1 |
Developing the silviculture of continuous cover forestry : using the data and experience collected from the Glentress Trial AreaMacKintosh, Hamish January 2013 (has links)
Continuous Cover Forestry (CCF) has become increasingly popular since the early 1990s. CCF utilises several silvicultural techniques in order to promote and enhance forest structural diversity and favours natural regeneration. As CCF is relatively new to the UK there are still areas of knowledge regarding management interventions that need to be improved upon. This study utilises simple models, seedling physiology and a hybrid gap model and applies them to the Glentress Trial Area which has been under transformation from even-aged forestry since 1952. These efforts have led to an improved understanding of thinning interventions and the effects they may have on future stand structure. Since the formation of the Forestry Commission in 1919, clearfell-replant forestry has been the main form of management practiced in the UK. CCF management differs in several respects and is commonly practiced using expert knowledge in Continental Europe. In the UK the knowledge-base is still growing and therefore simple models can prove useful for guiding management. This study investigated the use of the idealised reverse-J and the Equilibrium Growing Stock (EGS). This study found that the reverse-J shaped diameter distribution is maintained at the Trial, Block and sub- Block scale indicating that an irregular structure is being approached. In addition, the diminution coefficient, a parameter of the reverse-J distribution, falls within values typical of continental Europe. Comparison of the actual diameter-frequency distribution against an ideal reverse-J distribution can inform both thinning intensity and which diameter classes to target. The EGS, which is a volume–diameter distribution, examines standing volume and how that volume is distributed across three broad diameter classes. Typical distributions from the Swiss Jura indicate that percentage volume should be split 20:30:50 across diameter classes. The EGS analysis showed that standing volume in the Trial Area is much lower than European values at just 174 m3 ha-1. In addition, the classic 20:30:50 percent split was not observed. The 1990 data set showed a 49:43:8 distribution but by 2008 it was 40:41:19. As natural regeneration is favoured in CCF a better understanding of seedling physiology is essential. This study established open (15-35 m2 ha-1) and closed canopy plots (>35 m2 ha-1). Plot characteristics were recorded and then seedlings were selected for physical measurements, chlorophyll fluorescence and gas-exchange measurements. There were clear differences between the physical characteristics with a mean Apical Dominance Ratio (APR) of 1.41 for the open plots and 0.9 for the closed plots which is consistent with previous studies suggesting an APR of 1 is needed for successful regeneration. The chlorophyll fluorescence measurements showed a linear relationship with PAR. However, although the results of the gas-exchange measurements showed an increase in photosynthetic rates with PAR for open plots, there was no obvious relationship in the closed plots. As a result, the study did not find a linear relationship between photosynthetic rate and chlorophyll fluorescence. Finally a complex, hybrid gap model was used to investigate the effects of management on predicted future stand structure. The hybrid gap model, PICUS v1.41, was parameterised for Sitka spruce. The model was used to explore different management scenarios on stand structure over two time periods; 1954-2008 and 1952- 2075. The output from the group selection with underplanting scenario, which resembled the actual management, produced realistic output that was comparable to the stand characteristics measured during the 2008 assessment. The output from the 1952-2075 runs suggested that thinning to a residual basal area suitable to allow natural regeneration (<30 m2 ha-1) or a group selection with underplanting were the best management options for maintaining structural diversity.
