| 1. |
- Böhlenius, Henrik
(författare)
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A Global Review on Innovative, Sustainable, and Effective Materials Composing Growing Media for Forest Seedling Production
- 2023
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Ingår i: Current Forestry Reports. - 2198-6436. ; 9, s. 413-428
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Forskningsöversikt (refereegranskat)abstract
- Purpose of Review The demand for forest tree seedlings is increasing globally, and Sphagnum peat moss is widely used as a component of growing media for container plant production. However, peat extraction is environmentally unsustainable. The forest nursery sector needs to switch to more sustainable alternatives to peat. This review aims to identify potential substitutes for peat by reviewing the worldwide literature on alternative materials for growing media in forest nurseries. Recent Findings Most studies on alternative growing media focused on single plant species growing under local conditions, thereby limiting generalizations about the effectiveness of alternative materials for plant production. To our knowledge, no systematic reviews of scientific literature on the effectiveness of new, alternative-to-peat materials for enhancing plant growth and the associated growing media characteristics for the forest nursery sector are currently available. Summary Most of the analyzed case studies focused on angiosperms (73.1%), with the majority of studies coming from tropical seasonal forests/savannas (36.5%), followed by woodlands/shrublands (31.6%), and temperate forests (15.0%) biomes. Compost was the most studied material (19.5%), followed by bark, other organic materials, and manure (9.8, 9.7, and 8.0%, respectively). Green and municipal wastes were the principal sources of compost (> 60%), while agriculture and green wastes were the first sources of other materials (> 90%). Tested materials were dependent on the geographic region. Thus, manure was the most tested material in Africa and South America, tree bark in North America, and compost in Europe, Asia, and Oceania. Alternative materials effectively provided optimal physicochemical characteristics of growing media and enhanced seedling nursery growth when compared with peat-based growing media in more than 60% of the case studies. This review helps to identify research gaps and, most importantly, provides the basis for the future application of alternative growing media materials in forest nursery management worldwide.
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| 2. |
- Böhlenius, Henrik, et al.
(författare)
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Biomass production and fuel characteristics from long rotation poplar plantations
- 2023
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Ingår i: Biomass and Bioenergy. - : Elsevier Ltd. - 0961-9534 .- 1873-2909. ; 178
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Tidskriftsartikel (refereegranskat)abstract
- One of the key elements in this transition is the securing of a large supply of sustainable biomass. In this study, the feedstock potential of long rotation poplar plantations (12–30 years with diameter of 15 of 30 cm) was determined and the properties of poplar biomass fuel were analyzed with the aim of using thermochemical conversion methods to produce biofuel. Our results demonstrate that Sweden has great potential for producing biofuels from long rotation poplar plantations, with a total of 1.8 million hectares (ha) consisting of arable (0.5 million ha) and forested arable land (1.3 million ha). Based on available land and biomass production potential, our results indicate that 10 million Mg DW could be produced annually. Regions in mid/southern Sweden have the largest potential (larger areas and higher biomass production. Our results further suggest that poplar biomass from these plantations has fuel characteristics similar to forest fuels from other conifer tree species, making the biomass suitable as feedstock for biofuel production based on thermochemical conversion methods. If 25% of the available land were used, 7.6 TWh methanol biofuels could be produced annually from 16 biofuel plants, using 160,000 Mg DW yr−1, primarily located in the southern part of Sweden. Two counties (Skåne and Västra Götaland) would be able to support their biofuel plants using poplar plantations as feedstock. Stable biofuel production in the other counties would depend on collaborating with neighboring counties.
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| 3. |
- Böhlenius, Henrik, et al.
(författare)
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CO/FT regulatory module controls timing of flowering and seasonal growth cessation in trees.
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 312:5776, s. 1040-3
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Tidskriftsartikel (refereegranskat)abstract
- Forest trees display a perennial growth behavior characterized by a multiple-year delay in flowering and, in temperate regions, an annual cycling between growth and dormancy. We show here that the CO/FT regulatory module, which controls flowering time in response to variations in daylength in annual plants, controls flowering in aspen trees. Unexpectedly, however, it also controls the short-day–induced growth cessation and bud set occurring in the fall. This regulatory mechanism can explain the ecogenetic variation in a highly adaptive trait: the critical daylength for growth cessation displayed by aspen trees sampled across a latitudinal gradient spanning northern Europe.
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| 4. |
- Böhlenius, Henrik, et al.
