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Silva Fennica vol. 32 no. 4 | 1998

Category : Research article

article id 677, category Research article

Pekka Leskinen, Jyrki Kangas. (1998). Analysing uncertainties of interval judgment data in multiple-criteria evaluation of forest plans. Silva Fennica vol. 32 no. 4 article id 677. https://doi.org/10.14214/sf.677

Keywords: forest planning; uncertainty; decision analysis; expert judgment; pairwise comparisons

Abstract | View details | Full text in PDF | Author Info

The use of interval judgments instead of accurate pairwise comparisons has been proposed as a solution to facilitate the analysis of uncertainties in the widely applied pairwise comparisons technique. A method is presented for deriving probability distributions for the pairwise comparisons and for utilizing the distributions in the analysis of uncertainties in the evaluation process. The first step is that the expert or the decision-maker is queried as to the best guess of the priority ratio of the attributes compared. This is followed by an adjusting query concerning the uncertainty in the comparison: what is the probability of the priority ratio being between the best guess ± 1 unit of the pairwise comparison scale? An application of the method is presented in the form of multiple-criteria evaluation of alternative management plans for a forest area.

Leskinen, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: pekka.leskinen@metla.fi
Kangas, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: jk@nn.fi

article id 676, category Research article

Erik Sundström. (1998). Afforestation of low-productive peatlands in Sweden – a tree species comparison. Silva Fennica vol. 32 no. 4 article id 676. https://doi.org/10.14214/sf.676

Keywords: Pinus sylvestris; fertilization; Picea abies; afforestation; drainage; tree species; climate; Pinus contorta; broadcast fertilization; spot fertilization

Abstract | View details | Full text in PDF | Author Info

In 1970, five low-productive treeless peatlands in Sweden, ranging from latitudes 56°N to 67°N, were drained and fertilized for afforestation. The aim of the study was to determine the effect of four ditch spacings, varying from 7.5 to 60 m, and five NPK-fertilizer combinations, on the survival and growth of planted Scots pine (Pinus sylvestris), lodgepole pine (Pinus contorta), Norway spruce (Picea abies), and silver birch (Betula pendula) seedlings. The assessments were carried out 18–22 years after planting. Neither silver birch, nor Norway spruce was regarded suitable for the site type. The mortality of silver birch was almost complete, and Norway spruce did not grow well in any of the study areas, however, better than Scots pine in the north. Lodgepole pine had better height and diameter growth but also higher mortality rates than Scots pine. In the two northernmost experimental areas no response to fertilization was found. In the other three areas, the response to fertilization did not differ between species. Phosphorus was the most effective of the added fertilizer elements, whereas nitrogen showed no positive effect. Broadcast fertilizer application, with three times higher amount of fertilizer per ha gave the same growth response as spot application.

Sundström, Swedish University of Agricultural Sciences, Dept. of Silviculture, S-901 83 Umeå, Sweden E-mail: erik.sundstrom@ssko.slu.se

article id 675, category Research article

Per Linder, Peter Jonsson, Mats Niklasson. (1998). Tree mortality after prescribed burning in an old-growth Scots pine forest in northern Sweden. Silva Fennica vol. 32 no. 4 article id 675. https://doi.org/10.14214/sf.675

Keywords: forest management; coarse woody debris; tree mortality; nature conservation; forest fire; dead trees

Abstract | View details | Full text in PDF | Author Info

Tree mortality and input of dead trees were studied after a prescribed burning in a forest reserve in northern Sweden. The stand was a multi-layered old-growth forest. The overstorey was dominated by Scots pine (Pinus sylvestris L.) and the understorey consisted of mixed Scots pine and Norway spruce (Picea abies L. Karst.). Ground vegetation was dominated by ericaceous dwarf-shrubs and feathermosses. The stand has been affected by six forest fires during the last 500 years. The prescribed burning was a low intensity surface fire that scorched almost 90% of the ground. Tree mortality for smaller pines and spruces (DBH < 10 cm) was over 80% in the burned parts of the reserve. For larger pines, 10–50 cm DBH, mortality showed a decreasing trend with increasing diameter, from 14% in class 10–20 cm DBH to 1.4% in class 40–50 cm DBH. However, pines with DBH ≥ 50 cm had a significantly higher mortality, 20%, since a high proportion of them had open fire scars containing cavities, caused by fungi and insects, which enabled the fire to burn inside the trunks and hollow them out. The fire-induced mortality resulted in a 21 m3 ha–1 input of dead trees, of which 12 m3 ha–1 consisted of trees with DBH ≥ 30 cm. An increased mortality among larger trees after low-intensity fires has not previously been described in Fennoscandian boreal forests, probably owing to a lack of recent fires in old-growth stands. However, since large pines with open fire scars were once a common feature in the natural boreal forest, we suggest that this type of tree mortality should be mimicked in forestry practices aiming to maintain and restore natural forest biodiversity.