|
2 |
Carbon Balance Implications of Forest Biomass Production PotentialPoudel, Bishnu Chandra January 2014 (has links)
Forests in boreal and temperate forest-ecosystems have importance for carbonbalance since they sequester large amount of atmospheric carbon by uptake ofcarbon-dioxide during photosynthesis, and transfer and store carbon in the forestecosystem. Forest material can be used for bio-fuel purposes and substitute fossilfuels, and supply wood products, which can replace carbon-and-energy-intensivematerials. Therefore it is vital to consider the role of forests regarding today´s aimto mitigate climate change. This thesis assess (i) how climate change affects futureforest carbon balance, (ii) the importance of different strategies for forestmanagement systems, and biomass production for the carbon balance, (iii) how theuse of forest production affect the total carbon balance in a lifecycle perspective,and (iv) how the Swedish carbon balance is affected from the standpoint of boththe actual use of forest raw material within Sweden and what Swedish forestryexports. The analysis was made mainly in a long-term perspective (60-300 years) toillustrate the importance of temporal and also the spatial perspective, as theanalysis includes stand level, landscape level, and national level. In this thesis, forestry was considered a system. All activities, from forestregeneration to end use of forest products, were entities of this system. In theevaluation, made from a systems perspective, we used life-cycle analysis toestimate carbon stock in different system flows. Different forest managementsystems and forest production were integrated in the analyses. Different forestmanagement scenarios were designed for the Swedish forest management incombination with the effect of future climate change; (i) intensive forest practiceaiming at increased growth, (ii) increased forest set-aside areas, changes in forestmanagement systems for biomass production, and (iii) how the use of forestproducts affect the total carbon balance (construction material, bioenergy and otherdomestic use). The results showed that future climate changes and intensive forest managementwith increased production could increase the biomass production and the potentialuse of forest raw material. This has a positive effect on carbon stock change in theforest biomass, litter production and below ground carbon stock and help reducingcarbon-dioxide emissions. Increased forest set-aside areas can increase the shorttermcarbon stock in forest ecosystems, but will reduce the total long-term carbonbalance. The net carbon balance for clear-cut forestry did not differ significantlyfrom continuous-cover forestry, but was rather a question of level of growth. Mostimportant, in the long term, was according to our analysis, how forest raw materialis used. Present Swedish forestry and use of forest raw material, both withinSweden and abroad, reduce carbon-dioxide emissions and mitigate climate change.The positive effect for the total carbon balance and climate benefit mostly takeplace abroad, due to the Swedish high level of export of wood products and thehigher substitution effects achieved outside Swedish borders. One strategy is toincrease production, harvest and use Swedish forest raw material to replace morecarbon intensive material, which can contribute to significant emission reduction.Carbon-dioxide mitigation, as a result of present Swedish forestry, was shown tobe almost of the same level as the total yearly emission of greenhouse gases. Thetotal carbon benefit would increase if the biomass production and felling increasedand if Swedish wood products replaced carbon intensive materials. This thesis shows also that, by changing forest management, increase thegrowth and the use of forest raw material and export of forest material we cancontribute to even larger climate benefits. In a long-term perspective, thesubstitution effects and replacement of carbon-and energy-intensive materials areof greater significance than carbon storage effects in forests. A more productionoriented forestry needs to make balances and increase the prerequisite forbiological diversity, improve recreation possibilities, and protect sensitive landareas and watersheds. Climate benefits, from Swedish forestry, are highly dependent on policydecision-making and how that can steer the direction for the Swedish forestry.
|
3 |
Trakhyggesbruk och hyggesfritt skogsbruk : En jämförelse av värderingar hos medlemmar i olika intresseorganisationer / Clearcutting and continuous-cover forestry : A comparison of values between members of various associationsJohansson, Anna January 2018 (has links)
There is a debate about clearcutting versus continuous-cover forestry in Sweden. In other studies forest owners and the general public have been seen to prefer different values. The aim of this study was to compare how members of various associations value clearcutting and continuous-cover forestry due to its effects on environmental-, social- and economical values. And also to understand the members motives for clearcutting and continuous-cover forestry, respectively. Through a web-based questionnaire this study found that members of all associations valued continuous cover forestry the highest, but members of Södra ranked clearcutting almost as high. It was also found that Södra-members differed by favoring clearcutting, whilst members of Friluftsfrämjandet and Svenska Naturskyddsföreningen instead preferred continuous-cover forestry. Clearcutting had mostly economical motives and continous-cover forestry had mostly environmental- and social motives. This confirms former studies and points out a need for dialogues and exchange of knowledge when striving for sustainable development.
|
4 |
Tillväxtreaktioner efter gallring på försöksytor med olika täthet i Östergötland / Growth reaction after thinning in plots of various density in ÖstergötlandHammarstedt, Kaisa January 2018 (has links)
Since the 1950-ies, the dominating silvicultural system in Sweden has included establishment and management of even-aged stands, including final felling. Alternative systems such as continuous cover forestry are increasingly catching interest due the lower impact on stand structure and biodiversity advantages for shade-tolerant species. However it is unknown especially to southern Sweden how trees in a continuous cover forestry system react to common silvicultural measures such as thinning. Therefore the effect of different levels of thinning on the radial growth of larger trees was measured and compared to the ingrowth and proportion of live crown at a site in Östergötland. Unlike previous findings the radial growth was higher in the treatment that had been slightly thinned than in the one that had been heavily thinned. The ability to react with increased radial growth after thinning was not depending on the thinning regime but on the tree’s reaction to a previous thinning. Only trees that had not reacted to the previous thinning increased in radial growth. The radial growth varied more within a treatment than between treatments, which points at the difficulty to allocate growth to specific trees.
