Dag Fjeld

Seniorforsker

(+47) 974 81 270
dag.fjeld@nibio.no

Sted
Ås - Bygg H8

Besøksadresse
Høgskoleveien 8, 1433 Ås

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Sammendrag

Seasonal variations in wood supply are linked to the regional operating environment. This study constitutes the Norwegian contribution to Era-Net MultiStrat (Multimodal strategies for more resilient wood supply) covering oceanic, sub-arctic and continental climate zones. The oceanic zone is characterized by considerable seasonal variation in both temperature and precipitation. The goal of the study was to seek solutions for more resilient wood supply under these conditions. The study started with a general mapping of wood supply management processes including common demand and supply risks (WP1). The work continued with analysis of three years of production and transport reports (2014-2016) with tracking of roadside stocks and transport lead times (WP2). Daily temperature, precipitation, and snowpack were tracked with data from 65 surrounding weather stations. A simple multimodal transport problem with a rolling selection of planning horizons was then used to find the efficient multimodal solutions for the core, adjacent and peripheral supply regions through 12 balance periods per year (WP3). The transport analysis covers 65 supply districts feeding 6 assortment groups to 10 mills via 11 shipping terminals. The transport analysis varied both vessel cargo capacity and cargo collection practices. The results demonstrated a wide range of solutions to ensure roundwood availability with limited increases in system costs. While the transport analysis demonstrated the contribution of the multimodal solutions to structural flexibility, it also revealed a bottleneck for resilience of the wood supply system; seasonal variation in truck transport output (m3km/week). The geographical distribution of seasonality showed the main source to be one particular supply region. A subsequent wood supply planning workshop with production managers indicated that a bottleneck for improved production planning was short wood purchase and planning horizons. A simple optimization experiment was therefore set up to quantify the feasibility of more specific site-type selection according to actual soil and seasonal weather conditions for the selected region. On-line grid-based groundwater modeling was used to monitor weekly geographical variations in bearing capacity and the experiment provided a plausible re-scheduling of flows to reduce variation in delivery volumes and transport output.

Sammendrag

Utredningens hovedmål har vært å kvantifisere de økonomiske konsekvensene av flaskehalser for tømmertransport i det kommunale veinettet i Sogn og Fjordane. Hovedmålet ble delt i to delmål. Det første delmålet var å vurdere ulike metoder for beregning av potensiell transportgevinst pr. kommune ved oppskriving til 19,5 m/50 t. Det andre delmålet var å beregne den samlede transportgevinsten for dagens transporter og presentere en prognose for utviklingen 20 år fremover. Med dagens avtalte kippe-tillegg (30 kr/m3) er transportgevinsten for skogeierene i Sogn og Fjordane beregnet til ca. 1 mill. kr/år. Dagens prisavtaler for tømmertransport indikerer i tillegg en mulig indirekte dekning av kippekostnader gjennom et forhøyet fastledd i transporttariffene. Økningen i fastleddet betales på hele transportvolumet, og dekkes av transportkjøper. De faktiske merkostnadene med kipping er beregnet til over 60 kr/m3 (ved 3 km kippeavstand). Med forventet økning i hogstklasse 5 og økt hogst framover, stiger de beregnede merkostnadene fra 2,1 mill. kr/år i 2015-2020 til 2,6 og 2,9 mill. kr/år i periodene 2021-2030 og 2031-2040. De kommunene som har og vil få størst kippekostnader er Stryn (1449), Eid (1443), Gaular (1430) og Førde (1432). Resultatene forutsetter samme kippeandel framover som det har vært i analyseperioden 2016-2018, dvs. ca. 29 %. Det er sannsynlig at mye av hogsten de siste årene har foregått i de områder hvor det er minst kipping. Uten opprusting av det kommunale veinettet er det derfor sannsynlig at kippeandelen vil øke i fremtiden. De beregnede merkostnader reflekterer skogsektorens transportgevinst. I tillegg vil oppgradering til 19,5 m/50 t også komme andre sektorer til gode.