Linder, Department of Forest Vegetation Ecology, SLU, S-901 83 Umeå, Sweden E-mail: pl@nn.se
Jonsson, Department of Forest Vegetation Ecology, SLU, S-901 83 Umeå, Sweden E-mail: pj@nn.se
Niklasson, Southern Swedish Forest Research Centre, SLU, Box 49, S-230 53 Alnarp, Sweden E-mail: mn@nn.se

article id 674, category Research article

Tuula Aalto. (1998). Carbon dioxide exchange of Scots pine shoots as estimated by a biochemical model and cuvette field measurements. Silva Fennica vol. 32 no. 4 article id 674. https://doi.org/10.14214/sf.674

Keywords: Pinus sylvestris; photosynthesis; Scots pine; CO2 exchange; cuvette measurements

Abstract | View details | Full text in PDF | Author Info

A biochemical model was used to calculate CO2 fluxes to Scots pine shoots in two boreal measurement stations, Hyytiälä in southern Finland (61°51’N, 24°17’E) and Värriö in northern Finland (67°46’N, 29°35’E). The results of the model were compared with cuvette measurements performed in field conditions. A differential equation for change in gas concentration inside a closed cuvette was constructed and solved in order to obtain conductances and fluxes. The results were generally in a good agreement, the correlation coefficients varied from 0.74 to 0.95. Some discrepancies were also found. The model followed more intensively changes in temperature. This could be seen in northern Finland measurements at low temperatures (< 18 °C). The modelled temperature response indicated low fluxes at low temperatures, but measurements did not show any decrease. The irradiation response was relatively similar in both measuring sites and according to the model. Cuvette measurements showed slightly smaller quantum yields as a result from shading of the needles. The temperature dependences of the biochemical model parameters Jmax and Vc(max) were re-evaluated from the field measurements. The results for Vc(max) agreed well with earlier estimations, while the results for Jmax indicated relatively high values at low temperatures especially in northern Finland. Exponential fitting produced also substomatal concentrations of CO2, which agreed quite well with the model. The daily minimum of substomatal/ambient concentration ratio varied from 0.4 to 0.8.

Aalto, Department of Physics, P.O. Box 9, FIN-00014 University of Helsinki, Finland E-mail: tuula.aalto@helsinki.fi

article id 673, category Research article

Lauri Palva, Eero Garam, Sari Palmroth, Raimo Sepponen, Pertti Hari. (1998). Utilizing a multipoint measuring system of photosynthetically active radiation in photosynthetic studies within canopies. Silva Fennica vol. 32 no. 4 article id 673. https://doi.org/10.14214/sf.673

Keywords: carbon dioxide; instrumentation; measurement; photosynthetically active radiation

Abstract | View details | Full text in PDF | Author Info

A novel multipoint measuring system of photosynthetically active radiation (PAR) has been constructed and operated within a Scots pine canopy. A regular grid of 800 measuring points has been incorporated into a cuvette to observe the spatial and temporal distribution of PAR incident on the needles of a twig along with simultaneous measurements of the CO2 exchange in order to determine the dependence of photosynthesis on PAR. It was shown that large errors can result if the photosynthetic rate is estimated using the mean value of PAR instead of the instantaneous values of PAR detected at given points in the region of the needles. The results demonstrate that the obtained regression between the CO2 exchange rate estimated using the multipoint PAR measuring system and the measured CO2 exchange rate is as good within a canopy as in unshaded conditions.

Palva, Helsinki University of Technology, Applied Electronics Laboratory, P.O. Box 3000, FIN-02015 HUT, Finland E-mail: lauri.palva@hut.fi
Garam, Helsinki University of Technology, Applied Electronics Laboratory, P.O. Box 3000, FIN-02015 HUT, Finland E-mail: eg@nn.fi
Palmroth, University of Helsinki, Dept. of Forest Ecology, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: sp@nn.fi
Sepponen, Helsinki University of Technology, Applied Electronics Laboratory, P.O. Box 3000, FIN-02015 HUT, Finland E-mail: rs@nn.fi
Hari, University of Helsinki, Dept. of Forest Ecology, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: ph@nn.fi

article id 672, category Research article

Rimvydas Vasiliauskas, Jan Stenlid. (1998). Spread of Stereum sanguinolentum vegetative compatibility groups within a stand and within stems of Picea abies. Silva Fennica vol. 32 no. 4 article id 672. https://doi.org/10.14214/sf.672

Keywords: Picea abies; Stereum sanguinolentum; somatic incompatibility; decay; wounds

