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  • 1. Dahlström, N
    et al.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The dynamics of coarse woody debris in boreal Swedish forests are similar between stream channels and adjacent riparian forests2006In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 36, no 5, p. 1139-1148Article in journal (Refereed)
  • 2.
    Esseen, Per-Anders
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Strong influence of landscape structure on hair lichens in boreal forest canopies2019In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 48, no 8, p. 994-1003Article in journal (Refereed)
    Abstract [en]

    This study examines how island size, isolation, and orientation influence epiphytic hair lichens in old-growth boreal spruce forests within a naturally heterogeneous landscape with approximately 1000 forest islands distributed in open wetland matrix. Forest structure, length of Alectoria sarmentosa (Ach.) Ach., Bryoria spp., and Usnea spp., and mass of Alectoria in the lower canopy (0–5 m) of Picea abies (L.) Karst. were quantified in 30 islands (0.11–10.9 ha). Length and mass of Alectoria were also studied in 25 edges with different orientation and fetch (wind exposure). Island area had a strong positive effect on length of Alectoria but a minor effect on Bryoria and Usnea. Edge orientation influenced length and mass of Alectoria, with the strongest reduction in wind-exposed western edges, whereas fetch size had no effect. Edge influence on microclimate drives hair lichen response to landscape configuration. The gradient from Bryoria in small islands to Alectoria in large islands is caused by the same mechanisms that influence vertical canopy gradients in large homogeneous stands, with Bryoria in the upper canopy and Alectoria in the lower canopy. Genus-specific, sun-screening pigments contribute to this niche differentiation, but thallus fragmentation by wind and water storage are also important. Our findings imply that lichen conservation must consider the spatial structure of the landscape.

  • 3.
    Esseen, Per-Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ekström, Magnus
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Statistics.
    Westerlund, Bertil
    Palmqvist, Kristin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jonsson, Bengt Gunnar
    Grafström, Anton
    Ståhl, Göran
    Broad-scale distribution of epiphytic hair lichens correlates more with climate and nitrogen deposition than with forest structure2016In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 46, no 11, p. 1348-1358Article in journal (Refereed)
    Abstract [en]

    Hair lichens are strongly influenced by forest structure at local scales, but their broad-scale distributions are less understood. We compared the occurrence and length of Alectoria sarmentosa (Ach.) Ach., Bryoria spp., and Usnea spp. in the lower canopy of > 5000 Picea abies (L.) Karst. trees within the National Forest Inventory across all productive forest in Sweden. We used logistic regression to analyse how climate, nitrogen deposition, and forest variables influence lichen occurrence. Distributions overlapped, but the distribution of Bryoria was more northern and that of Usnea was more southern, with Alectoria's distribution being intermediate. Lichen length increased towards northern regions, indicating better conditions for biomass accumulation. Logistic regression models had the highest pseudo R-2 value for Bryoria, followed by Alectoria. Temperature and nitrogen deposition had higher explanatory power than precipitation and forest variables. Multiple logistic regressions suggest that lichen genera respond differently to increases in several variables. Warming decreased the odds for Bryoria occurrence at all temperatures. Corresponding odds for Alectoria and Usnea decreased in warmer climates, but in colder climates, they increased. Nitrogen addition decreased the odds for Alectoria and Usnea occurrence under high deposition, but under low deposition, the odds increased. Our analyses suggest major shifts in the broad-scale distribution of hair lichens with changes in climate, nitrogen deposition, and forest management.

  • 4.
    Funda, Tomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Forest and Conservation Sciences, Faculty of Forestry, The University of British Columbia, Vancouver, Canada.
    Liewlaksaneeyanawin, Cherdsak
    Department of Forest and Conservation Sciences, Faculty of Forestry, The University of British Columbia, Vancouver, Canada.
    El-Kassaby, Yousry A.
    Department of Forest and Conservation Sciences, Faculty of Forestry, The University of British Columbia, Vancouver, Canada.
    Determination of paternal and maternal parentage in lodgepole pine seed: full versus partial pedigree reconstruction2014In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 44, no 9, p. 1122-1127Article in journal (Refereed)
    Abstract [en]

    Estimating seed orchards' maternal and paternal gametic contributions is of importance in assessing the genetic quality of seed crops. The advantage of full over partial pedigree reconstruction in investigating the mating dynamics in a lodgepole pine (Pinus contorta Dougl. ex. Loud. ssp. latifolia Engelm.) seed orchard population (N = 74) was demonstrated using nuclear and chloroplast microsatellite markers. We analyzed offspring of equivalent sample sizes representing full (bulk seed with unknown maternal and paternal parentage (n = 635)) and partial (11 maternal family arrays (n = 619)) pedigree reconstruction methods. Small differences in selfing rate, gene flow, and male reproductive success were observed between the two methods; however, the full pedigree reconstruction enabled simultaneous estimation of female-related fertility parameters (female reproductive success and effective number of maternal parents) that partial pedigree reconstruction could not provide. The use of bulk random sample of seed from orchards' crops is recommended when male and female fertility parameters, as well as selfing and contamination rates, are needed for seed orchards' seed crops genetic rating.

