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The quality of pollen is of fundamental importance for male reproductive success in spermatophytes, but our knowledge as to whether pollen quality is plastic and varies throughout the flowering season is limited. Pollen quality can be estimated indirectly through information about the chemical composition of pollen. In this study, pollen from Chamerion angustifolium was collected from a natural population over the course of a flowering season, lasting 48 days. The chemical composition of pollen was analyzed by Fourier-transform infrared (FTIR) spectroscopy. Pollen was found to be chemically different throughout the flowering season, revealing a clear correlation between chemical spectra and pollination day. Additionally, pollen size decreased through the flowering season and pollen chemistry differed between two populations. The indicated plasticity of pollen chemistry throughout the season is important, as it is a major prerequisite for seasonal changes in pollen quality. Whether changed pollen chemistry over the season results in altered pollen quality is still unknown. Additional studies should validate this, by combining FTIR spectroscopy measurements of pollen with measurements of pollen quality parameters. Pollenkvalitet er fundamentalt viktig for befruktningsprosessen hos frøplanter, men kunnskap om hvorvidt pollenets kvalitet er plastisk og endrer seg gjennom blomstringssesongen er begrenset. Pollenkvalitet kan estimeres indirekte ved å kjenne til pollenets kjemiske sammensetning. I denne studien ble pollen fra geitrams (Chamerion angustifolium) samlet fra en naturlig populasjon, i løpet av en blomstringssesong på 48 dager. Pollenets kjemiske sammensetning ble analysert ved bruk av Fourier-transformert infrarød (FTIR) spektroskopi. Resultatene viste at pollen er kjemisk forskjellig gjennom blomstringssesongen, og viser en klar korrelasjon mellom pollenets kjemiske spekter og pollineringsdato. I tillegg indikerer resultatene at pollenets størrelse reduseres i løpet av blomstringssesongen, og at pollenets kjemiske sammensetning er forskjellig mellom to populasjoner. Plastisitet i pollenkjemi gjennom sesongen er viktig, ettersom det er en sentral forutsetning for sesongmessig variasjon i pollenkvalitet. Hvorvidt endret pollenkjemi gjennom sesongen medfører endret pollenkvalitet er fortsatt uvisst. Videre studier bør validere dette ved å kombinere FTIR-spektroskopimålinger av pollen, med målinger av pollenkvalitet-parametere. M-NF

Skogen i Norge har ulike naturgitte forutsetninger på regional skala, hvor klima, vekstforhold og skogbrukshistorie påvirker det biologiske mangfoldet. Fragmentering av skogområder, langtransportert forurensning, skogbruk, planting av fremmede treslag og slukking av skogbranner har en påvirkning, særlig for arter som er tilknyttet kontinuitetsskog. For å kunne verne gammel naturskog, må skog som er viktig for biologisk mangfold kartlegges før det gjennomføres hogst. Dette gjelder særlig i områder som tidligere har vært utilgjengelige for skogbruk. Plukkhogde skoger kan, avhengig av omfanget på menneskelig aktivitet og skogens vekstgrunnlag, oppnå en struktur som tilsvarer naturskogkvaliteter ca. hundre år etter plukkhogstens opphør. Det er glidende overganger mellom gammel plukkhogd skog og gammel flatehogd skog, som betyr at det behøves gode kartleggingsmetoder for å skille skogbestand med forskjellig historikk fra hverandre slik at de kan forvaltes i tråd med Stortingets mål om miljøhensyn i skogbruket. Kartleggingssystemet Natur i Norge (NiN), skal brukes som verktøy til all kartlegging av norsk natur. NiN definerer naturskog på grunnlag av naturskogkriterier som vi vet er kjennetegn for naturskogstruktur. NiN’s definisjon på naturskog har møtt kritikk, og metoden er under revisjon. Kartlegging med flybåren laser har vist seg å være en egnet metode for å finne skog med naturskogkvaliteter, ved å måle vertikal og horisontal skogstruktur. I denne oppgaven ønsket jeg å finne svar på følgende spørsmål; 1) Hvor godt samstemmer NiN’s kategorisering av naturskog med skogbrukshistorikken til prøveflatene i denne oppgaven, og hvordan er fordelingen av naturskogelementene som utgjør NiN’s naturskogkriterier? 2) Klarer flybåren laser å kategorisere skog med naturskogkvaliteter som samvarer bedre med skogbrukshistorikken enn NiN’s naturskogkriterier, når man kartlegger de samme områdene med begge metoder? Feltarbeidet ble gjennomført i løpet av sommeren 2017. Det var 55 prøveflater, som besto av gammel plukkhogd og gammel flatehogd skog, hvor gammel plukkhogd skog ble regnet som fasit for naturskog. Registreringene fra feltarbeidet ble kategorisert i henhold til NiN’s naturskogkriterier, hvor 1 av 30 prøveflater i gammel plukkhogd skog kvalifiserte til naturskog. Dette var på grunn av NiN’s kriterie om fravær av hogststubber. Sett bort fra dette kriteriet, ble 12 av 30 prøveflater med gammel plukkhogd skog kategorisert til naturskog. Det ser ut til at forskjeller i bonitet hadde en effekt på fordelingen av naturskogkriteriene. For å undersøke om flybåren laser var bedre egnet til å skille gammel plukkhogd skog fra gammel flatehogd skog, ble det funnet modeller for kontinuerlige naturskogvariabler og laservariabler. Modellen som besto av naturskogvariabler stemte i større