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Silva Fennica 1926-1997
Acta Forestalia Fennica

Articles containing the keyword 'site index'.

Category: Research article

article id 54, category Research article
Urban Nilsson, Björn Elfving, Kjell Karlsson. (2012). Productivity of Norway spruce compared to Scots pine in the interior of northern Sweden. Silva Fennica vol. 46 no. 2 article id 54.
Productivity of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) was studied in 12 paired plots in the interior of northern Sweden. Stands were established between 1928 and 1959; yield plots were established between 1974 and 1983 during pre-commercial thinning of the stands. Gross stem-wood production was significantly higher for Scots pine than for Norway spruce, stem-wood production by Norway spruce being 29.4% that of Scots pine. The site index for Norway spruce was lower than for Scots pine at all sites except one; the average difference in site index was 4.8 m. The simulated maximum mean annual increment (MAImax) during the rotation was 19% higher than the MAImax estimated with the site index for Scots pine, whereas simulated MAImax and MAImax estimated from the site index was about the same for Norway spruce. The simulations also indicated that MAI peaked about 50 years later for Norway spruce than for Scots pine. More small trees were included in the diameter distribution of Norway spruce than of Scots pine resulting in a lower stem-wood volume for Norway spruce when stands with the same dominant height were compared. This study shows that the difference in growth and rotation length between Scots pine and Norway spruce has implications when choosing which species to grow in the interior of northern Sweden.
  • Nilsson, Swedish University of Agricultural Sciences (SLU), Southern Swedish Forest Research Centre, Alnarp, Sweden ORCID ID:E-mail: (email)
  • Elfving, SLU, Forest Ecology and Management, Umeå, Sweden ORCID ID:E-mail:
  • Karlsson, SLU, Unit of Field Based Research, Asa, Sweden ORCID ID:E-mail:
article id 512, category Research article
Juha-Pekka Hotanen. (2003). Multidimensional site description of peatlands drained for forestry. Silva Fennica vol. 37 no. 1 article id 512.
Sites (n = 119) on drained mires located in the southern aapa mire zone in Finland were analysed by multivariate techniques. The compositional trends of the understorey vegetation were analysed by means of hybrid multidimensional scaling (HMDS). In addition to field classification, two-way indicator species analysis (TWINSPAN) and flexible unweighted paired group arithmetic average (FUPGMA) classifications were used. The 1st HMDS dimension primarily reflected variation along a gradient from spruce mire influence to hummock-level bog influence. Variation in nutrient status was also connected to this gradient. Factors underlying the 2nd dimension were variation in nutrient status and drainage succession (moisture). Some sample plots representing herb-rich or Molinia-rich types were separated along the 3rd dimension. The variation in understorey vegetation (i.e. the ordination space) showed high maximum correlation with stand volume r = 0.81, mean annual stand volume increment r = 0.76, and post-drainage dominant height r = 0.75. The covariation between the vegetation and peat bulk density in both the 0–10 and 10–20 cm peat layers was also strong: r = 0.55 and r = 0.80. The correlations for Hv.Post were 0.64 and 0.81, respectively. Of the total macronutrient concentrations, phosphorus (r = 0.73, r = 0.75) and nitrogen (r = 0.59, r = 0.64) were the most strongly correlated with species composition. The environmental sample variables were also presented by the vegetation units of numerical classification. Most of the recorded variables, including nutrient amounts (kg ha–1), were examined in site quality (fertility) classes by succession phases as well. Border variants or transitional forms of the site types were common. Additional vegetation criteria (e.g. surface-water influence) more closely defined the ecology of the site. In addition to the site quality classes, a considerable amount of information about the tree stands, vegetation diversity and peat properties was associated with the separation of the succession phases, i.e. in this study transforming (phase II) vs. transformed (final phase III) sites. In conclusion, the actual vegetation appeared to well reflect various aspects of the ecological conditions, even in labile communities of commercial forests on drained peatlands.
  • Hotanen, Finnish Forest Research Institute, Joensuu Research Centre, P.O.Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail: (email)
article id 521, category Research article
Gordon Nigh. (2002). Site index conversion equations for mixed trembling aspen and white spruce stands in northern British Columbia. Silva Fennica vol. 36 no. 4 article id 521.
White spruce and trembling aspen are two important commercial species in British Columbia. They often grow in association, particularly in the Boreal White and Black Spruce and Sub-Boreal Spruce biogeoclimatic zones. Site index conversion equations are useful for estimating the site index of one species from the site index of another species. This study fills a need for site index conversion equations for mixed spruce/aspen stands. Seventy 0.01 ha study plots were established in mixed spruce/aspen stands. One site tree of each species was selected from each plot. The height and breast height ages of the site trees were measured and the site index was estimated with these data. The correlation between the site index of spruce and aspen was 0.6. Geometric mean regression was used to estimate the parameters of a linear site index conversion equation. The analysis did not reveal any differences in the conversion equations across the three major biogeoclimatic units (BWBSmw1, BWBSmw2, and SBS) that were sampled. Therefore, only one conversion equation is required.
  • Nigh, Ministry of Forests, Research Branch, P.O. Box 9519, Stn. Prov. Govt., Victoria, BC, Canada V8W 9C2 ORCID ID:E-mail: (email)

Category: Research note

article id 7818, category Research note
Roberts Matisons, Guntars Šņepsts, Līga Puriņa, Jānis Donis, Āris Jansons. (2018). Dominant height growth of European beech at the northeasternmost stands in Europe. Silva Fennica vol. 52 no. 1 article id 7818.
Highlights: The dominant height growth of the introduced European beech was modelled using the generalised algebraic difference approach; The Chapman-Richards and Sloboda models showed the best fit to the data; Height growth of the second generation trees exceeded the first generation trees; In the western part of Latvia, height growth of beech exceeded that in southern Sweden.

