This study was made in an attempt to give the forest research centre Mógilsá a producedtetratherm map and a better understanding of how topography and temperature influencethe growth of two tree species. The digital tetratherm map model, covering the northernpart of Iceland, was developed to investigate the correlation between tetratherm and thegrowth of Picea sitchensis and Larix (sukaczewii + sibirica). The study confirms theusefulness of digital terrain models in providing data for a lot of different factors and forthe tetratherm model. Hopefully will this tetratherm map be used in future studies.Secondly, investigations were made correlating the growth of the two species againsttopographic factors representing height above sea level, distance to the sea, slope andtopex. Thirdly, investigations were made comparing the aspect and the ground shape tothe growth.The growth rate of Larix had strong significant correlations to the tetratherm and thedistance to the sea- factors.

This literature study concerned the use and function of the radioactive isotope carbon-14, as a dating method of organic material, within the scientific field of physical geography. In this report it is presented the need of atmospheric calibration curves and the development of these as a necessity to translate carbon-14 years to calibrated calendar years. A number of common age-depth models that is used to give an approximation of an accumulation sequence and its related dates over the actual time period in different natural archives is presented and discussed. Different problems that commonly occur when age-depth models are utilized as for instance reservoir effects, contaminations or other age deviations are addressed and analyzed. The software CLAM in presented and discussed and was also used to produce age-depth models.

This survey was made during the summer of 2004 and the spring of 2005, on commission from the National Board of Forestry. The aim of this report was to investigate how often Norway spruce (Picea abies L. Karst), is planted on poor Scotch pine (Pinus Silvestries) sites and if it affects the yield of Norway spruce? In order to investigate this, data from 29 stands witch had a lower site index than T24 was collected. The investigated stands were situated in the southern-eastern Sweden. In 20 plots in each stand, the highest tree, age, number of seedlings, site index and tree species per stand were measured.

A secondary and a pioneer tree species can with advantage be included in a mixed stand to increase the use of sunlight. Nitrogen-fixing plants have been shown to increase the supply of nitrogen in the soil by, for example, litter fall. This deposition acts as a biological fertilization, which may be used by non-fixing plants. Alder is a nitrogen-fixing, pioneer tree species that loses its nitrogen-rich leaves late in the autumn. The aim of this study was to examine the effect on the total volume of production, when different proportions of nitrogen-fixing Alder were part of spruce stands.

The spruce bark beetle (Ips typographhus) is one of the 25 000 species of insects in Sweden, an insect of great economic importance because it can alone terminate forest of high value. During the past decade, insights of climate change received with increasing attention. If the future brings a milder climate in the north and therefore a longer growing season, one would think that it would only affect the forestry to the better? Yet in recent time, outbreaks after storm felling seems to occur more frequently. The Spruce bark beetle ruins millions of cubic meter of Norway spruce (Picea abies) in Sweden alone, with more frequent storm felling and a larger amount of wind thrown threes in the forests there will also be room for an advancing reproduction.

Bark-stripping by red deer (Cervus elaphus) cause extensive damage to economically valuable spruce trees (Picea abies) in Swedish forests. The underlying causes for bark-stripping are not fully understood, and the frequency and severity of damage unpredictably differ between regions. In this study, I investigated if landscape structure (e.g. agricultural dominated landscape opposed to forest dominated landscape), forage availability, population density and disturbance (e.g. roads and settlements) affect bark-stripping frequency.

Megalaria grossa is classified as Near treatened on the Swedish Red List. It is also a so called signals spieces, e. g. a spieces that function as an indicator, signalling a forest that is worthy of protection. The aim of this study was to clarify the status at selected localities in the province of Uppland and Gotland.

The forest property Fagerdal 2:10 was donated to the Swedish University of Agriculture in 1995 by Erik Rönnberg. The dominating species is Norwegian spruce (Picea abies) and the average age is high due to selective cutting. The aim of this study has been to analyze how the forest on the property should be managed and demonstrate how a better estimated forest data affects the future management. The impact of the management on the carbon stock of the property was also examined. A forestry plan established in 2009 by Skogssällskapet was used as a basis for the analyses.

Biodiversity is essential for human well-being and it is defined as the genetic variation within species and the variety of species and ecosystems. Biodiversity provides several ecosystem services which are necessary for human beings but there are different threats towards the biodiversity. The biodiversity linked to the forest in Sweden are threatened, about 50 % of the red-listed species in Sweden are associated with forests. This is linked to the commercial exploitation of the boreal forest in Sweden which started 200 years ago. The forestry the last 50 years, with clear-cuts, have contributed to a fragmented forest landscape.

