Occurrence, morphology and growth of understory saplings in Swedish forests

Growing demands for a multipurpose forestry leads to increased use of silvicultural systems that avoid clear-cutting. Regeneration in such systems is based on establishment and ingrowth of new seedlings under a more or less closed canopy. At long-term forestry planning reliable ingrowth models are needed to predict the future wood production. The objectives of this thesis were to review the field of ingrowth in established stands, to develop a model for prediction of ingrowth for the planning system Heureka and to deepen the insight in the ingrowth process by a case study. The ingrowth model consisted of four parts, describing: Probability for occurrence of saplings (1-39 mm diameter at breast height (DBH)) on plots with r = 5 m. Number of saplings on stocked plots (plots with saplings of target species). Probability for ingrowth of a sapling over 39 mm DBH during a 5-year period. Diameter of ingrown trees at the end of the 5-year period. The model was based on data from permanent plots at the National Forest Inventory. Separate functions were developed for seven species and species groups. Picea abies saplings had the widest distribution and occurred on 58 % of 12 469 representative plots in established forests. Betula spp. saplings occurred on 50 % of the plots, while the occurrence of saplings of other species was less than 20 %. Sapling density on stocked plots was highest for Betula spp, in average 10 per plot. Average ingrowth rate was 14.6 stems per ha and year, and P. abies made up more than half of this. The ingrowth varied according to the different functions with age, density and species composition of the stand and the moisture and fertility of the site. Growth and morphology of young conifers was examined in a species experiment on a clearcut and in shelterwoods of three different densities (41 – 124 stems per hectare). The largest intra-specific differences between clearcut and shelterwood were found for Pinus spp, while moderate differences were found for Picea spp. For Pinus spp, stem height and diameter decreased, while the stem slenderness increased with increasing shelterwood density. Moreover, the number of branches per whorl and the crown ratio decreased with increasing shelterwood density. The proportion of biomass in roots, stem, branches and needles was analysed as a function of estimated irradiance transmission for each individual. The proportion of stem decreased and the proportion of branches increased with increasing irradiance for Pinus spp. No significant trends were found for Picea spp