grad over ens med naturskogfasiten enn NiN’s naturskogkriterier. Modellen som hadde høyest nøyaktighet og som stemte best over ens med naturskogfasiten, besto av vertikale og horisontale laservariabler. Dette indikerer at kartlegging av naturskog med flybåren laser gir en høyere nøyaktighet enn naturskogvariabler registrert i felt, og derfor er mest hensiktsmessig å bruke til kartlegging av naturskog. The forest in Norway has various natural conditions on, where climate, growth conditions and forest history affect the abundance of saproxylic species. Fragmentation of forest areas, longtransported pollution, forestry, planting of foreign tree species and extinguishing of forest fires has an influence, especially for species associated with ecological forest continuity. In order to protect old natural forest, the forest areas must be mapped before they are felled. This is especially true in areas that have previously been inaccessible to forestry. Dimension felled forests can, depending on the extent of human activity and the growth rate of the forest, achieve a structure that corresponds with the qualities of a natural forest. There are blurred lines between old dimension felled forest and old clear- cut forests. This means that good mapping methods for separating forests with different history are needed, so that natural forest can be managed, according to achieve environmental sustainability for forest management. The system “Natur i Norge» (NiN) is to be used as a tool for all mapping of Norwegian nature. NiN defines natural forest on the basis of a set of criteria, that are known to be characteristics of a natural forest. NiN’s defined natural forest have been met with criticism to some extent, and the method is currently under revision. Mapping with airborne laser has proven to be a suitable method for finding forests with natural forest qualities, by measuring vertical and horizontal forest structure. I asked the following questions; 1) How well does NiN’s categorization of natural forest fit the history of past forestry of the test areas in this master thesis, and how is the distribution of the natural forest elements that make up NiN’s natural forest criteria? 2) Does airborne laser manage to categorize forest with natural forest qualities, that co- operate better with forest history than NiN’s natural forest criteria when mapping the same areas? The field work was carried out during the summer of 2017. There were 55 test areas, which consisted of old dimension felled forest and old clear- cut forest, where old dimension felled forest was considered a blueprint for natural forest. The registrations from the field were categorized according to NiN’s natural forest criteria, and 1 out of 30 test areas qualified for natural forest. This was due to NiN’s criterion of absence of stumps. Apart from this criterion, 12 out of 30 test areas with old dimension felled forest were categorized as natural forests. It seems that growth condition differences have an effect on the natural forest criteria. To investigate whether airborne laser data were better suited to distinguish old dimension felled forest from old clear- cut forests, a model for continuous variables for natural characteristics, and a model for laser variables were found. The model, which consisted of natural forest- variables, had a greater match with the natural forest blueprint than NiN’s natural forest criteria. The model, which had the highest accuracy and best matched the blueprint, consisted of vertical and horizontal laser variables. This indicates that mapping of natural forest with airborne laser variables gives a higher accuracy than natural forest variables registered in the field. And are therefore appropriate for mapping natural forest. M-NF

Mer enn 40 % av Norges landareal er dekket av skog og omtrent 60% av alle landets kjente arter er knyttet til dette biomet. Skogbruk har vært en viktig næring i landet i lengre tid, og skogbruket i Norge og Fennoskandia har i flere tiår vært blant de mest effektiviserte og mekaniserte i verden. Dette har gitt negative konsekvenser for biomangfoldet, og i tråd med nasjonale og internasjonale mål for vern jobbes det fortløpende med utvikling av egnet metodikk for kartlegging og verdisetting av skog og natur for øvrig. Natur i Norge (NiN) er systemet som skal brukes i offentlig kartlegging. Lav er en viktig funksjonell gruppe i skogøkosystemet og utgjør en god andel av skoglevende arter. Rundt 10 % av alle verdens lavarter finnes i Norge, mange av dem er knyttet til eldre skog og påvirkes negativt av moderne hogstmetoder. I dag finnes det svært lite uberørt skog tilbake og det er vesentlig å ivareta de arealer med høyest mulig verdi som gjenstår. Kartlegging med NiN-metodikk skal legges til grunn for vern av slike viktige skogarealer. Men det foreligger mye kritikk av metodikken, og blant annet av kriteriene for å skille ut naturskog og skog av høy verdi. Målet med denne undersøkelsen var å undersøke hvorvidt det lar seg gjøre å skille mellom normalskogens ulike kvaliteter som følge av hogsthistorikk, ved hjelp av NiN og tilstandsvariabelen skogsbestandsdynamikk, som blant annet har til hensikt å skille naturskog fra normalskog (kulturskog). Videre ble det undersøkt om det var forskjeller i epifyttisk lavbiomasse mellom to undersøkte skogtyper