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  • 51. Eriksson, Åsa
    et al.
    Moen, Jon
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Effekter av skogsbruk på rennäringen: en litteraturstudie2008Report (Other academic)
  • 52.
    Ersson, Back Tomas
    et al.
    Sveriges lantbruksuniversitet.
    Jundén, Linus
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Bergsten, Urban
    Sveriges lantbruksuniversitet.
    Servin, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Simulated productivity of one- and two-armed tree planting machines2013In: Silva Fennica, ISSN 0037-5330, E-ISSN 2242-4075, Vol. 47, no 2, article id 958Article in journal (Refereed)
    Abstract [en]

    To increase mechanized planting, planting machine productivity must increase in order to improve cost-efficiency. To determine if excavators with two crane arms could potentially help to increase planting machine productivity under Nordic clearcut conditions, we modelled one- armed and semi-automated two-armed excavators with one- and two-headed planting devices. Using a recently developed tool for discrete-event simulation, these machine models then mounded and planted seedlings on terrain models with moraine soil having various frequencies of obstacles (stumps, roots and stones). Compared to if the two heads were mounted pairwise on only one arm, the results showed that productivity did not increase if two planting heads were attached individually to two separate crane arms. But productivity did increase if the planting machine had four planting heads mounted pairwise on two separate arms. However, despite assuming automated mounding and crane motion between planting spots, the two-armed, four- headed model never achieved high enough productivity levels to make it more cost-efficient than one-armed machines. The simulations illustrate that our terrain models generate realistic root architecture and boulder content distributions in moraine soil, while our machine models functionally describe mechanized planting work. Based on our assumptions, we conclude that further development work on two-armed excavator-based planting machines for Nordic clearcut conditions is not warranted. Our simulations reveal that increasing the number of planting heads per crane arm rather than number of crane arms per base machine offers the greatest potential to raise the productivity of intermittently advancing planting machines.

  • 53.
    Ersson, Back Tomas
    et al.
    Sveriges lantbruksuniversitet.
    Linus, Jundén
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Bergsten, Urban
    Sveriges lantbruksuniversitet.
    Servin, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Simulations of Mechanized Planting: Modelling Terrain and Crane-Mounted Planting Devices2012In: OSCAR 2012: The Nordic Baltic conference on forestoperations / [ed] Andis Lazdiņš, Latvian State Forest Research Institute "Silava" , 2012, p. 15-19Conference paper (Other academic)
    Abstract [en]

    When reforesting clearcuts in southern Sweden, the Bracke Planter has shown to plant seedlings with better planting quality than operational manual tree planting (Ersson and Petersson 2011). Consequently, there is an increasing demand for intermittently advancing tree planting machines with crane-mounted planting devices in southern Sweden.

    Nevertheless, regardless of using one- (Bracke Planter) or two-headed planting devices (M-Planter), today’s average planting machine productivity is still too low (Rantala and Laine 2010, Ersson et al. 2011) for planting machines to cost-wise compete with manual tree planting in southern Sweden (Ersson 2010). There is, therefore, a need to develop new planting machines concepts that are significantly more productive on Nordic terrain, i.e. clearcuts on moraine soils with varying prevalences of stones and stumps where the slash has been harvested for bioenergy.

    For over 40 years, simulation studies have proven useful for testing prospective forest machine concepts (e.g. (Sjunnesson 1970)), including different types of planting heads (Andersson et al. 1977). In particular, simulations studies can nowadays help to cost-efficiently evaluate new ideas before real world implementation (Jundén 2011). However, previous forest machine simulations simplified terrain characteristics like stumps, roots and stones to the extent that these models are too simplistic for meaningful planting machine simulations. For this reason, we have built several terrain, base machine and planting device models for use during discrete-event simulations to test potential solutions that realistically might increase Nordic planting machine productivity. These simulations were performed using a simulator built with the SimPy discrete-event simulation language (Jundén 2011).

    TERRAIN MODELS

    Presently, our terrain models encompass stumps, roots and underground stones. To delineate the clearcuts, we used Herlitz’s (1975) type stands for clearcutting. These type stands also provided theinput data necessary for sizing and spatially allocating the stumps. To all stumps, we attached a root plate according to the deterministic data from Björkhem et al. (1975) and a stochastic root architecture inspired by Kalliokoski et al.’s (2010) root models.As concluded already during the 1960s (Bäckström 1978), the presence of non-visible, underground stones and boulders is what makes mechanized reforestation on moraine soils so difficult. To model this difficulty, we used parameter values from Andersson et al. (1977) to define incidences of stones and boulders (boulder quota or stoniness) and mean stone sizes. Then, we chose an exponential distribution to link stone frequency to stone diameter. In accordance with Eriksson and Holmgren (1996), our modelled stones are spherical in shape and are spatially allocated in a random manner.

    BASE MACHINE MODELS

    Today’s planting machines use excavators as base machines. If using standard components, it might be techno-economically feasible to add another arm to the excavator; thereby creating two- (Fig. 2) or four-headed planting machines where planting head interdependence is minimized. We hypothesized that the productivity of two-armed planting machines, compared to normal one-armed machines, might especially be higher on obstacle-rich terrain since one arm could be free to move while the other arm is busy working. Moreover, two-armed machines might particularly benefit from additional task automation. Preliminary results, however, show that this productivity increase might not be high enough to warrant further development of our two-armed planting machine concept.

    PLANTING DEVICE MODELS

    We modelled today’s two most common planting devices, the one-headed Bracke Planter and the two-headed M-Planter. During simulation, the planting machine operator searches sequentially for microsites free from visible obstacles (stumps and main lateral roots). However, both devices can be impeded by underground roots or stones during mounding, and by stones during the planting phase. Striking obstacles with the M-Planter can result in delays for one or both heads.

    FURTHER DEVELOPMENT

    We are currently expanding the terrain models to include humus layers and surface boulders, on which new multi-headed planting device concepts (with two to four planting heads) with obstacle-avoiding capabilities are being tested. Those simulation results will provide guidance as to how future crane-mounted planting devices should behave and be designed in order to increase planting machine productivity.

  • 54.
    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.

  • 55.
    Esseen, Per-Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Coxson, Darwyn S
    Lichens in forest ecosystems2015In: Routledge handbook of forest ecology / [ed] Kelvin S.-H. Peh, Richard T. Corlett and Yves Bergeron, Taylor & Francis, 2015, p. 250-263Chapter in book (Refereed)
  • 56.
    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.

  • 57. Falster, Daniel S.
    et al.
    FitzJohn, Richard G.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Evolution and Ecology Program, International Institutefor Applied Systems Analysis, Schlossplatz 1, A-2361 Laxen burg, Au stria.
    Dieckmann, Ulf
    Westoby, Mark
    plant: A package for modelling forest trait ecology and evolution2016In: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210X, Vol. 7, no 2, p. 136-146Article in journal (Refereed)
    Abstract [en]

    Population dynamics in forests are strongly size-structured: larger plants shade smaller plants while also expending proportionately more energy on building and maintaining woody stems. Although the importance of size structure for demography is widely recognized, many models either omit it entirely or include only coarse approximations. Here, we introduce the plant package, an extensible framework for modelling size- and trait-structured demography, ecology and evolution in simulated forests. At its core, plant is an individual-based model where plant physiology and demography are mediated by traits. Individual plants from multiple species can be grown in isolation, in patches of competing plants or in metapopulations under a disturbance regime. These dynamics can be integrated into metapopulation-level estimates of invasion fitness and vegetation structure. Because fitness emerges as a function of traits, plant provides a novel arena for exploring eco-evolutionary dynamics. plant is an open source R package and is available at . Accessed from R, the core routines in plant are written in C++. The package provides for alternative physiologies and for capturing trade-offs among parameters. A detailed test suite is provided to ensure correct behaviour of the code. plant provides a transparent platform for investigating how physiological rules and functional trade-offs interact with competition and disturbance regimes to influence vegetation demography, structure and diversity.

  • 58. Felton, Adam
    et al.
    Löfroth, Therese
    Angelstam, Per
    Gustafsson, Lena
    Hjältén, Joakim
    Felton, Annika M.
    Simonsson, Per
    Dahlberg, Anders
    Lindbladh, Matts
    Svensson, Johan
    Nilsson, Urban
    Lodin, Isak
    Hedwall, P. O.
    Sténs, Anna
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies.
    Lämås, Tomas
    Brunet, Jörg
    Kalen, Christer
    Kriström, Bengt
    Gemmel, Pelle
    Ranius, Thomas
    Keeping pace with forestry: Multi-scale conservation in a changing production forest matrix2019In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209Article in journal (Refereed)
    Abstract [en]

    The multi-scale approach to conserving forest biodiversity has been used in Sweden since the 1980s, a period defined by increased reserve area and conservation actions within production forests. However, two thousand forest-associated species remain on Sweden's red-list, and Sweden's 2020 goals for sustainable forests are not being met. We argue that ongoing changes in the production forest matrix require more consideration, and that multi-scale conservation must be adapted to, and integrated with, production forest development. To make this case, we summarize trends in habitat provision by Sweden's protected and production forests, and the variety of ways silviculture can affect biodiversity. We discuss how different forestry trajectories affect the type and extent of conservation approaches needed to secure biodiversity, and suggest leverage points for aiding the adoption of diversified silviculture. Sweden's long-term experience with multi-scale conservation and intensive forestry provides insights for other countries trying to conserve species within production landscapes.

