| 1. |
- Arnebrant, Kristina, et al.
(author)
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Effects of different fertilizer treatments on ectomycorrhizal colonization potential in 2 Scots pine forests in Sweden
- 1992
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In: Forest Ecology and Management. - : Elsevier BV. - 1872-7042 .- 0378-1127. ; 53:1-4, s. 77-89
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Journal article (peer-reviewed)abstract
- Ectomycorrhizal fungal colonization potential was studied in two low-productivity Scots pine (Pinus sylvestris L.) forests in Sweden treated with different fertilizers. Young Pinus sylvestris seedlings were used as baits for ectomycorrhizal fungi for one growing season and the total ectomycorrhizal colonization level and frequencies of different types were recorded. One of the experimental sites had been fertilized once with 600 kg nitrogen (N) ha-1, either as ammonium nitrate or urea, 13 years previously. At this site no difference in the total number of ectomycorrhizal root tips was found between the different treatments and approximately 70% of all root tips were ectomycorrhizal. The other experimental site had been continuously fertilized for 15 years with a balanced nutrient mixture, applied either daily as a solution (IF treatment), or as solid fertilizers once a year (F treatment). The IF treatment had received 1700 kg N ha-1 and the F treatment 950 kg N ha-1 until our study was conducted. At this site a significant decrease in total ectomycorrhizal infection level was found as an effect of the fertilizer treatment. In the non-fertilized plots, 70% of all root tips were ectomycorrhizal and the corresponding figure for fertilized plots was 55%. At both sites the frequency of one of the eight classified ectomycorrhizal types decreased significantly in all fertilized plots except in the urea treatment.
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| 2. |
- Lyytikäinen-Saarenmaa, Päivi, et al.
(author)
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Monitoring European pine sawfly population densities with pheromone traps in young pine plantations
- 1999
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In: Forest Ecology and Management. - 0378-1127. ; 124:2-3, s. 113-121
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Journal article (peer-reviewed)abstract
- Field trials utilizing pheromone traps were evaluated to develop a population monitoring and predicting system for the European pine sawfly (Neodiprion sertifer). Larval density was censused in a transect across each study site. Three traps per site were baited with 100μg of (2S,3S,7S)-3,7-dimethyl-2-pentadecyl (diprionyl) acetate. During a two-year period traps loaded with 1, 10 and 100 μg of diprionyl acetate were compared. Correlations and coefficients of determination between numbers of captured males and larvae of the same or successive generations were seldom high. Between-generation relationships were significant, when population density was increasing. Having years with increasing densities in a row, the present monitoring method might provide warning of an outbreak.
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| 3. |
- Bergstedt, Johan, et al.
(author)
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The impact of logging intensity on field-layer vegetation in Swedish boreal forests
- 2001
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In: Forest Ecology and Management. - 0378-1127. ; 154:1-2, s. 105-115
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Journal article (peer-reviewed)abstract
- The relationship between logging intensity and changes in ground cover vegetation was studied in 16 species and groups of species recorded at 10- or 11-year intervals in mature conifer-dominated forests. The 789 plots located in northern and central Sweden had been surveyed by the National Forest Inventory and the National Survey of Forest Soil and Vegetation. Thirty-seven percent of the plots had been subjected to a thinning or clear-cutting between the inventories. A principal components analysis showed that, of the variables considered, logging intensity had the highest explanatory power regarding change in ground cover vegetation between the inventories (the other variables were sum of temperatures, age of stand, timber volume, percentage Pinus sylvestris and site productivity). A multivariate direct gradient analysis technique (Redundancy analysis) showed that the logging intensity significantly affected the change in cover. This analysis also ranked the species in their responsiveness to logging. Epilobium angustifolium, narrow-leaved grasses and broad-leaved grasses, increased most with logging intensity. The response was not linear and only detectable at high logging intensities (>80%). In contrast, Vaccinium myrtillus seemed to decrease linearly with increased logging intensity. There was several years time-lag in the response to logging of E. angustifolium, V. myrtillus and narrow-leaved grasses. Several species and groups of species seemed unaffected by the logging. In sample plots unaffected by logging the cover of most species decreased.
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| 4. |
- Engelmark, O., et al.