(författare)
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Differences in Al sensitivity affect establishment of Populus genotypes on acidic forest land
- 2018
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Forest lands hold great potential for Populus plantations, but in native boreal forests, soils normally have low pH and thus higher levels of aluminum ions (Al3+ and hydroxides). Aluminum (Al) is one of the major factors limiting plant growth on these soils by inhibiting root growth, thus reducing water and nutrient uptake and slowing growth. There is a large variation in Al resistance both among and within species. In this study, growth responses of greenhouse-grown hybrid aspen (P. tremula x tremuloides) and poplar (P. trichocarpa hybrids) were monitored in relation to changes in Al concentrations. In quartz sand, hybrid aspen was more tolerant to exogenous application of Al than P. trichocarpa hybrids. This difference in Al-tolerance was further confirmed by hematoxylin staining of the roots, with hybrid aspen displaying less staining after Al treatment than poplar clones. When planted on forest land with low pH, hybrid aspen increased growth after planting and showed low mortality. This was not the case for poplar clones; plant height decreased after planting and mortality increased. Together, our results suggest that differences in initial growth and survival on forest land among hybrid aspen and the tested poplar clones may be connected to differences in Al tolerance. Our findings that staining with hematoxylin can identify Al-tolerant Populus genotypes may help identify Al-tolerant genotypes suitable for forest land.
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| 5. |
- Böhlenius, Henrik, et al.
(författare)
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Effects of Direct Application of Fertilizers and Hydrogel on the Establishment of Poplar Cuttings
- 2014
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Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 5, s. 2967-2979
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Tidskriftsartikel (refereegranskat)abstract
- The aim of poplar plantations is to achieve high biomass production over a short rotation period. This requires low mortality and fast development of the transplants. The experiment described in this paper examines methods aimed at enhancing survival and development of Populus trichocarpa plants by application of fertilizers, a hydrogel or a combination of both to dormant cuttings just before planting. The experiment was carried out at two agricultural sites with different soil characteristics, a loamy sand and a silty loam. It was demonstrated that none of the treatments influenced survival or early growth at the silty loam soil site, and plant development was delayed by the solid fertilizer. At the site with loamy sand, the solid fertilizer negatively affected both survival and early growth. Hydrogel and the combination of hydrogel and the solid fertilizer also hampered early growth. Overall, treatments of poplar cuttings with hydrogel or fertilizers alone, or in combination, may not be a method to reduce poplar cutting mortality or to enhance early plant development on agricultural land. However, our results demonstrate that establishing poplar with cuttings as transplants can be used on both loamy sand and silty loam soils.
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| 6. |
- Böhlenius, Henrik, et al.
(författare)
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Exploration of Optimal Agricultural Practices and Seedling Types for Establishing Poplar Plantations
- 2015
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Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 6, s. 2785-2798
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Tidskriftsartikel (refereegranskat)abstract
- Controlling competing vegetation during early growth is one of the most important practices for the successful establishment of poplar plantations. Today, most poplar plantations in temperate regions are established on abandoned marginal agricultural land where competing vegetation is usually present during the first years after planting. Thus, the objective of this study was to examine how the growth of two kinds of poplar planting materials, un-rooted cuttings and bare-rooted seedlings was influenced by different vegetation control and soil preparation practices. Across treatments, un-rooted cuttings grew more rapidly than the bare-rooted seedlings. Our results also show that mulching with a degradable carpet or permanent polyethylene plastic increased seedling growth to a similar extent and more strongly in the cases of no treatment (in control plots). In addition, the results suggest that soil preparation in the mulched area favored seedling growth, but this effect was restricted to the first year after planting. These findings indicate that optimal practices for establishing poplar plantations on former agricultural land include planting un-rooted cuttings in prepared soil and mulching.
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| 7. |
- Böhlenius, Henrik, et al.
(författare)
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Growth response of hybrid aspen (Populus × wettsteinii) and Populus trichocarpa to different pH levels and nutrient availabilities
- 2016
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Ingår i: Canadian Journal of Forest Research. - : Canadian Science Publishing. - 0045-5067 .- 1208-6037. ; 46, s. 1367-1374
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Tidskriftsartikel (refereegranskat)abstract
- Populus plantations are mainly established on agricultural land, but natural forests soils typically have lower pHs and nutrient contents. In this study, growth responses of two commonly used Populus genotypes, hybrid aspen (Populus x wettsteinii Hamet-Ahti) and black cottonwood (Populus trichocarpa Torr. & A. Gray ex Hook.), were monitored in the greenhouse in relation of changes in pH and fertilizer levels in quartz sand and forest moraine soil. In quartz sand, changes in pH had no impact on growth or mortality of the two species. In forest soils, the lowest pH values, i.e., 3.5 and 4.0, caused plant mortality for P. trichocarpa but not for P. x wettsteinii. Growth optimum of P. trichocarpa occurred at a pH range of 5.5-6.5, whereas P. x wettsteinii showed a broader growth optimum at a pH range of 4.0-7.0. Fertilization expanded the pH range of optimum growth for P. trichocarpa but not for P. x wettsteinii. In both species, foliar content of nitrogen and potassium content increased after fertilization, whereas the foliar content of phosphorus was similar to unfertilized plants. Our results suggest that differences in tolerance to low pH values between P. x wettsteinii and P. trichocarpa might be connected to tolerance against aluminum. These findings may improve future establishment methods and identification of poplar genotypes suitable for forest land.