  • 59.
    Felton, Adam
    et al.
    Sveriges lantbruksuniversitet, SLU.
    Nilsson, Urban
    Sveriges lantbruksuniversitet, SLU.
    Sonesson, Johan
    Skogforsk.
    Felton, Annika M.
    Sveriges lantbruksuniversitet, SLU.
    Roberge, Jean-Michel
    Sveriges lantbruksuniversitet, SLU.
    Ranius, Thomas
    Sveriges lantbruksuniversitet, SLU.
    Ahlström, Martin
    Sveriges lantbruksuniversitet, SLU.
    Bergh, Johan
    Linnéuniversitetet.
    Björkman, Christer
    Swedish University of Agricultural Sciences (SLU).
    Boberg, Johanna
    Swedish University of Agricultural Sciences (SLU).
    Drössler, Lars
    Sveriges lantbruksuniversitet (SLU).
    Fahlvik, Nils
    Swedish University of Agricultural Sciences (SLU).
    Gong, Peichen
    Swedish University of Agricultural Sciences (SLU).
    Holmström, Emma
    Sveriges lantbruksuniversitet (SLU).
    Keskitalo, E. Carina H.
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History.
    Klapwijk, Maartje
    Sveriges lantbruksuniversitet (SLU).
    Laudon, Hjalmar
    Sveriges lantbruksuniversitet, SLU.
    Lundmark, Tomas
    Swedish University of Agricultural Sciences (SLU).
    Niklasson, Mats
    Sveriges lantbruksuniversitet (SLU)/Foundation Nordens Ark.
    Nordin, Annika
    Sveriges lantbruksuniversitet, SLU.
    Pettersson, Maria
    Luleå tekniska universitet.
    Stenlid, Jan
    Swedish University of Agricultural Sciences (SLU).
    Sténs, Anna
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies.
    Wallertz, Kristina
    Sveriges lantbruksuniversitet.
    Replacing monocultures with mixed-species stands: Ecosystem service implications of two production forest alternatives in Sweden2016In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 45, p. 124-139Article in journal (Refereed)
    Abstract [en]

    Whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. To provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. Here, we conduct such an assessment in Sweden by contrasting even-aged Norway spruce (Picea abies)-dominated stands, with mixed-species stands of spruce and birch (Betula pendula or B. pubescens), or spruce and Scots pine (Pinus sylvestris). By synthesizing the available evidence, we identify positive outcomes from mixtures including increased biodiversity, water quality, esthetic and recreational values, as well as reduced stand vulnerability to pest and pathogen damage. However, some uncertainties and risks were projected to increase, highlighting the importance of conducting comprehensive interdisciplinary evaluations when assessing the pros and cons of mixtures.

  • 60. Ficko, Andrej
    et al.
    Lidestav, Gun
    Ní Dhubháin, A
    Karppinen, Heimo
    Westin, Kerstin
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History.
    European private forest owner typologies: a review of methods and use2019In: Forest Policy and Economics, ISSN 1389-9341, E-ISSN 1872-7050, Vol. 99, p. 21-31Article in journal (Refereed)
    Abstract [en]

    The increasing diversity of non-industrial private forest owners (PFOs) in Europe has been recognized by policy makers and the forestry sector at large. Typologies of these owners have been developed to provide an understanding of the diversity of owners' attitudes, values, beliefs, management objectives and behaviour. We analyzed PFO typologies from 28 European countries published from 1985 to 2015 in peer-reviewed journals and grey literature with respect to 1) research approaches and methods used; 2) typology objectives and problems addressed; 3) policy and management recommendations given. Using an on-line questionnaire we asked the first authors of the most relevant publications to retrospectively assess 4) the use of their typologies in education, science and forest policy. Most of the 66 publications reviewed share the common objective of providing a better understanding of forest ownership. Typologies were also developed to address roundwood mobilization, delivery of public goods, forest management approaches, involvement in PFO associations and entrepreneurship. The most common methodological approach was quantitative where owners were grouped by k-means clustering into 2 to 6 types and labelled with various names. Most frequently used labels were Multiobjective owners, Recreationists, Investors, Farmers, Indifferent owners, Conservationists, Multifunctional owners and Self-employed owners. Policy implications remain vague. The typologies had mostly been used in teaching and occasionally by politicians, civil servants or stake-holders. Only a half of the typologies had a follow-up study or was updated over time by the authors. After decades of classifying PFOs, it seems necessary to explore the link between typologies and forest owners' overt behaviour.

  • 61.
    Forsman, Mona
    et al.
    Department of Forest Resource Management, Swedish University of Agricultural Sciences.
    Börlin, Niclas
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Holmgren, Johan
    Department of Forest Resource Management, Swedish University of Agricultural Sciences.
    Estimation of tree stem attributes using terrestrial photogrammetry2012In: International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Copernicus Gesellschaft , 2012, p. B5-261-B5-265Conference paper (Other academic)
    Abstract [en]

    The objective of this work was to create a method to measure stem attributes of standing trees on field plots in the forest using terrestrial photogrammetry. The primary attributes of interest are the position and the diameter at breast height (DBH).

    The developed method creates point clouds from image from three or more calibrated cameras attached to a calibrated rig. SIFT features in multiple images in combination with epipolar line filtering are used to make high quality matching in images with large amounts of similar features and many occlusions. After projection of the point cloud to a simulated ground plane, RANSAC filtering is applied, followed by circle fitting to the remaining points.

    To evaluate the algorithm, a camera rig of five Canon digital system cameras with a baseline of 123 cm and up to 40 cm offset in height was constructed. The rig was used in a field campaign at the Remningstorp forest test area in southern Sweden. Ground truth was collected manually by surveying and manual measurements.

    Initial results show estimated tree stem diameters within 10% of the ground truth. This suggest that terrestrial photogrammetry is a viable method to measure tree stem diameters on circular field plots.

  • 62.
    Forsman, Mona
    et al.
    Department of Forest Resource Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Börlin, Niclas
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Holmgren, Johan
    Department of Forest Resource Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Estimation of Tree Stem Attributes using Terrestrial Photogrammetry with a Camera Rig2016In: Forests, ISSN 1999-4907, E-ISSN 1999-4907, Vol. 7, no 3, article id 61Article in journal (Refereed)
    Abstract [en]

    We propose a novel photogrammetric method for field plot inventory, designed for simplicity and time efficiency on-site. A prototype multi-camera rig was used to acquire images from field plot centers in multiple directions. The acquisition time on-site was less than two minutes. From each view, a point cloud was generated using a novel, rig-based matching of detected SIFT keypoints. Stems were detected in the merged point cloud, and their positions and diameters were estimated. The method was evaluated on 25 hemi-boreal forest plots of a 10-m radius. Due to difficult lighting conditions and faulty hardware, imagery from only six field plots was processed. The method performed best on three plots with clearly visible stems with a 76% detection rate and 0% commission. Dieameters could be estimated for 40% of the stems with an RMSE of 2.8-9.5 cm. The results are comparable to other camera-based methods evaluated in a similar manner. The results are inferior to TLS-based methods. However, our method is easily extended to multiple station image schemas, something that could significantly improve the results while retaining low commission errors and time on-site. Furthermore, with smaller hardware, we believe this could be a useful technique for measuring stem attributes in the forest.

  • 63.
    Forsman, Mona
    et al.
    Department of Forest Resource Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Börlin, Niclas
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Olofsson, Kenneth
    Department of Forest Resource Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Reese, Heather
    Department of Forest Resource Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Holmgren, Johan
    Department of Forest Resource Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
    Bias of cylinder diameter estimation from ground-based laser scanners with different beam widths: a simulation study2018In: ISPRS journal of photogrammetry and remote sensing (Print), ISSN 0924-2716, E-ISSN 1872-8235, Vol. 135, p. 84-92Article in journal (Refereed)
    Abstract [en]

    In this study we have investigated why diameters of tree stems, which are approximately cylindrical, are often overestimated by mobile laser scanning. This paper analyzes the physical processes when using ground-based laser scanning that may contribute to a bias when estimating cylinder diameters using circle-fit methods. A laser scanner simulator was implemented and used to evaluate various properties, such as distance, cylinder diameter, and beam width of a laser scanner-cylinder system to find critical conditions. The simulation results suggest that a positive bias of the diameter estimation is expected. Furthermore, the bias follows a quadratic function of one parameter - the relative footprint, i.e., the fraction of the cylinder width illuminated by the laser beam. The quadratic signature opens up a possibility to construct a compensation model for the bias.