Abstract | View details | Full text in PDF | Author Info

A total of 57 naturally established Stereum sanguinolentum isolates was obtained from artificially wounded Picea abies stems in a forest area of 2 ha in Lithuania. Somatic incompatibility tests revealed 27 vegetative compatibility groups (VCGs) that contained 1–10 isolates. There was no spatial clustering of S. sanguinolentum VCGs within the forest area. The extent of S. sanguinolentum decay was analysed in 48 P. abies stems, 9–26 cm in diameter at breast height. Within 7 years of wounding, the length of S. sanguinolentum decay column in stems was 107–415 cm (291.5 ± 77.3 cm on average), lateral spread of the fungus at the butt was 38–307 cm2 (142.3 ± 66.8 cm2) and decayed proportion of the stem cross-section at the wound site (the butt) was 3–84% (36.8 ± 19.7%). In average, S. sanguinolentum VCG that infected 10 trees exhibited more slow growth inside the stem than VCGs that infected only one tree, and vertical growth varied to a greater extent within this VCG than among different VCGs. Correlation between stem diameter and vertical spread of S. sanguinolentum was not significant (r = –0.103). Despite uniformity of debarked area on all stems 7 years ago (300 cm2), open wound sizes on individual trees at the time of study were between 97–355 cm2 (215.1 ± 59.2 cm2) indicating large differences in wound healing capacity.

Vasiliauskas, Department of Plant Protection, Lithuanian University of Agriculture, LT-4324 Kaunas, Lithuania E-mail: rv@nn.lt
Stenlid, Department of Forest Mycology & Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, S-750 07 Uppsala, Sweden E-mail: js@nn.se

Category : Research note

article id 679, category Research note

Hans-Örjan Nohrstedt, Gunnar Börjesson. (1998). Respiration in a forest soil 27 years after fertilization with different doses of urea. Silva Fennica vol. 32 no. 4 article id 679. https://doi.org/10.14214/sf.679

Keywords: mineral soil; Pinus sylvestris L.; carbon mineralization; humus; podzol

Abstract | View details | Full text in PDF | Author Info

A number of previous studies have shown that N fertilization often reduces respiration in forest soils. However, the durability of this effect has not been fully explored. In this study, the response of soil respiration to a single fertilization with urea, applied 27 years earlier, was examined in a field experiment located in a stand of Pinus sylvestris in central Sweden. The doses that had been added were 120, 240 and 600 kg N ha–1. Samples were taken from the humus layer and the upper 7.5 cm of the mineral soil. Sieved samples were incubated in the laboratory. No effect of the previous fertilization on soil respiration was found, thus indicating that the reduction shown in earlier studies is not persistent. There was a tendency that the highest N dose had caused a higher N concentration and a lower C/N-ratio in the humus layer and a higher C concentration in the mineral soil.

Nohrstedt, The Forestry Research Institute of Sweden, Uppsala Science Park, S-751 83 Uppsala, Sweden E-mail: hans-orjan.nohrstedt@skogforsk.se
Börjesson, Department of Microbiology, Swedish University of Agricultural Sciences, P.O. Box 7025, S-750 07 Uppsala, Sweden E-mail: gb@nn.se

article id 678, category Research note

Ian A. Nalder, Ross W. Wein. (1998). A new forest floor corer for rapid sampling, minimal disturbance and adequate precision. Silva Fennica vol. 32 no. 4 article id 678. https://doi.org/10.14214/sf.678

Keywords: boreal; moss; bulk density; variability; forest floor; corer; western Canada

Abstract | View details | Full text in PDF | Author Info

We describe an effective and inexpensive device for sampling forest floors. It is based on a rechargeable, battery-powered drill that drives a sharpened steel coring tube. The corer is simple to fabricate, is lightweight (3.5 kg) and can be used easily by one person to obtain intact, natural volume cores of the forest floor. It has been used extensively to obtain samples in 114 boreal forest stands of western Canada. We found that coefficients of variation were typically 30% for forest floor organic matter and bulk density, and tended to be higher in Pinus banksiana stands than in Picea glauca and Populus tremuloides. Ten samples per stand gave adequate precision for a study of forest floor dynamics and autocorrelation did not appear to be a problem with five-metre sampling intervals. In addition to sampling forest floors, the corer has proven suitable for sampling moss and lichen layers and mineral soil down to about 20 cm. A similar powered system can also be used for increment boring of trees.

Nalder, University of Alberta, Department of Renewable Resources, 442 Earth Sciences Building, Edmonton, Alberta, Canada T6G 2E3 E-mail: inalder@gpu.srv.ualberta.ca
Wein, University of Alberta, Department of Renewable Resources, 442 Earth Sciences Building, Edmonton, Alberta, Canada T6G 2E3 E-mail: rww@nn.ca

Category : Discussion article

article id 680, category Discussion article

Sakari Mykrä, Sami Kurki. (1998). ESC-strategy for rational operationalization of forest biodiversity maintenance in Finland. Silva Fennica vol. 32 no. 4 article id 680. https://doi.org/10.14214/sf.680

Keywords: biodiversity; Finland; ESC

View details | Full text in PDF | Author Info

Mykrä, Section of Ecology, Department of Biology, University of Turku, FIN-20014 Turku, Finland E-mail: sakmyk@utu.fi
Kurki, Section of Ecology, Department of Biology, University of Turku, FIN-20014 Turku, Finland E-mail: sk@nn.fi

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