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Silva Fennica vol. 39 no. 3 | 2005

Category : Research article

article id 479, category Research article

Ken Olaf Storaunet, Jørund Rolstad, Ivar Gjerde, Vegard S. Gundersen. (2005). Historical logging, productivity, and structural characteristics of boreal coniferous forests in Norway. Silva Fennica vol. 39 no. 3 article id 479. https://doi.org/10.14214/sf.479

Keywords: boreal forest; stand structure; decaying wood; forest history; naturalness; selective logging; dead trees

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

Conservation of forest biodiversity has brought about an interest in evaluating the naturalness of forests, and to locate and protect semi-natural and old-growth forests in the Fennoscandian countries. However, it is not always clear how natural these forests really are, and how the past management history has affected their present structural composition. We studied the relationships between cut stumps from historical logging activity (50–100 years ago) and forest structural characteristics of today in a total of 385 0.25 ha plots in three boreal coniferous forests which are parts of National Nature Reserves in Norway. We also studied how forest productivity influenced these relationships. In plots with negligible logging impact we found the amount of living trees, dead wood, and size of the oldest trees mainly to increase with increasing productivity, whereas the age of the oldest trees decreased. The amount of deciduous trees was generally low irrespective of productivity. The intensity of logging did not consistently influence most of these forest structural variables, neither at low- nor at high-productive sites. The only consistent relationship in all study areas was a decreasing amount of dead wood with increasing logging intensity at high-productive sites. Also, the decay class distribution of dead wood was more right-skewed (indicating on-going accumulation of dead wood) the more logging had occurred at high-productive sites. Except from the effects on dead wood, previous logging does not show up as a major determinant of other stand structures of today.

Storaunet, Norwegian Forest Research Institute, Høgskolevegen 8, NO-1432 Ås, Norway E-mail: ken.storaunet@skogforsk.no
Rolstad, Norwegian Forest Research Institute, Høgskolevegen 8, NO-1432 Ås, Norway E-mail: jr@nn.no
Gjerde, Norwegian Forest Research Institute, Fanaflaten 4, NO-5244 Fana, Norway E-mail: ig@nn.no
Gundersen, Norwegian Forest Research Institute, Fanaflaten 4, NO-5244 Fana, Norway E-mail: vsg@nn.no

article id 377, category Research article

Saara Lilja, Timo Kuuluvainen. (2005). Structure of old Pinus sylvestris dominated forest stands along a geographic and human impact gradient in mid-boreal Fennoscandia. Silva Fennica vol. 39 no. 3 article id 377. https://doi.org/10.14214/sf.377

Keywords: disturbances; restoration; stand structure; managed forest; old growth forest

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

Stand structural characteristics were examined in old Pinus sylvestris dominated sites in three regions along a broad geographic and human impact gradient in mid-boreal Fennoscandia. The study regions were: 1) Häme in south-western Finland, with a long history of forest utilization, 2) Kuhmo in north-eastern Finland, with a more recent history of intensive forest utilization, and 3) Vienansalo in Russian Karelia, still characterized by a large near-natural forest landscape. Within each region the sampled sites were divided into three human impact classes: 1) near-natural stands, 2) stands selectively logged in the past, and 3) managed stands treated with thinnings. The near-natural and selectively logged stands in Häme and Kuhmo had a significantly higher Picea proportion compared to stands in Vienansalo. In comparison, the proportions of deciduous tree volumes were higher in near-natural stands in Vienansalo compared to near-natural stands in Häme. The pooled tree diameter distributions, both in near-natural and selectively logged stands, were descending whereas managed stands had a bimodal diameter distribution. Structural diversity characteristics such as broken trunks were most common in near-natural stands and in stands selectively logged in the past. The results demonstrate the higher structural complexity of near-natural stands and stands selectively logged in the past compared to managed stands, and highlight that old near-natural stands and stands selectively logged in the past vary widely in their structures. This obviously reflects both their natural variability but also various combinations of pre-industrial land use and human impact on fire disturbance. These factors need to be acknowledged when using “natural” forest structures as a reference in developing strategies for forest management, restoration and nature conservation.