  • 64. Franklin, Oskar
    et al.
    Johansson, Jacob
    Dewar, Roderick C.
    Dieckmann, Ulf
    McMurtrie, Ross E.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Dybzinski, Ray
    Modeling carbon allocation in trees: a search for principles2012In: Tree Physiology, ISSN 0829-318X, E-ISSN 1758-4469, Vol. 32, no 6, p. 648-666Article, review/survey (Refereed)
    Abstract [en]

    We review approaches to predicting carbon and nitrogen allocation in forest models in terms of their underlying assumptions and their resulting strengths and limitations. Empirical and allometric methods are easily developed and computationally efficient, but lack the power of evolution-based approaches to explain and predict multifaceted effects of environmental variability and climate change. In evolution-based methods, allocation is usually determined by maximization of a fitness proxy, either in a fixed environment, which we call optimal response (OR) models, or including the feedback of an individual's strategy on its environment (game-theoretical optimization, GTO). Optimal response models can predict allocation in single trees and stands when there is significant competition only for one resource. Game-theoretical optimization can be used to account for additional dimensions of competition, e.g., when strong root competition boosts root allocation at the expense of wood production. However, we demonstrate that an OR model predicts similar allocation to a GTO model under the root-competitive conditions reported in free-air carbon dioxide enrichment (FACE) experiments. The most evolutionarily realistic approach is adaptive dynamics (AD) where the allocation strategy arises from eco-evolutionary dynamics of populations instead of a fitness proxy. We also discuss emerging entropy-based approaches that offer an alternative thermodynamic perspective on allocation, in which fitness proxies are replaced by entropy or entropy production. To help develop allocation models further, the value of wide-ranging datasets, such as FLUXNET, could be greatly enhanced by ancillary measurements of driving variables, such as water and soil nitrogen availability.

  • 65.
    Fransson, Peter
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Optimal thinning: a theoretical investigation on individual-tree level2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Paper I: In paper I, we asked how a tree should optimally allocate its resources to maximize its fitness. We let a subject tree grow in an environment shaded by nearby competing trees. The competitors were assumed to have reached maturity and had stopped growing, thus creating a static light environment for the subject tree to grow in. The light environment was modeled as a logistic function. For the growth model we used the pipe model as a foundation, linking tree width and leaf mass. This allowed us to construct a dynamic tree-growth model where the tree can allocate biomass from photosynthesis (net productivity) to either stem-height growth, crown-size growth, or reproduction (seed production). Using Pontryagin's maximum principle we derived necessary conditions for optimal biomass allocation, and on that built a heuristic allocation model. The heuristic model states that the tree should first invest into crown-size and then switch to tree height-growth, and lastly invest into crown-size before the growth investments stop and all investments are allocated to reproduction. To test our heuristic method, we used it to determine the growth in several different light environments. The results were then compared to the optimal growth trajectories. The optimal growth was determined by applying dynamic programming. Our less computationally demanding heuristic performed very well in comparison. We also found there exist a critical crown-size: if the subject tree possessed a larger crown-size, the tree would be unable to reach up to the canopy height.

    Paper II: One of the most important aspects of modelling forest growth, and modelling growth of individual trees in general, is the competition between trees. A high level of competition pressure has a negative impact on the growth of individual trees. There are many ways of modelling competition, the most common one is by using a competition index. In this paper we tested 16 competition indices, in conjunction with a log-linear growth model, in terms of the mean squared error and the coefficient of determination. 5 competition indices are distance-independent (i.e. distance between the competitors are not taken into consideration) and 11 are distance-dependent. The data we used to fit our growth model, with accompanying competition index, was taken from an experimental site, in northern Sweden, of Norway spruce. The growth data for the Norway spruce comes from stands which were treated with one of two treatments, solid fertilization, liquid fertilization, or no treatment (control stand). We found that the distance-dependent indices perform better than the distance-independent. However, both the best distance-dependent and independent index performed overall well. We also found that the ranking of the indices was unaffected by the stand treatment, i.e. indices that work well for one treatment will work well for the others.

    Paper III: In this paper we studied how spatial distribution and size selection affect the residual trees, after a thinning operation, in terms of merchantable wood production and stand economy. We constructed a spatially explicit individual-based forest-growth model and fitted and validated the model against empirical data for Norway spruce stands in northern Sweden. To determine the cost for the forest operation we employed empirical cost functions for harvesting and forwarding. The income from the harvested timber is calculated from volume-price lists. The thinnings were determined by three parameters: the spatial evenness of residual trees, the size selection of removed trees, and the basal area reduction. In order to find tree selections fulfilling these constraints we used the metropolis algorithm. We varied these three constrains and applied them for thinning of different initial configurations of Norway spruce stands. The initial configurations for the stands where collected from empirical data. We found that changing the spatial evenness and size selection improved the net wood production and net present value of the stand up to 8%. However, the magnitude of improvement was dependent on the initial configuration (the magnitude of improvement varied between 1.7%—8%).

    Paper IV: With new technology and methods from remote sensing, such as LIDAR, becoming more prevalent in forestry, the ability to assess information on a detailed scale has become more available. Measurements for each individual tree can be more easily gathered on a larger scale. This type of data opens up for using individual-based model for practical precision forestry planning. In paper IV we used the individual-based model constructed in paper III to find the optimal harvesting time for each individual tree, such that the land expectation value is maximized. We employed a genetic algorithm to find a near optimal solution to our optimization. We optimized a number of initial Norway spruce stands (data obtained from field measurements). The optimal management strategy was to apply thinning from above. We also found that increasing the discount rate will decrease the time for final felling and increase basal area reduction for the optimal strategy. Decreasing relocation costs (the cost to bring machines to the stand) led to an increase in the number of optimal thinnings and postponed the first thinning. Our strategy was superior to both the unthinned strategy and a conventional thinning strategy, both in terms of land expectation value (>20% higher) and merchantable wood production.

  • 66.
    Fransson, Peter
    et al.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Franklin, Oskar
    Ecosystems Services and Management Program, International Institute for Applied Systems Analysis.
    Lindroos, Ola
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences.
    Nilsson, Urban
    Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Evolution and Ecology Program, International Institute for Applied Systems Analysis, Laxenburg, Austria.
    A simulation-based approach to a near optimal thinning strategy: allowing for individual harvesting times for individual trees2019In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037Article in journal (Refereed)
    Abstract [en]

    As various methods for precision inventories, such as LiDAR, are becoming increasingly common in forestry, individual-tree level planning is becoming more viable. Here, we present a method for finding the optimal thinning times for individual trees from an economic perspective. The method utilizes an individual tree-based forest growth model that has been fitted to Norway spruce (Picea abies (L.) Karst.) stands in northern Sweden. We find that the optimal management strategy is to thin from above, i.e. harvesting trees that are larger than average. We compare our optimal strategy with a conventional management strategy and find that it results in approximately 20% higher land expectation value. Furthermore, we find that increasing the discount rate will, for the optimal strategy, reduce the final harvest age and increase the basal area reduction. Decreasing the cost to initiate a thinning (e.g., machinery-related transportation costs) increases the number of thinnings and delays the first thinning.

  • 67.
    Fransson, Peter
    et al.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Franklin, Oskar
    Ecosystems Services and Management Program, International Institute for Applied Systems Analysis.
    Nilsson, Urban
    Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences.
    Comparing distance-independent and distance-dependent competition indices for Picea abiesManuscript (preprint) (Other academic)
    Abstract [en]

    Competition between individual trees is important for forest growth. Modeling the underlying interactions is difficult and sometimes not possible. Consequently, simplified competition indices are often used as a proxy. Several studies have shown that including competition indices into growth models will improve accuracy. However, there is no consensus on which or what type of indices work well. Here, we compare several indices of two qualitatively different types: distance-independent and distance-dependent indices. These indices are incorporated into a log-linear growth model and tested against 5-year diameter growth data collected from three Norway spruce plots that each have different fertilization treatments. We find that although distance-dependent indices performed better, distance-independent indices can also perform well; R2adj = 0.66 vs. 0.62 for the best indices in each category. We find that Bella’s index to be the best distance-dependent index (the index depends on distance between competitors and their diameters) and Reineke’s index to be the best distance-independent index (this index depends on the mean quadratic diameter and density in the stand). We also find that the performance ranking of indices is consistent across three different fertilization treatments.

  • 68.
    Fransson, Peter
    et al.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Nilsson, Urban
    Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Alnarp, Sweden.
    Lindroos, Ola
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Franklin, Oskar
    Ecosystems Services and Management Program, International Institute for Applied Systems Analysis, Laxenburg, Austria.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Evolution and Ecology Program, International Institute for Applied Systems Analysis, Laxenburg, Austria.
    Model-based investigation on the effects of spatial evenness, and size selection in thinning of Picea abies stands2019In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 34, no 3, p. 189-199Article in journal (Refereed)
    Abstract [en]

    Size and spatial distribution of trees are important for forest stand growth, but the extent to which itmatters in thinning operations, in terms of wood production and stand economy, has rarely beendocumented. Here we investigate how the choice of spatial evenness and tree-size distribution ofresidual trees impacts wood production and stand economy. A spatially explicit individual-basedgrowth model was used, in conjunction with empirical cost functions for harvesting andforwarding, to calculate net production and net present value for different thinning operations inNorway spruce stands in Northern Sweden. The in silico thinning operations were defined by threevariables: (1) spatial evenness after thinning, (2) tree size preference for harvesting, and (3) basalarea reduction. We found that thinning that increases spatial evenness increases net productionand net present value by around 2.0%, compared to the worst case. When changing the spatialevenness in conjunction with size preference we could observe an improvement of the netproduction and net present value up to 8.0%. The magnitude of impact differed greatly betweenthe stands (from 1.7% to 8.0%) and was highest in the stand with the lowest stem density.