High levels of Hg in fish in Swedish lakes have been a problem along time in Sweden. The major concern is production and accumulation of the most toxic form of mercury; methyl mercury (MeHg). Consequently, in about half of our 83 000 lakes fish contain concentrations above the recommended limit for human consumption of 0,5 mg mercury per kg fresh weight (most of it in the form of MeHg). Consumption of fish containing too high levels of MeHg may cause problems for both humans and animals. Three major sources of MeHg in surface waters are: 1) runoff from terrestrial areas, 2) deposition from the atmosphere, and 3) internal production of MeHg in lakes and streams. The aim of this study was to investigate the effect of clear-cutting on the concentration of Hg and MeHg into draining streams.

Sedan täckrotplantornas introduktion i slutet av 1960 talet har man försökt att hittaodlingsätt som minskar rotformationer (t ex rotsnurr och rotknän) hos plantorna. Närrötterna är deformerade ökar risken för instabilitet, stamkrökar, tjurved, rotröta ochrotbrott hos trädet. Många olika behållartyper har tagits fram under åren. En av desenaste metoderna för att undvika deformationer går ut på att odlingsbehållarnas insidorbeläggs med en kopparbaserad färg. Metoden innebär att rötterna, då de kommer emotden belagda kanten, slutar att växa på längden, roten går som i dvala.

Peat  lands  are  a  great  potential  resource  for  increased  forest  growth  in  Sweden, there  are  approximately  6.5  million  hectares  of  peat  lands,  whereof  around  70% produce less wood than one m3sk/ha and year and are therefore classed as forest waste  land.  There  are  over  200  000  hectares  of  peat  land  that  is  already  drained and  wooded,  and  that may  be  suitable  for  fertilization.  Forest  production  on  peat soils  usually  requires  drainage  and  fertilization.  Dewatering  requires  ditching  the area, so that the roots can have access to oxygen. Nitrogen is often abundant in the peat but other nutrients; especially potassium is in short supply. The  purpose  of  this  work  was  to examine  the effects  of  potassium  fertilization  on the  growth  of  spruces  that  were  planted  on  drained  peat  land  and  how  different amount of fertilizers affects the growth. Potassium deficiency is strongly growth inhibiting, since potassium is important for substance  transport  in  the  tree.  Potassium  is  also  important  for  the  carbohydrate formation, and because increasing the sugar content of the cells constitutes a lower freezing temperature does potassium availability in the soil play a major role in the winter  resistance  of  many  species.  Potassium  is  not  found  in  any  organic compounds in the tree, but is present in cell and tissue fluids. A fertilization trial was started in 1978 in Siljansfors Experimental Forest. The plots in the experiment were fertilized with different amounts of potassium and one plot was  left  without  fertilization.  All  plots  that  were  fertilized  with  potassium  grew considerably better than the unfertilized plot. The difference in production between the unfertilized plot and the plot that received the most potassium was 7.2 m3sk/ha and year. The unfertilized plot can still be classified as waste land. The theoretical production capacity was estimated using a Swedish system for site quality  estimation  of  wetlands  after  ditching  (dikningsbonitering).  The  plot  with most  potassium  produced  after  fertilizationaproximately  in  level  with  theoretical estimations.  Key  words:  Peat  land,  Fertilization,  Ditching,  Growth,  site  quality..

Kravet på användning av förnyelsebara energikällor ökar, år 2020 ska de stå för 50 % av all energianvändning. För att öka utbudet av skogsbränsle och utveckla bränslekedjan i hållbar riktning måste ny kunskap och teknik utvecklas för intensivodling av snabbväxande trädslag på skogsmark. Mot denna bakgrund har ett trädslagsförsök anlagts i södra Sverige, med syftet att på sikt besvara frågorna kring intensivodling av skog. Avgången hos plantor är som störst under de första åren efter plantering för att därefter plana ut vid cirka 10 års ålder. Överlevnaden under föryngringsfasen beror i hög grad på vilken utsträckning snytbaggar förekommer samt vilka åtgärder man vidtagit för att få så bra etablering av plantorna som möjligt. Syftet med studien var att undersöka överlevnaden, skador och höjdutvecklingen för de ingående trädslagen tall, gran, björk, hybridasp och poppel, 1 till 2 år efter plantering. Resultatet visade en lägre överlevnad andra året jämfört med första året. Detta berodde delvis på en okänd skada hos poppeln, som troligtvis också hade inverkan på höjdutvecklingen.

Each year, Heterobasidion spp. is a major cause of economic losses to forestry in the northernhemisphere, including Sweden. New results indicate that pre?commercial thinnings could be at riskfor Heterobasidion spp. infections.

This study is about how changed light conditions induce dormancy in plants. It is divided in two parts. First a literature study where quantification of light, the concept dormancy, photoperiod and light quality are discussed. Second an experimental part, where the importance of light for sprouting capacity in root buds of perennial sow thistle (Sonchus arvensis L.) is investigated.In the science in how flowering in plants are induced the concepts short day/long day plants and light dominant/dark dominant are well-established. These concepts can also be applied to how light induce dormancy in plants.