som begge i dag omfattes av normalskogsbegrepet. Analysen baserer seg på data samlet inn i løpet av sommeren 2017, fra skogarealer med etablerte prøveflater beliggende i Hurdalsområdet Nord for Oslo, samt fra tidligere undersøkelser av lokalitetene. Det ble vist at det forekommer større mengde lavbiomasse i skog som kun har vert plukkhogget (naturskogsnær skog) enn i skog som har vert gjennom åpen hogst (kulturskog). Forskjellen skylles ulik skogstruktur hvor den naturskogsnære skogen var mer åpen enn den gamle kulturskogen. Dette viser at denne skogen skiller seg fra kulturskog og er verdifull selv om den ikke tilfredsstiller naturskogskriteriet i NiN. NiN-kartlegging resulterte i at bare tre av de 55 kartlagte prøveflatene ble skilt ut som naturskog etter naturskogskriteriet, til tross for at noen flere prøveflater oppfylte flere av minsteverdiene for naturskogselementer, og således hadde kvaliteter som er av betydning for biomangfoldet. Dette er en indikasjon på at kriteriet er for strengt i forhold til målsettingen om å skille ut skog med høy verdi. More than 40 % of the Norwegian land mass is covered by forest and approximately 60 % of all known species in the country are affiliated with this biome. Forestry have been an important industry for Norway since the1500s and the forestry in both Norway and the other countries of Fennoscandia have been amongst the most efficient and mechanized in the world for several decades. This have caused negative consequences for biodiversity. To secure preservation of nature and forest areas development of suitable methods for forest assessment in line with national and international conservation objectives are ongoing. “Natur i Norge” (NiN) in now the official assessment system in Norway. Lichens, which are an important functional group to the forest ecosystems, make up a large amount of the forest dwelling species. Approximately 10 % of all known lichen species can be found in Norway and many are affiliated with older forest and negatively affected by modern forestry methods. There is very little pristine forest left and the need to preserve areas of high biological value is essential for survival of species. Assessment of areas by use of methods in NiN shall provide a foundation for conservation of valuable forest areas. But the method has received much critique, amongst others the criteria for identifying natural forest and forest of high value. The aim of this analysis was to investigate whether it is possible to separate different qualities of older managed forest with differences in historic logging with the use of NiN and the variable of condition of stand dynamics which is intended to separate natural forests from managed forests. Furthermore, an investigation of differences in epiphytic lichen biomass in two forest types both categorized as older managed forest was conducted. The analysis was based on data collected from established research stands in the Hurdal area north of Oslo in the summer of 2017, as well as data from earlier external studies. The results show more lichen biomass in forest that had only been subject to selective dimension logging (near natural forest) than in forest that had been clear cut (old managed forest). This was due to structural differences where the near natural forest was more open than the managed forest. This shows that the near natural forest differs from managed forest and is valuable even though it did not qualify as natural forest as defined in NiN. The NiN-assessment resulted in only three of 55 assessed stands being identified as natural forest according to the natural forest criterium, even though several stands did fulfil more than one of the minimum values of natural forest elements required and therefore showed valuable qualities for biodiversity. This indicates that the criterium for natural forest is too strict in relation to the objective of identifying high value forest for conservation. M-NF

The construction of road infrastructure leads to negative effects on animals, such as wildlife-vehicle collisions, fragmentation, degradation of habitats and increased levels of disturbance. Amphibians are of a special concern, as they depend on different habitats (terrestric and aquatic) to complete their life cycle. Crossing structures (such as overpasses and underpasses) are important to mitigate these negative effects on mobile animals. The use of crossing structures is poorly investigated in Norway, especially with respect to impacts on amphibians and small game (such as mice and rats). It is important that above mentioned crossing structures are functional, not only because they are costly, but for ethical reasons as well. This study has two main goals. Firstly, I estimate the functionality of five different underpasses − for amphibians and small game − with wildlife cameras. I also include data from big game, but what makes my study highly innovative, is the quantification of amphibian and small game activity in Norwegian underpasses. These underpasses are located in southeast Norway. In total, I registered 16 different species and 1890 observations of animals, of which 431 of these were mice, 59 rats and 145 amphibians. Differences in activity among localities was significant and four out of five underpasses were frequently used. In contrast, one out