Lilja, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: saara.lilja@helsinki.fi
Kuuluvainen, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: tk@nn.fi

article id 376, category Research article

Nils Lexerød, Trond Eid. (2005). Recruitment models for Norway spruce, Scots pine, birch and other broadleaves in young growth forests in Norway. Silva Fennica vol. 39 no. 3 article id 376. https://doi.org/10.14214/sf.376

Keywords: regeneration; national forest inventories; growth simulators; probability models; conditional models; Norway

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

The objective of the present study was to develop recruitment models for Norway spruce, Scots pine, birch and other broadleaves in young growth forests in Norway. The models were developed from permanent sample plots established by the National Forest Inventory, and they will be included in a growth simulator that is part of a large-scale forestry scenario model. The modelling was therefore restricted to independent variables directly or indirectly available from inventories for practical forest management planning. A two-stage modelling approach that suited the stochastic nature of recruitment in boreal forests was used. Models predicting the probability of recruitment were estimated in a first stage, and conditional models for the number of recruits were developed in a second. The probability models as well as the conditional models were biologically realistic and logical. The goodness of fit tests revealed that the probability models fitted the data well, while the coefficients of determination for the conditional models were relatively low. No independent test data were available, but comparisons of predicted and observed number of recruits in different sub-groups of the data revealed few large deviations. The high level of large random errors was probably due to the great variability observed in number of recruits rather than inappropriate specifications of the models. Provided the generally high level of uncertainty connected to analysis performed with large-scale forestry scenario models and the stochastic nature of recruitment, the presented models seem to give satisfactory levels of accuracy.

Lexerød, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: nils.lexerod@umb.no
Eid, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway. E-mail nils.lexerod@umb.no E-mail: te@nn.no

article id 375, category Research article

Edgar Víquez, Diego Pérez. (2005). Effect of pruning on tree growth, yield, and wood properties of Tectona grandis plantations in Costa Rica. Silva Fennica vol. 39 no. 3 article id 375. https://doi.org/10.14214/sf.375

Keywords: wood quality; teak; heartwood volume; stem form; knot-free volume

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Reduced plantation densities have the effect that obtaining natural pruning and stem straightness are less assured. The physiological process of self-pruning is replaced by manual pruning. Generally, plantations are denser and have more uniform spacing than natural forests. In many, if not most species, natural pruning is never a satisfactory option, even after branch senescence, if production of clear wood is a management objective. Natural pruning can only be considered on a species by species basis. This study reports on the first results of a pruning trial for Tectona grandis L.F. plantations in Costa Rica. The treatments consisted of pruning heights of 3.0, 4.0, and 5.0 meters, and the Control without pruning. Differences among treatments in DBH and total height were significant at 3.2, 5.2, and 6.1 years of age, but not at 7.3 years. Under an intensive pruning regime, a teak tree at rotation (20 years) may yield over 40% of knot-free volume (over 60% of the merchantable tree volume). Current findings open a scope for new management options, aiming at improving stem form and wood quality by means of an intensive pruning regime, without having a detrimental effect on tree growth and stand yield.

Víquez, Tropical Agricultural Research and Higher Education Center (CATIE), Apartado 7170 CATIE, Turrialba, Costa Rica E-mail: eviquez@catie.ac.cr
Pérez, Ambiente Tierra S.A., Apartado 733-2250, Tres Ríos, Cartago, Costa Rica E-mail: dp@nn.cr

article id 374, category Research article

Jyrki Hytönen, Paula Jylhä. (2005). Effects of competing vegetation and post-planting weed control on the mortality, growth and vole damages to Betula pendula planted on former agricultural land. Silva Fennica vol. 39 no. 3 article id 374. https://doi.org/10.14214/sf.374

Keywords: Betula pendula; vegetation control; herbicides; mulch; cover crop; vole damage; weed cover

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Effects of competing vegetation and weed control methods (fibre board mulch, cover crop of clover, various herbicides) on the survival and growth of and vole damage to silver birch (Betula pendula Roth) were analysed based on data from a field experiment established in southern Finland. The cover percentage of competing vegetation and its shading effect were assessed, and seedling size and vitality were recorded several times during the 11-year research period. Mean seedling height and height increment decreased linearly with increasing vegetation cover. Seedling mortality started to significantly increase once the vegetation cover had reached the level of 60–80%. Herbicides significantly retarded increase of weed cover on the initially weedless areas for two to three years, and a cover crop promoted increase in cover percentage. Successful weed control with herbicides significantly increased seedling growth and survival. After 11 years, the average stem volume on the herbicide-treated plots (28.9 m3 ha–1) was 2.5-fold as compared to that of the control plots (11.6 m3 ha–1). Furthermore, seedling mortality on the control plots (21%) was almost 3.5-fold as compared to the seedling mortality on herbicide-treated plots (6%). Having a cover crop proved to be an ineffective weed control method both in terms of seedling growth and survival. The application of mulch had only a slight effect on height increment (0.6 m in 11 years), but on the other hand, it considerably decreased seedling mortality (control: 21%, mulch treatment: 1.5%). These differences were not, however, statistically significant. Small seedling size, high shading class, and high vegetation coverage percentage increased the risk of voles damaging the seedlings.