  • 69. Fraver, Shawn
    et al.
    D'Amato, Anthony W.
    Bradford, John B.
    Jonsson, Bengt Gunnar
    Jonsson, Mari
    Esseen, Per-Anders
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Tree growth and competition in an old-growth Picea abies forest of boreal Sweden: influence of tree spatial patterning2014In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 25, no 2, p. 374-385Article in journal (Refereed)
    Abstract [en]

    Question What factors best characterize tree competitive environments in this structurally diverse old-growth forest, and do these factors vary spatially within and among stands? Location Old-growth Picea abies forest of boreal Sweden. Methods Using long-term, mapped permanent plot data augmented with dendrochronological analyses, we evaluated the effect of neighbourhood competition on focal tree growth by means of standard competition indices, each modified to include various metrics of trees size, neighbour mortality weighting (for neighbours that died during the inventory period), and within-neighbourhood tree clustering. Candidate models were evaluated using mixed-model linear regression analyses, with mean basal area increment as the response variable. We then analysed stand-level spatial patterns of competition indices and growth rates (via kriging) to determine if the relationship between these patterns could further elucidate factors influencing tree growth. Results Inter-tree competition clearly affected growth rates, with crown volume being the size metric most strongly influencing the neighbourhood competitive environment. Including neighbour tree mortality weightings in models only slightly improved descriptions of competitive interactions. Although the within-neighbourhood clustering index did not improve model predictions, competition intensity was influenced by the underlying stand-level tree spatial arrangement: stand-level clustering locally intensified competition and reduced tree growth, whereas in the absence of such clustering, inter-tree competition played a lesser role in constraining tree growth. Conclusions Our findings demonstrate that competition continues to influence forest processes and structures in an old-growth system that has not experienced major disturbances for at least two centuries. The finding that the underlying tree spatial pattern influenced the competitive environment suggests caution in interpreting traditional tree competition studies, in which tree spatial patterning is typically not taken into account. Our findings highlight the importance of forest structure - particularly the spatial arrangement of trees - in regulating inter-tree competition and growth in structurally diverse forests, and they provide insight into the causes and consequences of heterogeneity in this old-growth system.

  • 70.
    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.

  • 71.
    Funda, Tomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Wennstrom, Ulfstand
    Almqvist, Curt
    Torimaru, Takeshi
    Gull, Bengt Andersson
    Wang, Xiao-Ru
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Low rates of pollen contamination in a Scots pine seed orchard in Sweden: the exception or the norm?2015In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 30, no 7, p. 573-586Article in journal (Refereed)
    Abstract [en]

    We investigated mating structure and gene flow in a clonal seed orchard of Scots pine (Pinus sylvestris L.) over three consecutive pollination seasons (2010-2012) with nine nuclear microsatellite markers. The paternity of 1991 offspring from four maternal parents was assigned to 28 candidate fathers using an exclusion procedure and a likelihood-based method implemented in the program CERVUS. Relative reproductive success was highly variable among pollen parents but consistent across years and ranged from 0.1% to 18.3%. Consequently, the seed crops' effective number of fathers was reduced to 52.9%, 48.8%, and 45.7% of the census in the three seasons, respectively. Self-fertilization fluctuated around the orchard's expected value of 5.1%, reaching 4.05%, 7.71%, and 6.61%, respectively. Pollen contamination was estimated to be 5.64%, 7.29%, and 4.89%, respectively, after correction for cryptic gene flow. CERVUS provided similar results as the exclusion method, but estimates greatly varied depending on the input parameters, mainly the proportion of fathers sampled. These results indicate the studied seed orchard is a well-functioning production population with only minor negative effects of self-fertilization and pollen contamination on the quality of seed crops. Genotyping issues associated with microsatellites as a potential source of false paternity assignment and exclusion are discussed.

  • 72.
    Funda, Tomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Department of Forest Genetics and Plant Physiology, UPSCSwedish University of Agricultural Sciences, Umeå, Sweden.
    Wennström, Ulfstand
    Almqvist, Curt
    Andersson Gull, Bengt
    Wang, Xiao-Ru
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Mating dynamics of Scots pine in isolation tents2016In: Tree Genetics & Genomes, ISSN 1614-2942, E-ISSN 1614-2950, Vol. 12, no 6, article id 112Article in journal (Refereed)
    Abstract [en]

    Seed orchards are forest tree production populations for supplying the forest industry with consistent and abundant seed crops of superior genetic quality. However, genetic quality can be severely affected by non-random mating among parents and the occurrence of background pollination. This study analyzed mating structure and background pollination in six large isolation tents established in a clonal Scots pine seed orchard in northern Sweden. The isolation tents were intended to form a physical barrier against background pollen and induce earlier flowering relative to the surrounding trees. We scored flowering phenology inside and outside the tents and tracked airborne pollen density inside and outside the seed orchard in three consecutive pollination seasons. We genotyped 5683 offspring collected from the tents and open controls using nine microsatellite loci, and assigned paternity using simple exclusion method. We found that tent trees shed pollen and exhibited maximum female receptivity approximately 1 week earlier than trees in open control. The majority of matings in tents (78.3 %) occurred at distances within two trees apart (about 5 m). Self-fertilization was relatively high (average 21.8 %) in tents without supplemental pollination (SP), but it was substantially reduced in tents with SP (average 7.7 %). Pollen contamination was low in open controls (4.8-7.1 %), and all tents remained entirely free of foreign pollen. Our study demonstrates that tent isolation is effective in blocking pollen immigration and in manipulating flowering phenology. When complimented with supplemental pollination, it could become a useful seed orchard management practice to optimize the gain and diversity of seed orchard crops.

  • 73.
    Geijer, Erik
    et al.
    Sveriges Lantbruksuniversitet.
    Andersson, Jon
    Sveriges Lantbruksuniversitet.
    Bostedt, Göran
    Brännlund, Runar
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Economics.
    Hjältén, Joakim
    Sveriges Lantbruksuniversitet.
    Safeguarding species richness vs. increasing the use of renewable energy: the effect of stump harvesting on two environmental goals2014In: Journal of Forest Economics, ISSN 1104-6899, E-ISSN 1618-1530, Vol. 20, no 2, p. 111-125Article in journal (Refereed)
    Abstract [en]

    Deadwood is recognized as one of the most important resources affecting forest biodiversity.Its absence from the forest landscape is, therefore, of concern, such that one official Swedishenvironmental objective is to increase the volume of deadwood. However, increasing the useof renewable energy sources, another environmental goal, is likely to work against thisbiodiversity objective. In this study we utilize a regional economic forest sector model,focusing on northern Sweden, in order to estimate the effect of a large scale introduction ofstump harvest on the future use of forest fuel. In addition, an ecological model, describing therelationship between the availability of dead wood and the abundance of saproxylic beetles, islinked to the economic model.The parameters used in the economic model are derived from a data set spanning 28 yearswhile the ecological model is derived from a survey of ten clear cuts, undertaken seven yearsafter the clear cutting, in order to investigate the abundance of saproxylic beetles in stumps.We simulate the effects of an increased demand for wood fuels in northern Sweden, with orwithout stump harvest. The two scenarios have different effects on all major round woodmarkets in the region, as well as on the abundance of saproxylic beetles. More specifically,the harvest of stumps is associated with a 5% reduction in the mean abundance of saproxylicbeetles living in deadwood on future clear cuts and a 3% increase in the use of renewableenergy recourses in heating plants.

  • 74.
    Gong, Peichen
    et al.
    SLU.
    Löfgren, Karl-Gustaf
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Economics.
    Forest taxation2013In: Encyclopedia of energy, natural resource, and environmental economics: Volume 2 / [ed] Jason Shogren, Elsevier, 2013, p. 176-182Chapter in book (Refereed)
    Abstract [en]

    This article presents an overview of the application of taxation as a policy instrument in forestry. Forests cover about 30% of the total land area and constitute one of the most important natural resources on the planet. Forests worldwide produce a great amount of timber and various non-wood products, and they provide a wide range of ecological services. Following a brief review of the major forms of inefficiency of forest management in free markets, we discuss the behavioral effects of the general types of taxes targeted at forest assets and forestry income. This is followed by a review of the forest taxation systems in four selected countries (China, Finland, Sweden, and the United States). It is concluded that forest taxation has been used mainly for the purpose of collecting public revenues. Two common forms of inefficiency with respect to forest management are overharvesting (especially in developing countries) of existing forests and underinvestment in reforestation. Forest taxes and subsidies that are effective in correcting one type of inefficiency usually intensify the type of inefficiency. The effectiveness of taxes as a policy instrument to promote sustainable management of forest resources, remain to be evaluated.

  • 75. Grimberg, Åsa
    et al.
    Lager, Ida
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Robinson, Kathryn M
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Marttila, Salla
    Mähler, Niklas
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Ingvarsson, Pär K.
    Bhalerao, Rishikesh P.
    Storage lipid accumulation is controlled by photoperiodic signal acting via regulators of growth cessation and dormancy in hybrid aspen2018In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 219, no 2, p. 619-630Article in journal (Refereed)
    Abstract [en]

    The signalling pathways that control seasonal modulation of carbon metabolism in perennial plants are poorly understood. Using genetic, metabolic and natural variation approaches, we identify factors mediating photoperiodic control of storage lipid accumulation in the model tree hybrid aspen (Populus tremula x tremuloides). We characterized lipid accumulation in transgenic hybrid aspen with impaired photoperiodic and hormonal responses. Genome-wide association mapping was performed in Swedish aspen (P.tremula) genotypes to determine genetic loci associated with genotype variation in lipid content. Our data show that the storage lipid triacylglycerol (TAG) accumulates in cambial meristem and pith rays of aspen in response to photoperiodic signal controlling growth cessation and dormancy induction. We show that photoperiodic control of TAG accumulation is mediated by the FLOWERING LOCUS T/CONSTANS module, which also controls the induction of growth cessation. Hormonal and chromatin remodelling pathways also contribute to TAG accumulation by photoperiodic signal. Natural variation exists in lipid accumulation that is controlled by input from multiple loci. Our data shed light on how the control of storage metabolism is temporally coordinated with growth cessation and dormancy by photoperiodic signal, and reveals that storage lipid accumulation between seeds and perennating organs of trees may involve distinct regulatory circuits.

