| 1. |
- Böhlenius, Henrik, et al.
(författare)
-
Differences in Al sensitivity affect establishment of Populus genotypes on acidic forest land
- 2018
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 13
-
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.
|
|
| 2. |
- Böhlenius, Henrik, et al.
(författare)
-
Exploration of Optimal Agricultural Practices and Seedling Types for Establishing Poplar Plantations
- 2015
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 6, s. 2785-2798
-
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.
|
|
| 3. |
- Böhlenius, Henrik, et al.
(författare)
-
Growth response of hybrid aspen (Populus × wettsteinii) and Populus trichocarpa to different pH levels and nutrient availabilities
- 2016
-
Ingår i: Canadian Journal of Forest Research. - : Canadian Science Publishing. - 0045-5067 .- 1208-6037. ; 46, s. 1367-1374
-
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.
|
|
| 4. |
- Böhlenius, Henrik, et al.
(författare)
-
Growth response of hybrid poplars to different types and levels of vegetation control
- 2015
-
Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 30, s. 516-525
-
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.
|
|
| 5. |
- Böhlenius, Henrik, et al.
(författare)
-
Impact of seedling type on early growth of poplar plantations on forest and agricultural land
- 2016
-
Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 31, s. 733-741
-
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.
|
|
| 6. |
- Böhlenius, Henrik, et al.
(författare)
-
Influence of Cutting Type and Fertilization in Production of Containerized Poplar Plants
- 2017
-
Ingår i: Forests. - : MDPI AG. - 1999-4907. ; 8
-
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.
|
|
| 7. |
|
|
| 8. |
- Cleary, Michelle, et al.
(författare)
-
Susceptibility of common tree species in Sweden to Phytophthora cactorum, P. cambivora and P. plurivora
- 2017
-
Ingår i: Forest Pathology. - : Wiley. - 1437-4781 .- 1439-0329. ; 47
-
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.
|
|
| 9. |
- Ding, Jihua, et al.
(författare)
-
GIGANTEA-like genes control seasonal growth cessation in Populus
- 2018
-
Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 218:4, s. 1491-1503
-
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.
|
|
| 10. |
- Drössler, Lars, et al.
(författare)
-
Early development of pure and mixed tree species plantations in Snogeholm, southern Sweden
- 2015
-
Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 30, s. 304-316
-
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.
|
|