of five underpasses were only sporadically used. The other main goal of this study was to discuss animal ethical perspectives in relation to road construction, animal lives and wildlife-vehicle collisions. In this context, I highlight science about animal pain, and also the thoughts of moral philosophers about the intrinsic value of animals. Animal ethics is in many ways part of both applied ecology and conservation biology, and should therefore be a larger part of future decisions. Bygging av veier medfører negative effekter for dyrelivet i form av viltpåkjørsler, fragmentering, forringelse av leveområder og økte forstyrrelser. Her er amfibier spesielt utsatt ettersom de bruker ulike habitater for å fullføre sin livssyklus. Viltpassasjer – i form av over- og underganger – har blitt konstruert flere steder for å motvirke noen av de negative effektene av veikonstruksjon på dyrelivet, slik som fysiske barrierer og påkjørsler. Bruken av viltpassasjene er lite undersøkt i Norge, spesielt med tanke på småvilt og amfibier. Det er viktig at viltpassasjene er funksjonelle, ikke bare fordi de er kostbare tiltak, men også av dyreetiske grunner. Oppgaven min har to hovedmål. Først og fremst estimerer jeg funksjonaliteten til fem ulike viltunderganger for småvilt og amfibier ved hjelp av viltkameraer. Her inkluderer jeg også data på storvilt, men det som gjør min oppgave nyskapende, er at det er første gangen at det har vært fokus på å kvantifisere aktiviteten til amfibier og mindre småvilt (som mus og rotte) i forskjellige norske viltunderganger. Disse undergangene er lokalisert i Sørøst-Norge. Totalt observerte jeg 16 forskjellige arter og 1890 registreringer, hvorav 431 av disse var mus, 59 rotte og 145 amfibier. Det var signifikant forskjell i aktiviteten mellom undergangene og fire av fem underganger ble flittig brukt, mens én av undergangene ble veldig lite brukt. Det andre formålet med oppgaven er å drøfte dyreetiske betraktninger knyttet til veikonstruksjoner, dyreliv og viltpåkjørsler. Her tar jeg blant annet for meg hva forskning viser om dyrs evne til å føle smerte i tillegg til hva kjente moralfilosofer mener om dyrs egenverdi. Dyreetikk er på mange måter en del av både den anvendte økologien og bevaringsbiologien, og bør derfor bli tatt mer hensyn til i fremtiden. M-BIOL

The alien, invasive species Bunias orientalis and Lupinus polyphyllus are in expansion in Norway and pose an ecological threat to native species. The species form large and dense populations on wastelands, previous agricultural land, and along linear, anthropogenic structures like railways and road sides. L. polyphyllus reproduce primarily by seeds, but also via vegetative propagation. One plant can produce hundreds of seeds, which can be viable after 50 years. B. orientalis produce 200-5000 seeds per individual, and reproduce by seeds only. The aim of this study was to improve knowledge on seed dispersal ability of Bunias orientalis and Lupinus polyphyllus and to document their flowering and seed production phenology, which are relevant for future control of the species. The seed dispersal and phenology study were implemented at two sites of L. polyphyllus in Ås, and two sites of B. orientalis in Oslo. Three source populations of 3x3 m2 were fixed randomly at each site. A total of eight seed traps were placed in a straight line in the cardinal directions north - south at each side of the source population in respectively 0.5, 1, 2 and 4 meters distance. The source population functioned as a source for seed dispersal, as every individual of the target species outside, were cut down. The seed traps were emptied throughout the assessment period. Estimates of total mean seed production per source population were calculated to evaluate how much seeds were caught in the traps. The significance of cardinal direction regarding seed dispersal, and the species-specific differences in seed dispersal distances per species, were tested statistically. To obtain information on the distribution of seed dispersal throughout the season, when the predominance occurred and how long it transpired, fruits were counted on three individuals per source population each week. The dispersal of fruits was recorded through the decrease in fruits per individual. Simultaneously, the pods and siliquae were divided into the stages of flower, unripe, medium ripe and ripe to document the phenology of the target species. The phenology study provides approximate estimates of when the life cycle events can be presumed to occur for populations of the target species in SE Norway, though it vary annually. Control and management of the species should take place during the inflorescence, which in this study ended around 15.07 for both species. The results indicated that the ripening process and dispersal of fruits of the target species were very reciprocal to climate and habitat factors, and will probably be expedited with future climate changes. Despite extensive seed production in all source populations, there were few seeds caught in the traps, mostly at 0.5 and 1 meters distance. There was a significant difference in seed dispersal to the different trap distances for L. polyphyllus, however, not for B. orientalis. The occurrence of insect and rodent activity around the traps at the sites of L. polyphyllus, indicated