Kolsänkan av levande biomassa i fjällnära skog

The study focuses on facts about the role of the forests, near the mountains in the northwestern part of Sweden, from a climate perspective. This refers to the net removal in living tree biomass while the substitution effect is omitted. The area-based (design based) estimates are based on data from the Swedish National Forest Inventories permanent sample plots in two areas close to the mountains. The first area refers to the above limit for forests close to the mountains (above GFS) according to the Swedish Forest Agency and the second according to a map layer that is considered important of protection for biodiversity reasons according to the Swedish Environmental Protection Agency (SEPA). Of the 8.1 Mha of land above the limit for forests close to mountains, 3.1 Mha is forest land, of which 1.7 Mha is formally protected forest land. Productive forest land used for timber production amounts to less than 0.5 Mha. For both formally protected forest land and non-formally protected forest land, living biomass constitutes a net uptake of -1 Mton CO2 / year during the period 1990-2016 on a reasonably similar area. If all forest land above GFS is excluded from timber production, the short-term increase in net removal in the forest will be approximately -0.4 Mton CO2 / year, which corresponds to harvest. Then we do not expect any substitution effect and believe that other carbon pools (dead wood, soil, litter and the carbon pool harvested wood products) in the short term are not affected by the stopping of felling. The Swedish Environmental Protection Agency has selected an area close to the mountains where two thirds comprise forest land. No land is formally protected. Of approximately 1.0 Mha of forest land, 0.39 Mha was assessed as forest land for timber production. The net uptake in living biomass of forest land amounted to approximately -1 Mton CO2 / year during the period. On productive forest land for timber production, the net uptake was approximately -0.6 Mton CO2 / year during the period. If all forest land according to the map layer is excluded from timber production, the short-term increase in net removal in the forest will be approximately -0.1 Mton CO2 / year, which corresponds to harvest. Then we do not expect any substitution effect and believe that other carbon pools in the short term are not affected by the stopping of felling.The study focuses on facts about the role of the forests, near the mountains in the northwestern part of Sweden, from a climate perspective. This refers to the net removal in living tree biomass while the substitution effect is omitted. The area-based (design based) estimates are based on data from the Swedish National Forest Inventories permanent sample plots in two areas close to the mountains. The first area refers to the above limit for forests close to the mountains (above GFS) according to the Swedish Forest Agency and the second according to a map layer that is considered important of protection for biodiversity reasons according to the Swedish Environmental Protection Agency (SEPA). Of the 8.1 Mha of land above the limit for forests close to mountains, 3.1 Mha is forest land, of which 1.7 Mha is formally protected forest land. Productive forest land used for timber production amounts to less than 0.5 Mha. For both formally protected forest land and non-formally protected forest land, living biomass constitutes a net uptake of -1 Mton CO2 / year during the period 1990-2016 on a reasonably similar area. If all forest land above GFS is excluded from timber production, the short-term increase in net removal in the forest will be approximately -0.4 Mton CO2 / year, which corresponds to harvest. Then we do not expect any substitution effect and believe that other carbon pools (dead wood, soil, litter and the carbon pool harvested wood products) in the short term are not affected by the stopping of felling. The Swedish Environmental Protection Agency has selected an area close to the mountains where two thirds comprise forest land. No land is formally protected. Of approximately 1.0 Mha of forest land, 0.39 Mha was assessed as forest land for timber production. The net uptake in living biomass of forest land amounted to approximately -1 Mton CO2 / year during the period. On productive forest land for timber production, the net uptake was approximately -0.6 Mton CO2 / year during the period. If all forest land according to the map layer is excluded from timber production, the short-term increase in net removal in the forest will be approximately -0.1 Mton CO2 / year, which corresponds to harvest. Then we do not expect any substitution effect and believe that other carbon pools in the short term are not affected by the stopping of felling

Sveriges klimatrapportering - markanvändning och skogsbruk

SLU sammanställer Sveriges rapportering av utsläpp och upptag av växthusgaserfrån markanvändning och skogsbruk.Om man undantar markanvändning och skogsbruk var Sveriges utsläpp avväxthusgaser under 2020 46 miljoner ton CO2-ekvivalenter.Markanvändning och skogsbruk bidrog samma år till ett nettoupptag på40 miljoner ton CO2-ekvivalenter, varav skogsmark stod för 96 %.Det största nettoupptaget av kol i levande biomassa sker i produktionsskog,men upptaget per arealenhet är något större i skog som skogsägarnafrivilligt undantagit från skogsbru

The multi-faceted Swedish Heureka forest decision support system: context, functionality, design, and 10 years experiences of its use

For several decades, computerized forest decision support systems (DSS) have helped managers and decision makers to analyze different management options and supported the search for preferred management alternatives. In Sweden, a country rich in forests and with a long tradition in intensive forest management, such systems have been developed and available since the 1970s. Changes in societal as well as in forest owners' preferences and objectives in the 1990s led to a need for forest DSS handling broader perspectives compared to precedent single-objective timber-oriented systems. In Sweden, this led to the initiation of a research programme in the beginning of the 2000s aiming at developing a versatile and multi-objective forest DSS, resulting in the first version of the Heureka forest DSS released in 2009. The system handles several forest values, such as timber and biofuel production, carbon sequestration, dead wood dynamics, habitat for species, recreation and susceptibility to forest damages (spruce bark beetle, wind-throw and root rot). It contains a suite of software for different problem settings and geographical scales and uses simulation as well as optimization techniques. Three software handle projections of the forest using a common core of growth and yield models for simulating forest dynamics. A fourth software, built for multi-criteria decision analysis and including a web-version, enables also group decision making and participatory planning. For more than 10 years, the Heureka system has been used in teaching, environmental analysis, research and as decision support in practical forestry. For example, several research groups using the system for analyses in different problem areas have so far published more than 80 scientific papers. The system is used for nation-wide forest impact analysis for policy support and all large and many medium-sized forest owners use it for their long-term forest planning, meaning that it directly influences forest management decisions and activities on more than 50% of the Swedish forest area. Besides presenting the present system and its use, we also discuss lessons learned and potential future development