|
5 |
Lokalt eller hållbart producerat? : Jämförelse mellan koldioxidutsläpp från två alternativa trävirke för brobygge över Skellefteälven. / Locally or sustainably produced? : Comparison between carbon dioxide emissions from two wood source alternatives for bridge construction over SkellefteälvenBerggren, Sally January 2022 (has links)
Emissions of greenhouse gasses, such as carbon dioxide, have been shown to be strongly connected global warming. In 2020 the European Union adopted the goal of reducing emissions of greenhouse gasses to a net of zero before year 2050. This is essential for keeping the average global temperature rise below 1.5 degrees. A large source of carbon dioxide emissions in Sweden is the forestry sector. The carbon balance in ecosystems is usually disturbed due to clear-cutting, which is the main silvicultural system used in Sweden. Introducing more sustainable silvicultural systems, such as continuous cover forestry, is a measure that authorities advocate. This study aimed to examine emissions of carbon dioxide from two timber sources that may be used for a bridge construction in Skellefteå. The timber would either come from a local clear-cut, transported by truck, or from continuous cover forestry in Lithuania, transported to Sweden by ship. The result is based on literature and calculations on data from previous studies. The results showed effects on carbon balance due to different silvicultural systems are complex, though the alternative with continuous cover forestry seemed to contribute to less emissions, despite the timber not being locally produced. The main factor between the systems, and therefore the different levels of emissions, seems to be highly dependent on how much of the harvested trees that is suitable for timber. However, emissions will also depend on local conditions such as timber storage. Therefore, it is important to take this into account when comparing silvicultural systems.
|
6 |
Economic analysis of a target diameter harvesting system in radiata pinePerry, Christopher January 2013 (has links)
Target diameter harvesting (TDH) is a forest management system in which all stems above a set minimum diameter are harvested on a periodic basis. There is evidence in the literature that TDH can achieve a rate of return on a similar scale to a clearfelling regime, with added benefits of regular cash flow from partial harvests, and preservation of non-timber values.
Economic analysis was carried out on 12 years of TDH using permanent sample plot (PSP) data from Woodside Forest, a 30ha plantation of radiata pine (Pinus radiata). The Woodside Forest management regime has a target diameter of 60cm, and a harvest cycle of two years. Economic analysis considered the option to partial harvest or clearfell every two years, and compared the outcome of each option in terms of land expectation value (LEV). Comparisons are made between regimes with different numbers of partial harvests, assessing the effect of TDH on stand LEV.
Results show that in three of four applicable stands, LEV reached a maximum at ages 30 – 32, (near the time when partial harvesting commenced), and reduced slowy with increased numbers of partial harvests. This shows there is a small opportunity cost associated with choosing TDH over a clearfell system. The effect of revenue from early partial harvesting operations on LEV was small as the majority of stand value is still in the standing crop. This limited the conclusions that can be drawn form this study due to the short time frame analyzed.
The study was limited by a small dataset which did not accurately represent average stand values. Because of this, no attempt to quantify the value of the opportunity costs was made. Despite this, the results support the notion that TDH can achieve economic returns similar to clearfelling in radiata pine forests.
|
7 |
En sudie av hur Södras medlemmar upplever rådgivning gällande hyggesfria skogsbruksmetoder : Det viktigaste är att vara engagerad / A study on how members of Södra experience advice regarding continuous cover forestry methods : The most important thing is to be committedNilsson, Petra, Axelsson, Molly January 2024 (has links)
Intresset för hyggesfria skogsbruksmetoder har ökat i Sverige, men enligt forskningen och politiska utvärderingar har användningen av dessa metoder inte ökat. De flesta privata skogsägare anlitar skogsägarföreningar eller skogsbolag för rådgivning och förvaltning. Syftet med studien var att undersöka och beskriva hur Södras medlemmar upplevde Södras rådgivning och support gällande hyggesfria skogsbruksmetoder. Studien tittade även på om medlemmarna saknade något när det gällde rådgivningen och supporten från Södra angående hyggesfria skogsbruksmetoder. Studien genomfördes med en kvalitativ metod där data samlades in genom intervjuer. Urvalet bestod av privata skogsägare som var medlemmar i Södra skogsägarna. Slutsatsen av studien påvisade att Södras engagemang kring hyggesfria skogsbruksmetoder är det som har störst betydelse över hur medlemmarna upplevde rådgivningen.