  • 5. Gauslaa , Y.
    et al.
    Palmqvist, Kristin
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Solhaug, K. A.
    Holien , H.
    Hilmo, O.
    Nybakken, L.
    Myhre, L.
    Ohlson, M.
    Growth of epiphytic old forest lichens across climatic and successional gradients2007In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 37, no 10, p. 1832-1845Article in journal (Refereed)
    Abstract [en]

    This paper aims to assess the influence of canopy cover on lichen growth in boreal forests along a regional forest gradient. Biomass and area gain, and some acclimation traits, were assessed in the old-forest lichens Lobaria pulmonaria (L.) Hoffm., Pseudocyphellaria crocata (L.) Vain., and Usnea longissima Ach. transplanted 110days in three successional Norway spruce (Picea abies (L.) Karst.) forest stands (clearcut, young, and old forest) repeated along a rainfall gradient (continental, suboceanic, and Atlantic zones) in Scandinavia. Lichen growth peaked in Atlantic rainforests with mean dry matter (DM) gain up to 36%-38%. The alectorioid lichen U. longissima showed the widest range of growth responses and no signs of chlorophyll degradation. Its highest DM gain consistently occurred in clearcuts, whereas the DM gain was close to zero in the shadiest young forest. The two foliose lichens L. pulmonaria and P. crocata exhibited maximal growth rates in old forests, but apparently growth was limited by low light even in old forests. Their DM gain was reduced in the most sun-exposed clearcuts due to chlorophyll degradation and was relatively high under closed young canopies, suggesting a better adaptation to shade. The lichen responses show that a high frequency and dominance of young and dense fast-growing forest stands at a landscape level are not compatible with large populations of these old-forest lichens and that a lack of lichens under an industrial forestry regime may not necessarily be determined by low dispersal efficiency only.

    Cet article a pour but d'évaluer l'influence du couvert de la canopée sur la croissance des lichens dans les forêts boréales le long d'un gradient forestier régional. Le gain en biomasse et en superficie ainsi que certains caractères d'acclimatation ont été évalués chez les lichens des forêts âgées, Lobaria pulmonaria (L.) Hoffm., Pseudocyphellaria crocata (L.) Vain. et Usnea longissima Ach., qui ont été transplantés pendant 110 jours dans trois peuplements d'épicéa commun (Picea abies (L.) Karst.) rendus à différents stades de succession (forêt coupée à blanc, jeune et vieille forêts). L'expérience a été répétée le long d'un gradient pluvial (zones continentale, subocéanique et atlantique) en Scandinavie. La croissance des lichens a culminé dans les forêts pluviales atlantiques avec un gain moyen en matière anhydre allant jusqu'à 36%-38%. Le lichen alectorioïde U. longissima a montré la plus vaste gamme de réponses en croissance végétative et aucun signe de dégradation de la chlorophylle. Son gain maximal en matière anhydre est survenu essentiellement dans les coupes à blanc alors qu'il était presque nul dans la jeune forêt la plus ombragée. Les deux lichens foliacés, L. pulmonaria et P. crocata, montraient des taux maximum de croissance dans les vieilles forêts, mais la croissance était apparemment limitée par la faible luminosité, même dans les forêts âgées. Leur gain en matière anhydre était réduit dans la plupart des coupes à blanc exposées au soleil à cause de la dégradation de la chlorophylle alors qu'il était relativement élevé sous les jeunes canopées fermées, ce qui indique une meilleure adaptation à l'ombre. La réponse des lichens montre qu'une fréquence élevée et une forte dominance de jeunes peuplements forestiers à croissance rapide à l'échelle du paysage ne sont pas compatibles avec de grandes populations de ces lichens, typiques des forêts matures, et que le manque de lichens sous un régime forestier industriel pourrait ne pas nécessairement être dû seulement à la faible efficacité de dispersion des lichens.