On the role of forests and the forest sector for climate change mitigation in Sweden

We analyse the short- and long-term consequences for atmospheric greenhouse gas (GHG) concentrations of forest management strategies and forest product uses in Sweden by comparing the modelled consequences of forest resource use vs. increased conservation at different levels of GHG savings from carbon sequestration and product substitution with bioenergy and other forest products. Increased forest set-asides for conservation resulted in larger GHG reductions only in the short term and only when substitution effects were low. In all other cases, forest use was more beneficial. In all scenarios, annual carbon dioxide (CO2) sequestration rates declined in conservation forests as they mature, eventually approaching a steady state. Forest set-asides are thus associated with increasing opportunity costs corresponding to foregone wood production and associated mitigation losses. Substitution and sequestration rates under all other forest management strategies rise, providing support for sustained harvest and cumulative mitigation gains. The impact of increased fertilization was everywhere beneficial to the climate and surpassed the mitigation potential of the other scenarios. Climate change can have large—positive or negative—influence on outcomes. Despite uncertainties, the results indicate potentially large benefits from forest use for wood production. These benefits, however, are not clearly linked with forestry in UNFCCC reporting, and the European Union\u27s Land Use, Land-Use Change and Forestry carbon accounting, framework may even prevent their full realization. These reporting and accounting frameworks may further have the consequence of encouraging land set-asides and reduced forest use at the expense of future biomass production. Further, carbon leakage and resulting biodiversity impacts due to increased use of more GHG-intensive products, including imported products associated with deforestation and land degradation, are inadequately assessed. Considerable opportunity to better mobilize the climate change mitigation potential of Swedish forests therefore remains

Vidareutveckling av nationell metod för beräkning av koldioxidutsläpp från träprodukter

Enligt överenskommelse från klimatmötet i Durban 2011 ska träprodukter (Harvested Wood Products (HWP)) inkluderas i Annex-1 ländernas rapportering till klimatkonventionen och Kyotoprotokollets andra åtagandeperiod (Anon. 2012). Under senare år har det mesta pekat på att så skulle bli fallet och därför utvecklades under 2010 i uppdrag av naturvårdsverket en nationell metod för beräkning av koldioxidutsläpp från HWP (Wikberg 2011). Den metoden bygger på IPCC’s så kallade Tier 1 modell (Pingoud m.fl 2006) som går ut på att skatta nettoutsläpp av koldioxid baserat på mellanårsskillnader av HWP-poolens storlek med hjälp av data från FAO och nedbrytning enligt första ordningen. Varje år tillförs en viss mängd nya produkter medan en viss mängd förbrukas. Resultatet kan bli att HWP-poolen ökar eller minskar i storlek, vilket motsvaras av ett upptag eller utsläpp av koldioxid. Den nationella metoden avviker från IPCC’s Tier 1 modell främst i hur inflödet av nya produkter beräknas. Den nationella metoden har under 2011 förbättrats och byggts ut. Data från FAO har bytts ut mot nationella datakällor helt och hållet, modellen har byggts ut med ”Stock Change Approach” (importen inkluderas och exporten exkluderas), historisk produktion av sågade trävaror från och med 1850 har inkluderats, handel av ytterligare råvarukategorier har tagits med, det är möjligt att inkludera mellanårsskillnader i rundvirkeslagrens storlek, etc. Modellen har även kompletterats med ett beräkningsverktyg för scenarioberäkningar