Hytönen, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FI-69101 Kannus, Finland E-mail: jyrki.hytonen@metla.fi
Jylhä, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FI-69101 Kannus, Finland E-mail: pj@nn.fi

article id 373, category Research article

Anna Saarsalmi, Pekka Tamminen. (2005). Boron, phosphorus and nitrogen fertilization in Norway spruce stands suffering from growth disturbances. Silva Fennica vol. 39 no. 3 article id 373. https://doi.org/10.14214/sf.373

Keywords: Norway spruce; fertilization; needles; height growth; recovery; boron; growth disorders; soil

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Growth disturbance symptoms typical of B deficiency have been reported on Norway spruce (Picea abies (L.) Karst.) trees in many parts of eastern Finland. In order to test the B deficiency hypothesis and explore the possibilities of curing the disturbed trees with B fertilization, three experiments were established in October 1999 in young Norway spruce stands growing on fertile sites in eastern Finland. All the stands contained healthy, slightly and severely damaged trees with growth disturbances typical of B deficiency (B < 5 mg kg–1). 40 healthy, 40 slightly damaged, and 40 severely damaged trees were selected as sample trees in each stand. In May 2000, the trees were fertilized with 2.0 kg B ha–1 as borax (B), 2.0 kg B ha–1 and 40 kg P ha–1 as superphosphate (B+P) or 200 kg N ha–1 as urea (N). The control trees were not fertilized (0). The needle response to B fertilization was rapid, relatively high B concentrations being achieved already after one growing season. Boron fertilization cured the growth disorders and increased height growth within four years, but had no effect on diameter growth. The trees also recovered without B fertilization, but to a lesser extent compared to the B fertilized trees. Compared to the control, boron fertilization increased the height growth in all the disorder classes, i.e. 5, 17 and 19 cm yr–1 for healthy, slightly and severely damaged trees, respectively. As the healthy trees also seemed to benefit from B fertilization, this indicates that B deficiency in fact retards height growth before any disorder symptoms become apparent in individual trees. Compared with B alone, the application of P together with B gave no additional benefit. Nitrogen fertilization alone appeared to have a detrimental effect on height growth in the severely disturbed trees.

Saarsalmi, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: anna.saarsalmi@metla.fi
Tamminen, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: pt@nn.fi

article id 372, category Research article

Ulf Sikström. (2005). Pre-harvest soil acidification, liming or N fertilization did not significantly affect the survival and growth of young Norway spruce. Silva Fennica vol. 39 no. 3 article id 372. https://doi.org/10.14214/sf.372

Keywords: Picea abies; regeneration; limestone; sulphur powder; urea

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

Acidification, liming, and N fertilization affect a number of soil properties. Such changes may have an impact on forest regeneration and yield. The aim of this study was to investigate the survival and growth of Picea abies (L.) Karst. planted on plots that had been acidified (in 12 annual treatments totalling 600 or 1200 kg S ha–1 in the form of elemental sulphur), limed (12 x 500 = 6000 kg lime ha–1 in the form of CaCO3) or N-fertilized (3 x 200 = 600 kg N ha–1 in the form of urea) prior to harvest. Trees growing on plots treated with a combination of the N plus the lower S application were also tested. None of the treatments, applied in three replicate stands, significantly influenced either survival or growth of Picea abies trees during the first 11 growing seasons after planting.

Sikström, SkogForsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: ulf.sikstrom@skogforsk.se

article id 371, category Research article

Mika Nieminen, Erkki Ahti, Hannu Nousiainen, Samuli Joensuu, Martti Vuollekoski. (2005). Capacity of riparian buffer zones to reduce sediment concentrations in discharge from peatlands drained for forestry. Silva Fennica vol. 39 no. 3 article id 371. https://doi.org/10.14214/sf.371

Keywords: ditching; suspended solids; peatlands; erosion; riparian buffer zones; water quality protection

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

In 1995–2001, the efficiency of riparian buffer zone areas to reduce the concentrations of suspended solids in discharge from peatlands drained for forestry purposes was studied at 7 locations in south-central Finland. The two largest buffer zones reduced the concentrations of suspended solids by > 70%. The efficiency of the three medium-sized buffer zones to reduce through-flow sediment concentrations was 50–60%, but no reduction occurred at the smallest two buffer areas. Thus, the capacity of buffer zones to reduce sediment concentrations was strongly related to their size. However, significant correlations were also found between reduction capacity and inflow water sediment concentrations, although the correlations at the two smallest buffer zones were low. The use of buffer zones in reducing sediment load from peatlands drained for forestry purposes is recommended, but relatively large areas for efficient removal capacity are needed.