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| 8. |
- Böhlenius, Henrik, et al.
(författare)
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Growth response of hybrid poplars to different types and levels of vegetation control
- 2015
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 30, s. 516-525
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Tidskriftsartikel (refereegranskat)abstract
- Poplar plantations established on agricultural or forest land can be adversely affected by abundant competing vegetation already present or that grows after planting. In this paper, we investigate how different intensities of manual vegetation control and mulching with polypropylene plastic effect poplar growth during the first two years after planting. Field data revealed that, during the first year, mulching with polypropylene plastic increased seedling growth more than manual vegetation control when performed over the same area. However, during the second year, these differences diminished and poplar seedlings continued to grow at the same rate irrespective of vegetation control. The difference in growth between treatments seems to be related to the fact that mulching positively influences water and nutrient availability to a greater extent that manual vegetation control during the early phase of establishment. Vegetation control also affected biomass allocation, with a relative increase in leaf biomass and decrease in stem biomass. The increase in leaf biomass associated with vegetation control was a result of both an increase in leaf number and increased leaf size.
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| 9. |
- Böhlenius, Henrik, et al.
(författare)
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Impact of seedling type on early growth of poplar plantations on forest and agricultural land
- 2016
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 31, s. 733-741
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Tidskriftsartikel (refereegranskat)abstract
- Today, most poplar plantations in the temperate region are established on abandoned marginal agricultural land, but there is great potential for planting poplars on forest land as the available area is large and does not compete with food production. The objective of this study was to examine how different planting types (un-rooted cuttings, bare-rooted and containerized plants) affect the establishment and early growth of poplar plants on forest and agricultural sites. Our results suggest that on the agricultural site, survival and growth during the first two years are not influenced by plant type. However, at the forest sites, survival of rooted plants was superior compared to un-rooted cuttings. The height and biomass (stem and root) increment of bare-rooted plants was low; greater height and biomass growth was found for containerized plants. Container sizes had no effect on height growth, but leaf and stem biomasses were higher if the largest containers were used. When using the largest containers, concentrations of macronutrients (N, P) were increased compared to bare-rooted plants. Thus, these results suggest that practices for establishing poplar plantations of agricultural land include planting of un-rooted cutting, but on forest land, a plant grown in a container of 470ml should be used. Together, this can reduce the cost of establishment, increase the available area for poplar plantations and have an impact on poplar plantation economics in Sweden.
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| 10. |
- Böhlenius, Henrik, et al.
(författare)
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Influence of Cutting Type and Fertilization in Production of Containerized Poplar Plants
- 2017
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Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Most poplar plantations are planted on marginal agricultural land, but poplar plantations also hold the potential for increased profits compared to plantations of other species on non-agricultural, previously forested land. To date, the establishment of poplar plantations on previously forested land is limited by the production of suitable containerized poplar stock for planting. The objective of this study is to investigate how different cutting quality and fertilizer treatments influence height, diameter, and root biomass growth and root-to-shoot ratio, all important variables for plant establishment. Our results show that fertilization increases plant growth and that single-bud and two-bud cuttings with cutting diameters of 5 to 10 mm can be used in the production of containerized plants. Root biomass was similar between these plant types but the number of roots per plant was higher if two-bud cuttings were used. In contrast to fertilized plants, only one cutting type (two-bud 10 mm) grew to a sufficient height and diameter for use in poplar plantation establishment. Interestingly, the root-to-shoot ratio for this cutting type was 0.16 while the ratio for the same cutting type is 0.11 if fertilized. Together, these results suggest that most types of poplar cuttings can be used to establish poplar plantations if fertilizer is used and that the largest cutting type (two-bud 10 mm) might be more suitable to establish poplar plantations at harsh sites, thus reducing the cost of poplar plant production.
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| 11. |
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| 12. |
- Böhlenius, Henrik, et al.