(author)
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Ecological effects and management aspects of an exotic tree species : the case of lodgepole pine in Sweden
- 2001
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In: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 141:02-jan, s. 3-13
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Journal article (peer-reviewed)abstract
- The North American tree Pinus contorta var, latifolia was experimentally introduced in Sweden already in the 1920s, and has been used in Swedish forestry on a large scale since the 1970s. These plantations now cover 565,000 ha, mainly in the northern area. In this paper we summarize and discuss existing ecological knowledge of this species introduction. With regard to longterm sustainability we suggest management means to minimize harmful effects of the introduction on ecosystems. These include aspects of self dispersal, pests, ecosystem and landscape structures, and also ecological processes and biodiversity. We also focus on observed and possible interactions in the ecosystems. As Pinus contorta seeds are disseminated and trees regenerated outside initial plantations, this may have future bearings on biodiversity. We suggest a strategy which takes account of the uncertainty in predicting future ecological effects. The strategy includes areal restrictions and zones without Pinus contorta, but also to set up a monitoring program. Observations of adverse effects from the plantations would then give the possibility to adjust P. contorta management.
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| 5. |
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| 6. |
- Gustafsson, Petter, 1948-, et al.
(author)
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STRUCTURE AND REGULATION OF PHOTOSYNTHESIS GENES IN PINUS-SYLVESTRIS (SCOTS PINE) AND PINUS-CONTORTA (LODGEPOLE PINE)
- 1991
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In: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 43:3-4, s. 287-300
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Journal article (peer-reviewed)abstract
- The structure and regulation of one nuclear and one chloroplast gene was studied in Pinus sylvestris (Scots pine) and Pinus contorta (lodgepole pine). cDNA copies of the nuclear located cab genes of Pinus sylvestris, coding for the light-harvesting chlorophyll a/b-binding proteins of photosystem II (LHC-II), were cloned. cab-II genes coding for both types of LHC-II polypeptides, Types 1 and 2, were found. An analysis of the DNA sequences of several different cab-II cDNAs shows that they have a high bias for the nucleotides G and C at the third base positions of the codons, making them more similar to monocot than to dicot genes. Two of the three genes were found to be located within CpG islands. The cab-II genes were found to be expressed in dark-grown seedlings in contrast to what has been found for most angiosperms. The chloroplast genomes of conifers were shown to lack the inverted repeat organization normally found in higher plants, mosses and green algae. The psbA gene, located in the chloroplast genome and coding for the D1 polypeptide in the reaction center of photosystem II, was found to be tandemly duplicated in P. contorta. Cloning and sequence analysis of the two psbA genes and the surrounding regions showed that the duplicated segment is 1.97 kb long and that it ends 19 bp downstream from the psbA stop codon. The corresponding locus of P. sylvestris, which lacks the duplication, was cloned and characterized. A comparison with P. contorta indicates how the duplication/insertion event has occurred. A comparison of third codon position between P. contorta psbA and that of other plants indicated an almost equidistant evolutionary relationship between P. contorta, spinach (or barley) and Marchantia polymorpha.
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| 7. |
- Hazell, P, et al.
(author)
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Presence and abundance of four epiphytic bryophytes in relation to density of aspen (Populus tremula) and other stand characteristics
- 1998
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In: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 107:1-3, s. 147-158
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Journal article (peer-reviewed)abstract
- The influence of the local density of aspen on the presence and abundance of four epiphytic bryophytes was investigated in four mixed forest stands in Central Sweden, each about 30 ha and aged 70-120 yr. Cover of the bryophytes Nyholmiella obtusifolia, Orthotrichum speciosum, Pylaisia polyantha and Radula complanata (the four most frequent aspen-specific epiphytic bryophytes in this region) was recorded on the bark of 155 systematically sampled aspen stems. In circular plots with 10 m radius surrounding each sampled aspen, information on ground vegetation, soil moisture and stand density was collected. In these plots, and also in plots with 5 m and 20 m radius, stem number and diameters of aspen trees were recorded together with an observation of the presence/absence of the four bryophytes. There was no general and consistent relation between aspen density and presence or abundance of the studied bryophytes. Site, host aspen diameter and forest stand structures were more important for the bryophytes. The site factor explained more of the variation than any of the studied variables. All species except N. obtusifolia were favoured by a large diameter of the host tree, and the density of the surrounding forest stand had a positive effect on the cover of Pyl. polyantha and R. complanata. The practical implications of the results are discussed.
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| 8. |
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| 9. |
- Akselsson, Cecilia, et al.