that the species were dependent upon zoochory. Furthermore, compared to from the target species, there were more seeds of other species caught in the traps, at all sites. This was also, presumably due to that seeds of the target species were transported outside the traps, considered that L. polyphyllus and B. orientalis have a successful expansion, and mainly reproduce by seeds. The results indicated that the seed dispersal ability of L. polyphyllus and B. orientalis not was very efficient. Dispersal are probably highly effectuated by slipstreams from e.g. vehicles or trains, and germplasm being transported by vehicles or humans contribute to spread. The target species would not have been so effectively dispersed and managed to pose a threat to endemic species, if it was not for human intervention, and is otherwise dependent upon zoochory for dispersal of seeds. M-NF

Climate change is expected to cause a transformation from spruce to beech dominated forests in a large part of southeast Norway. A shift in dominating tree species may have a large effect on the factors controlling the rate of litter decomposition, and consequently the rate of greenhouse gas induced climate change. To better understand how this transformation will influence the carbon balance in these forest ecosystems, we need to understand the factors controlling decomposition. A litter bag experiment was conducted in neighbouring beech and spruce forests in southeast Norway. Litter bags with beech and spruce litter was placed in manipulated litter layer plots in the two forest types. This was done to investigate the relative importance of litter type, forest type, the litter layer, and their interactions as determinants of litter decomposition rate. The litter layer manipulations were: transplanted beech litter, transplanted spruce litter, and removal of litter. Un-manipulated plots served as control. After incubation, litter mass loss and nitrogen release as a function of mass were calculated. The interaction between litter type and forest type had a significant effect on mass loss. In the spruce forest, spruce litter lost significantly more mass than beech litter, but there were no significant differences between the two litter types when placed in the beech forest. Litter layer transplantations also had significant effects. More mass was lost when litter was placed in the transplanted beech compared to the transplanted spruce and removal plots. Individually, neither the litter type nor the forest type had significant effects on mass loss. This indicates that litter type in the litter layer is more determining for the decomposition rate than forest type. Higher mass loss in plots with beech compared to spruce in the litter layer indicates that a transformation from spruce to beech forests will likely lead to a faster decomposition rate. This may especially be true in the transitional phase when the forests are mixed. The implication of a transformation from sprue to beech dominated forests may thus be a faster release of CO2 to the atmosphere, contributing to increased global warming. Det antas at klimaendringene vil føre til et skifte fra gran- til bøkedominerte skoger i store deler av sørøst-Norge. Et skifte i dominerende treslag kan ha stor innvirkning på faktorene som kontrollerer hastigheten til strønedbrytningen, og dermed hastigheten til fremtidige klimaendringer. For å øke forståelsen av hvordan et slikt skifte vil påvirke karbonbalansen i disse økosystemene, må vi øke kunnskapen om faktorene som kontrollerer nedbrytningshastigheten. Et strøposeeksperiment ble utført i en gran- og en bøkeskog som grenser til hverandre i sørøst-Norge. Strøposer med bøkeløv og grannåler ble plassert i ruter med manipulert strølag i de to skogtypene. Dette ble gjort for å undersøke den relative viktigheten av strøtype, skogtype og strølaget, samt deres interaksjoner som bestemmende for nedbrytningshastigheten. Manipulasjonene i strølaget var: transplantert bøk, transplantert gran og fjerning av strø. Umanipulerte ruter fungerte som kontroll. Tap av masse fra strøet og frigjøring av nitrogen som en funksjon av masse ble beregnet. Interaksjonen mellom strøtype og skogtype hadde en signifikant effekt på tap av masse. I granskogen var det et signifikant større tap av masse fra granstrøet enn fra bøkestrøet, men det var ingen signifikant forskjell mellom de to strøtypene i bøkeskogen. Strølagstransplantasjon hadde også en signifikant effekt. Mer masse gikk tapt da strøet ble plassert i ruter med transplantert bøk enn i ruter med transplantert gran og ruter der strøet hadde blitt fjernet. Derimot hadde verken strøtype eller skogtype individuell effekt på tap av masse. Dette indikerer at strøtypen i strølaget har større betydning for nedbrytningshastigheten enn skogtypen. Den raskere nedbrytningen i ruter med bøk sammenlignet med gran i strølaget viser at et skifte fra gran- til bøkeskog trolig vil føre til en raskere nedbrytningshastighet, spesielt i blandingsskogene som oppstår i overgangsfasen. Resultatene tyder på at et skifte fra gran- til bøkeskog vil føre til et større utslipp av CO2 til atmosfæren, som vil bidra til økt global oppvarming. M-ECOL