Nieminen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mika.nieminen@metla.fi
Ahti, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ea@nn.fi
Nousiainen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: hn@nn.fi
Joensuu, Forestry Development Centre Tapio, Soidinkuja 4, FI-00700 Helsinki, Finland E-mail: sj@nn.fi
Vuollekoski, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mv@nn.fi

article id 370, category Research article

Pekka Tamminen, John Derome. (2005). Temporal trends in chemical parameters of upland forest soils in southern Finland. Silva Fennica vol. 39 no. 3 article id 370. https://doi.org/10.14214/sf.370

Keywords: soil chemistry; acidification; time series

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

Changes in chemical soil properties during periods of 12 to 28 years were studied in 54 stands in southern Finland. Relative slopes (%/year) were calculated for the changes in soil variables in order to utilise all the sampling occasions (2–6) covered by the study period. Only the results of new analyses made on the soil samples could be used owing to unpredictable differences between the results of the original and new analyses. During the study period the acidity (pH, exchangeable acidity) of the organic layer had decreased, and the mineral soil had become more acidic only in terms of increased exchangeable aluminium concentrations. An increasing trend in the amount of soil organic matter best explained the acidity variables: it lowered acidity in the organic layer, but increased it in the mineral soil. Acid ammonium acetate extractable nutrients showed decreasing trends over time, apart from an increasing trend for sulphur in the 0–30 cm mineral soil layer. Total concentrations of most elements in the organic layer, including nitrogen and sulphur, also showed a decreasing trend. Changes in the soil variables could not be firmly connected to deposition, wood production or the amount of nutrients accumulated in woody tissues. However, the decrease in sulphur concentrations in the organic layer was clearly linked with the decrease in sulphur deposition in recent years.

Tamminen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: pekka.tamminen@metla.fi
Derome, Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: jd@nn.fi

Category : Review article

article id 378, category Review article

Yaoqi Zhang, Daowei Zhang, John Schelhas. (2005). Small-scale non-industrial private forest ownership in the United States: rationale and implications for forest management. Silva Fennica vol. 39 no. 3 article id 378. https://doi.org/10.14214/sf.378

Keywords: non-industrial private forest; forest land parcelization; timber supply; transaction costs; economic efficiency; land use change

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

The transaction cost approach is used to explain why small non-industrial private forest (NIPF) ownerships are increasing in the U.S. We argue that the number of small NIPF owners have increased because: 1) a significant amount of forestland is no longer used economically if primarily for timber production, but rather for non-timber forest products and environmental services (particularly where population density is high), 2) when a person makes frequent use of non-timber products and services, owning forestland is more efficient for them because it saves the transaction costs involved in getting them from the market, 3) forestland parcelization takes place when non-timber value increases faster than timber value, and 4) marginal value for non-timber product is diminishing much faster than that for timber production. The paper also discusses implications of the parcelization of NIPF ownerships on forest management.

Zhang, School of Forestry & Wildlife Sciences, Auburn University, AL 36849-5418, USA E-mail: yaoqi.zhang@auburn.edu
Zhang, School of Forestry & Wildlife Sciences, Auburn University, AL 36849-5418, USA E-mail: dz@nn.us
Schelhas, Southern Research Station, USDA Forest Service, Tuskegee University, AL, USA E-mail: js@nn.us

Category : Research note

article id 379, category Research note

Daniel Ligné, Lars Eliasson, Tomas Nordfjell. (2005). Time consumption and damage to the remaining stock in mechanised and motor manual pre-commercial thinning. Silva Fennica vol. 39 no. 3 article id 379. https://doi.org/10.14214/sf.379

Keywords: birch; Scots pine; cleaning; time study; brush saw; Husqvarna; Vimek

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

Selective pre-commercial thinning (PCT) is usually carried out by workers with a brush saw in order to increase the growth of the potential crop trees (main stems) through removal of competing trees. In the last decade relative PCT costs have increased, partly because stands are denser and have higher trees when treated, which has led to new interest for mechanised PCT. The objective was to compare mechanised and motor manual PCT regarding productivity and damage to remaining main stems. Time consumption for, and damage after, mechanised and motor manual PCT were studied on 50 plots per treatment in mixed pine birch stands with an initial stand density exceeding 4500 stems ha–1. In the present study productivity was influenced by stand density, stand height and the quota between height and diameter. Irrespectively of these factors, mechanised PCT was 0.74 hours ha–1 slower than motor manual PCT. Motor manual PCT of the average stand (average height 3.69 m, 10 816 stems ha–1) took 5.06 effective hours. In average 2475 and 2805 main stems ha–1 were left after the mechanised and motor manual treatments, respectively, whereof 1.3 and 2.1% were damaged by the treatments. The results show that efficiency in motor manual PCT has increased in dense and tall stands compared to older studies. Motor manual PCT was more time effective than mechanised PCT, and thereby also even more cost-effective. However, the potential for technical and methodological development of mechanised PCT is probably larger than for motor manual PCT.

Ligné, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: dl@nn.se
Eliasson, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: lars.eliasson@norraskogsagarna.se
Nordfjell, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: tn@nn.se

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