  • 76. Guo, Jinggang
    et al.
    Gong, Peichen
    Brännlund, Runar
    Umeå University, Faculty of Social Sciences, Umeå School of Business and Economics (USBE), Economics.
    Impacts of Increasing Bioenergy Production on Timber Harvest and Carbon Emissions2019In: Journal of Forest Economics, ISSN 1104-6899, E-ISSN 1618-1530, Vol. 34, no 3-4, p. 311-335Article in journal (Refereed)
    Abstract [en]

    Using a partial equilibrium model of the Swedish forest sector, this study analyzes the impacts of an increasing bioenergy production on the timber harvest and forest growing stock. The impacts on the carbon balance of forests are also examined. The results suggest that, when compared with the base scenario, in which the current use pattern of forests continues, increased bioenergy production will lead to a 10–14 million m3 (Mm3) increase in the total harvest, depending on the extraction rate of forest residues. Increasing the use of forest residues will reduce the harvest and leave more room for accumulation of the forest stock in the early years, while the stock accumulation will be partially offset by the increased timber harvest in the long run. Increasing bioenergy production will have a negative impact on the carbon balance primarily due to a net loss of carbon stored in forests. Overall, the joint contribution of forest-based mitigation is significant, equivalent to or higher than 65% of the country’s annual GHG emissions. To achieve an ambitious bioenergy target in the long run, a fraction of pulpwood will be consumed as fuelwood that will inevitably intensify the competition between the two timber products, though increasing the use of forest residues could slightly reduce the competition in the short run.

  • 77.
    Hall, David
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå Plant Science Centre, Department of Forest Genetics and Plant PhysiologySwedish University of Agricultural Sciences, Umeå, Sweden.
    Hallingbäck, Henrik R.
    Wu, Harry X.
    Estimation of number and size of QTL effects in forest tree traits2016In: Tree Genetics & Genomes, ISSN 1614-2942, E-ISSN 1614-2950, Vol. 12, no 6, article id 110Article in journal (Refereed)
    Abstract [en]

    Mapping the genetic architecture of forest tree traits is important in order to understand the evolutionary forces that have shaped these traits and to facilitate the development of genomic-based breeding strategies. We examined the number, size, and distribution of allelic effects influencing eight types of traits using 30 published mapping studies (linkage and association mapping) in forest trees. The sizes of allelic effects, measured as the phenotypic variance explained, generally showed a severely right-skewed distribution. We estimated the numbers of underlying causal effects (n(qtl)) for different trait categories by improving a method previously developed by Otto and Jones (Genetics 156: 2093-2107, 2000). Estimates of n(qtl) based on association mapping studies were generally higher (median at 643) than those based on linkage mapping (median at 33). Comparisons with simulated linkage and association mapping data suggested that the lower n(qtl) estimates for the linkage mapping studies could partly be explained by fewer causal loci segregating within the full-sib family populations normally used, but also by the cosegregation of causal loci due to limited recombination. Disease resistance estimates based on linkage mapping studies had the lowest median of four underlying effects, while growth traits based on association mapping had about 580 effects. Theoretically, the capture of 50% of the genetic variation would thus require a population size of about 200 for disease resistance in linkage mapping, while growth traits in association mapping would require about 25,000. The adequacy and reliability of the improved method was successfully verified by applying it to the simulated data.

  • 78. Han, Xue-Min
    et al.
    Yang, Qi
    Liu, Yan-Jing
    Yang, Zhi-Ling
    Wang, Xiao-Ru
    College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China.
    Zeng, Qing-Yin
    Yang, Hai-Ling
    Evolution and Function of the Populus SABATH Family Reveal That a Single Amino Acid Change Results in a Substrate Switch2018In: Plant and Cell Physiology, ISSN 0032-0781, E-ISSN 1471-9053, Vol. 59, no 2, p. 392-403Article in journal (Refereed)
    Abstract [en]

    Evolutionary mechanisms of substrate specificities of enzyme families remain poorly understood. Plant SABATH methyltransferases catalyze methylation of the carboxyl group of various low molecular weight metabolites. Investigation of the functional diversification of the SABATH family in plants could shed light on the evolution of substrate specificities in this enzyme family. Previous studies identified 28 SABATH genes from the Populus trichocarpa genome. In this study, we re-annotated the Populus SABATH gene family, and performed molecular evolution, gene expression and biochemical analyses of this large gene family. Twenty-eight Populus SABATH genes were divided into three classes with distinct divergences in their gene structure, expression responses to abiotic stressors and enzymatic properties of encoded proteins. Populus class I SABATH proteins converted IAA to methyl-IAA, class II SABATH proteins converted benzoic acid (BA) and salicylic acid (SA) to methyl-BA and methyl-SA, while class III SABATH proteins converted farnesoic acid (FA) to methyl-FA. For Populus class II SABATH proteins, both forward and reverse mutagenesis studies showed that a single amino acid switch between PtSABATH4 and PtSABATH24 resulted in substrate switch. Our findings provide new insights into the evolution of substrate specificities of enzyme families.

  • 79.
    Hansson, Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Servin, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Semi-autonomous shared control of large-scale manipulator arms2010In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 18, no 9, p. 1069-1076Article in journal (Refereed)
    Abstract [en]

    Semi-autonomous operation with shared control between the human operator and control computer has been developed and examinedfor a large-scalemanipulator for gripping and lifting heavy objects in unstructured dynamical environments. The technique hasbeen implemented on a electro-hydraulic actuated crane arm with redundant kinematic structure. Several modes of automation andinteraction were evaluated. Experiments show satisfactory smoothness in the transitions between autonomous, shared and manualcontrol, increased performance in log loading for inexperienced operators while experienced operators reported reduced workload.

  • 80. Hasselquist, Eliza Maher
    et al.
    Lidberg, William
    Sponseller, Ryan A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Agren, Anneli
    Laudon, Hjalmar
    Identifying and assessing the potential hydrological function of past artificial forest drainage2018In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 47, no 5, p. 546-556Article in journal (Refereed)
    Abstract [en]

    Drainage of forested wetlands for increased timber production has profoundly altered the hydrology and water quality of their downstream waterways. Some ditches need network maintenance (DNM), but potential positive effects on tree productivity must be balanced against environmental impacts. Currently, no clear guidelines exist for DNM that strike this balance. Our study helps begin to prioritise DNM by: (1) quantifying ditches by soil type in the 68 km(2) Krycklan Catchment Study in northern Sweden and (2) using upslope catchment area algorithms on new high-resolution digital elevation models to determine their likelihood to drain water. Ditches nearly doubled the size of the stream network (178-327 km) and 17% of ditches occurred on well-draining sedimentary soils, presumably making DNM unwarranted. Modelling results suggest that 25-50% of ditches may never support flow. With new laser scanning technology, simple mapping and modelling methods can locate ditches and model their function, facilitating efforts to balance DNM with environmental impacts.

  • 81. Hasselquist, Niles J.
    et al.
    Metcalfe, Daniel B.
    Inselsbacher, Erich
    Stangl, Zsofia
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Oren, Ram
    Näsholm, Torgny
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden.
    Högberg, Peter
    Greater carbon allocation to mycorrhizal fungi reduces tree nitrogen uptake in a boreal forest2016In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 97, no 4, p. 1012-1022Article in journal (Refereed)
    Abstract [en]

    The central role that ectomycorrhizal (EM) symbioses play in the structure and function of boreal forests pivots around the common assumption that carbon (C) and nitrogen (N) are exchanged at rates favorable for plant growth. However, this may not always be the case. It has been hypothesized that the benefits mycorrhizal fungi convey to their host plants strongly depends upon the availability of C and N, both of which are rapidly changing as a result of intensified human land use and climate change. Using large-scale shading and N addition treatments, we assessed the independent and interactive effects of changes in C and N supply on the transfer of N in intact EM associations with similar to 15 yr. old Scots pine trees. To assess the dynamics of N transfer in EM symbioses, we added trace amounts of highly enriched (NO3-)-N-15 label to the EM-dominated mor-layer and followed the fate of the N-15 label in tree foliage, fungal chitin on EM root tips, and EM sporocarps. Despite no change in leaf biomass, shading resulted in reduced tree C uptake, ca. 40% lower fungal biomass on EM root tips, and greater N-15 label in tree foliage compared to unshaded control plots, where more N-15 label was found in fungal biomass on EM colonized root tips. Short-term addition of N shifted the incorporation of N-15 label from EM fungi to tree foliage, despite no significant changes in below-ground tree C allocation to EM fungi. Contrary to the common assumption that C and N are exchanged at rates favorable for plant growth, our results show for the first time that under N-limited conditions greater C allocation to EM fungi in the field results in reduced, not increased, N transfer to host trees. Moreover, given the ubiquitous nature of mycorrhizal symbioses, our results stress the need to incorporate mycorrhizal dynamics into process-based ecosystem models to better predict forest C and N cycles in light of global climate change.

