| 1. |
- Angelstam, Per, et al.
(författare)
-
Protecting forest areas for biodiversity in Sweden 1991–2010: the policy implementation process and outcomes on the ground
- 2011
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 45, s. 1111-1133
-
Tidskriftsartikel (refereegranskat)abstract
- Swedish forest and environmental policies imply that forests should be managed so that all naturally occurring species are maintained in viable populations. This requires maintenance of functional networks of representative natural forest and cultural woodland habitats. We first review the policy implementation process regarding protected areas in Sweden 1991-2010, how ecological knowledge was used to formulate interim short-term and strategic long-term biodiversity conservation goals, and the development of a hierarchical spatial planning approach. Second, we present data about the amount of formally protected and voluntarily set aside forest stands, and evaluate how much remains in terms of additional forest protection, conservation management and habitat restoration to achieve forest and environmental policy objectives in the long-term. Third, a case study in central Sweden was made to estimate the functionality of old Scots pine, Norway spruce and deciduous forest habitats, as well as cultural woodland, in different forest regions. Finally, we assess operational biodiversity conservation planning processes. We conclude that Swedish policy pronouncements capture the contemporary knowledge about biodiversity and conservation planning well. However, the existing area of protected and set-aside forests is presently too small and with too poor connectivity. To bridge this gap, spatial planning, management and restoration of habitat, as well as collaboration among forest and conservation planners need to be improved.
|
|
| 2. |
- Backlund, Ingegerd, et al.
(författare)
-
Biomass Production of Dense Direct-Seeded Lodgepole Pine (Pinus contorta) at Short Rotation Periods
- 2012
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 46, s. 609-623
-
Tidskriftsartikel (refereegranskat)abstract
- Backlund, I. & Bergsten, U. 2012. Biomass production of dense direct-seeded lodgepole pine (Pinus contorta) at short rotation periods. Silva Fennica 46(4): 609-623. Lodgepole pine (Pinus contorta) is a fast-growing species that is suitable for producing woody biomass in Nordic countries. Direct seeding of this species is cheaper than planting and creates dense, stable stands. The objective of this study was to quantify the stem volume and biomass production of direct seeded lodgepole pine stands grown under different site conditions with different stem densities, at an age that would permit extensive harvesting of biomass. A circle-plot inventory was performed in 16 of the oldest direct seeded lodgepole pine stands in mid-northern Sweden. Stemwood production of almost 200 m(3)/ha was achieved on average on the best sites, rising to about 300 m(3)/ha for the best circle-plots within 30 years of direct seeding despite the fact that pre-commercial thinning was made once or twice. This corresponds to 100 and 140 tons of dry weight biomass/ha, respectively. Higher stand stem densities (>= 3000 st/ha) yielded more biomass with only slight reductions in diameter at breast height. The development of stem volume with respect to dominant height in direct seeded stands was becoming comparable to that in planted stands with similar spacing. It therefore seems that there is an unutilized potential for cost-effectively growing lodgepole pine in dense stands for biomass production after direct seeding. It may be possible to devise regimes for short(er) rotation forestry that would yield substantial amount of inexpensive biomass for biorefineries within a few decades.
|
|
| 3. |
- Barbeito, Ignacio, et al.
(författare)
-
Production of genetically improved silver birch plantations in southern and central Sweden
- 2022
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 56
-
Tidskriftsartikel (refereegranskat)abstract
- Investing in planting genetically unproved silver birch (Betula pendula Roth) in Swedish plantations requires understanding how birch stands will develop over their entire rotation. Previous studies have indicated relatively low production of birch compared to Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). This could result from using unrepresentative basic data, collected from unimproved, naturally-regenerated birch (Betula spp.) growing on inventory plots often located in coniferous stands. The objective of this study was to develop a basal area development function of improved silver birch and evaluate production over a full rotation period. We used data from 52 experiments including planted silver birch of different genetic breeding levels in southern and central Sweden. The experimental plots were established on fertile forest sites and on former agricultural lands, and were managed with different numbers of thinnings and basal area removal regimes. The model best describing total stand basal area development was a dynamic equation derived from the Korf base model. The analysis of the realized gain trial for birch showed a good stability of the early calculated relative differences in basal area between tested genotypes over time. Thus, the relative difference in basal area might be with cautious used as representation of the realized genetic gain. On average forest sites in southern Sweden, improved and planted silver birch could produce between 6-10.5 m(3) ha(-1) year(-1), while on fertile agriculture land the average productivity might be higher, especially with material coming from the improvement program. The performed analysis provided a first step toward predicting the effects of genetic improvement on total volume production and profitability of silver birch. However, more experiments arc needed to set up the relative differences between different improved material.