  • 6.
    Hosseini, Ahmad
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Lindroos, Ola
    Sveriges lantbruksuniversitet, Swedish University of Agricultural Sciences.
    Wadbro, Eddie
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    A holistic optimization framework for forest machine trail network design accounting for multiple objectives and machines2019In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 49, no 2, p. 111-120Article in journal (Refereed)
    Abstract [en]

    Ground-based mechanized forestry requires the traversal of terrain by heavy machines. The routes they take are often called machine trails, and are created by removing trees from the trail and placing the logs outside it. Designing an optimal machine trail network is a complex locational problem that requires understanding how forestry machines can operate on the terrain as well as the trade-offs between various economic and ecological aspects. Machine trail designs are currently created manually based on intuitive decisions about the importance, correlations, and effects of many potentially conflicting aspects. Badly designed machine trail networks could result in costly operations and adverse environmental impacts. Therefore, this study was conducted to develop a holistic optimization framework for machine trail network design. Key economic and ecological objectives involved in designing machine trail networks for mechanized cut-to-length operations are presented, along with strategies for simultaneously addressing multiple objectives while accounting for the physical capabilities of forestry machines, the impact of slope, and operating costs. Ways of quantitatively formulating and combining these different aspects are demonstrated, together with examples showing how the optimal network design changes in response to various inputs.

  • 7.
    Maher, Eliza L.
    et al.
    Department of Biological Sciences, Idaho State University.
    Germino, Matthew J.
    Department of Biological Sciences, Idaho State University.
    Hasselquist, Niles J.
    Department of Biological Sciences, Idaho State University.
    Interactive effects of tree and herb cover on survivorship, physiology, and microclimate of conifer seedlings at the alpine tree-line ecotone2005In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 35, no 3, p. 567-574Article in journal (Refereed)
    Abstract [en]

    Factors affecting the establishment of trees in subalpine meadows are important to population dynamics of trees in the alpine tree- line ecotone ( ATE). Interactive effects of tree and herb cover on conifer seedlings were investigated in the ATE of the Snowy Range, Wyoming, USA. Microclimate, physiology, and survivorship of first-year conifer seedlings of Pinus albicaulis Engelm., Picea engelmannii Parry, and Abies lasiocarpa Hook. were measured in response to manipulations of surrounding herb and tree cover, as well as water availability. Tree and herb cover had nearly additive effects on survivorship and photosynthesis of conifer seedlings, except under alleviated water stress. In P. albicaulis, photosynthesis was greater near compared with away from trees and herbs, and photosynthetic efficiency ( F-v/ F-m) increased under herb cover. Tree cover led to greater nighttime temperatures, soil water contents, and, like herb cover, shade from solar radiation for seedlings. We did not detect any negative responses of conifer seedlings to surrounding vegetation. Furthermore, the effect of surrounding vegetation on conifer establishment appeared dependent on the type of surrounding vegetation, the species of conifer, and microsite stress level. These factors may lead to variation in the way conifer seedlings interact with surrounding vegetation and could explain changes in the relative abundances of tree species during forest succession in ATEs.

  • 8.
    Ringdahl, Ola
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Hellström, Thomas
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Lindroos, Ola
    Dept. of Forest Resource Management, Swedish University of Agricultural Sciences.
    Potentials of possible machine systems for directly loading logs in cut-to-length harvesting2012In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 42, no 5, p. 970-985Article in journal (Refereed)
    Abstract [en]

    In conventional mechanized cut-to-length systems, a harvester fells and cuts trees into logs that are stored on the ground until a forwarder picks them up and carries them to landing sites. A proposed improvement is to place logs directly into the load spaces of transporting machines as they are cut. Such integrated loading could result in cost reductions, shorter lead times from stump to landing, and lower fuel consumption. However, it might also create waiting times for the machines involved, whereas multifunctional machines are likely to be expensive. Thus, it is important to analyze whether or not the advantages of any changes outweigh the disadvantages. The conventional system was compared with four potential systems, including two with autonomous forwarders, using discrete-event simulation with stochastic elements in which harvests of more than 1000 final felling stands (containing in total 1.6 million m3) were simulated 35 times per system. The results indicate that harwarders have substantial potential (less expensive on ≥80% of the volume and fuel consumption decreased by ≥18%) and may become competitive if key innovations are developed. Systems with cooperating machines have considerably less potential, limited to very specific stand conditions. The results conform with expected difficulties in integrating processing and transporting machines’ work in variable environments.

  • 9.
    Ringvall, Anna
    et al.
    SLU.
    Snäll, Tord
    University of Colorado at Boulder, USA.
    Ekström, Magnus
    Centre of Biostochastics, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden.
    Ståhl, Göran
    SLU.
    Unrestricted guided transect sampling for surveying sparse species2007In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 37, no 12, p. 2575-2586Article in journal (Refereed)
    Abstract [en]

    We present a modification of an earlier presented method using prior auxiliary information in the layout of survey strips. The idea is to imitate a skilled surveyor who purposively seeks the species of interest. Yet, the method “unrestricted guided transect sampling” (UGTS) is a probability sampling method. In comparison with a strip survey using no auxiliary information, UGTS gave 11%–64% lower standard errors for estimates of species population size in three simulated forest types. In a test in six stands where European aspen (Populus tremula L.) and an epiphytic moss (Orthotrichum speciosum Nees) had been mapped, UGTS gave a small improvement in some stands but considerably higher standard errors in other stands with kNN estimates of volume of deciduous trees derived from satellite images as covariate values. With covariates values simulated from aspen basal area, UGTS gave 8%–75% lower standard error than a strip survey using no auxiliary information. The study shows a gain in precision by using auxiliary information both in the design and in estimation when surveying sparse species but also that the correlation between the covariate and the variable of interest has to be relatively strong to make the method worthwhile.