The height growth of trees influences the productivity of stands and the competitiveness of species, shaping the range of their distribution. Dominant height growth was assessed for European beech (Fagus sylvatica L.), growing outside of its natural distribution range in the western part of Latvia. In 10 neighbouring experimental stands, 20 dominant trees were felled for stem analysis. Height growth was modelled using the generalised algebraic difference approach, applying several non-linear equations and mixed procedures. The Chapman-Richards and Sloboda models showed the best fit to the data. Height growth of the second generation (younger) trees exceeded that of the first generation, and followed curve for a higher site index, suggesting sufficient adaptation and improving conditions. Height growth of the studied beech exceeded predictions for beech in southern Sweden, which is considered to be the northern limit of the species range, yet the growth pattern differed. In Latvia, slower height growth was estimated for site indices < 32 m (in 100 years) during the first 60 years, yet larger maximal height was predicted, suggesting a longer establishment period. Nevertheless, the improving height growth indicated increasing potential for the application of the species in commercial forestry, and an expansion of the species within the region even during the 21th century.

  • Matisons, Latvian State Forest Research Institute “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: (email)
  • Šņepsts, Latvian State Forest Research Institute “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail:
  • Puriņa, Latvian State Forest Research Institute “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail:
  • Donis, Latvian State Forest Research Institute “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail:
  • Jansons, Latvian State Forest Research Institute “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail:

Category: Article

article id 5568, category Article
Tord Johansson. (1996). Site index curves for European aspen (Populus tremula L.) growing on forest land of different soils in Sweden. Silva Fennica vol. 30 no. 4 article id 5568.

Growth data were collected from 40 European aspen (Populus tremula L.) stands growing on eight localities in Sweden. The stands ranged in latitude from 56 to 66°N. The mean age of the stands was 32 years (range, 12–63), the mean stand density 1978 stems ha-1 (range, 300–6,000), and the mean diameter at breast height (on bark) 17 cm (range, 8–34).

Site index curves were constructed for total age. Curves for H40 (dominant height at 40 years total age) were made for total Sweden. Curves fitted for H40 total age have another shape than curves presented by other Nordic studies. The curves from the present study have slower growth for young aspens than curves from Norwegian and Finnish conditions. For 50–70-year-old aspen stands, curves from the present study indicate taller heights than from Nordic studies.

Classified soil types from the stands were grouped into three groups: sandy till (17), light clay (15) and medium clay till (4). As there was only one stand growing in the fine sand group and one stand in the heavy clay till group and two stands in the silty till group, these stands were not presented with growth curves. There were no statistically significant differences in site index between the three soil type groups. Some recommendations for management of aspen stand are given. Damages caused by moose, fungi and other injuries are discussed as a problem for height yield production and a good timber quality.

  • Johansson, ORCID ID:E-mail:
article id 7594, category Article
Yrjö Kangas. (1977). Die Messung der Bestandesbonität: 3. Teil. Acta Forestalia Fennica no. 160 article id 7594.
English title: Measurement of stand classification based on height over age: Part 3.

The data used to control the developed methods are presented in chapter two. The third chapter presents the statistical analysis conducted. The factor analysis shows that tree stand characteristics must be divided into three factors to able the information needed for site indexing to distinguish different site classes. The phases of model development are presented and the results of calculations with control data are shown.   

The results indicate that for calculations of nature-normal forests the suitable amount of tree stand characters for creating the site indexing function, is three.  These are: number of trees (N), basal area of the stand (G) and mean height (H).

The PDF contains a summary in Finnish. 

  • Kangas, ORCID ID:E-mail:
article id 7586, category Article
Yrjö Kangas. (1976). Die Messung der Bestandesbonität: 1-2 Teil: Theoretische Grundlagen. Acta Forestalia Fennica no. 152 article id 7586.
English title: Measurement of stand classification based on height over age: Part 1-2: Theoretical basis.

The article is the first part of a wider project aiming to study the measurement practices of stand’s height-over-age based classifications and to develop new methods for actually measuring the side index.  

The first part of the article presents the concepts of site indexing and discusses it with a mathematical model. The second part of the article examines the structure of site indexing system regarding the reliability of the method. Third part presents the factors affecting the method development and the fourth part discusses the possible site index classes and their characteristics.   

The PDF contains a summary in Finnish. 

  • Kangas, ORCID ID:E-mail:

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