(författare)
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Liming increases early growth of poplars on forest sites with low soil pH
- 2020
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 138
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Tidskriftsartikel (refereegranskat)abstract
- Poplars are traditionally grown on former agricultural land but forest land holds great potential for poplar production as the available area is large. However, knowledge of how to establish poplars on forestland is poor. This study investigates how soil treatments (mix, patch and mound) and liming influence early growth of poplars during the first four years after planting. Our results suggest that soil treatments have a limited effect on survival or growth of newly-established plants compared to plots with no soil treatments. Liming increased plant survival at the fourth year and highly increased plant height and diameter growth when combined with either patch or mounding soil treatments. At these treatments, application of lime resulted in plant heights of 200 cm at experimental site Vinsasen or 150 cm at site Tonnersjoheden and compared to plots without lime growth is doubled These results suggest that poplar plantations on acid forest land should be established with both soil treatments and application of lime. These practices can enable poplar plantations on forest sites, increasing the available area for poplar plantations in the boreal/nemoral regions. Our findings also encourage further investigations of the production potential of poplar plantation on forestland and identification of genetic material suitable for forest sites.
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| 13. |
- Böhlenius, Henrik, et al.
(författare)
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Monitoring and control of forest seedling quality in Europe
- 2023
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Ingår i: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 546
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between the quality of forest seedlings and their outplanting survival and growth has long been recognized. Various attributes have been proposed to measure the quality of planted seedlings in forest regeneration projects, ranging from simple morphological traits to more complex physiological and performance attributes, or a combination thereof. However, the utility and meaning of seedling quality attributes can differ significantly among regions, nursery practices, site planting conditions, species and the establishment purpose. Here, forest scientists compiled information using a common agreed questionnaire to provide a review of current practices, experiences, legislation and standards for seedling quality across 23 European countries.Large differences exist in measuring seedling quality across countries. The control of the origin of seed and vegetative material (genetic component of plant quality), and control of pests and diseases are common practices in all countries. Morphological attributes are widely used and mandatory in most cases. However, physiological attributes are hardly used at the operative level and mainly concentrated to Fennoscandia. Quality control legislation and seedling quality standards are less strict in northern European countries where seedling production is high, and quality control relies more on the agreements between producers and local plant material users. In contrast, quality standards are stricter in Southern Europe, especially in the Mediterranean countries.The control of seedling quality based on plantation and reforestation success is uncommon and depends on the conditions of the planting site, the traditional practices and the financial support provided by each country. Overall, European countries do not apply the "target seedling concept" for seedling production except for seed origin. Seedling production in many countries is still driven by traditional "know-how" and much less by scientific knowledge progress, which is not adequately disseminated and transferred to the end-users.Our review highlights the need for greater harmonization of seedling quality practices across Europe and the increased dissemination of scientific knowledge to improve seedling quality in forest regeneration activities.
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| 14. |
- Böhlenius, Henrik
(författare)
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Risks, benefits, and knowledge gaps of non-native tree species in Europe
- 2022
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Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 10
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Forskningsöversikt (refereegranskat)abstract
- Changing ecosystem conditions and diverse socio-economical events have contributed to an ingrained presence of non-native tree species (NNTs) in the natural and cultural European landscapes. Recent research endeavors have focused on different aspects of NNTs such as legislation, benefits, and risks for forestry, emphasizing that large knowledge gaps remain. As an attempt to fulfill part of these gaps, within the PEN-CAFoRR COST Action (CA19128) network, we established an open-access questionnaire that allows both academic experts and practitioners to provide information regarding NNTs from 20 European countries. Then, we integrated the data originating from the questionnaire, related to the country-based assessment of both peer-reviewed and grey literature, with information from available datasets (EUFORGEN and EU-Forest), which gave the main structure to the study and led to a mixed approach review. Finally, our study provided important insights into the current state of knowledge regarding NNTs. In particular, we highlighted NNTs that have shown to be less commonly addressed in research, raising caution about those characterized by an invasive behavior and used for specific purposes (e.g., wood production, soil recultivation, afforestation, and reforestation). NNTs were especially explored in the context of resilient and adaptive forest management. Moreover, we emphasized the assisted and natural northward migration of NNTs as another underscored pressing issue, which needs to be addressed by joint efforts, especially in the context of the hybridization potential. This study represents an additional effort toward the knowledge enhancement of the NNTs situation in Europe, aiming for a continuously active common source deriving from interprofessional collaboration.
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| 15. |
- Cleary, Michelle, et al.