  • 82.
    Haugen, Katarina
    et al.
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History, Economic and social geography.
    Karlsson, Svante
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History, Economic and social geography.
    Westin, Kerstin
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History.
    New forest owners: Change and continuity in the characteristics of Swedish non-industrial private forest owners (NIPF owners) 1990-20102016In: Small-scale Forestry, ISSN 1873-7617, E-ISSN 1873-7854, Vol. 15, no 4, p. 533-550Article in journal (Refereed)
    Abstract [en]

    This paper presents a total survey of the characteristics and changes over time (1990–2010) within the entire population of Swedish non-industrial private forest owners (NIPF owners). By charting the changed demographic, socio-economic and geographic profile of the NIPF owners, it also provides a baseline for a discussion and analysis of potential implications for forest management, policy and values. NIPF owners differ in important ways from the general population of Sweden. However, the gap has narrowed over time with regard to, e.g., educational level and sex composition. The ongoing urbanization process is evident in the growing share of non-residential NIPF owners who live at a distance from their forest property and who differ from their residential (rural) peers through, e.g., higher education, higher income and a higher prevalence of co-ownership of their forest holdings. Although these changes might translate into updated views on forest values among NIPF owners, there could be a delay before this impacts on forest management practices and output.

  • 83. Hedwall, P-O
    et al.
    Strengbom, J
    Nordin, A
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Can thinning alleviate negative effects of fertilization on boreal forest floor vegetation?2013In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 310, p. 382-392Article in journal (Refereed)
    Abstract [en]

    Society's increased interest in renewable energy and materials put pressure on forest biomass production. Intensive fertilization of young Norway spruce (Picea abies) forest has a considerable potential to increase the production of tree biomass, but there are concerns about negative side-effects on forest ecosystem structure and function. Fertilization of young forest has a strong negative impact on light availability below the tree canopy and reduces the abundance of the forest floor vegetation. The silvicultural practice of thinning has been shown to affect composition and diversity of forest floor vegetation, and it has been proposed, but rarely tested, that the effects of fertilization are interdependent on the type of thinning performed. Here we present responses on the forest floor vegetation following 25 years of fertilization and eighth years after thinning (removing 30% or 60% of the tree basal area) in a Norway spruce forest in northern Sweden. Fertilization without thinning led to a considerable reduction in abundance of most forest floor plants. It did not affect species richness but resulted in an increased evenness. Thinning reduced the fertilization effects so that the total abundance of the vegetation was comparable to the unfertilized control plots. A considerable change in species composition had, however, taken place. Thinning favored early-successional species and pteridophytes on the account of dwarf-shrubs. Thinning also increased species richness and functional richness, while none, or negative effects were seen on evenness and functional evenness, respectively. A comparison with data from the National Forest Inventory revealed that the type of vegetation generated by fertilization, without or in combination with thinning, is a type of vegetation very uncommon in Swedish boreal forests. First, we conclude that the effects of fertilization on forest floor vegetation in young stands of Norway spruce are largely dependent on thinning regime. Secondly, fertilization will, independently of thinning, lead to considerable changes in the vegetation, including a functional shift from dwarf-shrubs with ericoid mycorrhiza to ferns and grasses with arbuscular mycorrhiza, resulting in a functional type of vegetation that is rare in this part of the boreal forest biome. Finally, in contrast to what previously has been suggested for unfertilized forests, thinning of fertilized forests may not promote late-successional species.

    (C) 2013 Elsevier B.V. All rights reserved.

  • 84. Heiri, C.
    et al.
    Wolf, A.
    Umeå University. Forest Ecology, Institute of Terrestrial Ecosystems, Department of Environmental Sciences, Swiss Federal Institute of Technology ETH, Universitätstr. 22, CH 8092 Zurich, Switzerland .
    Rohrer, L.
    Bugmann, H.
    Forty years of natural dynamics in Swiss beech forests: Structure, composition, and the influence of former management2009In: Ecological Applications, Vol. 19, no 7, p. 1920-1934Article in journal (Refereed)
    Abstract [en]

    We investigated forest development after the cessation of management based on inventory data from six beech forest reserves in Switzerland covering nearly 40 years, using observed changes to assess the textbook understanding of natural beech forest dynamics. Specifically, we evaluated the importance of light as a driver of tree species composition, and we aimed to disentangle the role of site characteristics and past management regimes for shaping today’s forest properties. Forest dynamics in the reserves showed a clear trend toward a broadening of the diameter distribution, an increase in basal area and standing dead wood, an increase in beech dominance, and a reduction of tree species diversity over time, conforming to expectations. However, the expected development of specific structural features, such as significant amounts of large living trees and snags or a small-scale mosaic of various developmental phases, appears to take longer than the time elapsed since the cessation of management. The observed loss in species richness can be attributed to decreasing light availability, as almost all species that disappeared were shade intolerant. Additionally, the shade-intolerant tree species had a characteristic bell-shaped diameter distribution in all reserves, indicating a lack of recruits, whereas shade-tolerant species had an irregular to monotonically decreasing diameter distribution, demonstrating sustained regeneration. Along the environmental gradient covered by the six reserves, abiotic factors are sufficient to explain tree species distribution, with management history not contributing additional information. This suggests that at larger scales, tree species composition is determined by abiotic factors, but historical management strategies were obviously adapted well to the species’ autecological requirements. Analyses such as ours provide the foundation for refining forest management systems as well as for developing effective and target-oriented conservation strategies. © 2009 by the Ecological Society of America beech forests;.

  • 85. Heiri, Caroline
    et al.
    Wolf, Annett
    Swiss Fed Inst Technol, Inst Terr Ecosyst, Dept Environm Sci, CH-8092 Zurich, Switzerland.
    Rohrer, Lukas
    Brang, Peter
    Bugmann, Harald
    Successional pathways in Swiss mountain forest reserves2012In: European Journal of Forest Research, ISSN 1612-4669, E-ISSN 1612-4677, Vol. 131, no 2, p. 503-518Article in journal (Refereed)
    Abstract [en]

    Knowledge on the natural dynamics of Norway spruce-European silver fir forests is scarce, but is of high importance for the sustainable management of these ecosystems. Using a unique data set from five forest reserves in the Swiss Alps that covers up to 35 years, we elucidated communalities and differences in stand structure and species composition across the reserves and over time and investigated the role of site conditions versus intrinsic forest dynamics. For the early and late successional phases, we found a clear relationship between stand structure (diameter distributions) and species composition. Two pathways of early succession were evident as a function of the disturbance regime. Thus, the spatial extent of disturbances in spruce-fir forests strongly determines the pathway in early succession. Contrary to earlier descriptions of clearly distinguishable optima phases, our data did not reveal a relationship between stand structure and species composition for the early, mid-, and late optimum phases. Although the reserves investigated here are characterized by highly different climatic and soil conditions, their temporal development was found to fit well into a single successional scheme, suggesting that in spruce-fir mountain forests, the life-history strategies of the tree species may have a stronger influence on successional trajectories than site conditions per se.

  • 86.
    Hellgren, Jenny Maria
    SLU.
    Ethylene and Auxin in the Control of Wood Formation2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis considers aspects of the regulation of growth rate and fibre properties in forest trees. These properties are both genetically determined and influenced by environmental stimuli. Induction of reaction wood is an environmentally induced process involving changes in growth rate and fibre properties that can be readily studied. Plant hormones are signalling agents that play important roles in the initiation and coordination of wood formation; in this thesis the plant hormones auxin and ethylene were investigated using gas chromatography/mass spectrometry (GC/MS). A novel MS technique for measuring the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) in minute amounts of plant tissue was developed. Ethylene is often connected to stress responses in plants, and ethylene evolution is increased when reaction wood is formed. Here it is demonstrated that this increase is regulated by ACC oxidase, the enzyme catalysing the last step in the ethylene biosynthetic pathway. This is in contrast to most of the earlier findings that tended to indicate that ethylene production directly reflects the availability of ACC. Although ethylene is strongly up-regulated during reaction wood formation, its role in modulating the growth rate and fibre properties remains unknown. Further, it is demonstrated that reaction wood in both poplar (Populus tremula L.) and pine (Pinus sylvestris L.) is formed without changes in auxin concentration in the cambial tissues. This suggests that the previously held assumption that the difference in auxin concentration is key factor in the induction of reaction wood is unsound. Further, auxin concentrations were compared in hybrid aspen trees (Populus tremula L. x tremuloides Michx.) growing vertically at different growth rates. These trees showed good correlations between auxin levels and growth rates. The growth rate was mediated by increases in the cell cycling rate rather than in the width of the cell division zone. Thus, the growth rate in poplar was correlated to auxin levels in normal wood formation, but not during reaction wood formation.