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Sammendrag

The goal of this study was to assess the long-term effects of partial harvesting and supplementary soil scarification on the frequency of root and butt rot in managed uneven-sized Norway spruce stands. Frequency of rot and the population structure of the rot fungi were assessed on 1353 stumps after clear-cutting 21 years after a selection harvesting experiment. The initial experiment was comprised of three harvest strength (low, intermediate and high) of single-tree selection, removing approximately 25, 45 and 65% of the stand basal area. Uncut control plots were established at the same time. Supplementary soil scarification was applied in subplots within the single-tree selection plots, using a medium-sized excavator. After clear-cutting the stumps were analyzed with respect to rot caused by Heterobasidion parviporum, Armillaria spp., Stereum sanguinolentum as well as other rot fungi. Rot caused by Armillaria spp. was most common (8.6% of the stumps), while infection by H. parviporum (2.9%) or S. sanguinolentum (3.0%) was less frequent. The group “other rot” (5.4%) comprised 21 identified taxa, each occurring in 1–15 stumps. Significantly lower rot frequencies were found for the uncut control (16.3%) and intermediate harvest strength (15.7%), compared with low harvest strength (23.6%). A rot frequency of 21.0% was found in the high harvest strength. In two of three harvest strengths, the rot frequency was higher than for the uncut control. As the observed rot frequencies did not increase consistently with increasing harvest strength, the results do not completely support the initial expectations of increased rot after single-tree selection compared with the uncut control. However, since the probability of rot in individual stumps on plots treated with single-tree selection was significantly affected by the distance to the nearest strip road (H. parviporum) as well as dependent on the size of and distance to the nearest stump of trees cut during the experimental harvest (H. parviporum, S. sanguinolentum and total rot), it is evident that the single-tree selection harvesting was partially responsible for some of the observed rot. One of the selection criteria in the initial harvest was a sanitary removal of trees of poor vitality. Varying degrees of sanitation felling may therefore have offset the effects of new infections in wounds or spread of rot fungi through adjacent stumps. Supplementary soil scarification in small gaps of the residual stand had no significant effect on the frequency of rot, suggesting that such treatment may be used to facilitate regeneration in uneven-sized spruce stands on similar sites.

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Sammendrag

Improved transport planning and pricing is dependent on correct cycle times. The objective of this study was to quantify the effect of road curvature, surface roughness, gradient and truck weight on the operating speed of a conventional 60-tonne gross vehicle weight logging truck. The study used a 320-km test track consisting of both public and forest roads. The track was driven with various gross vehicle weights. Speed data was retrieved from the truck’s CAN-bus system and road data was measured with a profilograph. The key factors for operating speed were curvature and surface roughness, both of which were correlated to each other as well as partially captured by functional road class. Regression analysis quantified the individual effects of these factors as well as gradient, undulation and interactions with truck weight. A regression model is presented which explained 80% of the variation in operating speed. The results were consistent with previous studies, and the proposed models can be used to improve transport planning, cost estimation, operative route path selection and road investments.

Sammendrag

Efforts to improve efficiencies in the forest industries have mainly focused on problems within the borders of the company. Thus, there is an unexploited potential for increased efficiency through integrating and coordinating activities between companies. This poster presents games that mimic the forest industry and demonstrate to...

Sammendrag

Two games, called “Wood Supply Games”, are developed based on the structure and dynamics of the Beer Game. The games are intended as student exercises in forestry logistics courses. By introducing divergent and convergent flows in the supply chain, the relevance to the forest sector is increased. Results from pilot experiments of the games are presented and discussed in terms of how different degrees of complexity in supply chain structures may affect their efficiency. Measures of efficiency are accumulated costs, amplification of demand and the sample variance of order rates. Results indicate that supply chain performance is negatively affected by increasing rigidity of constraints at points of divergence. Furthermore, lower degrees of efficiency and predictability are observed as complexity of supply chain structure increases. Testing of results and proposed hypotheses can be accomplished by running numerous replications of the games, or alternatively, by development of appropriate simulation models.