(författare)
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Susceptibility of common tree species in Sweden to Phytophthora cactorum, P. cambivora and P. plurivora
- 2017
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Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 47
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden, invasive Phytophthora pathogens have been recognized as a growing threat to urban and production forests, calling for an urgent update of regeneration strategies for infested areas. Stem inoculation tests were performed to test the relative susceptibility of common conifer and broadleaved tree species Pinus sylvestris, Picea abies, Larix x eurolepis, Betula pendula, Quercus robur, Fagus sylvatica, Populus trichocarpa and Tilia cordata to the root pathogens Phytophthora cactorum, P. cambivora and P. plurivora commonly isolated from Swedish soils. Results indicate that all the species tested were susceptible and formed lesions following stem inoculation with all three Phytophthora species, but to varying degrees. Of particular interest are the high levels of susceptibility in P. trichocarpa to all three Phytophthora species compared to other tested tree species.
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| 16. |
- Ding, Jihua, et al.
(författare)
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GIGANTEA-like genes control seasonal growth cessation in Populus
- 2018
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 218:4, s. 1491-1503
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Tidskriftsartikel (refereegranskat)abstract
- Survival of trees growing in temperate zones requires cycling between active growth and dormancy. This involves growth cessation in the autumn triggered by a photoperiod shorter than the critical day length. Variations in GIGANTEA (GI)-like genes have been associated with phenology in a range of different tree species, but characterization of the functions of these genes in the process is still lacking. We describe the identification of the Populus orthologs of GI and their critical role in short-day-induced growth cessation. Using ectopic expression and silencing, gene expression analysis, protein interaction and chromatin immunoprecipitation experiments, we show that PttGIs are likely to act in a complex with PttFKF1s (FLAVIN-BINDING, KELCH REPEAT, F-BOX 1) and PttCDFs (CYCLING DOF FACTOR) to control the expression of PttFT2, the key gene regulating short-day-induced growth cessation in Populus. In contrast to Arabidopsis, in which the GI-CONSTANS (CO)-FLOWERING LOCUS T (FT) regulon is a crucial day-length sensor for flowering time, our study suggests that, in Populus, PttCO-independent regulation of PttFT2 by PttGI is more important in the photoperiodic control of growth cessation and bud set.
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| 17. |
- Drössler, Lars, et al.
(författare)
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Early development of pure and mixed tree species plantations in Snogeholm, southern Sweden
- 2015
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 30, s. 304-316
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Tidskriftsartikel (refereegranskat)abstract
- There is a lack of experimental studies comparing the forest production of mixed tree species stands and monocultures. As a case study, in 1994 an experiment was established in an afforestation landscape in southern Sweden with 66 plots: 18 planted with single tree species (including most native Swedish trees, plus Populus and Larix hybrids) and 48 with various non-replicated mixtures. Fifteen years after planting, stand growth did not differ significantly between the mixtures and the monocultures. However, the monocultures did exhibit a higher variation in growth levels relative to the moderate but comparatively consistent growth levels exhibited by the mixtures; particularly those comprised of more than two species. A specific analysis of mixtures containing either the tree species Picea abies or Quercus robur and their corresponding monocultures demonstrated the importance of the tree species admixed as a determinant of production outcomes early in the rotation. In the case of P. abies, tree species mixtures tended to reduce production, whereas in the case of Q. robur, mixtures tended to increase production. In addition no consistent differences in the mean height and mean diameter growth of P. abies and Q. robur between mixtures and monocultures were detected. A major conclusion is that adding more than two species did not increase stand volume growth.
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| 18. |
- Lindbladh, Matts, et al.
(författare)
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Short-rotation bioenergy stands as an alternative to spruce plantations: implications for bird biodiversity
- 2014
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Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 48
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Tidskriftsartikel (refereegranskat)abstract
- Global efforts to decrease dependence on fossil fuels have increased interest in bioenergy production. One source of bioenergy is fast growing deciduous tree species, such as hybrid aspen (Populus x wettsteinii Hamet-Ahti). The majority of research on hybrid aspen which assesses biodiversity implications, has however primarily focused on agricultural lands as the reference condition. This has resulted in a substantial gap in our knowledge regarding the biodiversity implications of replacing production forest types with hybrid aspen, a form of reforestation taking place in northern Europe. In this study we address this knowledge gap by comparing the avian biodiversity of young hybrid aspen and spruce (Picea abies L.) plantations of similar age, the latter being the most prevalent forestry alternative in in southern Sweden. We found that hybrid aspen stands had higher bird species richness and abundance as well as a distinct community composition compared to the spruce stands. We suggest that the most likely driver was the greater structural and tree species complexity in the aspen stands, provided for by the fenced exclusion of ungulates from the regenerating hybrid aspen stands. Our results indicate that at least during early stages of regeneration, and in comparison to the dominating production forest type in the region, hybrid aspen stands can support relatively high levels of bird diversity, and a bird species composition more closely associated with broadleaf habitat types requiring restoration in this region.
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