Glaciers are melting and retreating on a global scale due to climate change. Rapid glacier retreat leave behind large areas of barren ground, in which primary succession and plant establishments can start. However, a typical feature in glaciers forelands is that vascular plants are lacking in a distinct area close to the front of melting glaciers. To explain the absence of plants in this unpopulated area, I have conducted seed sowing, transplantation, and soil seed bank experiments to explore the establishment and survival success in eight pioneer species (i.e. Saxifraga stellaris, Poa alpina, Poa arctica, Oxyria digyna, Arabis alpina, Cerastium cerastoides, Arabis petraea and Beckwithia glacialis) along a chronosequence in the glacier foreland of Hellstugubreen in Jotunheimen, central Norway. Interestingly, my results from the field experiments showed that the study species generally had significantly higher germination success, survival, vitality and better performance in the unpopulated area nearest to the glacier as compared to in the positions furthest away from the glacier. Moreover, the soil seed bank experiment revealed that there was no seed bank in the unpopulated area closest to the glacier front. From these results, I draw the main conclusion that dispersal limitation, and not germination- and survival limitations, explained the absence of plants in the unpopulated area in front of the Hellstugubreen glacier. In addition, to understand what environmental factors that limits the growth of the important pioneer species, i.e. A. alpina, I conducted a growth experiment under four controlled combinations of temperature and light conditions. Here, my results showed that A. alpina grew better under cold and high light conditions, and that the proportion of fertile individuals were significantly reduced with increased temperatures. Isbrear smeltar og trekkjer seg tilbake globalt grunna klima endringar. Når isbrear trekkjer seg raskt tilbake blir det lagt att eit stort område av naken grunn der primærsuksesjon og plantekolonisering kan byrja. Men eit typisk karakteristikk på isbre-forland er mangelen på vaskulære planter i eit klart område framom isbrefronten på ein smeltande isbre. For å forklare manglelen på planter i detta område utan busetnad, gjorde eg eit såfrø-, transplanterings- og jord frøbank eksperiment for å utforske etablering og overlevingssuksess hjå åtte pioner artar (som Saxifraga stellaris, Poa alpina, Poa arctica, Oxyria digyna, Arabis alpina, Cerastium cerastoides, Arabis petraea and Beckwithia glacialis) langs ein tidsserie i isbreforlandet av Hellstugubreen i Jotunheimen, i sentral Noreg. Mine resultat frå felteksperimenta viste interessant at studieartane hadde generelt signifikant høgare spiringssuksess, overleving, vitalitet og betre yting i det området utan busetnad nærmast isbreen, samanlikna med i posisjonen lengst unna isbreen. I tillegg, viste jord frøbank eksperimentet at det var inga frøbank i det området utan busetnad nærmast isbreen. Frå dessa resultata, trakk eg hovudkonklusjonen at det var spreiingsavgrensing, og ikkje spirings- og overlevingsavgrensing, som forklara mangelen på planter i det området utan busetnad ved fronten av Hellstugubreen isbre. I tillegg, for å forstå kva miljøfaktorar som avgrensar vekst hjå den viktige pionerarten A. alpina, gjorde eg eit veksteksperiment under fire kontrollerte kombinasjonar av temperatur og ljos forhold. Her viste resultata at A. alpina veks betre under kaldt og høgt ljos forhold, og at andelen fertile individ vart signifikant redusera med høgare temperatur. M-ECOL

The environmental effects that determine the altitude of the tree line have been discussed for a long time. Alpine ecosystems are known to be particularly sensitive to climate warming, and both biotic interactions as well as abiotic factors, such as temperature and precipitation, are important shapers of plant alpine communities. Identifying the rate of response of the alpine tree line to changes in climate is crucial for understanding and predicting the future of alpine species as the world gets warmer. This study took place in the nature reserve of Trillemarka-Rollagsfjell, located in Buskerud County, south-eastern Norway. The goal was to see if there was an observable correlation between both summer temperature and precipitation, and the recruitment and growth of Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and birch (Betula pubescens) above the timberline in south-eastern Norway. Both climatic data and physical samples were collected. The samples were all collected from two areas, between late July and early September 2015. For each area, ten different plots of 10x10 meters were established and sampled. The climate data was gathered from the Norwegian Meteorological Institute. The results showed no clear correlation, but depicted a large local variance in annual growth and recruitment, both for each site and in-between the species. In addition, an increase both in yearly growth and recruitment seemed to be evident, which could indicate that an increase in tree line altitude is happening. The results appear to underline the importance of microhabitat and small-scale disturbances, such as grazing and snow-cover, in regard to individual establishment success and growth rate. As it stands, the results show that neither temperature nor precipitation alone are the most limiting for the trees in the tree line ecotone in Trillemarka-Rollagsfjell.

