samanlikna med det lågaste. Normal og alternativ (cyanid-resistent) respirasjon blei målt i stengel- og rotsegment og på avskorne bladskiver frå dei tre bjørkepopulasjonane. Den totale og alternative mørkerespirasjonen minka med aukande temperatur i bladskiver og stengelsegment. I rotsegment frå dei same plantene auka derimot totalrespirasjonen med temperaturen. Ved lågt gjødselnivå var det ein viss reduksjon av respirasjonen i skot ved høg temperatur, og det meste av denne var cyanid-resistent, i.e. ikkje kopla til veksten. Den økologiske tydinga av dette er at ved låg temperatur kan auka alternativ respirasjon i blad og stengel føra til redusert vekst. Ved høg temperatur derimot, tyder auka totalrespirasjon i røter på auka absorbsjon av nitrogen i røter, som igjen fører til auka fotosyntesekapasitet, som kan kompensera for karbohydratmangel ved sterk vekst. Den alternative respirasjonen ved lågt næringsnivå og temperatur kan vera ein mekanisme for å unngå vekst ved ugunstige forhold.
Abstract
No abstract has been registered
Authors
Peder GjerdrumAbstract
Fuktforandringer i trelasten etter tørking før den når frem til sin endelige bruk er studert. En dynamisk modell for fuktutvikling i stabilt klima er utviklet og analysert. Temperaturområdet er 3 - 60 gr C, og modellen gjelder for planker av 50 mm gran. Arbeidet inngår i bestrebelene for å finne frem til en mer generell modell for et reelt, vekslende klima.
Authors
E. Mäenpää Oddvar Skre E. Malila R. Partanen Frans-Emil Wielgolaski Kari M. LaineAbstract
Gjennom tre sesongar (1983-85) blei det hausta prøver av bjørk (Betula pubescens) og ulike planteslag i feltskiktet på på seks lokalitetar i bjørkeskog langs ein kyst-innlandsgradient i bjørkeskog i Nord-Skandinavia. Prøvene blei skilt i grupper etter vevstype og analysert for stivelse og løyselege sukker. Analysene viste ein kraftig nedgang i karbohydratinnhaldet gjennom vekstfasen om våren, etterfølgt av ei gradvis oppbygging frå fotosyntesen i nye blad. Deretter var det ein gradvis nedgang, først på grunn av frukt- og frøutvikling, deretter sekundærvekst, og endeleg respirasjonstap gjennom mørkeperioden om vinteren. Denne nedgangen var størt på lågtliggande lokalitetar med lite nedbør.
Authors
H. Saxe M.G.R. Cannell Øystein Johnsen M.G. Ryan G. VourlitisAbstract
No abstract has been registered
Authors
Sondre Skatter R.R. ArcherAbstract
No abstract has been registered
Abstract
Understanding sulfate transport and retention dynamics in forest soils is a prerequisite in predicting SO4 concentration in the soil solution and in lake and stream waters. In this study forest soil samples from the Grdsjn catchment, Sweden, were used to study SO4 transport in soil columns from the upper three soil horizons (E, Bs and BC).The columns were leached using a sequential leaching technique. The input solutions were CaSO4 equilibrated with forest floor material. Leaching behavior of SO4 and concentration in the effluent were measured from columns from individual horizons.SO4 was always retained in the Bs and BC horizons, while the pattern for the E horizon varied. Attempts were also made to model SO4 breakthrough results based on miscible displacement approaches and solute convection-dispersion equation (CDE) in porous media. Several retention mechanisms were incorporated into the CDE in order to account for possible reversible and irreversible SO4 reactions in individual soil layers.The model was not successful in describing the mobility of SO4 in the top (E) horizon. Moreover, a linear equilibrium approach was generally inadequate for describing sulfate mobility in the Bs and BC horizons whereas improved model descriptions were obtained when non-linear equilibrium and kinetic approaches were utilized.We conclude that sulfate retention during transport in this forest soil is most likely controlled by kinetic reactivity of SO4 by reversible and irreversible mechanisms.
Authors
Morten Ingerslev E. Mälkönen Petter Nilsen H.Ö. Nohrstedt H. Óskarsson Karsten Raulund-RasmussenAbstract
Previous research has documented that nitrogen fertilization can lead to a significant tree growth increase in large parts of Scandinavia. Nutrient management of Nordic forests is currently under debate, mainly because environmental values are believed to be unnecessarily endangered by these actions. Nutrient management including fertilization, liming, recycling of wood ash or application of alternative nutrient sources can counteract nutrient deficiencies and imbalances, and be used for compensating the nutrients removed through harvesting. For successful implementation of nutritional management measures, several questions should still be studied. These questions mainly concern diagnosis of the need for applications, nutritional sustainability and treatment effects on the forest ecosystem and the surrounding environment.
Authors
Lars Sandved Dalen M. GriffithAbstract
Adaptation to cold and freezing temperatures is crucial for survival in temperate and boreal areas. Compared with angiosperms, little is known about the mechanisms of freezing tolerance in gymnosperms. Coniferous species such as Norway spruce (Picea abies L. Karst.) have a wide distribution in boreal areas, indicating a strong ability to adapt to lasting periods of cold and freezing temperatures.Freezing-tolerant perennial plants survive subzero temperatures by forming ice in intercellular spaces and the xylem. Certain proteins associated with pathogen attack have been found to exhibit antifreeze activity, i.e. the ability to bind and modify the growth of ice.In order to study the possible role of pathogenesis-related proteins in development of freezing tolerance in Norway spruce, we looked at the accumulation of chitinases during hardening under both artificial and natural conditions.Our findings show that chitinases and other pathogenesis-related proteins, as well as antifreeze activity, are present in needles of Norway spruce, and that they increase in response to shorter daylengths and cold temperature. It is possible that pathogenesis-related proteins accumulated in conifers during cold acclimation could also exhibit antifreeze activity, and thus play an important role during development of freezing tolerance in perennial plants such as the gymnosperm Norway spruce.