|
|
| 4. |
- Berg, Staffan, et al.
(författare)
-
Comparison of co-existing forestry and reindeer husbandry value chains in northern Sweden
- 2016
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 50
-
Tidskriftsartikel (refereegranskat)abstract
- Forestry in Mala, northern Sweden, coexists with other land uses. Reindeer husbandry is in the area for centuries and requires large areas of grazing land. Competing land uses may threaten the Mala Sami village. The aim of the study was to evaluate increased consideration in forest management towards 1) reindeer husbandry, 2) nature and 3) a combination of the two. These scenarios were compared with forest management as it was in 2009. Results indicate that all three scenarios lead to a decrease in annual harvesting volumes of 0.2 to 0.4 million m(3). Forest industry dominated the economic viability in the area. Forest management adapted to the needs of reindeer husbandry resulted in less potential for yearly harvest, employment and profits from forest industry. On the other hand, it led to an increase in growing stock and consequently the potential for carbon sequestration over time. Indeed the increased sequestration would compensate for all fossil emissions of carbon from the Forest Wood Chain (FWC). The nature scenario had minor effects on economic result and on the emissions of fossil carbon. The combined scenario gave a reduced economic performance for the FWC. A scenario based on forest management accommodating the needs of reindeer husbandry gave the best economic result for the reindeer chain, due to high survival rate of the reindeer. However the economic importance of reindeer husbandry in the region was small compared to the FWC. Results from scenario analysis could serve as a platform for mutual understanding between stakeholders.
|
|
| 5. |
- Berg, Simon, et al.
(författare)
-
Effect of stump size and timing of stump harvesting on ground disturbance and root breakage diameter
- 2015
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 49
-
Tidskriftsartikel (refereegranskat)abstract
- Stump wood is a possible alternative to fossil fuel. Its harvesting, however, disturbs the ground and this has not yet been quantified at stump level. Such disturbance is likely to be dependent on stump size, type of soil and timing of stump harvesting. Therefore, we measured ground disturbance and root breakage diameter at two Norway spruce sites with sandy glacial till soil. The sites were harvested with a fork type head, 6 and 18 months after clear cutting. Measurements were made within 2 weeks of harvest. No difference was found between the two sites. The mean area of disturbed ground was 6.06 (std 3.14) m(2) per stump and increased exponentially with stump size. A regression function modelling the relationship was constructed. Unexpectedly, many fine roots where extracted in the harvest. The arithmetic and basal area weighted mean root breakage diameter was 4.6 (std 2.2) and 29.5 (std 17.9) mm, respectively. There seems to be a limited increase in root breakage diameter with increased stump size. The small root breakage diameter is associated with reduced fuel quality and greater nutrient removal. It appears that much of the ground disturbance is associated with the creation of ruts rather than stump harvest per se. Stump harvesting disturbs a larger percentage of the area of a harvested site than mounding. Postponing stump harvest by one year did not decrease the ground disturbance or increase the root breakage diameter. To achieve less disturbance and larger root breakage diameter, probably new stump harvesting technology is required.
|
|
| 6. |
- Bergsten, Urban, et al.