Forest soils represents the largest terrestrial carbon (C) pool and thus play a critical role in the global C cycle. Predicted climate change is expected to change the size of forest soil C pools by driving a shift in vegetation that will fundamentally transform the ecosystem. It is assumed that the nemoral deciduous tree species European beech (Fagus sylvatica L.) will outcompete the boreal coniferous tree species Norway spruce (Picea abies (L.) Karst.) in southeastern Norway. The aim of this study was to investigate differences of C storage in the subsoil between a beech forest, a first-generation spruce forest located on a site of former beech forest, and a second-generation spruce forest. Measurements of C and nitrogen (N) concentration, C/N ratio, amount of fungal biomass and pH were conducted along fine-scaled subsoil profiles. Ergosterol was used as a proxy to estimate fungal biomass. The study showed that concentrations of C, N and free ergosterol, C/N ratio and pH varied significantly with soil depth, and the forests caused significant vertical differences in C, N and free ergosterol concentration with soil depth. However, there was no significant difference in total C storage between the three forests. The findings contradict the conventional and wellestablished assumption that spruce forests soils store more C compared to beech forest soils, and that this may be ascribed to various site conditions. Skogsjord utgjør de største karbonlagrene i biosfæren på land og spiller dermed en avgjørende rolle i den globale karbonsyklusen. Forventede klimaendringer antas å føre til forandringer i størrelsen på karbonlagrene i skogsjord ved å forårsake en vegetasjonsendring med påfølgende fundamentale økosystemendringer. Det er forventet at europeisk bøk (Fagus sylvatica L.) vil utkonkurrere norsk gran (Picea abies (L.) Karst.) i Vestfold, Norge. Hensikten med denne studien var å undersøke forskjeller i karbonlagring mellom en bøkeskog, en førstegenerasjon granskog som er plantet på et område hvor det tidligere var bøkeskog, og en andregenerasjon granskog. Målinger av C- og nitrogen (N)-konsentrasjon, C/N ratio, mengde soppbiomasse og pH-verdier ble utført langs fin-skalerte dybdeprofiler av mineraljorda. Ergosterol ble brukt som en proxy for å måle soppbiomasse. Studien fant at konsentrasjoner av C, N og fri ergosterol, C/N ratio og pH varierte betydelig med jorddybde, og skogene medførte betydelige vertikale forskjeller i C-, N- og fri ergosterolkonsentasjon med jorddybde. Men det var ingen signifikant forskjell i total karbonlagring mellom skogene. Resultatene av dette studiet skiller seg fra den konvensjonelle og veletablerte antakelsen om at granskog lagrer mer karbon i jorda enn bøkeskog. M-NF

Sammendrag: Stammeskiver fra stubber etter hogst og levende og døde furutrær med brannlyrer ble samlet inn fra fem innsamlingsfelt (300-400 daa) for å forklare brannhistorien på Varaldskogen (50 km2) sørøst i Norge. En 730 år lang tidsperiode og 62 ulike brannår ble datert dendrokronologisk fra 64 stammeskiver. Det ble funnet to tydelige endringer i brannregimet i perioden. (1) Fra få branner før ca. 1600, som brant seint i vekstsesongen, til en hyppigere brannfrekvens og flere branner som brant tidlig i vekstsesongen i perioden 1600-1850. (2) En reduksjon i antall branner rundt 1850 til ingen branner etter 1870 frem til i dag. Gjennomsnittlig intervall mellom brannårene er beregnet til 24 år. Andre studier i Fennoskandia har funnet det samme mønster i brannregimet, men endringene har skjedd til ulike tider. Mye tyder derfor på at økningen i brannfrekvens skyldes menneskelig antenninger med formål om å dyrke mat og forbedre utmarksbeitet. Endringen av brannregimet fra mange branner til få blir ofte knyttet til økte tømmerverdier. Til tross for et aktivt skogbruk på Varaldskogen siden tidlig 1700-tallet besto brannregimet med mange branner helt frem til slutten av 1800-tallet. Dette kan trolig forklares med områdes kulturhistorie. Mange husmenn var etterkommere av finske innvandrere. Disse hadde en jordbrukskultur som innebar å brenne svedjer. Hovedgrunnen til at brannfrekvensen forble høy var trolig at grunneiere aksepterte noe svedjebrenning for å sikre arbeidskraft på eiendommen. Abstract: Fire-scared wood samples of Scots pine were collected from five sites of 30-40 ha to reveal the fire history at Varaldskogen (50 km3), in southeastern Norway. A 730 years period and 62 different fire-years were dated dendrochronologically from 64 wood samples. Two distinct changes in fire regime were found in the period. (1) From few fires before ca. 1600, which burned late in the growth season to an increased fire frequency more often with early seasonal fires in the period after (1600-1850). (2) A reduction in the number of fires around 1850 to no fires after 1870. Mean fire interval in single samples was 24 years. Other studies in Fennoscandia have found the same pattern in fire regime, but the changes may have happened at other times. The results indicate that the increase in fire frequency was caused by slash-and-burn cultivation and to improve the conditions for livestock grazing. The decreasing frequency of fires is often associated with increased timber values. Although active forestry was common in the 16. century at Varaldskogen the fire regime did not change until the end of the 17. century. This was possibly an agreement between the inhabitants and the landowners. Many of the inhabitants was descendants of Finnish immigrants who lived as smallholders. The Finnish descendants in the area was known to use slash-and-burn techniques in their farming culture. Despite the risk of damaging the timber, the landowners may have allowed the smallholders to continue the slash-and-burn cultivation practices to secure workers for the farm. M-SF