Sammendrag

Injuries and mortality to advance growth (saplings) after selection harvesting was studied in 17 multi-storied Norway spruce (Picea abies (L.) Karst.) stands. Harvest removals ranged from 33 to 67 % of initial basal area. Four of the stands were harvested motor-manually (chain saw + skidding with farm tractors; M-FT). The remaining stands were harvested with single-grip harvesters and forwarders (H-FW). In each stand, injury rates were evaluated on a 24x48 m plot, located between the centrelines of two parallel striproads that were spaced 24 m apart. All logging teams had at least five years of experience in clear-cutting and thinning operations. The trees to be removed, and striproad centrelines, were marked prior to harvest. Mortality varied between 5 and 51 %, whereas total injury (injured + dead saplings) varied between 17 and 76 %. Mortality- and injury levels were generally highest on H-FW plots. Crown reduction and leaning stems were the most frequent types of injury, regardless of operating method. Injury rates increased with sapling height with the H-FW method, whereas the opposite was found on M-FT plots. Saplings without pre-harvest damage in the form of top- or leader defects had a higher probability of being injured than saplings with such damage in stands harvested with the M-FT method. A similar difference was not found on H-FW plots. A logistic regression model show that the spatial risk for injury depends on the interaction between forest condition factors and operational characteristics. Forest condition factors influencing the risk of injury are sapling height and the location of saplings relative to larger residual trees and striproads. Corresponding operational characteristics are operating method and harvest intensity.

Sammendrag

Structural changes in the sawmilling industry imply more wood transport as distance between sawmills is increasing. One of the factors that determines the potential for economies of scale is the trade-off between reduced production costs and increased transport costs. The methods used in this study are based on geometric properties of wood procurement areas.The effects of the distribution of forest (area coefficient) and the road net (winding coefficient) upon average transport distance was explored, and considerable regional variation was found.The transport net factor (t) is the product of the area coefficient (a) and the winding coefficient (w) and gives a relative measure of the potential for efficient procurement logistics with respect to the distribution of productive forest area and the road net. The transport net factor is estimated for two wood procurement areas in each of four regions.When studying the sawlogs procurement in regions with different density of sawlogs buyers, average transport distance increases relatively more in areas where several buyers are competing for a limited timber supply than in areas with few competitors.

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Sammendrag

This study examines the role of forest operations strategies in sector development for Norway's fjord region. The paper starts with an examination of forest owner attitudes and perceptions in relation to their harvesting behaviour, use of contractor harvesting and road net extension. The influence of forest owner decisions, contractor mechanisation and road net extension standards on operational efficiency is examined in a simple deterministic model of the regional wood chain. Average wood procurement costs are calculated for increasing sector capacity. Direct and indirect harvesting costs are also followed throughout this development.

Sammendrag

Strukturelle endringer i trelastindustrien medfører økt transportarbeid. Stordriftsfordelene er resultat av en avveining mellom reduserte produksjonskostnader og økte kostnader for tømmertransport. Med betydelige variasjoner med hensyn til både transportavstand og transportkostnad per tonnkm, kan stordriftsfordelene variere mellom regioner. Forholdet mellom virkesforbruk og gjennomsnittlig transportavstand ble undersøkt som første del av et kommende doktorarbeid innen logistikk, der de regionale forskjellene ble kvantifisert.