|
8 |
Hyggesfritt skogsbruk - privata skogsägares metoder, mål och utmaningar / Continuous cover forestry - methods, goals and challenges for private forest ownersGustavsson, Karina January 2022 (has links)
Hyggesfritt skogsbruk är en övergripande term som innebär att skogen sköts så att marken alltid är trädbevuxen utan att det uppstår några större kalhuggna ytor. Syftet med studien var att få en ökad förståelse för hur hyggesfritt skogsbruk fungerar i praktiken för privata enskilda skogsägare i Sverige. Frågeställningarna berörde vilka metoder som tillämpas, vilka mål som skogsägarna har och vilka utmaningar de ställs inför genom att bruka skogen hyggesfritt. Studien genomfördes med hjälp av en webbenkät. Resultaten visade att den vanligaste hyggesfria metoden för de privata skogsägarna var plockhuggning. De vanligaste målen med det hyggesfria brukandet var bevarad skogskänsla, ökad variation i skogen och ökad biologisk mångfald. Skogsägarnas utmaningar med det hyggesfria brukandet var främst relaterade till maskinparken, brist på kunskap och tillgång till rådgivning. Det finns ett behov av mer forskning om hyggesfritt skogsbruk.
|
9 |
Skogsbruksplanläggning i fullskiktad skog / Forestry planning in uneven-aged forestBlomgren, Andreas January 2021 (has links)
Intresset för olika hyggesfria skogsbruksmetoder ökar men frågan är hur en skogsbruksplan kan anpassas till detta och vilken metod som kan användas. Denna studie inriktade sig på att mäta i fullskiktade skogar med enkla verktyg för att få ut beståndsdata till nytta för skötseln och att användas till en skogsbruksplan. För att få fram diameterspridningen klavades träden. Det krävdes minst 600 m2 för att få tillräcklig kvalitet i diameterspridning. För volymen jämfördes klavning, relaskopmätning och laserdata. Resultatet visade att det är svårt att mäta volym i fullskiktade bestånd beroende på tätheten och ojämnheten. Inte minst gäller detta relaskopmätning som undervärderade volymen. Klavning och laserdata fick ungefär samma precision. Studien visade också att tidsåtgången i fält för klavning jämfört med vanlig planläggning med relaskop endast skiljde några få minuter. Om klavning kombineras med att hämta volymen från laserdata kan till och med denna metod vara mer tidseffektiv.
|
10 |
Attitudes, existing support and required incentives to increase Continuous Cover Forestry in SwedenLejon, Victoria January 2023 (has links)
An increasing wave of critique against conventional forestry favouring even-aged monoculture plantations and intense ground preparation in Sweden is arising, where some researchers are warning about the negative consequences of the long history of intense forestry and increasing extraction due to the growing demand for bioenergy has caused devastating consequences on ecosystems in forests such as loss of biodiversity. Additionally, reports are revealing that Sweden will not meet its own national environmental goals. Meantime, a growing interest in Continuous Cover Forestry (CCF) has increased due to prioritising biodiversity and conserving ecological and social values in the forests. Therefore, this study aims to explore pathways towards more diverse and varied forest management by examining the attitudes, existing support and required incentives for stakeholders in the Swedish forest sector towards an increase of CCF. This study follows an interpretive approach, where qualitative semi-structured interviews are conducted with different actors within the Swedish forest sector along with a literature review. The empirical data is analysed through a coding procedure and analysed with the multi-level perspective approach. The main findings of this study suggest that the existing attitude and support contribute as well as prevent an increase of CCF to some extent, however, the required incentives are crucial for forest actors’ ability to increase CCF. To conclude, the incentives are discussed to affect the ability to increase CCF, and if implemented, the incentives will in turn influence the attitudes of willingness to increase CCF and the existing support to develop in relation to CCF.
|
Page generated in 0.1001 seconds