  • 87.
    Hellström, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Hohnloser, Peter
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Ringdahl, Ola
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Tree diameter estimation using laser scanner2012Report (Other academic)
    Abstract [en]

    Accurate vehicle localization in forest environments is still an unresolved problem. GPS has obvious limitations in dense forest, and has to be mixed with other techniques to provide satisfying solutions. One possible way is to localize the vehicle relative to trees detected around the vehicle. The first step to implement this method is is to find reliable methods to detect trees, and also to match them to maps. The reliability of this matching operation is improved by accurate estimations of tree diameter. In this paper we evaluate a number of existing algorithms for detection of trees and estimation of tree diameter. Three new algorithms are also suggested. All algorithms were evaluated in field experiments at three different locations with varying tree trunk visibility. The results show that one of the existing algorithms is clearly less reliable than the other two. Noticeable is that the existing algorithms often overestimate tree trunk diameter. The new algorithms mostly underestimate, but are most accurate in some situations. 

  • 88.
    Hellström, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Lärkeryd, Per
    Indexator .
    Nordfjell, Tomas
    Department of Forest Resource Management, Swedish University of Agricultural Sciences.
    Ringdahl, Ola
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Autonomous forest vehicles: historic, envisioned, and state-of-the-art2009In: International Journal of Forest Engineering, ISSN 1494-2119, E-ISSN 1913-2220, Vol. 20, no 1, p. 33-38Article in journal (Refereed)
    Abstract [en]

    The feasibility of using autonomous forest vehicles (which can be regarded as logical developments in the ongoing automation of forest machines), the systems that could be applied in them, their potential advantages and their limitations (in the foreseeable future) are considered here. The aims were to analyse: (1) the factors influencing the degree of automation in logging; (2) the technical principles that can be applied to autonomous forest machines, and (3) the feasibility of developing an autonomous path-tracking forest vehicle. A type of vehicle that is believed to have considerable commercial potential is an autonomous forwarder. The degree of automation is influenced by increased productivity, the machine operator as a bottle-neck, cost reduction, and environmental aspects. Technical principles that can be applied to autonomous forest vehicles are satellite navigation, wheel odometry, laser scanner and radar. A new path-tracking algorithm has been developed to reduce deviations from the desired path by utilizing the driver’s steering commands. The presented system has demonstrated both possibilities and difficulties associated with autonomous forest machines. It is in a field study shown that it is quite possible for them to learn and track a path previously demonstrated by an operator with an accuracy of 0.1m on flat ground and also to detect and avoid unexpected obstacles. Although the forest machine safely avoids obstacles, the study shows that further research in the field of obstacle avoidance is needed to optimize performance and ensure safe operation in a real forest environment.

  • 89.
    Hellström, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Lärkeryd, Pär
    Nordfjell, Thomas
    Ringdahl, Ola
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Autonomous forest machines: Past present and future2008Report (Other academic)
    Abstract [en]

    The feasibility of using autonomous forest vehicles (which can be regarded as logical developments in the ongoing automation of forest machines), the systems that could be applied in them, their potential advantages and their limitations (in the foreseeable future) are considered here. The aims were to analyse: (1) the factors influencing the degree of automation in logging; (2) the technical principles that can be applied to autonomous forest machines, and (3) the feasibility of developing an autonomous path-tracking forest vehicle. A class of such vehicles that are believed to have considerable commercial potential is autonomous wood shuttles (forwarders). The degree of automation is influenced by increased productivity, the machine operator as a bottle-neck, cost reduction, and environmental aspects. Technical principles that can be applied to autonomous forest vehicles are satellite navigation, laser odometry, wheel odometry, laser scanner and radar. The presented system has demonstrated both possibilities and difficulties associated with autonomous forest machines. It is in a field study shown that it is quite possible for them to learn and track a path previously demonstrated by an operator with an accuracy of 0.1m on flat ground. A new pathtracking algorithm has been developed to reduce deviations by utilizing the driver’s steering commands.

  • 90.
    Herberg, Erik R.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Kiel School of Sustainability, Christian-Albrechts-Universitat zu Kiel, Kiel, Germany.
    Sarneel, Judith M.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Ecology & Biodiversity Group and Plant Ecophysiology Group, Utrecht University, CH Utrecht, The Netherlands.
    Recruitment of riparian plants after restoration of geomorphic complexity in northern Sweden2017In: Applied Vegetation Science, ISSN 1402-2001, E-ISSN 1654-109X, Vol. 20, no 3, p. 435-445Article in journal (Refereed)
    Abstract [en]

    Question: Restoration of channelized streams increases geomorphic complexity but it remains unclear how this interacts with processes that drive future vegetation changes (dispersal, germination and establishment). This study asks if increased geomorphic complexity increases recruitment conditions of sown seeds or affects post-dispersal natural seedling densities. Location: Vindel River catchment, northern Sweden. Methods: We selected seven study streams with paired reaches that differed in the degree to which geomorphic complexity was restored. Basic reaches used simple restoration methods while enhanced reaches additionally added large boulders and woody debris. We sowed seeds of six species at ten locations in each reach in 2014 and counted the number of seedlings after 8wk and the number of naturally occurring seedlings in a plot adjacent to the sowing locations in 2013 and 2014. Using factor analysis based on 34 complexity measurements, overall geomorphic complexity was quantified for eight of the 14 reaches. Results: Total numbers of sown (2014) and natural seedlings (2013 and 2014) summed per reach did not differ between restoration types when tested pair-wise. Enhanced restoration did not always significantly increase geomorphic complexity, which differed considerably between the streams. More complex reaches were steeper, had larger size sediment and more nutrient-poor soils. Total recruitment of sown species significantly decreased with increasing complexity. Numbers of natural seedlings differed considerably from 2013 to 2014, but were not related to complexity. In 2014, a potential parent plant of the same species occurred within the same plot for 71.8% of the natural seedlings that could be identified. Conclusions: The recruitment of sown seeds was affected by overall geomorphic complexity rather than by the enhanced restoration. The absence of a correlation between geomorphic complexity and natural seedlings could indicate that natural seedling dynamics are not solely determined by recruitment conditions, but also by dispersal.

  • 91. Hjältén, J.
    et al.
    Hägglund, R.
    Löfroth, T.
    Roberge, J-M
    Dynesius, Mats
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Olsson, J.
    Forest restoration by burning and gap cutting of voluntary set-asides yield distinct immediate effects on saproxylic beetles2017In: Biodiversity and Conservation, ISSN 0960-3115, E-ISSN 1572-9710, Vol. 26, no 7, p. 1623-1640Article in journal (Refereed)
    Abstract [en]

    Today, the importance of restoring natural forest disturbance regimes and habitat structures for biodiversity is widely recognized. We evaluated the immediate effects of two restoration methods on wood-inhabiting (saproxylic) beetles in boreal forest voluntary set-asides. We used a before-after control-impact experimental set-up in 15 set-asides; each assigned to one of three treatments: (1) restoration burning, (2) gap cutting and (3) no-treatment reference stands. Before treatment, abundance, species richness and assemblage composition of trapped beetles did not differ significantly among treatments. Burning resulted in a significant change in assemblage composition and increased species richness and abundance compared to reference stands. As predicted, saproxylic species known to be fire favoured increased dramatically after burning. The immediate response shows that, initially, fire favoured species are attracted from the surrounding landscape and not produced on site. Gap cutting increased the abundance of cambium consumers but had no significant effect on total species richness or assemblage composition of saproxylic beetles. The stronger effect of burning compared to gap cutting on saproxylic assemblages is probably due to the very specific conditions created by fires that attracts many disturbance-dependent species, but that at the same time disfavour some disturbance-sensitive species. By contrast, gap cutting maintained assemblage composition, increased abundances and is likely to increase species richness in the years to follow, due to elevated level of dead wood. The restoration methods applied in this study may prove particularly useful, partly because of positive effect on saproxylic beetles, but also due to the cost-efficiency of the measures; the voluntary set-asides were already established and the restoration costs fully covered by revenue from the extracted timber.

  • 92.
    Hjältén, Joakim
    et al.
    SLU, Umeå.
    Axelsson, E Petter
    SLU, Umeå.
    Whitham, Thomas G
    Arizona, United States of America.
    LeRoy, Carri J
    Washington, United States of America.
    Julkunen-Tiitto, Riitta
    Joensuu, Finland.
    Wennström, Anders
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Pilate, Gilles
    Orle´ans, France.
    Increased Resistance of Bt Aspens to Phratora vitellinae (Coleoptera) Leads to Increased Plant Growth under Experimental Conditions2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 1, article id e30640Article in journal (Refereed)
    Abstract [en]

    One main aim with genetic modification (GM) of trees is to produce plants that are resistant to various types of pests. The effectiveness of GM-introduced toxins against specific pest species on trees has been shown in the laboratory. However, few attempts have been made to determine if the production of these toxins and reduced herbivory will translate into increased tree productivity. We established an experiment with two lines of potted aspens (Populus tremulaxPopulus tremuloides) which express Bt (Bacillus thuringiensis) toxins and the isogenic wildtype (Wt) in the lab. The goal was to explore how experimentally controlled levels of a targeted leaf beetle Phratora vitellinae (Coleoptera; Chrysomelidae) influenced leaf damage severity, leaf beetle performance and the growth of aspen. Four patterns emerged. Firstly, we found clear evidence that Bt toxins reduce leaf damage. The damage on the Bt lines was significantly lower than for the Wt line in high and low herbivory treatment, respectively. Secondly, Bt toxins had a significant negative effect on leaf beetle survival. Thirdly, the significant decrease in height of the Wt line with increasing herbivory and the relative increase in height of one of the Bt lines compared with the Wt line in the presence of herbivores suggest that this also might translate into increased biomass production of Bt trees. This realized benefit was context-dependent and is likely to be manifested only if herbivore pressure is sufficiently high. However, these herbivore induced patterns did not translate into significant affect on biomass, instead one Bt line overall produced less biomass than the Wt. Fourthly, compiled results suggest that the growth reduction in one Bt line as indicated here is likely due to events in the transformation process and that a hypothesized cost of producing Bt toxins is of subordinate significance.