Sammendrag

Tidlegare undersøkingar om prestasjonar i ungskogpleie dekkjer uttakstyrkar opp til 1000 stammar pr. dekar i lett terreng. På Vestlandet er tal tre i uttaket ofte langt høgare og terrenget brattare. Det var derfor nødvendig å gjera ei undersøking i landsdelen som kunne utfylle resultata frå Austlandet. Denne undersøkinga har vist at det er ein klår samanheng mellom uttaksstyrke, stigning, røynsle og tidsforbruket i ungskogpleie. Lang røynsle med ryddesag og høgt uttak gjorde at ryddesag vart føretrekt. Motorsag gjev lågast gjennomsnittleg tidsforbruk, men gjev og høgast ryggbelastning. Først ved stigningar over 60 %, er ryggbelastninga låg nok til at motorsag kan anbefalast. Det bør utfrå ein ergonomisk synsstad gjerast meir for å auke bruken av ryddesaga på Vestlandet, først og framst ved riktig opplæring og god oppfølging av dei som skal drive med ungskogpleie. Ungskogpleie kan medverke til jamnare sysselsetting i periodar då det er lite hogst eller anna skogkulturarbeid.

Sammendrag

I prosjektets første del (Faunahensynets utforming og tiltakenes omfang i et fjordlandskap) var det ønskelig å finne ut hvilke faunahensyn som kan være aktuelle i Vestlandsskogbruket, for deretter å undersøke hvilke omfang og konsekvenser disse kan ha. I et større fjordlandskap i Hordaland, er det undersøkt virkningen av noen definerte fauna- og habitathensyn på den andelen av landskapet som var disponibelt for skogbruk. Undersøkelsen ser også på forskjellige nivåer av faunahensyn. I dette tilfellet ble tilgang på produktivt skogareal redusert med 4 til 13% av faunahensyn. Ellers var 31% av skogarealet allerede utilgjengelig pga. manglende adkomst. Dagens tilgang på stående volum i hogstklassene IV og V ble redusert med 22 til 28%. Mellom 6 og 15% av restvolumet skulle avvirkes gjennom andre hogstformer enn snauhogst. Sett i mer langsiktig perspektiv, er det to forhold som har større innvirkning på eierens ressurstilgang enn faunahensyn; adkomst til skogarealet og andel av skogarealet som treslagskiftes i lavereliggende område. I prosjektets første del fant man at en mindre andel av dagens stående volum i hogstklassene IV og V skulle avvirkes på annen måte enn ved snauhogst. I prosjektets andre del (Skjermstillingshogst i oseanisk furuskog) sammenligner avvirkningsarbeidet ved snauhogst og skjermstillingshogst for både hjulgående og kabelbaserte driftssystemer. Det ble påvist forskjell i tidsforbruket ved forskjellige hogstformer. Dette skyldtes hovedsakelig ulikheter i gjennomsnittlig trevolum i uttaket, og gjaldt både ved motormanuell og maskinell hogst. Den samme tendensen ble vist for lunning med slepebane. Redusert uttaksstyrke vil også øke tidsforbruket for sideflytting av banen. Bruk av kabelsystemer til disse hogstformene krever bruk av buffertrær til å styre både ståltau og lass for å redusere skadene i det gjenstående bestandet. Enkelte av de mer nyanserte skogbehandlingene, særlig de som forutsetter lave hogststyrker, kan ha begrenset verdi for faunaen. Dette skyldes at uttak av de riktige trærne ikke var teknisk gjennomførbart under alle forhold. Flere av disse behandlingene ville heller ikke bidra til en tilfredsstillende naturlig foryngelse av arealene.

Sammendrag

I et forsøk med maskinell flekkmarkberedning er arbeidskvaliteten undersøkt ved ulik skjermtetthet (Trondheim og Trysil). Arbeidskvaliteten er sammenlignet på snauflater og i skjermstillinger med 17 til 36 trær pr. daa. To kriterier for arbeidskvalitet er anvendt: Arealdekningen av markberedningstamme- og rotskader på gjenstående skjerm. Det ble benyttet både en- og to-rads traktoraggregat og gravemaskinmontert markberedningsutstyr. Forsøket viser at arealdekningen av kranmontert markberedningsutstyr er mindre påvirket av skjermtetthet enn traktormontert. Skader på gjenstående skjermtrær består primært av rotskader. Skadeprosenten er høy og øker med økt skjermtetthet. Resultatene indikerer at den viktigste faktor for skadeprosenten kan være andelen av blottlagt mineraljord