Nationell metod för beräkning av koldioxidutsläpp från träprodukter

Enligt Kyotoprotokollets artikel 3.4 får de s.k. annex 1 länderna bokföra utsläpp/upptag från skogsbruk som en frivillig aktivitet inom ramen för markanvändningssektorn (Land Use, Land Use Change and Forestry (LULUCF)). I princip innebär detta att utsläpp från skogsmark beräknas genom att skatta förändringar i kolförrådets storlek i kolpoolerna Levande biomassa (ovan och under mark), Död ved, Förna och markkol mellan år. Kolförrådet i levande biomassa (träd) beror av tillväxt, avgångar och avverkning. Fraktionen som avverkas och som tas ut ur skogen benämns i rapporteringssammanhang som ”Harvested Wood Products (HWP)”. HWP kan ses som en mellanlagring av kol som tagits upp vid fotosyntesen och som fördröjer återförandet av kolet tillbaka till atmosfären. Denna mellanlagring har hittills inte beaktats inom kolrapporteringen under Kyotoprotokollet. Istället antas att allt kol som tas ut ur skogen återvänder till atmosfären inom samma år, s.k. ”instant oxidation”, vilket innebär att mängden kol i HWP förblir oförändrad över tiden. Länderna har alltså i nuläget ingen möjlighet att bokföra effekten av att använda HWP. Länderna kan dock frivilligt redovisa utsläpp från HWP under klimatkonventionen. I en framtida klimatregim kan HWP komma att inkluderas som en obligatorisk del i rapporteringen. IPCC föreslår i de senaste riktlinjerna olika sätt för hur detta kan gå till (Pingoud m.fl. 2006) och beskriver en metod baserad på FAO-data (http://faostat.fao.org/) som alla länder kan använda (s.k. Tier 1) samt tillhandahåller ett excel-baserat beräkningsverktyg för detta. IPCC föreslår vidare att länderna använder egna datakällor (Tier 2), och uppmuntrar även länderna att utarbeta egna metoder (Tier 3). På uppdrag av Naturvårdsverket har ett förslag till en nationell Tier 3 metod tagits fram anpassad för Svenska förhållanden. I den här rapporten presenteras metoden och resultat från beräkningar av koldioxidutsläpp från 1960-2009. Scenarioberäkningar för 2010-2020 redovisas samt känslighetsanaylser av ändrade livslängder och ändrad användning av råvaror. Metoden bygger på IPCC’s Tier 1 med avseende på beräkningsgång och utflödesberäkningar men avviker med avseende på inflödesberäkningarna. Data från FAO har använts utom i en del fall då uppgifter från nationella datakällor använts istället. Metoden innefattar endast HWP från Svensk skog och gör det möjligt att hålla isär exporterade och inhemskt konsumerade produkter. Osäkerheter och fortsatt utvecklingsarbete diskuteras

Harmonisering av skattningar av koldioxidutsläpp mellan kolpoolerna skogsprodukter och levande trädbiomassa inom ramen för FN:s klimatkonvention och Kyotoprotokollet

I ordinarie rapportering av koldioxidupptag eller utsläpp från kolpoolen skogsprodukter används data om industrins produktion och handel av halvfabrikat. En brist med den metodiken är att det inte finns någon direkt koppling till rapporteringen av kolpoolen levande trädbiomassa. Här presenteras en metodik där inflödet av nya skogsprodukter baseras på Riksskogstaxeringens permanenta stickprov som även som ligger till grund för rapporteringen av levande biomassa. Avverkningen fördelades ut på olika halvfabrikat med ledning av förhållandet mellan produktion av respektive produktkategori och industrins rundvirkeskonsumtion enligt ordinarie metod. Det resulterande nettoupptaget med den modifierade metoden låg på ungefär samma nivå som med ordinarie metod, men skillnaderna var vissa enskilda år betydande.  Den modifierade metoden är direkt kopplad till kolpoolen levande trädbiomassa och kan ersätta ordinarie metod om detta prioriteras