  • 93.
    Hof, Anouschka R.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences (SLU), SE 901 83 Umea, Sweden.
    Svahlin, Anna
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Not erroneous but cautious conclusions about the potential effect of climate change on the geographical distribution of insect pest species in the Swedish boreal forest. Response to Bjorklund et al. (2015)2016In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 31, no 1, p. 128-129Article in journal (Refereed)
    Abstract [en]

    We argue that the conclusions drawn from the paper The potential effect of climate change on the geographical distribution of insect pest species in the Swedish boreal forest, published in the Scandinavian Journal of Forest Research were not erroneous as stated by a letter published in the same journal by Bjorklund et al. (2015. Erroneous conclusions about current geographical distribution and future expansion of forest insects in Northern Sweden: Comments on Hof and Svahlin (2015). Scand. J. Forest Res), but cautious. We regret possible underestimations caused by lack of occurrence records for some species for some areas. However, basing predictions of the impact of future climate change on the distribution of species on current range maps likely leads to grave overestimations of future range predictions since current range maps assume species are homogenously distributed throughout the landscape, which is often not the case. We argue that underestimating the distribution range of pest species rather than overestimating their distribution pinpoints areas that may need extra attention in future better, and therefore chose to be cautious rather than bold. We further like to stress that one should always be aware of possible insect outbreaks throughout the region, not only because predictions may underestimate the future distribution of species but also since the location and likelihood of insect pest outbreaks is not only determined by climatic factors.

  • 94.
    Hof, Anouschka R.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences (SLU), Umea SE 901 83, Sweden.
    Svahlin, Anna
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The potential effect of climate change on the geographical distribution of insect pest species in the Swedish boreal forest2016In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 31, no 1, p. 29-39Article in journal (Refereed)
    Abstract [en]

    With the expected rising temperatures, outbreaks of insect pests may be more frequent, which can have large consequences on forest ecosystems and may therefore negatively affect the forestry sector. In order to be better able to predict where, but not if, outbreaks may occur in future we investigated the potential future (2070) geographical distribution of 30 prospective insect pest species (Coleoptera and Lepidoptera) by applying species distribution modelling. We also assessed the geographical extent to which the boreal forest in Sweden may be affected. We found that numerous species may experience large increases in their potential distribution in future, which may result in outbreaks in new areas. It is therefore likely that more trees will be infested by pests in future, which may have large implications for the Swedish forestry sector.

  • 95.
    Holm, Stig-Olof
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    A Management Strategy for Multiple Ecosystem Services in Boreal Forests2015In: Journal of Sustainable Forestry, ISSN 1054-9811, E-ISSN 1540-756X, Vol. 34, no 4, p. 358-379Article in journal (Refereed)
    Abstract [en]

    A change of the forestry management approach where semi-natural forests are re-created after logging instead of tree plantations will contribute to a sustainable forestry. Such a change will increase resilience to damages on trees, thus contributing to a more reliable supply of wood, improve reindeer husbandry, and reduce climate-driving gases. Furthermore, re-creation of semi-natural forests will better secure biodiversity. Since adequate protection of many threatened forest species, however, is not compatible with even moderate logging, a functional conservation model also has to include total saving of parts of the forest landscape.

  • 96. Holmes, Thomas P.
    et al.
    Allen, Will
    Haight, Robert G.
    Keskitalo, E. Carina H.
    Umeå University, Faculty of Social Sciences, Department of Geography and Economic History.
    Marzano, Mariella
    Pettersson, Maria
    Quine, Christopher P.
    Langer, E.R.
    Fundamental economic irreversibilities influence policies for enhancing international forest phytosanitary security2017In: Current Forestry Reports, ISSN 2198-6436, Vol. 3, no 3, p. 244-254Article in journal (Refereed)
    Abstract [en]

    National and international efforts to manage forest biosecurity create tension between opposing sources of ecological and economic irreversibility. Phytosanitary policies designed to protect national borders from biological invasions incur sunk costs deriving from economic and political irreversibilities that incentivizes wait-and-see decision-making. However, the potential for irreversible ecological and economic damages resulting from failed phytosanitary policies argues for precautionary measures, creating sunk benefits while increasing the risk of over-investment in phytosanitary security. Here, we describe the inherent tension between these sources of irreversibility in economic terms, relate these forces to type I and type II errors, and use this framework to review national and international efforts to protect forests from biological invasions. Available historical evidence suggests that wait-and-see phytosanitary decision-making has dominated the adoption of precautionary measures in most regions and that willingness to under-regulate may sometimes be orders of magnitude greater than willingness to over-regulate. Reducing scientific uncertainty about threats to biosecurity may help mitigate the tendency to under-regulate, and phytosanitary security measures with relatively modest sunk costs could help protect forests as scientific learning advances. A fuller accounting of the costs associated with type II errors, particularly regarding the suite of non-market ecosystem services at risk, would help decision-makers better understand the trade-offs between the sunk costs of policies and long-term economic losses to stakeholders.

  • 97.
    Horstkotte, Tim
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Institute of Geography and Geology, Turku University, Finland.
    Lind, Torgny
    Moen, Jon
    Quantifying the Implications of Different Land Users' Priorities in the Management of Boreal Multiple-Use Forests2016In: Environmental Management, ISSN 0364-152X, E-ISSN 1432-1009, Vol. 57, no 4, p. 770-783Article in journal (Refereed)
    Abstract [en]

    In the management of natural resources, conflicting interests and objectives among different stakeholders often need to be considered. Here, we examine how two contrasting management scenarios of boreal forests in northern Sweden differ in their consequences on forest structural composition and the economic gains at harvest. Management strategies prioritize either (i) forest characteristics that promote grazing resources for reindeer herded by the indigenous Sami, or (ii) timber production as practiced in Sweden today. When prioritizing reindeer grazing, forest stands develop a higher abundance of older age classes with larger trees and lower stem density, which reduces harvest and revenue levels by approximately 20 % over a 100-year period. The differences between these strategies illustrate the complexity in finding a trade-off for coexistence between industrial land users and other livelihoods that share the same landscape. Political support and institutional solutions are necessary to initiate changes in policy in finding such trade-offs in the management of environmental resources and thereby influence the optimal distribution of costs and benefits between different actors.

  • 98.
    Horstkotte, Tim
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Moen, Jon
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Successional pathways of terrestrial lichens in changing Swedish boreal forests2019In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 453, article id 117572Article in journal (Refereed)
    Abstract [en]

    The current decline of terrestrial lichens in Swedish boreal forests is a major challenge for reindeer husbandry, as lichens constitute essential grazing resources for reindeer during winter. Using a 30-year data set covering northern Sweden, we explore how the successional dynamics of lichen cover depend on several forest characteristics, as well as management strategies regarding both reindeer and forestry. We found a 36% reduction of plots with lichen cover, with a decrease in lichen cover becoming more likely in recent years. Year-round presence of reindeer in forests, compared to winter grazing only, had slightly negative impacts on lichens. We found increases in lichen cover in young forests following final harvest. However, increasing basal areas as forest grow older affected lichens negatively and supported dominance of mosses. Forest management that prioritizes less dense forests with larger trees would therefore improve the ability of lichens to persist as forage resource for reindeer.

  • 99.
    Horstkotte, Tim
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Roturier, Samuel
    AgroParisTech, Univ. Paris Sud, Orsay, France.
    Does forest stand structure impact the dynamics of snow on winter grazing grounds of reindeer (Rangifer t. tarandus)?2013In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 291, p. 162-171Article in journal (Refereed)
    Abstract [en]

    The landscape in boreal Sweden is dominated by even-aged, single-layered forest monocultures and clearcuts. Few forest stands with a more complex, multi-layered structure remain as landscape elements. Westudied the impact that different forest management regimes have on snow conditions and the metamorphosisof snow, and discuss how these factors may affect suitability for reindeer grazing.Over two winters, we recorded the development of snow depth and hardness in clear cuts and two differentforest types, and their changes with weather events. In the forests, the dynamics of snow characteristicswere analyzed in relation to stand structure and at the level of individual trees.There were no clear differences in snow characteristics between single-layered and multi-layeredstands, although snow hardness was more variable in the latter. In single-layered stands, snow depthand hardness were spatially uniformly distributed in relation to stand characteristics. Contrastingly,the complex structure of multi-layered stands did influence snow depth significantly. However, hardnesswas highly heterogeneous in these stands. Due to the absence of tree effects, clear cuts had deeper butsofter snow than forested stands, although hardness increased towards spring.Weather affected the metamorphosis of the snow blanket. The magnitude of the effects depended onboth timing and severity of discrete weather events and forest structure, but generally weather had agreater influence on snow cover characteristics than forest structure per se. In their interaction withweather, different forest structures affect the snow and thus suitability as winter grazing area for reindeer.Reindeer herders, therefore, require diversity in the landscape in order to respond to such weathervariations and their impact on grazing conditions.

  • 100.
    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.

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