  • 10. SUNDBLAD, LG
    et al.
    SJOSTROM, M
    MALMBERG, G
    Oquist, Gunnar
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    PREDICTION OF FROST HARDINESS IN SEEDLINGS OF SCOTS PINE (PINUS-SYLVESTRIS) USING MULTIVARIATE-ANALYSIS OF CHLOROPHYLL-A FLUORESCENCE AND LUMINESCENCE KINETICS1990In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 20, no 5, p. 592-597Article in journal (Refereed)
  • 11.
    Talbot, Patricia
    et al.
    bLaurentian Forestry Centre, Canadian Forest Service, Natural Resources Canada, 1055 rue du PEPS, Québec, QC G1V 4C7, Canada.
    Thompson, Stacey Lee
    bLaurentian Forestry Centre, Canadian Forest Service, Natural Resources Canada, 1055 rue du PEPS, Québec, QC G1V 4C7, Canada.
    Schroeder, William
    cAgroforestry Development Centre, AAFC Agri-Environment Services Branch, P.O. Box 940, No. 2 Government Road, Indian Head, SK S0G 2K0, Canada.
    Isabel, Nathalie
    bLaurentian Forestry Centre, Canadian Forest Service, Natural Resources Canada, 1055 rue du PEPS, Québec, QC G1V 4C7, Canada.
    An efficient single nucleotide polymorphism assay to diagnose the genomic identity of poplar species and hybrids on the Canadian prairies2011In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 41, no 5, p. 1102-1111Article in journal (Refereed)
    Abstract [en]

    Hybridization frequently occurs among poplars, both naturally and artificially, hindering identification. Over 32 million clonal poplars, predominantly hybrids, have been planted throughout the Canadian prairies over the past century, making confirmation of genomic identity important. We developed a genotyping assay that rapidly diagnoses four compatible Populus species (Populus balsamifera L. and Populus deltoides Bartr. ex Marsh.: indigenous, Populus laurifolia Ledeb. and Populus nigra L.: exotics) and their hybrids found throughout this ecozone. First, we sequenced 23 genes from representative provenances of the four Populus species to discover single nucleotide polymorphisms (SNPs). Second, we developed and validated a medium-throughput genotyping assay of 26 diagnostic SNPs within these genes. We used this assay to genotype 198 trees from natural populations as well as 30 clones (pure species and hybrids), including those broadly distributed by Agriculture and Agri-Food Canada's Agroforestry Development Centre since 1910. This suite of SNPs has the resolving power to correctly identify pure species and hybrids of Populus. We confirmed the identity of clones of well-documented origin, complex hybrids with exotic components, and paternity of open-pollinated progenies from breeding programs. This diagnostic tool should prove useful for efficient molecular fingerprinting of breeding material and for further studies of interspecific gene flow on the Canadian prairies.

  • 12. Young, Amanda B.
    et al.
    Cairns, David M.
    Lafon, Charles W.
    Moen, Jon
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Martin, Laura E.
    Dendroclimatic relationships and possible implications for mountain birch and Scots pine at treeline in northern Sweden through the 21st century2011In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 41, no 3, p. 450-459Article in journal (Refereed)
    Abstract [en]

    Changing climate in the Arctic is expected to have significant effects on the pattern and distribution of terrestrial vegetation. Species characteristic of specific zones in the mountains of northern Sweden have been shown to migrate up- and down-slope with changes in climate over the Holocene. This study evaluates the potential for Scots pine (Pinus sylvestris L.) to become a treeline dominant at Fennoscandian treelines, replacing mountain birch (Betula pubescens subsp. czerepanovii (Orlova) Hämet-Ahti). Data from paired mountain birch and Scots pine tree-ring chronologies for eight locations in northern Sweden are used to develop climate – tree ring width index (RWI) relationships. Modeled climate–RWI relationships are then used to predict the relative RWI values of the two species under a suite of climate-forcing scenarios using an ensemble of three global climate models. Results indicate that mountain birch and Scots pine RWI are both correlated with summer temperatures, but Scots pine is more likely than mountain birch to be influenced by moisture conditions. Predictions of RWI under future climate conditions indicate that mountain birch is unlikely to be replaced by Scots pine within the next century.

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