(författare)
-
Frost Heaving of Picea abies Seedlings as Influenced by Soil Preparation, Planting Technique, and Location along Gap-Shelterwood Gradients
- 2009
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 43, s. 39-50
-
Tidskriftsartikel (refereegranskat)abstract
- The effects or soil preparation, planting technique and location along gap-shelterwood gradients (position and orientation) oil frost heaving damage to seedlings were studied in Vindeln Experimental Forests, northern Sweden. The forest was harvested in a grid pattern in winter 2004-2005, forming gaps and shelterwood areas of 30x40 m each. Gap-shelterwood gradients were delimited in four orientations and subdivided into five positions: 7 ill and 15 m into the gap and shelterwood, and at the gap edge. At each position, three replicates of three soil preparations were made: exposed E and B horizons and HuMinMix (milled vegetation and humus layers mixed with surface mineral soil). In early October 2005, one-year-old containerized Picea abies (L.) Karst. seedlings were planted using four techniques: normal and deep planting, and mobile and fixed experimental containers. After one winter, frost heaving damage was highest for seedlings oil B horizon combined with the mobile container (51 +/- 6%) and normal planting (43 +/- 6%). Normal- or deep-planted seedlings in HuMinMix had the least damage (5-6.6 +/- 2.5%). Compared to normal planting, deep planting reduced frost heaving damage only on B horizon. When considering the orientation, seedlings in the experimental containers had more or similar frost heaving damage than normal- or deep-planted seedlings. Along the eastern gradient, seedlings incurred more frost heaving damage in the center of the gap than under the canopy.
|
|
| 7. |
- Bergström, Dan
(författare)
-
Comparing the characteristics of boom-corridor and selectively thinned stands of Scots pine and birch
- 2021
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 55
-
Tidskriftsartikel (refereegranskat)abstract
- Young, dense forest in Finland and Sweden urgently need to receive first thinning. In such stands, conventional selective thinning methods make the harvester work time consuming and, thus, costly. To make small-sized trees economically competitive as raw material for bioenergy and biorefining, new harvesting technologies and/or thinning methods need to be developed. A potential solution is boom-corridor thinning (BCT), rendering effective cutting work. The aim of this study was to describe and compare the stand structure of two Scots pine stands (Pinus sylvestris L.) and one birch-dominated (Betula pendula Roth with natural downy birch, B. pubescens Ehrh.) stand after BCT and selective thinning at the first thinning phase. Furthermore, simulations were conducted to predict the future stand development after the first thinning treatments. The density of the growing stock was 16-46% higher after BCT treatment than after selective thinning because BCT stands included more small and supressed trees with a dbh < 100 mm. However, the numbers of future crop trees with a dbh > 140 nun per hectare were at the same level in both treatments. The stem volume removal per hectare did not differ between treatments. However, simulation of stand development and intermediate thinning and clearcutting revealed that the total removal volume was 10-18% higher in BCT stands compared to selectively thinned ones. The saw log volumes harvested did, however, not differ between treatments. This study shows that BCT generates stands with higher biodiversity compared to conventional thinning as higher levels of biomass removal can be reached throughout stand rotations.
|
|
| 8. |
- Bergström, Dan, et al.
(författare)
-
Comparison of Boom-Corridor Thinning and Thinning From Below Harvesting Methods in Young Dense Scots Pine Stands
- 2010
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 44, s. 669-679
-
Tidskriftsartikel (refereegranskat)abstract
- At present, only a small proportion of the potential extractable bioenergy from young dense forests in Sweden is utilized. The conventional mechanized first thinning systems used in such stands suffer from low productivity, so the operation is only profitable in stands with bigger trees and high standing volumes. Conventional harvesters are used for this operation equipped with accumulating felling heads designed for handling several trees during each crane cycle. In thinning from below the felling and bunching work requires many time-consuming nonlinear crane movements to avoid felling or damaging of future crop trees. However, higher productivity can be achieved when trees between strip roads are harvested in about 1 m-wide corridors with a length corresponding to the reach of the crane. We refer to this operation as boom-corridor thinning. The objective of this study was to compare felling and bunching productivity in young dense stands when employing thinning from below or boom-corridor thinning. Experiments were performed using a randomized block design involving between 4400 and 18600 treesxha(-1) with a corresponding average tree size of 7.2 and 3.2 cm dbh, respectively. Based on the average tree being removed at a dbh of 5.7 cm, the productivity (ODtxPW-hour(-1)) was significant (almost 16%) higher for the boom-corridor thinning than for thinning from below treatment. At the same time, the time taken for the work element "Crane in-between" (the period between the loaded crane starting to move towards a tree and the felling head rapidly slowing down for positioning) was significantly reduced, by almost 17%. The positive results were achieved even though the operator was new to the method. To achieve a significantly higher efficiency during the felling and bunching operation, development of new harvesting equipment and operating techniques seems crucial.