Traditional cultural landscapes are threatened in Europe due to changed land-use practices. However, the historical extent of this human land-use practice is not yet fully known. This thesis describes the vegetation history and human land-use at the summer farm Finnerudseter located in Nordmarka, the forested area north of Oslo. Historical documents states that the human land-use goes back to AD 1600 at this summer farm. However, extensive human landuse at Finnerudseter most likely predates AD 1600, and pollen and charcoal from a small forest hollow situated near Finnerudseter were analysed to reconstruct the local vegetation history at the site. The aims of the study was to document the general vegetation history, and to estimate in how long time and to what extent human land-use have taken place at Finnerudseter. The period investigated covered the vegetation history at the site from c. 2587 to 1334 cal. yr. BP (cal. yr., and all following dates are also presented as cal. yr.). Based on the results from the pollen count, the vegetation history was divided into 4 vegetation zones. Zone I Pinus period (c. 2587–2452 BP); Zone II Betula–Pinus–Alnus period (c. 2425–2237 BP); Zone III Betula–Pinus–Alnus–Picea period (c. 2183–1779 BP); Zone IV Picea–Betula period (c. 1630–1334 BP). Pinus was the dominant tree species from c. 2587–2452 BP. In addition, Picea established locally at the site during this period, c. 2479 BP. A local fire c. 2452 BP led to a shift in the tree species composition with a reduction in Pinus and increase in the pioneer trees Betula and Alnus. The finding of a single pollen from Cerealia may indicate small-scale cultivation c. 2425 BP. Small-scale livestock grazing seem to have been present from c. 2290 BP. Picea increased in amount c. 2183 BP, and the varying presence from c. 2183 to 1779 BP seem to be due to further forest clearing and human land-use. Picea became the dominant tree species c. 1630 BP, at the same time as human impact at Finnerudseter increased. The results clearly showed that human impact at Finnerudseter predated AD 1600 and probably started already in the Early Iron Age. However, there is gap from c. 1334 BP to 350 PB (AD 1600), which has not been investigated in this thesis, further research is therefore needed to get a more complete vegetation history at the summer farm Finnerudseter. M-ECOL

The aim of this study was to investigate species related differences in soil carbon and nitrogen concentration, pH and condensed tannin content in topsoil’s in Norway spruce (Picea abies) European beech (Fagus sylvatica) forests. Samples were collected in two Norway spruce sites and one old-growth European beech forest in South-Eastern Norway. Research on spatial distribution and differences in soil properties in beech and spruce has been studied in the temperate zone. However, no comparative studies have investigated differences in secondary compounds in topsoil’s between European beech and Norway spruce forests. This might be of importance as larger tannin structures decompose slower, and are believed to be able to remain in the soil over time and potentially add to the stable carbon pool found in boreal forest soils. Also, in the literary studies done in conjunction with this thesis, no research showing differences in topsoil content of condensed tannins between spruce and beech where to be found. Topsoil samples were collected in old-growth beech forest, a Norway spruce forest growing in an area previously dominated by beech, and in a younger primary Norway spruce forest. The samples were analysed for carbon and nitrogen concentration, C/N ratio, pH and total condensed tannin content. Topsoil samples were collected at spatial intervals of 2 meters, with samples being taken up to 10 meters in all cardinal directions from a centre point. The results suggest that a change from spruce to beech forest will not induce significant changes to the concentrations and distribution of the measured soil properties. Few significant differences in the measured variables were found between the forest sites, and the highest variation was found within forest sites. This indicates that other factors than dominating tree species are more influential for small-scale spatial variations in soil properties. However, the results for spatial distribution of the measured variables does not constitute evidence that the parameters for soil properties would not show temporal variation with a shift towards more beech forest. To conclude further on this, more sampling sites and a larger number of samples would have to be included in the model. M-BIOL

Freshwater wetland restoration is intended to replace both area and function as part of compensatory mitigation, including restoration of biogeochemical soil processes. This study examined the amount of carbon (C) and nitrogen (N) found in the soils of twenty-two wetland restoration sites in the Puget Sound region of Washington State, USA, and assessed whether vegetative strata, hydrologic regime, hydrogeomorphic class, and soil type influenced C and N accumulation rates. The wetland restoration sites were constructed between 1993 and 2013, representing a 20-year chronosequence with multiple sites constructed each year. Soil samples and data regarding vegetative strata, hydrologic regimes, and soil characteristics were collected in July and August 2015, and additional soil samples and hydrologic data was collected in December 2015. Overall, total C decreased over time, with an estimated rate of -0.70 Mg C ha-1 yr-1, while total N increased slightly over time (0.004 Mg N ha-1 yr-1). Soil characteristics such as color and texture were used to divide soils into upper and lower soil layers. The soil layer distinction was a significant variable in assessing trends of C, N, and bulk density (g cm-3). Bulk density (gr cm-3) was found to generally increase with increasing time. There were no statistically significant relationships between the amount of C or N in the soils and hydrogeomorphic class, hydrologic regime, or soil type. Nevertheless, C:N ratio had a negative relationship with increased age, suggesting that C loses were greater than N losses through time. This study reports the surprising result that rather than increasing through time (as is common in natural ecosystems), mitigation processes can lead to an initial decrease through time in average soil C and N. The results suggest that C and N are not specifically influenced by distinct restoration site design components (i.e., vegetation, hydrology, soil type), but that soil amendments added to wetland restoration sites may influence soil biogeochemical processes in unexpected ways. M-ECOL