(author)
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Critical biomass harvesting - Applying a new concept for Swedish forest soils
- 2018
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In: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 409, s. 67-73
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Journal article (peer-reviewed)abstract
- The contribution of forest harvesting to base cation losses and soil acidification has increased in recent years in Sweden, as the demand for bioenergy has increased and the sulphur deposition has decreased. Thus, new policy tools are required to evaluate the progress of the recovery from acidification, and as a basis for forest management recommendations. In this study we introduce and test a concept, Critical biomass harvesting. The concept builds on the concept Critical loads, which has been used world-wide for several decades as a bridge between science and policies related to transboundary air pollution and acidification. The basis for the concept is an acidity mass balance, with sources and sinks of acidity. A critical limit defines the highest acceptable acidification status of the water leaving the root zone. Based on the critical limit, the highest allowed biomass harvesting can be calculated, keeping the other parameters constant. In this study the critical limit was set to ANC (Acid Neutralizing Capacity) = 0. Nitrogen was assumed to be affecting acidity only if it leaches from the root zone. The critical biomass harvesting was calculated for almost 12000 National Forest Inventory sites with spruce and pine forest, using the best available data on deposition, weathering and nitrogen leaching. The exceedance of critical biomass harvesting was calculated as the difference between the estimated harvest losses and the critical biomass harvesting. The results were presented as median values in merged catchments in a catchment database, with totally 2079 merged catchments in Sweden. According to the calculations, critical biomass harvesting was exceeded in the southern half of Sweden already at stem harvesting in spruce forests. Whole-tree harvesting expanded the exceedance area, and increased the exceedance levels in southern Sweden. The exceedance in pine forest was lower and affected smaller areas. It was concluded that the concept of critical biomass harvesting can be successfully applied on the same database that has been used for critical load calculations in Sweden, using basically the same approach as has been extensively applied, evaluated and discussed in a critical load context. The results from the calculations in Sweden indicate that whole-tree harvesting, without wood ash recycling, can be expected to further slow down recovery, especially in the most acidified parts of the country, in the southwest.
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| 10. |
- Akselsson, Cecilia, et al.
(author)
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Nutrient and carbon budgets in forest soils as decision support in sustainable forest management
- 2007
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In: Forest Ecology and Management. - : Elsevier BV. - 1872-7042 .- 0378-1127. ; 238:1-3, s. 167-174
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Journal article (peer-reviewed)abstract
- Knowledge about the nutrient and carbon budgets in forest soils is essential to maintain sustainable production, but also in several environmental issues, such as acidification, eutrophication and climate change. The budgets are strongly influenced by atmospheric deposition as well as forestry. This study demonstrates how budget calculations for nitrogen (N), carbon (C) and base cations (BC) can be used as a basis for policy decisions on a regional level in Sweden. The study was based on existing nutrient and C budget calculations on a regional scale in Sweden. The nutrient budgets have been calculated for each square in a national 5 km x 5 km net by means of mass balances including deposition, harvest losses, leaching, weathering (BC) and fixation (N). Scenarios with different deposition and forestry intensity have been run and illustrated on maps. A simplified C budget has been estimated by multiplying the N accumulation with the C/N ratio in the organic layer, based on the assumption that the C/N ratio in the accumulating organic matter is equal to the ratio in the soil organic matter pool. The budget approaches differ from earlier budget studies since they involve regional high resolution data, combine deposition and forestry scenarios and integrate different environmental aspects. The results indicate that whole-tree harvesting will cause net losses of N and base cations in large parts of Sweden, which means that forestry will not be sustainable unless nutrients are added through compensatory fertilization. To prevent net losses following whole-tree harvesting, compensatory fertilization of base cations would be required in almost the whole country, whereas N fertilization would be needed mainly in the northern half of Sweden. The results further suggest that today's recommendations for N fertilization should be revised in southern Sweden by applying the southwest-northeast gradient of the N budget calculations. The C and N accumulation calculations show that C sequestration in Swedish forest soils is not an effective or sustainable way to decrease the net carbon dioxide emissions. A better way is to apply whole-tree harvesting and use the branches, tops and needles as biofuel replacing fossil fuels. This could reduce the present carbon dioxide emissions from fossil fuels substantially. The study shows that high resolution budget calculations that illuminate different aspects of sustainability in forest ecosystems are important tools for identifying problem areas, investigating different alternatives through scenario analyses and developing new policies. Cooperation with stakeholders increases the probability that the research will be useful. (c) 2006 Elsevier B.V. All fights reserved.
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