|
|
| 9. |
- Bergström, Dan
(författare)
-
Precision and accuracy in moisture content determination of wood fuel chips using a handheld electric capacitance moisture meter
- 2018
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 52
-
Tidskriftsartikel (refereegranskat)abstract
- According to the Swedish Timber Measurement Act, measurements affecting payments for wood fuels to landowners must be accurate and precise. In this regard, moisture content is an important quality parameter for wood chips which influences the net calorific value as received and thus the economic value. As standard practice moisture content is determined with the oven-drying method, which is cumbersome to use for deliveries to facilities without drying-ovens, which in turn necessitates that samples are taken elsewhere for measurement. An alternative solution is to use a portable moisture meter. Our aim was to evaluate the precision of a handheld capacitance moisture meter. Accuracy and precision of a capacitance meter was determined in the lab and a calibration function was made. Thereafter, the calibrated moisture meter was compared with the standard method for moisture content determination of truckloads of chips. The capacitance meter showed a moderate accuracy by underestimating moisture content by 6.0 percentage points (pp), compared to the reference method, at a precision of +/- 3.8 pp (CI 95%). For chips with M> 50%, both accuracy and precision decreased. Calibration increased the accuracy in the follow up study by 3 pp for chips with M <50% but could not be made for wetter chips. The oven-drying method and the capacitance meter can provide equally accurate estimates of mean moisture content for chips with M <50% if a larger sample is taken with the latter. It should be possible to use capacitance meters to measure moisture content even when used to calculate payments depending of the needed accuracy. A calibration function for each assortment is needed.
|
|
| 10. |
- Bohlin, Inka, et al.
(författare)
-
Lessons learned from assessing the cover and yield of bilberry and lingonberry using the national forest inventories in Finland and Sweden
- 2021
-
Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 55
-
Tidskriftsartikel (refereegranskat)abstract
- Bilberry (Vaccinium myrtillus L.) and lingonberry (V. vitis-idaea L.) can be a part of healthy diet and are important for many animals. Two approaches are described to assessing their vegetation cover and berry yield via national forest inventory (NFI) observations. The aim was to provide estimates and predictions of the abundance and yield of the species at regional and national levels in Finland and Sweden. In Finland, the model-based predictions are used in evaluating the impacts of cutting intensity on forest berries needed in forest-related decision making. In Sweden, seasonal inventory-based estimates are used to evaluate the annual national and regional berry yields, and in a forecasting system aimed at large public and berry enterprises. Based on the NFI sample plots measured between 2014 and 2018, the total annual yields are estimated to be 208 Mkg of bilberry and 246 Mkg of lingonberry on productive forest land (increment at least 1 m3 ha–1 year–1) in Finland, and 336 and 382 Mkg respectively in Sweden (average of NFI inventories in 2015–2019). The predicted development of berry yields is related to the intensity of cuttings in alternative forest management scenarios: lower removals favoured bilberry, and higher removals lingonberry. The model-based method describes the effects of stand development and management on berry yields, whereas the inventory-based method can calibrate seasonal estimates through field observations. In providing spatially and timely more accurate information concerning seasonal berry yields, an assessment of berry yields should involve the elements of both inventory-based and model-based approaches described in this study.
|
|
